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Smartphones are considered to be one of the 8 key technologies contributing to the digital revolution . The number of smartphone users has been increasing rapidly. In 2014, there were 1.57 billion smartphone users worldwide, and this is predicted to increase to 2.87 billion by 2020; the upshot is that in 2017, 96% of UK respondents aged between 16 and 34 years reported owning a smartphone .
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other
| 99.94 |
Mobile health (mHealth) is a critical part of the digital transformation of health care. The Global Observatory for eHealth defined mHealth as medical and public health practice supported by mobile devices such as mobile phones, patient monitoring devices, personal digital assistants, and other wireless devices . Technological advances, coupled with the unique ability of mobile apps to reach all smartphone owners at a relatively low cost, have accelerated the market growth for mHealth apps , such that in 2016, there were more than 259,000 mHealth apps available on the major app stores. It is predicted that by 2020, 2.6 billion people will have downloaded an mHealth app at least once—551 million of these will be active users .
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other
| 99.9 |
mHealth apps can offer a number of benefits for users, such as improved treatment accessibility, real-time symptom and activity monitoring, treatment progress tracking, personalized feedback, motivational support, portability, and flexibility . They seem to represent a feasible and acceptable means of administering health interventions and have the potential to be effective in eliciting health improvements in conditions ranging from diabetes to depressive symptoms . Conversely, there are also a number of notable drawbacks of mHealth apps that need to be considered. These include technical problems, data security, patient privacy, timely management of assistance from a medical professional , as well as psychological barriers to adoption and effective user engagement.
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review
| 98.8 |
The World Health Organization reported in 2017 that noncommunicable diseases (NCDs) are the cause of 70% of all global deaths. Cardiovascular disease, cancer, respiratory diseases, and diabetes are the biggest contributors to NCD deaths equating to 81% thereof. Risk factors such as frequent tobacco use, alcohol abuse, poor diet, and physical inactivity increase likelihood of NCDs . A number of smartphone apps address these issues using behavioral change mechanisms to modify behavior and promote a healthier lifestyle.
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review
| 99.7 |
The cognitive behavioral therapy (CBT) model is based on the idea that thoughts, emotions, and behavior interact with and influence each other. CBT is commonly used in the treatment of mental health disorders especially because of its ability to alleviate distress caused by unhelpful cognitions and reframe these cognitions to lead to more adaptive behaviors . This type of psychotherapy has been incorporated within clinical guidelines because of its strong evidence base , which supports the idea that it represents an effective method to elicit health behavior change . Importantly, with nearly three-fourths of current smokers reporting that they wanted to give up smoking , CBT has also shown to be effective in smoking cessation .
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review
| 99.9 |
The evidence base for the efficacy of computerized low-intensity psychological CBT interventions for anxiety and depression is particularly strong . Moreover, evidence has shown that, alongside CBT provided through a computer-based platform, CBT delivered via mobile apps could significantly improve outcomes for patients . However, limited research on its use in smoking cessation exists. This, combined with the cost-effectiveness of this intervention, advocates a need for research investigating its effectiveness in this context.
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review
| 99.9 |
The purpose of this study was, therefore, first, to explore users’ perceptions of two mHealth apps, one CBT-based app, Quit Genius (QG), and one non-CBT-based app, National Health Service (NHS) Smokefree (SF), over a variety of critical themes. Second, the study also sought to investigate the perceptions and health behavior with respect to smoking cessation for users of each app. To do so, a qualitative short-term longitudinal study was conducted based on semistructured interviews with users, followed by a thematic analysis, which resulted in several higher themes and subthemes. Descriptive statistics regarding participants’ willingness to continue using each of the apps, as well as perceptions and health behavior in relation to smoking cessation, were also calculated.
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study
| 100.0 |
A total of 45 participants were recruited for the study, to account for any dropouts. This sample size was chosen in accordance with the recommendations for qualitative studies present in the literature, which indicate a sample size of 5 to 50 to achieve saturation of results . The following inclusion criteria were used: (1) smoker who intends to quit, (2) Apple iPhone smartphone user, (3) access to English App Store, (4) English speaker, (5) age >18 years, (6) has mental capacity, (7) has some experience/knowledge regarding mobile apps. Application of the inclusion criteria led to an initial sample of 45 users. Users were randomly allocated to one of 2 apps, resulting in 18 users allocated to QG and 27 users allocated to SF.
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study
| 100.0 |
A qualitative short-term longitudinal study based on one-to-one semistructured interviews with users allocated to one of the 2 selected apps was conducted. The literature investigating the use of CBT in smoking cessation, specifically via a mobile digital platform, is limited. Due to this, an exploratory approach was used, setting out to gather data around the topic, the analysis of which would facilitate the emergence of research questions and theory. Thus, a qualitative, inductive approach was adopted. From the primary data collected, thematic analysis was carried out using a 6-phase framework . This was used to generate themes from ideas that emerged during the interviews. Descriptive statistics based on quantitative data gathered as part of the interviews are also provided.
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study
| 100.0 |
The rationale behind the choice of apps was to compare a smoking cessation app that uses CBT against one that does not. Therefore, QG (Figure 1) and NHS SF (Figure 2) were chosen. Figures 1 and 2 represent screenshots of the app interfaces at the time of the data collection. Both apps are gamified, smoking cessation, smartphone apps and offer a number of different features (see Table 2). Gamification refers to the introduction of game-like elements and principles to nongame contexts, with a view to encouraging participation and involvement .
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other
| 98.3 |
Each participant was interviewed twice, 1 week apart, before and after they had used their allocated app. Interviews included mostly qualitative, but also a small number of quantitative (ie, 1-10 rating scales) elements. The first interview provided a short, baseline assessment of the individual’s smoking habits and history, as well as of their perceptions of digital therapeutics and mobile apps in health care. Participants were also given standardized instructions regarding app use. Interviewers were instructed to neither encourage nor discourage the participants’ smoking behavior, to minimize bias.
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study
| 99.94 |
Interview questions were initially prepared, then piloted using 4 independent participants. Adjustments to the interview questions were made based on findings from these pilot interviews. The pilot study confirmed the suitability of the 2 chosen apps. The results of the pilot were not included in the final study.
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study
| 99.94 |
Braun and Clarke’s 6-phase framework was used for our thematic analysis. An inductive approach was adopted during the coding process; all concepts and ideas that arose were coded, regardless of relevance to the original research question. A manual coding process was undertaken. The transcripts were printed, and individual codes were highlighted and transferred onto post-it notes, in the process of identifying segments of the data. The post-it notes were color-coded to facilitate easy visualization of codes for the development of themes. Once coded, each transcript was then reread by a second researcher to check the rigor of coding and to increase the conformability of the codes created. The codes were analyzed to form overarching themes, and ambiguities were resolved via discussion among members of the research team.
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study
| 99.9 |
The thematic analysis resulted in five overarching (higher) themes that influenced the impact of the interventions on health behavior. Three of the higher themes were associated with several subthemes (Figure 3). The themes were explored with a view to determining the relationship and differences between the 2 apps. The five higher themes were not exclusively related to smoking cessation.
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study
| 100.0 |
Multiple users also mentioned that the SF “savings” feature was inaccurate, and this led to a lack of trust in the app, making users question the integrity of all aspects of its design. Conversely, other users appreciated the existence of the “savings” feature and used it as motivation to continue with the program.
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other
| 99.94 |
On the other hand, a significant number of SF users commented that the SF tips functions and notifications were generic and not useful, some even choosing to ignore them all together. Some, however, found the tips function useful, helping them commit to their goals.
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other
| 99.94 |
Users also mentioned that they enjoyed the multimedia functionality of QG. They commented particularly on the audio feature being soothing and engaging. Multiple QG users also commented on the quizzes, suggesting that they helped reinforce the knowledge that the app provided. One of the users said:
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other
| 99.94 |
Multiple participants appreciated how QG could be listened to, with audio being considered more insightful than just reading text on a screen. Some even associated the benefits of audio with convenience, as it can be carried out while performing other activities. However, some users preferred using the transcript alone as it allowed them to set their own pace. This is evident from the following statements:
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other
| 99.94 |
Overall, the majority of QG participants were impressed by the quality of information. The QG content went beyond what the users expected, helping them understand the consequences of smoking. It was also well received when the content was found to be relatable, as users felt a more personal connection:
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other
| 99.94 |
Several SF participants stated displeasure in the quality of information provided in the app. SF users lost interest in the app when provided with information they already knew. Poor information quality seemed to leave a lasting impression on the participants:
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other
| 99.94 |
Multiple users spoke favorably of the potential of mobile apps in providing therapy, commenting that apps are easy to access and use without the need for previous training or advice. The time commitment required is generally less than in the case of other treatment forms. It was further reported that mobile apps have the advantage of being low cost with a wide reach. Users also identified benefits because of the fact that one can receive treatment on one’s own terms, independently, and with an element of privacy. This is echoed by the following statements:
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other
| 99.9 |
QG users noted a significant number of changes in their perceptions. Most participants reported that they had changed the way they thought about smoking to some degree. Many users appreciated the purpose of CBT and valued the way that CBT provided information and tools to make their own decisions and trained the brain to think in new ways. Participants reported that the app helped them explore their own smoking journeys and was valuable in understanding psychological triggers and cues of why they smoked and reevaluate their smoking behavior:
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other
| 99.9 |
QG increased confidence in users who had previously perceived quitting as an impossible task such that they reported that quitting now seemed more feasible. Many QG users identified how the app had improved their willpower to quit smoking. In contrast, relatively few users reported decreased motivation to quit after the week, with one user reporting they felt a lot of effort needed to be inputted to feel engaged by the app:
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other
| 99.9 |
A small number of participants also displayed successful internalization as they reported that they applied a visualization exercise provided by the app in their day-to-day life. These participants emphasized that doing the exercise did not require direct access to the app. Referring to this exercise, one of the participants said:
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other
| 99.9 |
One user quit smoking on the first day of the study, reporting that they felt highly motivated to stop so that they could log being “smoke free” on the app. A few participants reported that the SF app itself increased the urge to smoke, resulting in an increase in smoking:
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other
| 99.7 |
The SF users specified several individual improvements. Visualization, such as a graphical representations monitoring health, was deemed to be a key feature of an ideal app with a number of SF users. Some users also suggested regular health news updates such as smoking taxes and bans.
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other
| 99.94 |
In addition, participants having used QG for 1 week reported, on average, several positive behavior changes, such as increased motivation to quit smoking and reduction in the number of cigarettes smoked per day (Table 4). QG participants were similarly more likely to recommend the app, compared with SF participants.
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study
| 99.94 |
Five higher themes and several subthemes resulted from the thematic analysis. QG users were generally more positive and receptive with regard to the app’s features, design, as well as information engagement and quality, compared with SF users. QG users also reported changing their perceptions and way of thinking with respect to smoking. It is possible that the root of this effect may lie in CBT, which gives users the opportunity to explore and change their thoughts and perceptions related to smoking.
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other
| 99.75 |
On average, QG users also noted an increased willingness to use a smoking cessation app in general to manage health. They also showed increased motivation to quit smoking, as well as more willingness to continue using their allocated app after 1 week. These participants also showed changes in their smoking behavior although this was in the context of our limited sample, not allowing for the finding to be generalizable as of yet.
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study
| 99.7 |
A change in the manner of thinking about smoking was deemed important by participants with regard to a possible change in behavior. This was prominent in QG users, and it is possible that this is because of the app’s use of CBT. Users reported that the app allowed them to question why they smoke, what smoking means to them, as well as their thoughts about quitting and why this is something they want to achieve. QG also allowed users to reframe the way they thought about themselves and their behavior in relation to smoking. For example, several QG users reported that perception-altering exercises such as labeling themselves as “nonsmokers” as opposed to “ex-smokers” helped them dissociate themselves from the behavior and contributed to a reduction in smoking in these users. No such effects were reported by the SF users.
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other
| 99.9 |
QG users also reported that the CBT method contributed to their intrinsic motivation to quit, making them perceive themselves at the source of their decisions and therefore feel empowered to take control of their own actions in relation to their journey to smoking cessation. This coincided not only with an increase in self-efficacy, that is, one's belief in one's ability to succeed in specific situations or accomplish a task but also with an increase in behavioral control, that is, the level of difficulty an individual associates with a behavior . Specifically, QG users reported that they believed the app had equipped them with increased confidence in their ability to quit, making the concept of quitting seems easier, more realistic, and thus more achievable. SF users did not report such a change in their belief related to their ability to quit smoking; many noted that the advice and tips provided by the app were already known and too generic. However, some SF users noted that just by downloading the app, they felt more equipped to quit than previously.
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other
| 99.75 |
Although users of both apps understood and reported some of the benefits of smoking cessation, such as better health and saving money, SF users mostly felt that their knowledge was left unchanged, as the information provided, for example, regarding the harms of smoking, was generic and well known. Therefore, this had no impact on their understanding of the consequences of smoking. Conversely, QG users were positive about the effect on their knowledge, mentioning that reinforcement of the consequences at multiple points during the progress gave them greater motivation to quit smoking. This fits well with the health belief model , in which the perceived threat (in this case, the health hazards associated with smoking) plays a vital part in the individual’s likelihood to engage in health-promoting behavior. Generally, users reported feeling bored using SF, which provided information already known to the users, whereas QG was seen as novel and informative. This is not surprising, as implementing CBT in such a gamified app is a new concept.
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study
| 71.06 |
Users also highly commended QG for not using scare tactics to drive change in behavior but instead supporting and guiding users gently through the process. This goes against common literature that suggested fear-appeal and antismoking tactics are effective in promoting smoking cessation . A possible explanation in this study may be related to the fact that a large proportion of our participants were relatively young and, therefore, identified scare tactics as an out-of-date strategy, preferring to be given the information and opportunities to make their own decisions. Another reason may be that scare tactics make reference to information that is already vastly known to people about the dangers of smoking, but these tactics do not acknowledge the great difficulties associated with nicotine addiction and fail to provide practical support.
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other
| 98.1 |
The findings of this study suggest that a mobile app based on CBT was favorably perceived by users in terms of features, design, as well as information engagement and quality, in the context of smoking cessation. This was associated with changes in users’ perception and thinking manner with regard to smoking. On average, users of the gamified CBT-based app also showed increased willingness to use a smoking cessation app, in general, to manage health, as well as increased motivation to quit smoking and positive changes in smoking behavior. A non-CBT-based mobile app was less favorably perceived, yet some users viewed some features and the app’s interface as useful. Other apps based on therapeutic principles such as acceptance and commitment therapy (ACT), which has common elements with CBT, have also been developed and shown to be effective in smoking cessation .
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study
| 99.9 |
Given the significant estimated smoking-related cost to the NHS (£2.6bn in 2015; ), the possibility of using mobile apps to influence health behavior may have implications in the current economic climate of health care, contributing to the growing use of mobile apps in this domain. Specifically, exploiting such advances in technology could contribute to the needed efficiency savings of 2% to 3%, compared with the current 0.8%, noted in the NHS England Five Year Forward Review, in the context of the £30 billion funding gap predicted to occur by 2020/2021 .
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review
| 98.4 |
Further advantages of apps include opportunities for scalability across the NHS and eliminating postcode lottery issues, as well the possibility of increased adherence to interventions because of the convenience of use. Indeed, the review suggested expanding the set of NHS-accredited health apps available to patients , whereby apps may even be prescribed as treatment or part thereof in the future.
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review
| 99.9 |
However, reengineering processes to implement mHealth apps into daily medical practice, such as first-line treatment recommendations, will involve a rigorous change management process. A crucial aspect of this is ensuring that apps are compliant with privacy standards, as illustrated by the release and subsequent withdrawal of the NHS mHealth Applications Library pilot in 2013 because of noncompliance. mHealth apps have the capability to collect a vast amount of data, which can then be used to improve medical care in the future via predictive analytics and artificial intelligence. However, extensive security and privacy systems need to be put in place before apps can be confidently recommended.
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other
| 99.9 |
Another possible barrier to wider use of mHealth apps is that of digital exclusion. A significant proportion of the population lacks Internet access or has low digital literacy. These tend to be the elderly, disabled, and ethnic minorities . These populations require health care the most, hence exemplifying the inverse care law . This barrier is continuously being tackled through the work of the Tinder Foundation, providing online resource training to 220,000 people .
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other
| 99.94 |
Furthermore, even with Internet access and a sufficient level of digital literacy so as to be open to using a healthy living app, as is the case of 37% of UK individuals, only 3% use them . This highlights that more research needs to be undertaken in exploring the factors that influence individuals’ attitudes and behavioral intentions to use such apps. For example, previous research has shown that gamification, “the use of game design elements in nongame contexts” , can represent a highly effective way to engage users with mHealth apps . Another important consideration is that, in the present study, users of not only SF but also QG stated that the lack of human contact from a trained health care worker made mobile apps less attractive as a single therapy form for them. This raises important questions in terms of the overall capabilities of CBT delivered via mobile apps. Such findings suggest the need for a study investigating both objective and subjective measures, as well as their interaction.
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study
| 99.94 |
There are a number of limitations to this study. First, because of time constraints, participants were only able to use and evaluate the apps for the duration of 1 week. Although it allowed for participants to form opinions on the themes explored, this short period prevented users from completing the programs offered by each of the 2 apps (8 weeks for QG and 4 weeks for SF), which would possibly have provided them with a more comprehensive impression of the apps and their effects. This period may also have been insufficient to determine the sustained effects of the apps. Therefore, the descriptive statistics we report are not necessarily an appropriate representation of the expected behavioral and perceptual effects which would be anticipated with the completion of the programs. Second, convenience sampling was used, where recruitment took place on a university campus, resulting in a sample of mostly university students with a mean age of 24.66 years. This may have led to a misrepresentation of the overall population, thereby bringing into question the transferability and generalizability of the conclusions. Third, the study lacked a control condition, against which the effects of each app on users’ positive behavior change could be compared, so as to evaluate these effects more accurately.
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study
| 100.0 |
Therefore, future studies should consider using a randomized controlled trial design in a larger, more representative sample with more varied demographic characteristics, running over a longer period of time, allowing for the completion of the programs offered by each of the apps. This would produce more generalizable, conclusive, and reliable results. After this, more in-depth research could address any differences in behavioral changes elicited by the use of the app(s), as well as the effect of increased options for tailoring and personalization on measures of behavioral change and adherence. Numerous health care offerings are being digitally transformed. Yet, important questions remain about effective user engagement across different digital platforms , and the potential of digital health solutions for improving people’s lives and enhancing their willingness to recommend new digital solutions to family, friends, and colleagues . Additional research into the understanding of psychological barriers to adoption of new mHealth solutions and technologies that can inform the design and communication of new mobile health care solutions to facilitate behavior change is richly deserving.
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review
| 99.4 |
In conclusion, investigating the results of the thematic analysis carried out in this study revealed a generally more positive attitude of QG users with regard to the app’s features, design, as well as information engagement and quality, compared with SF users. QG users also reported changing their perceptions and way of thinking with respect to smoking, and noted, on average, increased willingness to use a smoking cessation app in general to manage health, as well as increased willingness to continue using their allocated app, and increased motivation to quit smoking after 1 week of app use. On average, these participants also showed changes in their smoking behavior although, of note, this was in the context of our limited sample, not allowing for the finding to be generalizable as of yet. It is possible that the root of these effects may lie in CBT, which gives users the opportunity to explore and change their thoughts and perceptions related to smoking.
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study
| 100.0 |
This suggests that CBT has the potential to work effectively in the context of a gamified mobile app for smoking cessation; however, future research involving wider distributed samples and longer periods is required to draw more generalizable conclusions. The findings also suggest that a mobile app must be well developed, preferably with an underlying behavioral change mechanism, to promote positive perceptual and health behavior change in the context of smoking cessation. The potential of digital CBT delivered through a gamified mobile platform should be seen as a powerful tool to overcome current health care challenges.
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other
| 96.56 |
Get ready, set, go! The start of the 100 m final is one of the most anticipated moments of any major athletics championship. The importance of an athlete’s start performance (SP) is inversely related to the length of the track event. It is therefore very important in the 100 m, less so in the 200 m and potentially most significant in 60 m indoor events. Despite the fact that, for a typical 100-m race, the start (including reaction time) only takes up about 5% of the total duration , around one third of the athlete’s maximal velocity is generated during push-off from the blocks . As a result, average centre-of-mass (CoM) acceleration is highest during this phase of the race.
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other
| 99.9 |
Following Newton’s second law of motion, horizontal CoM acceleration requires net propulsive forces to be applied to the body of the athlete in the running direction. If force application is accompanied by motion of the sprinter, mechanical work is performed. Completing a given quantity of work in less time corresponds to an increase in average power generation over that period, so this parameter is considered an excellent descriptor of SP in sprinters . Muscle tissue is capable of converting metabolic energy into mechanical work at high rates during contraction , which makes muscle–fascicle contraction crucial for developing high CoM acceleration from a resting position. Elastic components of the muscle tendon units, but also elastic materials utilized in the dedicated running-specific prostheses (RSPs) of amputee sprinters (ASs) can store and return energy. However, they cannot increase the potential or kinetic energy of the sprinter from rest unless they have been pre-loaded by means of co-contraction prior to the initiation of the acceleration task. Given the relatively small forces applied to the blocks in the set position, pre-loading amplitudes are relatively low when compared to the forces exerted during the push-off phase . Therefore, while the efficient energy storage and return provided by RSPs is beneficial in longer events like the 400 m where a high level of running economy is required , it seems theoretically improbable that they would allow ASs to achieve the levels of performance seen in top NASs during the sprint start. In line with this hypothesis, Taboga, Grabowski, di Prampero, & Kram found that, during the block phase, unilateral below-knee, mostly sub-elite amputees performed worse than performance-matched NASs. Nevertheless, the current literature lacks empirical evidence for reduced SP in ASs at the elite level, as well as for athletes with bilateral or transfemoral amputations. Furthermore, detailed descriptions of the mechanisms underlying impaired SP in ASs are also lacking.
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study
| 99.9 |
It is generally accepted that good acceleration performance in sprinting tasks requires highly efficient application of horizontal force [8, 9] in order to increase horizontal impulses generated during ground-contact phases. In addition, good acceleration performance requires high extension moments and positive power output by lower extremity joints in the start and early acceleration phase, particularly at the hip, knee and ankle joint [5, 10–12].
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other
| 99.7 |
The aforementioned references indicate that acceleration performance can be improved by increasing the capacity of the musculoskeletal system to create power from a resting position. Furthermore, they show that the efficiency of horizontal force application might play an important role in improving acceleration during the start phase . The ability to direct a great amount of the total force in the running direction can be considered a key technical skill that determines the quality of a sprinter’s starting technique. Currently, it is not clear whether the capacity for high leg power output and that for efficient direction of forces in the running direction are independent abilities that could be worked on separately, or whether both are simultaneously influenced by an underlying “acceleration ability” factor.
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study
| 99.4 |
Therefore, in the present study we first explored potential latent factors (determined by exploratory factor analysis [EPA]; see methods section for details) influencing ground-force application during the sprint start, and how such factors might relate to start performance in NASs. Based on the literature it was hypothesized that at least two latent factors affect force application to the blocks: One was the overall resultant force the athlete applies to them and the other was the direction of that force. Based on the enhanced understanding provided by this initial part of our study, we then compared the start performance and ground-force application characteristics of ASs and NASs.
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study
| 100.0 |
Our study sample included 154 NASs at a wide range of 100-m sprint performance levels (100 m PRs, 9.58 s– 14.00 s). This NAS group comprised 103 males (mean age, 20.8 ± 3.7 years; mean body mass, 74.8 ± 7.5 kg; mean standing height, 1.81 ± 0.06 m) and 51 females (mean age: 20.0 ± 3.6 years; mean body mass, 60.8 ± 5.6 kg; mean standing height, 1.71 ± 0.06 m). The remainder of the study sample consisted of seven male ASs (see Table 1 for physical characteristics and PRs). All 100 m PR times were achieved prior to data collection, but not necessarily within the same competitive season. In unilateral amputee athletes (n = 6), body height was determined while standing on the unaffected leg. For the bilateral amputee (n = 1), standing height was measured while wearing his sprinting prostheses and leaning against a wall in order to maintain a stable standing position.
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study
| 100.0 |
Written informed consent was obtained from all participants and the experimental procedures were in line with the guidelines stated in the Declaration of Helsinki. Approval was obtained from the ethical committee of the German Sport University, Cologne, Germany.
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other
| 99.94 |
To obtain the force data, we used a custom-made instrumented starting block consisting of a very stiff steel centre rail and separate block bases and force sensing units for each foot. Base units were available for different inclination angles and were screwed to the centre rail in order to provide a sufficiently stiff system for the force measurements, while enabling adjustment of start-block settings to those used for training and competition. Small custom-made force platforms, each including four piezo-type 3D force transducers (Kistler AG, Winterthur, Switzerland), were screwed onto the tops of the block bases for force measurements (Fig 1). Analog force signals were converted to digital at a sampling rate of 10,000 Hz. Further details of the instrumented starting blocks are provided in reference . Force signals were filtered using a recursive 4th order digital Butterworth filter (120 Hz cut-off frequency). Force signals were transformed from the local (tilted) starting-block reference system to a global coordinate system before further analysis was performed. The orientation of the global coordinate system was as follows: The x-axis pointed forward along the running surface (horizontal plane), the y-axis pointed to the left along the same surface plane and the z-axis pointed vertically upwards. Mediolateral forces were described as follows: Positive values were used if the block reaction forces were in the direction of the contralateral leg, and negative values corresponded to the opposite situation. Because the dominant component of force was positive in the front leg and negative in the rear leg, maximal positive values in the front leg and minimal values in the rear leg were considered the maximum mediolateral forces applied to the blocks.
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study
| 100.0 |
The following parameters were extracted for analysis: Overall start performance was described using normalized average horizontal (in the running direction) block power (NAHBP) . Average horizontal block power was defined as the change in horizontal kinetic energy during push-off from the blocks (TBlock): P¯=m(Vf2−Vi2)2TBlock(1)
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study
| 98.06 |
We measured block time (TBlock, time from first reaction to block clearance) and CoM velocity at block clearance (Vf, determined by integration of mass-normalized horizontal force curves with initial velocity equalling zero). Body mass (m) included the mass of the prosthetic parts in ASs. As the initial velocity (Vi) is zero in the set position of the sprint start, the formula for the calculation of average horizontal block power (P¯) can be simplified by omitting the Vi2 term: P¯=mVf22TBlock(2)
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study
| 99.94 |
Because athletes with different body masses and dimensions require different average powers to translate their CoM to the same extent, average horizontal block power was further normalized to body mass (m) and body height (h) in order to achieve a dimensionless normalized average horizontal block power (NAHBP; , corrected in ): NAHBP=P¯mg32h12(3)
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other
| 99.8 |
In contrast to the approach taken by Bezodis et al. , body height was used for normalisation instead of leg length, since leg length could not be obtained from all participants. To describe the force application on the starting blocks we determined average forces and impulses of the front and rear leg in antero–posterior, mediolateral, vertical and resultant directions. First reaction (i.e. the start of the push-off phase) was determined as the first instant when the resultant force curves rose from the baseline force in the set position. Block clearance was defined as the first instant when the resultant force of the front block dropped below a threshold of 50 N. To specify the efficiency of force application to the blocks, the ratio of horizontal (in the running direction) to resultant block reaction force impulse of both legs (RHRI, ) and the ratio of mediolateral to resultant block reaction force impulses (RMLRI) were calculated.
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study
| 100.0 |
Each athlete performed at least three full-effort sprint starts over a distance of 20 m. The best start (based on NAHBP) was selected for further analysis. To identify potential latent factors affecting SP, we performed an exploratory factor analysis (EFA) using selected force parameters. EFA is a statistical procedure used to analyze variability among measured correlated variables with respect to a potentially lower number of unobserved (unmeasured) or latent variables, which are termed factors. For example, it could be the case that variations in a great number of observed sprint-start kinetic parameters are actually just the result of variability in a much smaller group of underlying parameters (factors) that represent more fundamental sprint-start abilities. EFA is aimed at finding measured parameters that vary as a group in response to latent variables. In our case, the dataset representing the observed variables included average and peak forces in all directions and parameters describing the push-off direction (RHRI, RMLRI). Using Matlab’s (R2015b; Mathworks, Natick, MA, USA) built-in “factoran” function, we calculated the maximum likelihood estimate (MLE) of the factor loadings matrix Λ in the factor-analysis model, x=μ+Λf+e ; where x is a vector of observed force parameters, μ is a constant vector of means, Λ is a matrix of factor loadings, f is a vector of independent, standardized common factors, and e is a vector of independent specific factors. To identify the number of factors to extract for further analysis, the Kaiser criterion and the scree test were applied. In a subsequent step, factor loadings and scores were rotated using the “varimax” method in order to improve interpretability. To identify the relationship between these latent factors and SP (NAHBP), multiple linear regression was performed with latent factor scores as the predictors and the NAHBP as dependent variable in an approach similar to Basilevsky . Using forward selection, models including intercept and quadratic terms were fitted using Matlab’s “fitlm” function. The best model was determined by the Akaike information criterion . Further regression analyses were performed to identify the relationships between force-application parameters, SP and 100 m PRs. For the identification of differences between ASs and NASs, two different approaches were taken. In the first, ASs were matched to NASs with similar absolute PRs, and in the second, athletes were matched with respect to their relative PRs (relative to the current world record in their particular starting class, based on International Paralympic Committee classification rules). The matching procedure was aimed at finding the three closest absolute or relative 100 m PRs for each athlete. If a NAS matched with more than one amputee athlete, s/he was only included once. Comparison between ASs and matching NASs were performed using independent-samples t tests. To address potential problems due to unequal variances, Satterthwaite's approximation for the effective degrees of freedom was used [20, 21]. The significance level, α, was set at 0.05. Due to the low size in the AS sample and related statistical power, we also calculated effect sizes (Cohens d) in order to allow for an estimation of the strength of an observed difference . Effect sizes greater than 0.2 were considered small, greater 0.5 medium and greater than 0.8 large .
|
study
| 100.0 |
SP shared 42% of its variance with 100 m PR in the NAS group (Table 2, Fig 2). Combined, block time and horizontal CoM velocity at block clearance predicted 98% of the variance of the start performance (NAHBP) in a multiple linear regression model, while horizontal CoM velocity and block time respectively shared 82% and 27% of their variance with NAHBP in separately performed, simple linear regression analyses (Table 2, Fig 2).
|
study
| 100.0 |
The factor analysis model revealed that, based on both the Kaiser criterion (eigenvalue > 1) and by visual inspection of the scree plot (Fig 3), the first seven factors provide a sufficient representation of the force-application characteristics of NASs, across a wide range of overall sprint performance levels. After varimax rotation, the following interpretation was made based on analysis of the factor-loading structure (Fig 3): Variables associated with force application to the rear block and front block in the sagittal plane of motion were highly loaded on factors 1, 4 and 6 (eigenvalues after rotation, 5.4, 3.0 and 1.8), respectively (Fig 3), which were thus considered to represent underlying factors affecting the forces applied to propel the athlete forward out of the blocks. Parameters related to force application to the front block were highly loaded on factors 4 and 6, but in a different manner for each factor. High factor-4 scores were correlated with high peak force application that was concentrated at the end of the push-off phase after a moderate initial rise in force (Fig 4A). Parameters associated with high average force application, not necessarily with a high peak force but with a pronounced rise in force at the beginning of the push-off phase were more strongly loaded on factor 6 (Fig 4B). Fig 4 visualizes the differences between the two factors by showing the resultant front-block force-application waveforms of athletes with the ten highest and lowest scores for factors 4 and 6, respectively.
|
study
| 100.0 |
In A and B, the resultant force curves of the front block of athletes with the highest and lowest scores for factors 4 (A) and 6 (B) are visualized. Note the pronounced force peak at the end of the push-off phase for athletes scoring high on factor 4 (A), and the high force application in the early push-off phase for athletes scoring high on factor 6 (B).
|
study
| 100.0 |
Mediolateral force application in the front and rear blocks and the corresponding mediolateral push-off directions loaded high on factors 2 and 5 (eigenvalues after rotation, 3.7 and 2.8), respectively (Fig 3). Parameters describing the direction of forces applied in the sagittal plane (RHRI) of the front and rear blocks loaded high on factors 3 and 7 (eigenvalues after rotation, 3.1 and 1.3), respectively (Fig 3). Therefore, we interpreted this factor as the ability to apply forces in the desired horizontal (running) direction in the sagittal plane.
|
study
| 100.0 |
When fitting linear regression models using the scores of the first seven varimax-rotated factors, an adjusted R² value of 0.86 was obtained (Table 2, middle). This model did not include interaction terms, but it explained only 1% less of the variance when compared to a model that included interaction terms. Furthermore, we found that a reduced model including only five factors as predictors achieved the same adjusted R2 values as the complete model including all seven factors (Table 2, bottom and middle). The highest coefficient was estimated for factor 1, which represents the amplitude of the forces applied to the rear block. Coefficients of factors 3, 4 and 6, which describe the force amplitude and direction were all similar (0.026–0.032), highlighting the similarity of their influence on overall SP. Interestingly, in the rear blocks, the coefficient for force amplitude (Factor 1) had a substantially higher coefficient estimate versus factor 7 (0.040 vs. 0.010), which describes push-off direction from the rear block. Therefore, it can be concluded that in the rear block, the strength of the push-off is more important than its direction.
|
study
| 100.0 |
Start performance was 33.8% lower (p<0.001) in ASs versus NASs matched with respect to relative 100 m PR (Table 3). When matched based on absolute 100 m PRs, a smaller and almost significant (p = 0.08) reduction of 17.7% was observed (Table 4). Force application to the rear block differed significantly between ASs and NASs in the sagittal plane (Tables 3 and 4), while effects were greater when subjects were matched with respect to their relative PRs. The direction of force application was more vertical for amputee athletes, particularly in the front block. Block times were significantly increased by 23.9% and 9.6% for ASs when compared to relative and absolute PR matched NASs, respectively (Tables 3 and 4).
|
study
| 100.0 |
In all unilateral amputees, the rear leg was the affected side. Values are presented in terms of the mean ± SD, 95% confidence interval of the difference between means, p values and effect sizes (Cohen’s d). Bold rows indicate a significant difference for this parameter (p < 0.05).
|
study
| 100.0 |
In all unilateral amputees, the rear leg was the affected side. Values are presented in terms of the mean ± SD, 95% confidence interval of the difference between means, p values and effect sizes (Cohen’s d). Bold printed rows indicate a significant difference for this parameter (p < 0.05).
|
study
| 100.0 |
When comparing athletes with different amputation levels, it was seen that athletes with more proximally (higher) located amputations exerted less force with their affected limb than athletes with a more distal (lower) amputation or a bilateral amputation (Fig 7). Nonetheless, the unilateral transfemoral (proximal) amputees analyzed in the present study compensated for this deficiency by applying a proportionally greater force with the (non-affected) front leg, thereby achieving a better overall SP than transtibial (distal) amputees.
|
study
| 100.0 |
Here, controls were matched with respect to the individual’s amputation level. For each amputee athlete, three non-amputee athletes were matched with respect to (A) their absolute 100 m personal record (PR) or (B) their 100 m PR relative to the respective 100 m world record (for the corresponding amputation level). The results are displayed as relative differences (%) with respect to the matching controls. Positive axis directions were defined such that better performances in a certain parameter are outside of the zero difference (non-amputee) line and worse performances are inside that line.
|
study
| 100.0 |
The first task of the present study was to investigate the presence of a potentially underlying factor structure for ground-force application during the sprint start. The present NAS dataset was very well suited for such an analysis as it was sufficiently large and represented 100 m sprinters from all relevant performance categories, including even the highest level of performance. Although seven factors seem to be a good choice for proper representation of the variability contained in the ground-force application data set based on the Kaiser and elbow criteria, the results of the present study indicate that only five factors are needed to explain 86% of the variance observed in SP. The remaining two factors, which are related to force application in the mediolateral direction, did not significantly improve the predictive power of any of our multiple linear regression models. This suggests that no performance benefit would accrue from modifying a non-amputee’s starting-technique to minimize mediolateral-force application and achieve a straighter push-off in the forward direction.
|
study
| 100.0 |
Using the scores from the above explorative factor analysis as predictors in a multiple regression analysis offers two main advantages over the more common practice of implementing all directly measured parameters in the multiple regression analysis: On the one hand, when estimating the coefficients of the regression model, it avoids potential problems that can result from multicollinearity among the predictor variables . In the present study, multicollinearity was clearly evident among the force-application parameters. This outcome is understandable since many of these parameters (e.g. for different force components) cannot be considered independent of each other, as they are the product of the same biomechanical action. On the other hand, absolute values of the estimated coefficients in the regression model can be directly compared to evaluate their importance. This is because the original parameters were standardized to have a mean of 0 and a standard deviation of 1 before being used in the factor-analysis calculations. As a result, the importance of each latent factor for the prediction of start performance can be directly derived from the coefficients of the regression model.
|
study
| 100.0 |
In the present study, the factor representing force application to the rear block showed the highest estimated coefficient (0.040; factor 1), followed by those representing push-off direction in the sagittal plane (0.032; factor 3) and force application to the front block (0.030 and 0.026; factors 4 and 6). The 95% confidence intervals of factor 1 overlap minimally with those of the other factors, indicating that it is potentially more important for SP than the other factors. This highlights the importance of high force application to the blocks in the sprint start. High coefficient estimates were also found for factors representing the amplitude and direction of force application to the front block. With respect to starting technique, this indicates that a high average force needs to be applied to both blocks in the horizontal direction. It is interesting to note that factors relating to force-application amplitude and direction were of similar magnitude in the front block, whereas in the rear block, the coefficient estimate for the direction factor (0.010; factor 7) was 4-fold lower than the corresponding amplitude coefficient (0.040; factor 1). This result indicates that forces at the rear block need to be maximised, but ensuring that they are well aligned to the running direction is less important. In contrast, at the front block, both force amplitude and direction were of similar importance.
|
study
| 100.0 |
Another interesting result of the present study is the fact that two factors (4 and 6) were related to the force amplitude at the front block. As these factors are independent of each other, they may represent two different targets for improving SP. Looking at Fig 4, we can see that athletes scoring differently on factors 4 and 6 used different strategies for resultant-force application. Those with high factor-4 scores exerted substantially more force (about double) towards the end of the push-off versus the onset. In contrast, although athletes with high factor-6 scores also peaked towards the end, relative to high factor-4 athletes they pushed harder early on and less at the end, thereby producing a more even distribution of force over the duration of the push-off. The latter strategy for maximising the resultant impulse appears to focus less on achieving a high peak force and more on attaining high amplitudes in the first half of the push-off. Future studies should investigate these strategies in greater depth, in order to establish whether they are the result of different technical models of athletes and how they are related to the block distance, distance to the starting line and other parameters related to starting technique.
|
study
| 100.0 |
If instrumented starting blocks are available for performance diagnostics or for biofeedback training, we recommend use of at least the average resultant forces in the front and the rear blocks, as well as the ratio of the anterior and resultant impulses as criterion parameters, since they were highly loaded on most of the factors important for prediction of SP. As mediolateral-force application parameters did not improve the prediction of starting performance, they appear to be of less importance for these tasks. The design of instrumented starting blocks for performance diagnostics or biofeedback might therefore be simplified by using only 2D force sensors to measure forces in the running and vertical directions.
|
other
| 99.7 |
Once our exploratory analysis of the NAS data was complete, we compared the start performance of ASs and NASs. All unilateral ASs preferred to place their affected leg on the rear block, which is consistent with observations from video recordings summarized in Taboga et al. ; 86% of unilateral ASs utilized this pattern of leg placement in the 2012 Paralympic Games. The results of the present study show that force application to the blocks is clearly impaired in ASs using sprint-specific prostheses, which is in line with the data of Taboga et al. . This impairment was higher for athletes with above-knee amputations (versus below-knee amputees), but the difference was not statistically assessed owing to the low sample sizes. When considering the fact that force application to rear block (factor 1) is more important than for the front block, it is interesting to note that most ASs prefer putting their affected legs in the rear block. Still, the factor analysis revealing the importance of rear block force application was performed within the NAS dataset only. Therefore, any inference from these results to a NAS population might be invalid. Other factors, like dynamic stability or the performance in subsequent steps might be more important in ASs and might therefore have a stronger influence on their foot placement strategy. Future research on a bigger ASs sample needs to identify the underlying mechanisms responsible for start performance in a similar way as it has been achieved for NASs in the present study.
|
study
| 100.0 |
Comparing ASs and NASs that were matched with respect to their relative (to corresponding world record) 100 m PRs, SP was reduced by 33.8% for the amputee athletes, and this was associated with an average increase in block time of 0.08 s. Interestingly, average resultant forces applied to the front blocks were not lower in ASs, but they were applied in a more vertical direction, which has been shown to be detrimental for acceleration performance [8, 9]. Furthermore, forces in the front block were applied in a more laterally oriented fashion by the ASs, which might be a consequence of the specific requirements put upon transfemoral amputees when swinging the rear leg forwards after leaving the blocks. Because they are not capable of actively achieving and maintaining a flexed knee angle by means of hamstring and/or gastrocnemius force generation, they are required to rotate their affected leg laterally in order to avoid contacting the ground with the prosthesis.
|
study
| 100.0 |
When the two groups were matched with respect to their absolute 100 m PRs, start performance was again reduced, this time by 17.7%—however, with a p value of 0.08, this reduction was not sufficient to be considered statistically significant. Both groups of athletes were similar with respect to their overall 100 m race performance (100 m PR). From these results, it can be concluded that during the race phases where speed was constant, ASs must have performed better compared to their non-amputee counterparts. We suggest two possible explanations for this. Firstly, the level of professionalism may be significantly higher for the particular ASs in this study. Some of these athletes compete at the very highest level of their sport, in the 100 m, 200 m and long jump, and this is reflected in the significant difference for relative 100 m PRs (109% vs. 119%, respectively). These amputee athletes may simply spend, on average, more time and effort on training and active recovery than the matching NASs. The second possible explanation is that sprint-specific prostheses, though inferior during the start phase, performed better in replacing the functionality of biological limbs during the maximum-constant-speed phase of the race by enabling the spring-like energy exchange in the lower limbs during ground contact . Additionally, they might be allowing for a more rapid limb-swing motion owing to their low mass and moment of inertia . During the start and early acceleration phases of a 100 m race, the majority of the mechanical work is performed by the contractile components of the muscle–tendon-units, but as the race goes on, the contribution of passive elastic structures, like tendons and ligaments, becomes dominant . In amputee athletes, the ratio of passive elastic structures to active contractile muscle mass is higher than in non-amputee athletes, which makes their legs better suited to constant speed running than to accelerating.
|
study
| 100.0 |
Nevertheless, the interaction between passive prosthetics and the remaining limb anatomy is challenging from a coordinative perspective, not least on account of the missing sensory input from muscle spindles, Golgi tendon organs and other biological sensors at distal locations on the leg. Furthermore, it has been argued that maximum sprint velocity can be impaired by limitations that RSPs impose on ground-force application and leg stiffness [26, 27].
|
study
| 80.3 |
In summary, the results of the present study emphasize the importance of high average force application to both rear and front blocks. In addition, the forces should be applied as horizontally as possible, in the direction of forward motion. The avoidance of high mediolateral forces had no significant effect on start performance in non-amputee sprinters. These features of successful push-off from the starting blocks are consistent with recently published studies of world-class athletes . Force application to the starting blocks was clearly impaired in amputees using RSPs (versus non-amputees), with greater impairment occurring in athletes with more proximal amputations (higher up leg). This impairment led to significantly reduced start performance in the amputee sprinters. On the other hand, their RSPs appear to better replicate the functionality of biological limbs during the constant-speed phases of the 100-m race.
|
study
| 100.0 |
Henoch-Schonlein purpura (HSP) is the most common form of systemic vasculitis in children and involves inflammation of the small vessels of the skin, joints, gut, and kidney . Although the precise etiology remains unclear, it has been reported that vascular endothelial function plays a major role in the pathogenesis of HSP.
|
review
| 99.6 |
The earliest stage of atherosclerosis is based on endothelial dysfunction (ED) [5, 6], since a well functioning endothelium protects the blood vessels from damage by oxidative stress, by release of anti-coagulant, anti-inflammatory, fibrinolytic and vasodilating agents . ED can be basically defined as an impairment of vasodilatation in response to acetylcholine or hyperemia, both of which induce nitric oxide-dependent vasodilatation.
|
review
| 99.44 |
There are several methods to measure endothelial function. In the present study we used Peripheral Arterial Tonometry (PAT), a noninvasive technique that analyzes endothelial function by the measurement of vasodilatation in response to reactive hyperemia .
|
study
| 99.94 |
The study includes 19 patients with a previous history of HSP that were previously hospitalized in the pediatric department at Meyer Children’s Hospital, Rambam Medical Center in Israel and were followed in the pediatric rheumatology clinic. Their diagnosis was based on the clinical criteria for HSP . The minimal interval between the diagnosis of HSP and endothelial study was 5 months. Patients with chronic renal disease secondary to HSP or other chronic disease were excluded from the study.
|
study
| 100.0 |
Endothelial dysfunction evaluation was assessed utilizing the EndoPAT device (Itamar Medical Ltd, Caesarea, Israel). This is a noninvasive technology that captures a beat-to-beat plethysmographic recordings of the finger arterial pulse-wave amplitude (PWA) with pneumatic probes. It has been extensively used in our lab both in adults and in children [7, 9–12].
|
study
| 100.0 |
A finger probe is placed on the index finger of each hand, and the peripheral arterial tone (PAT) is recorded from both hands throughout the study. Endothelial function is assessed using the reactive hyperemia technique. Briefly, measurements of the pulse-wave amplitude were obtained during 5 min as baseline (at rest), followed by 5 min of blood flow occlusion in one arm by a cuff that was inflated on the upper arm to suprasystolic pressure (50 mmHg above systolic pressure) and then released to induce reactive (flow-mediated) hyperemia, for 10 min. The other arm remained un-occluded as a reference to correct for potential systemic vasomotor changes.
|
study
| 100.0 |
Endothelial function is calculated as the ratio between the magnitude of the average post-obstructive PWA (1.5–2.5 min after release of the arterial occlusion) and average 5 min of baseline PWA (pre-occlusion baseline period), corrected to systemic changes (observed at the non-obstructed arm). The threshold for a good EndoPAT result is an RHI of 1.67 and above (Fig 1).Fig. 1Correlation between TOA* to RHI
|
study
| 100.0 |
The study group comprised of 19 children and adolescents that were diagnosed with HSP. Endothelial function was compared to that of a known control group of 23 healthy children and adolescents matched controls. Among the control group, there was no differences in RHI values between male and female (1.85 ± 0.35 vs 1.8 ± 0.3 respectively p = 0.2) as well as between age and RHI levels in the control group (R-0.29 P = 0.18).
|
study
| 100.0 |
The average age in the HSP group was 13.5 ± 3.9 years (range 7–19.7 years) and was similar to the control group 12.8 ± 4.5 years (range 6–23 years) (p = 0.4), there were 11/19 male (57%) in the HSP group and 16/23 (69%) male in the control group (P = 0.35). BMI was similar in both groups, 22 ± 6.1 in the HSP group and 18.8 ± 3.8 in the control group p = 0.13.
|
study
| 100.0 |
Six children (31.6%) were treated with steroids during their hospitalization five of the six patients received steroids for abdominal pain, and for one patient the reason was not specified in the medical record. The average hospitalization were 3.6 ± 2 days (median −3 days).
|
clinical case
| 95.25 |
The average time from the diagnosis of HSP to endothelial function evaluation was 6 ± 3.5 years (median- 6 years). The average RHI value in the patients with HSP was similar to the control group (1.8 ± 0.7 vs 1.87 ± 0.35 p = 0.18). Twelve of 19 (63%) of the children with HSP had abnormal RHI compared with 7/23 (30%) in the control group (p = 0.06).
|
study
| 100.0 |
Correlation between RHI levels and different variables were assessed. No correlation was found between RHI and gender (p = 0.27), ethnicity (p = 0.48), BMI (p = 0.84) and clinical features such as abdominal pain (p = 0.62), renal involvement (p = 0.58) and length of stay in the hospital (p = 0.4).
|
study
| 100.0 |
In multivariant regression model to predict RHI level by different variables (age, gender, TOA, origin, and steroid therapy), the variable were chosen based on correlation between TOA and gender in the univariable analysis combined with basic demographic data. The final model included gender (female higher) (β = 0.58 P = 0.034), and the TOA that had a positive effect on RHI (β = 0.091, P = 0.025).\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ \mathrm{R}\mathrm{H}\mathrm{I} = 2.112 + 0.091*\mathrm{T}\mathrm{O}\mathrm{A} + 0.584*\mathrm{female}. $$\end{document}RHI=2.112+0.091*TOA+0.584*female.
|
study
| 100.0 |
When other clinical factors were compared between male and female no differences could be found (Table 1).Table 1Comparison of different clinical features between gendersMaleFemale p TOA6.2 ± 3.7 (6.6)5.8 ± 3.6 (5.2) P = 0.90Age at diagnosis of HSP7.03 ± 2.40 (7.1)8.08 ± 3.00 (7.2) P = 0.66Age of endothelial assessment13.24 ± 3.7 (13.3)13.9 ± 4.5 (14.2) P = 0.78Abdominal pain5 (45.5%)4 (50%) P = 1.00Arthritis9 (82%)8 (100%) P = 0.49Renal involvement6 (54.5%)1 (12.5%) P = 0.15Steroids treatment3 (30%)3 (37.5%) P = 1.00
|
study
| 100.0 |
The vascular endothelium is not only a semi-permeable barrier between the blood and the interstitium but also a homeostatic organ with physiological, biological, and endocrine functions. In adults, several studies have investigated the peripheral circulation using the forearm hyperemic response in patient with risk factors for atherosclerosis [13–16]. These studies have demonstrated that peripheral vascular endothelial function plays a crucial role in preventing the progression to coronary arteriosclerosis. However, in children, there have been only a few clinical reports of endothelial dysfunction following vasculitis such as Kawasaki disease as well as following other inflammatory disease such as SLE and JIA [17, 18].
|
review
| 99.9 |
There are few methods to evaluate endothelial function. Quantitive coronary angiography is the most accurate method. In this method during angiography the coronary response to acetylcholine injection is evaluated . However this is an invasive method and not suitable for children. A second alternative, brachial artery ultrasound scanning, is a noninvasive method using Doppler to measure the brachial artery diameter before and after manometric cuff was inflated to supra-systolic pressure [6, 20].
|
review
| 99.44 |
In this study, as in previous studies, we used the Peripheral Arterial Tonography –PAT, a non invasive technology that captures a beat-to-beat plethysmographic recordings of the finger arterial pulse-wave amplitude (PWA) with pneumatic probes before and after blood flow occlusion. In adults it has been demonstrated that endothelial function as measured by the PAT is highly correlated with the brachial artery ultrasound measurements .
|
study
| 100.0 |
RHI levels in patients with a history of HSP were similar to the control group. This finding fits with the known history of patients with HSP who usually develop no long-term damage in the affected organs. We demonstrate that more than half of patients with HSP had abnormal endothelial dysfunction compared to only 30% in the control group although this differences didn’t reach significance (p = 0.06). Our results suggest that endothelial damage may take a long time to recover possibly years. The only clinical feature that correlated with decreased RHI was corticosteroid therapy, which may suggest that patients with severe HSP may have greater endothelial damage. Several in vitro studies [25–27] demonstrated that circulating serum growth factor, adhesion molecules, or other markers of endothelial cell damage were elevated in the acute phase of HSP, especially in severe forms developing IgA nephritis. These vascular abnormalities reduce the availability of nitric oxide, which induces structural and mechanical changes, and may offer important insights into the development and progression of vasculitis initiated end-organ damage. The present study did not include patients with renal impairment, since we wanted to rule out other factors that may affect the endothelial function. Further study is needed to clarify differences between patients with and without renal impairment.
|
study
| 99.94 |
Considering that endothelial dysfunction can be the initial feature of atherosclerosis, and considering that atherosclerosis is a progressive process that can be delayed, halted or even be induced to regress , other studies on the effect of HSP on atherosclerosis may be needed.
|
other
| 99.3 |
The last limitation could be regarding the RHI levels at different ages. This can effect RHI data when comparing patients with more than 6 years since the diagnosis of HSP compared with those with less than 6 years. There is limited data on the influence of age on RHI and in the control group and so we couldn’t defined any differences in RHI levels related to age.
|
study
| 100.0 |
Our study was the first to demonstrate that HSP may have long term effect on endothelial function. These changes improve gradually and are not permanent. Further larger studies may be needed to assess the effect of HSP on early development of atherosclerosis.
|
study
| 99.94 |
Colorectal cancer (CRC) is the third leading cause of cancer related death worldwide . It is becoming increasingly important to identify prognostic and predictive markers for rectal cancer. Surgical resection remains the definitive treatment for CRC. However, rectal cancers are more challenging to resect than their colonic counterparts due to limited access within the pelvic space, as well as close proximity to the mesorectal fascia and pelvic organs. As a result, patients with rectal cancer consistently suffer from inferior survival outcomes relative to colon cancer patients . Preoperative radiotherapy aims to downstage the primary tumor, eradicate microscopic disease, and reduce recurrence rates [3–5]. Unfortunately, tumor response to radiotherapy varies between individuals, even after adjusting for clinico-histopathological variables. Tumor down staging following preoperative radiotherapy occurs in approximately 60% of patients, but only 10–30% will display a complete response . The availability of a predictive marker of radiation sensitivity would enable selective administration of therapy to those most likely to respond.
|
review
| 99.9 |
Radiotherapy instigates cell death by causing ionizing radiation-induced double-strand breaks (DSBs) in the DNA, which initiates the DNA damage response (DDR) leading to cell cycle arrest and repair of the damage or, if repair is unsuccessful, cell death. Two early, integral components in this pathway are ataxia telangiectasia mutated (ATM), a serine/threonine protein kinase belonging to the phosphatidylinositol 3-kinase-like (PIKK) family and the MRN complex, a trimer of MRE11 (meiotic recombination 11), RAD50 and NBS1 molecules. The latter complex binds to the DSBs and generates regions of single stranded DNA with its nuclease activity, which then recruits ATM to the site of genetic damage. ATM in turn affects cell cycle arrest .
|
study
| 99.9 |
As might be expected from the critical role of DNA repair in maintaining genomic integrity, many cancers, including CRC, exhibit deficiencies in the DNA damage response and DNA repair pathways. Specifically, MRE11 deficiency is associated with improved overall survival (OS) and long-term disease-free survival (DFS) in patients with stage III colon cancer independent of treatment , suggesting that MRE11 status has value as a prognostic marker in CRC.
|
study
| 99.8 |
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