The aim of this study is to develop a CBT-based mobile exercise application that complies with evidence-based physical activity recommendations, and to investigate the change in health-related physical fitness parameters university students with insufficient physical activity levels. As a result of 8 weeks of use of the ERVE mobile application, the change in body weight, BMI, body fat ratio, max VO2, hand grip strength, maximum push-ups, maximum sit-ups and body flexion values was investigated.
Looking at the change in the body composition of the participants, it can be stated that although there was a statistically significant difference (p<0.05) in the body weight and BMI values in favor of the experimental group as a result of the Intent-to-Treat analysis, there the change had no clinical significance. On the other hand, there was no statistically significant difference between the experimental and control groups in terms of body fat percentage (p>0.05). Participants received an average of 40 minutes aerobic exercises 2 days a week 2 days a week via the ERVE mobile application. These aerobic exercise sessions consist of dynamic movements based on time or repetition in order to increase the individual's pulse to a level above the resting pulse (for example, Jumping Jack, boxing, Burpee, etc.). Aerobic exercises may be the main reason for the statistically significant difference in body weight and BMI values between groups. This result is consistent with aerobic exercise studies in the literature [29]. On the other hand, poor clinical significance of this difference and no difference in body fat percentage may be due to short duration of the intervention and/or no intervention in the diet of the participants. It is observed in studies in the literature that changes in body fat ratio can be achieved over longer periods of time [30].
Considering the effectiveness of the application in terms of cardiorespiratory endurance characteristics, participants in the experimental group were found to statistically significantly differ compared to participants in the control group (p<0.05). However, the change in Max VO2 has a moderate (ηp2 =0.09) level impact according to the intent to treat analysis and a high level impact (ηp2 =0.21) according to the per-protocol analysis. Looking at the max VO2 values of the participants as a result of the first measurements in the study, their age group was found to be significantly lower than the average norm values [12]. This may be due to the insufficient physical activity levels of the participants. The ERVE mobile application aimed to keep participants in the experimental group physically active for an average of over 150 minutes per week (1 session is 40 minutes on the average; 4 sessions per week, 4 x 40 =160 min.). Therefore, the change seen in the max VO2 values of the experimental group may be related to the increased physical activity level of the participants. The moderate level of impact according to the result of the Intent-to-Treat analysis, and the high level of impact according to the Per-Protocol analysis shows that the change observed in max VO2 increases with the increase in the number of sessions performed. A positive relationship between high levels of physical activity and max VO2 values of individuals has been shown in previous studies in the literature [31].
When we examined the changes in the muscular fitness parameter, a statistically significant difference was found in the values of right hand grip strength, maximum push-ups and maximum sit-ups in favor of the experimental group as a result of the Intent-to-Treat analysis (p<0.05). Moreover, the change in right hand grip strength had a moderate level of impact (ηp2 =0.09), while the change in maximum push-ups (ηp2 =0.22) and maximum sit-ups (ηp2 =0.28) had a high level of impact. Participants were provided with approximately 40-minute strength exercises using their own body weight, without using an equipment, via the ERVE mobile application for 2 days a week (e.g., plank, sit-ups, push-ups, Russian twist, etc.) In addition, according to the progress principle of the exercise prescription, the difficulty level of the strength training movements was designed in an gradually-increasing manner. It has been shown in the literature that properly structured exercises can result in achieving significant changes in strength development [32,33].
When the body flexion values were examined to observe the change in flexibility characteristics, the experimental group was found to be statistically significantly different from the control group (p<0.05). According to the results of the Intent-to-Treat analysis, the change in the average values of the experimental group has a high level of impact (ηp2=0.16). In the ERVE application, the preliminary section of each exercise session contains dynamic warm-up flexibility exercises, and the final section contains static cooling flexibility exercises. Although the study group initially consisted of individuals with insufficient physical activity levels, no participant complained of an exercise-related injury or adverse condition at the end of the study. Studies in the literature show that low flexibility is positively associated with a high level of injury risk [34]. This may indicate that the flexibility training program in the ERVE mobile application allows the experimental group to appropriately improve their flexibility.
Along with all this information, recent research shows that mobile applications and the Internet-based approach are being used as an effective tool in the field of exercise and health. Researchers have tried to increase the level of physical activity or awareness in different groups, such as patients with cancer [41], children with heart disease [42], people with diabetes [43], the elderly [44] and office workers [45], through mobile applications. As a result of the literature review conducted in conjunction with these current approaches, there was no study of evidence-based physical activity recommendations with CBT-based training support. ERVE mobile exercise application can be stated to be the first study in the literature to have this approach.