The Association between Multidirectional Speed Performance, Dynamic Balance and Chronological Age in Young Soccer Players.

The ability to maintain a stable single-leg balance stance during a fast change of direction movement is a fundamental aspect both for improving sport-specific skills and for prevention strategies. The aim of this cross-sectional study was to investigate the associations between multidirectional speed performance (MDS), dynamic balance performance (DBP), and chronological age in young and uninjured soccer players. In addition, it was examined whether chronological age and balance can predict variance in speed performance. One-hundred forty-six young male soccer players (age range 11-19) performed the y-balance test (YBT) and the lower extremity functional test (LEFT). Descriptive statistics, Pearson correlation, and multiple regression analysis were executed. The analyses were carried out on the further variables: for the DBP, the YBT composite score % (CS dominant leg/CS non-dominant leg) and limb symmetry index % (LSI) were used; for the MDS, the LEFT time in seconds (s) was used. Findings revealed LEFT scores to have a significant association with chronological age (p = 0.000), CS dominant (p = 0.019) and LSI (p = 0.044) of the YBT. In addition, CS dominant and chronological age explained the variance of the LEFT by 44%, regardless of LSI. To conclude, MDS revealed a strong association with DBP of the dominant side but a small association with LSI. In addition, a small association was found between quick LEFT times and older players. Finally, MDS variance can be predicted from DBP of the dominant side and chronological age in young soccer players. The tests used in this study could be useful screening tools for the detection of performance deficits, the implementation of prevention training programs, and the optimization of selection strategies in soccer academies.

Validation of a smart shirt for heart rate variability measurements at rest and during exercise.

Heart rate variability (HRV) monitoring is a promising option to estimate the autonomic nervous system regulation responding to exercise. Textiles with embedded sensors recording heartbeat intervals are a simple tool for data collection. The so-called smart shirts offer comfort for daily use and are managed easily. Their measurement accuracy for HRV calculation at rest is promising, but remains questionable during exercise. Therefore, the present study validated the Ambiotex smart shirt using HRV indices (root mean square of successive differences, rel. HF power [high-frequency power percentage of total power] and rel. LF [low-frequency power percentage of total power] power) during exercise. Eighty-three healthy participants (31 ± 6 years; 39 females, 44 males) completed an incremental exercise test on a bicycle ergometer wearing the smart shirt and an electrocardiogram simultaneously. We compared HRV indices of segments at rest (5 min), at warm-up (3 min) and twice at the exercise test (each 5 min). At rest and at warm-up, we observed excellent linear relationship (r > 0.96; R2 ​​​​​ > 0.94), excellent relative reliability (intraclass correlation coefficient ≥ 0.98; α ≥ 0.98) and acceptable agreement (bias < 10%). During the exercise test, measurement accuracy declined with increasing intensity but remained high (>0.8), although results for partial HRV indices were insufficient. In addition, percentage bias was unacceptable during an exercise test. However, the findings support the validity of the smart shirt for measuring HRV, especially at rest and at warm-up. We suggest using the smart shirt for monitoring HRV indices on a daily basis, but caution should be taken in the interpretation of HRV indices obtained during moderate to vigorous exercise intensities.

Unilateral non-electric assistive walking device helps neurological and orthopedic patients to improve gait patterns.

BACKGROUND: Pathological gait patterns are common in neurological and orthopedic patients. These put them at risk of falling and restrict their autonomy and social participation. Novel assistive walking devices are designed to actively support physiological gait patterns by means of motor guidance and mechanical support of the lower limbs. RESEARCH QUESTION: Does a non-electric assistive walking device powered by a cam-spring mechanism (aLQ, Imasen) improve or otherwise affect pathological gait patterns in neurological and orthopedic patients? METHODS: A three-dimensional instrumented gait analysis was conducted on a treadmill (quasar, hp cosmos) using spatiotemporal, kinetic, and kinematic data obtained from synchronized motion capturing (Miqus M3, Qualisys), surface EMG (sEMG; Ultium, Noraxon), and pressure distribution measurements (FMD-T, Zebris). Participants with impaired walking were tested in a randomized repeated measures design (assisted/unassisted; at preferred/fast speed) and analyzed with regard to their medical condition (orthopedic or neurological group, n = 20 each). RESULTS: In both groups, participants showed a significant increase of step length and decrease of cadence during assisted walking compared to baseline. Immediate kinematic effects included enhanced sagittal hip flexion but reduced extension. On the contrary, knee joint angles and muscle activity of M. gastrocnemius and M. rectus femoris seemed to be unaffected by the aLQ device. SIGNIFICANCE: Participants appear to benefit from the assistive walking device regarding gait and movement patterns, which suggests that the tested device may help to improve patients' functional health status and quality of life. Activities of daily living (ADLs) that involve extensive hip flexion like stairs or curb climbing are promising applications. We propose the implementation of an invertible cam-spring that provides an additional resistance training option.

Effects of Full Body Exergaming in Virtual Reality on Cardiovascular and Muscular Parameters: Cross-Sectional Experiment.

BACKGROUND: In recent years, many studies have associated sedentary behavior in front of screens with health problems in infants, children, and adolescents. Yet options for exergaming-playing video games that require rigorous physical exercise-seem to fall short of the physical activity levels recommended by the World Health Organization. OBJECTIVE: The purpose of this study was to investigate the effect of a fully immersive virtual reality (VR)-based training system on cardiovascular and muscular parameters of young adults. METHODS: A cross-sectional experiment design was used to analyze muscle activity (surface electromyography), heart rate, perceived exertion (RPE), cybersickness symptoms, perceived workload, and physical activity enjoyment (PACES) in 33 participants performing two 5-minute flights on a new training device. RESULTS: Participants' performance of the planking position required to play the game resulted in moderate aerobic intensity (108 [SD 18.69] bpm). Due to the mainly isometric contraction of the dorsal muscle chain (with a mean activation between 20.6% [SD 10.57] and 26.7% [SD 17.39] maximum voluntary isometric contraction), participants described the exercise as a moderate to vigorous activity (RPE 14.6 [SD 1.82]). The majority reported that they enjoyed the exercise (PACES 3.74 [SD 0.16]). However, six participants had to drop out because of cybersickness symptoms and two because of muscle pain due to prior injuries. CONCLUSIONS: Our findings suggest that fully immersive VR training systems can contribute to muscle-strengthening activities for healthy users. However, the dropout rate highlights the need for technological improvements in both software and hardware. In prevention and therapy, movement quality is a fundamental part of providing effective resistance training that benefits health. Exergaming on a regular basis has the potential to develop strong muscles and a healthy back. It is essential that future VR-based training systems take into account the recommendations of sport and exercise science.