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Purpose: Physical activity is associated with altered levels of circulating microRNAs (ci-miRNAs). Changes in miRNA expression have great potential to modulate biological pathways of skeletal muscle hypertrophy and metabolism. This study was designed to determine whether the profile of ci-miRNAs is altered after different approaches of endurance exercise. Methods: Eighteen healthy volunteers (aged 24 ± 3 years) participated this three-arm, randomized-balanced crossover study. Each arm was a single bout of treadmill-based acute endurance exercise at (1) 100% of the individual anaerobic threshold (IANS), (2) at 80% of the IANS and (3) at 80% of the IANS with blood flow restriction (BFR). Load-associated outcomes (fatigue, feeling, heart rate, and exhaustion) as well as acute effects (circulating miRNA patterns and lactate) were determined. Results: All training interventions increased the lactate concentration (LC) and heart rate (HR) (p < 0.001). The high-intensity intervention (HI) resulted in a higher LC than both lower intensity protocols (p < 0.001). The low-intensity blood flow restriction (LI-BFR) protocol led to a higher HR and higher LC than the low-intensity (LI) protocol without BFR (p = 0.037 and p = 0.003). The level of miR-142-5p and miR-197-3p were up-regulated in both interventions without BFR (p < 0.05). After LI exercise, the expression of miR-342-3p was up-regulated (p = 0.038). In LI-BFR, the level of miR-342-3p and miR-424-5p was confirmed to be up-regulated (p < 0.05). Three miRNAs and LC show a significant negative correlation (miR-99a-5p, p = 0.011, r = − 0.343/miR-199a-3p, p = 0.045, r = − 0.274/miR-125b-5p, p = 0.026, r = − 0.302). Two partial correlations (intervention partialized) showed a systematic impact of the type of exercise (LI-BFR vs. HI) (miR-99a-59: r = − 0.280/miR-199a-3p: r = − 0.293). Conclusion: MiRNA expression patterns differ according to type of activity. We concluded that not only the intensity of the exercise (LC) is decisive for the release of circulating miRNAs—as essential is the type of training and the oxygen supply.
A glenohumeral internal rotation deficit (GIRD) of the shoulder, is associated with an increased risk of shoulder injuries in tennis athletes. The aim of the present study was to reveal the impact of 1) age, sex, specific training data (i.e. training volume, years of tennis practice, years of competitive play) and 2) upper extremity injuries on GIRD in youth competitive tennis athletes.
A cross-sectional retrospective study design was adopted. Youth tennis players (n = 27, 12.6 ± 1.80 yrs., 18 male) belonging to an elite tennis squad were included. After documenting the independent variables (anthropometric data, tennis specific data and history of injury), the players were tested for internal (IR) and external (ER) shoulder rotation range of motion (RoM, [°]). From these raw values, the GIRD parameters ER/IR ratio and side differences and TRoM side differences were calculated. Pearson’s correlation analyses were performed to find potential associations of the independent variables with the GIRD outcomes.
A significant positive linear correlation between the years of tennis training and IR side asymmetry occurred (p < .05). A significant negative linear relation between the years of tennis training and the ratio of ER to IR range of motion (RoM) in the dominant side (p < .05) was found. The analysis of covariance showed a significant influence of the history of injuries on IR RoM (p < .05).
Injury and training history but not age or training volume may impact on glenohumeral internal rotation deficit in youth tennis athletes. We showed that GIRD in the dominant side in youth tennis players is progressive with increasing years of tennis practice and independent of years of practice associated with the history of injuries. Early detection of decreased glenohumeral RoM (specifically IR), as well as injury prevention training programs, may be useful to reduce GIRD and its negative consequences.
Background: In March 2020, the COVID-19 outbreak led to the declaration of a pandemic. The accompanying restrictions on public life caused a change in the training routines of athletes worldwide. The present study aimed to investigate the effects of a 13-week supervised home training program on physical performance, sleep quality, and health-related quality of life in professional youth soccer players during the first COVID-19 lockdown in Germany.
Methods: Eight professional soccer players (age range 16–19; height: 1.81 ± 0.07 m; body weight: 72.05 ± 6.96 kg) from a Bundesliga team in Germany participated in this study. During the lockdown, they trained 5–6 days per week with home-based training plans and were monitored via tracking apps and video training. To determine the effects of home training, measurements were taken before (March 2020) and after (June 2020) the home training period. Bioelectrical impedance analysis was used to determine body composition, and an isokinetic strength test and a treadmill step test, including lactate measurements, were used to measure physical performance. Two questionnaires were responded to in order to assess health-related quality of life [Short-Form 36 Health Survey (SF-36)] and sleep quality (Pittsburgh Sleep Quality Index).
Results: When comparing measurements before and after the home training period, we observed significant increases in the following variables: body weight (72.05 ± 6.96 kg vs. 73.50 ± 6.68 kg, p = 0.034), fat mass (11.99 ± 3.13 % vs. 13.98 ± 3.92 %, p = 0.030), body mass index (22.04 ± 0.85 kg/m2 vs. 22.49 ± 0.92 kg/m2, p = 0.049), and mental health component summary score (MCS) of the questionnaire SF-36 (53.95 ± 3.47 vs. 58.33 ± 4.50, p = 0.044). Scores on the general health (77.88 ± 14.56 vs. 89.75 ± 13.76, p = 0.025) and mental health (81.50 ± 9.30 vs. 90.00 ± 11.71, p = 0.018) subscales of the SF-36 also increased significantly.
Conclusion: The COVID-19 lockdown led to an increase in body composition parameters and showed an improvement in the MCS and scores on the general and mental health subscales of the SF-36. Physical performance and sleep quality could be maintained during the home training period. These observations may help trainers for future training planning during longer interruptions in soccer training.