BackgroundThe number of commercial apps to improve health behaviours in children is growing rapidly. While this provides opportunities for promoting health, the content and quality of apps targeting children and adolescents is largely unexplored. This review systematically evaluated the content and quality of apps to improve diet, physical activity and sedentary behaviour in children and adolescents, and examined relationships of app quality ratings with number of app features and behaviour change techniques (BCTs) used.MethodsSystematic literature searches were conducted in iTunes and Google Play stores between May–November 2016. Apps were included if they targeted children or adolescents, focused on improving diet, physical activity and/or sedentary behaviour, had a user rating of at least 4+ based on at least 20 ratings, and were available in English. App inclusion, downloading and user-testing for quality assessment and content analysis were conducted independently by two reviewers. Spearman correlations were used to examine relationships between app quality, and number of technical app features and BCTs included.ResultsTwenty-five apps were included targeting diet (n = 12), physical activity (n = 18) and sedentary behaviour (n = 7). On a 5-point Mobile App Rating Scale (MARS), overall app quality was moderate (total MARS score: 3.6). Functionality was the highest scoring domain (mean: 4.1, SD: 0.6), followed by aesthetics (mean: 3.8, SD: 0.8), and lower scoring for engagement (mean: 3.6, SD: 0.7) and information quality (mean: 2.8, SD: 0.8). On average, 6 BCTs were identified per app (range: 1–14); the most frequently used BCTs were providing ‘instructions’ (n = 19), ‘general encouragement’ (n = 18), ‘contingent rewards’ (n = 17), and ‘feedback on performance’ (n = 13). App quality ratings correlated positively with numbers of technical app features (rho = 0.42, p < 0.05) and BCTs included (rho = 0.54, p < 0.01).ConclusionsPopular commercial apps to improve diet, physical activity and sedentary behaviour in children and adolescents had moderate quality overall, scored higher in terms of functionality. Most apps incorporated some BCTs and higher quality apps included more app features and BCTs. Future app development should identify factors that promote users’ app engagement, be tailored to specific population groups, and be informed by health behaviour theories.Electronic supplementary materialThe online version of this article (doi:10.1186/s12966-017-0538-3) contains supplementary material, which is available to authorized users.

Background and Objectives. Most performance theories were tested under controlled laboratory settings and offer therefore only limited transferability to real-life situations. E-sport competitions offer a relatively controllable while at the same time competitive setting, and our aim was to examine different influencing factors on competitive performance. Design and Methods. Salivary cortisol was measured immediately before, after, and 30 minutes after a game of 23 computer players during e-sport tournaments. The players answered the Flow Short Scale, which consists of the two subdimensions “flow experience” and “anxiety” subsequent to their game. The performance was assessed by the result of each player’s game (win or loss). Results. Mean cortisol levels increased significantly during the game but response patterns were inconsistent. Winners and losers differed significantly in anxiety with winners showing higher anxiety levels. After dividing the sample into three groups of different cortisol response patterns, significant differences in performance and anxiety were found, with low to moderate levels of cortisol being associated with the highest performance and anxiety. Conclusions. A low to moderate physiological arousal and a simultaneously high level of anxiety represent a favorable state for achieving optimal performance during e-sports. Anxiety seems to exert a stronger influence on performance than physiological arousal.

Over the last few years, the estimation of energy expenditure with accelerometers has become more and more accurate due to improvements in sensor technology. Significant enhancement could be reached by model-based estimation regarding different activity types. The kmsMove-sensor (movisens GmbH, Karlsruhe, Germany) is a device that is used to compute human energy expenditure using motiondependent calculation models. It is outfitted with an accelerometer to measure body acceleration during certain movements and activities. To validate its accuracy, the sensor was compared to indirect calorimetry as criterion measure. For this experiment, nine subjects (all males, age 46.4±10.9 years, 28-64 years) were equipped with the kmsMove-sensor as well as a portable indirect calorimeter and their energy consumption was measured over a time period of 100 min. Additionally, the energy consumption of seven out of the above-mentioned nine subjects was measured over an average of 7 h. The measurements took place in a rehabilitation clinic, where the subjects completed their regular daily rehabilitation activities. An analysis of the data revealed ICCs between the kmsMovesensor and indirect calorimetry for the time period of 100 min of 0.82 (0.38-0.96; p=0.003) and for an averaged measuring time of 7 h of 0.81 (0.22-0.97; p=0.01). Furthermore, a Bland-Altman analysis for the time period of 100 min led to a difference of the means of 4.3 kcal (limits of agreement: −94.3 and 102.9 kcal) and for the time period of an average of 7 h to −14.0 kcal (limits of agreement: −320.0 and 292.0 kcal). These findings indicate that the kmsMovesensor is an appropriate measuring device with relatively good accuracy to assess human energy expenditure in rehabilitation patients. However, this study has some limiting aspects (small sample size, artificial setting) which could influence validity.

Laboratory studies confirm physical activity and physical fitness to be protective factors against mental stressors. However, there is still little evidence on the transferability of these findings into real-life stress situations. The main aim of this study was to examine the impact of physical activity and physical fitness on real-life psychophysiological stress responses to a mental stressor. The final exam of a training course for firefighter incident commanders represented the real-life mental stressor of our study. Cortisol level, heart rate, and heart rate variability were measured in 48 male firefighters at rest and during the exam. Cognitive stress appraisal was assessed as a psychological stress indicator. Physical activity was estimated using the International Physical Activity Questionnaire. Maximal oxygen uptake was measured as a parameter for physical fitness. The participants were divided according to their level of physical activity and physical fitness into groups of lower and higher physical activity/fitness level. All subjects showed significant physiological stress responses and a moderate cognitive stress appraisal during the exam. Subjects with different physical activity and physical fitness levels did not differ significantly in their physiological stress responses. Cognitive stress appraisal seemed not to be influenced by physical fitness but by physical activity, as more active subjects experienced significantly higher stress levels. Cognitive stress appraisal did not predict physiological stress responses. The assumed stress-buffering effect of physical activity and physical fitness could not be observed during the real-life mental stress of an exam consisting of commanding a group of firefighters in an emergency simulation.

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