This study examined the effects of 8 weeks of twice-weekly combined plyometric and sprint with change-of-direction (CPSCoD) training into habitual training regimes of young male soccer players. Participants were randomly allocated to an experimental group (n = 17, age: 14.6 ± 0.44 years, body mass: 61.2 ± 7.34 kg, height: 1.67 ± 0.09 m, body fat: 11.2 ± 1.56%) and a control group (n = 16, age: 14.6 ± 0.39 years, body mass: 61.1 ± 3.96 kg, height: 1.67 ± 0.05 m, body fat: 11.8 ± 1.47%). Measures obtained pre- and post intervention included vertical and horizontal jump performance (i.e., squat jump (SJ), countermovement jump (CMJ), and standing long jump (SLJ)), and sprint performance (i.e., 5 m and 20 m sprint). In addition, Measures obtained pre- and post-intervention included change-of-direction ability (4 × 5 m sprint test (S 4 × 5 m) and sprint 9–3–6–3–9 m with backward and forward running (SBF)), repeated change of direction (RCoD), and static balance performance (stork balance test). The training group experienced superior jump (all p < 0.05; d ≥ 0.61), sprint (all p < 0.05; d ≥ 0.58), change-of-direction (CoD) ability (all p < 0.05; d ≥ 0.58), RCoD (all parameters except the fatigue index p < 0.01; effect size (d) ≥ 0.71), and static balance (all p < 0.05; d ≥ 0.66) improvement. Adding twice-weekly CPSCoD training to standard training improves the anaerobic performance of U15 male soccer players.

Background: Guiding athletes through the rehabilitation process and judging the time at which return to sports can be enabled after anterior cruciate ligament (ACL) injuries are still challenging processes. The purpose of this explorative cross-sectional study was to retrospectively compare unilateral vertical jump as well as vertical foot tapping outcomes in athletes returned to sports after ACL reconstruction (ACLR) with uninjured athletes.Methods: Seven-teen ACLR athletes (male/female: 12/5) were examined 11 (6–23) months after their ACL injury and after return to sport clearance together with 67 uninjured athletes (male/female: 51/16). Seventeen age and stature matched controls were selected from the sample of uninjured athletes. Participants unilaterally performed acyclic (squat jump, SJ; drop jump, DJ) and cyclic (foot tapping, FT) tests. SJ peak power, DJ take-off efficiency (TOE) and FT coefficients (FTC) were compared between ACLR and matched as well as unmatched control groups. Limb symmetry index (LSI) as well as performance score were calculated.Results: Analyses of the SJ peak power revealed moderate effects of group (right:P < 0.09, η_p² = 0.06; left:P < 0.05, η_p² = 0.08). The TOE was largely affected by group (right:P < 0.01, η_p² = 0.12; left:P < 0.01, η_p² = 0.13). No effect of group was found on the FTC (P > 0.8, η_p² < 0.01). The SJ peak power LSI (r = 0.46,P < 0.07) and TOE LSI (r = 0.38,P = 0.13) were positively associated with the performance score of the ACLR group.Conclusion: Although already returned to sports, the ACLR group underperformed the matched and unmatched control groups significantly. Unilaterally performed vertical jumps may provide additional information on athletes’ rehabilitation progress and help to manage the rehabilitation process and decisions on potential readiness after ACLR. More attention should be paid to the direction of the LSI results.

Knee osteoarthrosis (OA) is a widespread orthopedic problem and a high tibial osteotomy (HTO) is a common treatment to minimize degeneration of the affected compartment. The primary aim of this study was to evaluate the postural regulation and stability among patients who underwent HTO and rehabilitation. This prospective study included 32 patients (55.3 ± 5.57 years) diagnosed with medial tibiofemoral OA. Each subject completed postural regulation and stability testing (Interactive Balance System), as well as pain intensity (visual analogue scale) and quality of life questionnaires (SF-36) prior to HTO (exam 1), and at six weeks (exam 2), twelve weeks (exam 3) and six months (exam 4) post HTO. For postural comparison, all patients were matched (sex, age, height) with asymptomatic subjects. Significant time effects (exam 1 vs. exam 4) were found for weight distribution index (WDI; η_p² = 0.152), mediolateral weight distribution η_p² = 0.163) and anterior–posterior weight distribution η_p² = 0.131). The largest difference (exam 3: η_p² = 0.251) and the most significant differences to the matched sample were calculated for the stability indicator (exam 1: η_p² = 0.237; exam 2: η_p² = 0.215; exam 3: η_p² = 0.251; exam 4: η_p² = 0.229). Pain intensity showed a significant reduction (η_p² = 0.438) from exam 1 (50.7 ± 20.0 mm) to exam 4 (19.3 ± 16.0 mm). Physical pain was the quality of life parameter with the largest improvement between exams 1 and 4 (η_p² = 0.560). HTO allows patients to improve their mediolateral weight distribution, whereas postural stability is consistently lower than in asymptomatic subjects. This surgery leads to marked improvements in quality of life and pain.

This investigation explored the association between anthropometric measures, fitness, and academic attainment (mathematics and science grade point average [GPA]) in male schoolchildren from a soccer academy. Thirty-one males (age: 10.3 ± 1.19 years; body mass: 41.7 ± 6.5 kg; height: 1.43 ± 0.07 m; body mass index (BMI): 20.2 ± 2.8 kg/m²) participated. Body mass, body fat percentage (%BF), and BMI were used as measures of anthropometry. The Yo-Yo Intermittent Recovery Test (level 1), squat and counter-movement jumps (SJ and CMJ), static balance, 10 and 15 m sprint, and a T-half test for change-of-direction (CoD) performance were used to measure fitness parameters. The GPA of mathematics and science determined academic attainment. All physical performance tests showed excellent relative reliability. ICC was between 0.87 (10 m sprint) and 1.00 (15 m sprint, CMJ). Regarding correlations between fatness and academic attainment, we found three correlations of practical value (r > 0.5), but only for mathematics (BMI: r = 0.540, subscapular skinfold: r = 0.589, body fat: r = 0.560). Mathematics was relevantly correlated with 15 m sprint (r = 0.574) and Yo-Yo IR1 test (r = 0.770). Only static balance (r = 0.428) did not reach the relevance criteria (r > 0.5). Science only showed large correlations with static balance (r = 0.620) and Yo-Yo IR1 test (r = 0.730). In conclusion, fatness and fitness are related to academic attainment in schoolchildren. In addition, except for static balance, all physical performance parameters were relevantly (r > 0.5) correlated with mathematics.

Background: Oral health (OH) has been linked to overall health status and common physical performance (PP). Aim: The objective was to compare the OH and PP of two third league professional team players from different sports (soccer, ice hockey). Methods: Twenty-nine professional soccer players (mean ± standard deviation; age: 24.3 ± 4.1 years) and twenty-one ice hockey players (age: 27.7 ± 3.6 years) were investigated regarding several dental scores (DMFT, PSI, API, PBI) by one calibrated examiner. The PP diagnostic includes measurement of grip strength as well as postural stability and regulation using posturography. Results: Concerning dental scores, relevant sport-specific differences for PSI (1 vs. 2; p < 0.001), API (29 vs. 48; p = 0.001), and PBI (14 vs. 42; p < 0.001) in favor of soccer players were found. Ice hockey players reported significantly more tension of the temporomandibular joint (p = 0.004) and showed lower readiness for regular check-ups (p < 0.001) and additional oral hygiene (p = 0.045). In contrast, ice hockey players were more balanced and displayed a higher level of weight distribution (p < 0.001), especially in the anterior-posterior direction (p = 0.002). Conclusions: Based on more intensive oral hygiene and dental care, the investigated professional soccer players showed partially better OH conditions compared to the ice hockey players examined. In summary, the OH and PP results reflect the different sport-specific requirements and related training impacts on athletes.

Muscle activation increases tissue stiffness as measured by elastography. We applied ultrasound time‑harmonic elastography (THE) to the vastus lateralis muscle during passive tonic vibration reflex (TVR) and active voluntary contraction (VC) to test whether TVR can serve as a stimulation method for functional assessment of skeletal muscle stiffness. Twenty‑five asymptomatic volunteers (8 females, mean age 34 ± 8 years) underwent five consecutive THE examinations at three VC loads (15, 22, and 37 N) and during TVR stimulation with 100 Hz frequency and 200 µm (low) and 400 µm (moderate) amplitude. Using standard line‑by‑line ultrasound, THE acquired induced shear waves of 60, 70, and 80 Hz frequency with a frame rate of 100 Hz. Shear wave speed (SWS) was reconstructed as a proxy for muscle stiffness and statistically analyzed. SWS increased significantly from 1.66 ± 0.11 m/s at rest to 1.79 ± 0.12 m/s, 1.93 ± 0.13 m/s, and 2.16 ± 0.12 m/s with 15, 22, and 37 N VC load (p < 0.001). Similar effects were observed during TVR activation with increases to 1.93 ± 0.13 m/s and 2.18 ± 0.14 m/s for low and moderate TVR amplitudes (p < 0.001). Increase of SWS at moderate TVR amplitudes correlated with that of 37 N VC load (r = 0.67, p < 0.001). TVR-induced stiffness changes at a 100 Hz vibration frequency and moderate amplitude may serve as a more objective alternative to VC-based loading for assessing functional muscle stiffness in asymptomatic individuals. However, clinical translation of TVR-THE as a standardized tool for assessing activation-related stiffness requires further evaluation in patient populations.