Sports Health-A Multidisciplinary Approach最新文献

Background: Taurine (TAU) and creatine (Cr) are common ergogenic aids used by athletes to enhance performance; however, the effect of their combined supplementation, and on recovery in high temperature and humidity environments, has not been studied.

Hypothesis: Combined TUA and Cr will have greater effect on physiological indicators and repetitive sprint performance recovery after exhaustive exercise under hot and humid conditions than single supplementation or placebo.

Study design: Single-blind crossover randomized controlled study.

Level of evidence: Level 2.

Methods: Participants (12 sports students) were assigned randomly to 1 of 4 supplementation intervention groups: placebo (P), taurine (T), creatine (C), or taurine + creatine (T+C). Exercise protocol included exhaustion tests and repeated sprinting exercises were conducted in a laboratory environment at 35 °C/65% relative humidity. Heartrate, blood lactate (BLa), tympanic temperature, thermal sensation, and rating of perceived exertion were monitored throughout. Heartrate variability, time to exhaustion (TTE), reaction time, and countermovement jump (CMJ) height were tracked before and after exhaustion exercise and before sprint exercise.

Results: TTE was significantly higher in the T+C group than in the P group (P = 0.04). BLa and tympanic temperature increased rapidly in all 4 conditions, then decreased gradually, and T group peak values were higher than those of P group (P = 0.04; P < 0.01). CMJ decreased in the C and T+C groups (P = 0.04; P = 0.04) after exhaustive exercise, unlike other groups (P > 0.05). Indicators of repeated sprint exercise, peak power, mean power, and power decrement showed a decreasing trend within groups but no difference between groups (P > 0.05).

Conclusion: In this small student group, under hot and humid conditions, T+C supplementation significantly enhanced TTE.

Clinical relevance: TAU, Cr, and their combined supplementation do not significantly improve repeated sprint performance after exhaustive exercise under hot and humid conditions.

Background: Upper extremity physical-performance-tests are gaining interest for screening overhead athletes in view of injury prevention, individual performance, and return to play after injury. However, at present, no reference data are available for these tests in a junior tennis population. In addition, the construct validity of these tests with respect to shoulder strength is still unclear.

Hypothesis: Junior tennis players will exhibit differences in test performance based on age, sex, and side. Shoulder strength will be moderately to highly correlated with the seated medicine ball throw (SMBT) and the modified-closed-kinetic-chain-upper-extremity test (M-CKCUEST), but not with shoulder endurance test (SET) and the Y-balance-test-upper-quadrant (YBT-UQ).

Study design: Descriptive study, cross-sectional design.

Level of evidence: Level 3.

Methods: Four commonly used physical performance tests (PPTs) (YBT-UQ, M-CKCUEST, SMBT, and SET) were executed by 99 junior tennis players aged 9 to 18 years. In addition, isometric external and internal rotation strength was measured, using a hand-held dynamometer. Descriptive reference values were reported, and correlations between the PPTs and strength values were calculated.

Results: A linear regression model with backwards stepwise regression was used to identify possible age, sex, and side differences regarding PPTs and strength. Some, but not all reached statistical significance. Moderate-to-high correlations (Pearson correlation coefficients) were found between the M-CKCUEST, SMBT, and SET and strength measurements, establishing acceptable construct validity with respect to strength. No significant correlation was found between the YBT-UQ and strength.

Conclusion: Junior tennis players exhibit differences in test performance based on age, sex, and side. The MCKCUEST, SMBT, and SET may be valuable alternatives for strength testing in the clinical setting.

Clinical relevance: These tests may provide a valuable, user-friendly alternative for strength measurements in junior tennis players.

Background: Maximum repetitions to failure (RTF) and repetitions in reserve (RIR) can be estimated through fastest mean velocity (MV_fastest) and mean velocity (MV), respectively. However, the impact of inter-repetition intervals (IRI) on these relationships in free-weight back squat and bench press exercises is unclear.

Hypothesis: The IRI would affect RTF-MV_fastest and RIR-MV relationships, with a higher goodness-of-fit using self-selected IRI (SSIRI) compared with 0 seconds (IRI0) and 3 seconds (IRI3).

Study design: Crossover study design.

Level of evidence: Level 3.

Methods: Eighteen male participants completed 1 session per IRI configuration, consisting of 3 single sets of RTF (65%-75%-85% of the 1-repetition maximum) during the free-weight back squat and bench press exercises.

Results: Individualized RTF-MV_fastest and RIR-MV relationships were stronger than generalized (median R² = 0.98 vs 0.65 and 0.84 vs 0.40, respectively). The goodness-of-fit of the relationships was stronger for SSIRI than for IRI0 during back squat (P < .01) and comparable between IRIs during bench press (P ≥ .28). During back squat, MV_fastest values were higher for IRI0 than for IRI3 and SSIRI (eighth-fifteenth repetitions; P ≤ .07), whereas during the bench press, they were higher for IRI0 than for IRI3 (eleventh-fifteenth repetitions; P ≥ .28). Overall, MV values associated with each RIR were higher for IRI0 than for SSIRI (10 out of 18 comparisons) during back squat, and for IRI0 than for IRI3 and SSIRI (16 and 14 out of 18 comparisons) during bench press.

Conclusion: These results highlight the importance of standardizing the IRI during set-to-failure to establish RTF-MV_fastest and RIR-MV relationships, with SSIRI recommended as a more accurate and effective procedure.

Clinical relevance: This information may provide practitioners with a valuable tool to objectively quantify the level of effort being exerted during resistance training sets by measuring movement velocity in free-weight exercises.

Background: Women are typically more prone to knee injuries than men, possibly due to poorer hamstrings-to-quadriceps ratio (HTQ), particularly during fast velocity movements.

Hypothesis: Men would have greater HTQ across velocity than women.

Study design: Cross-sectional study.

Level of evidence: 2.

Methods: Ultrasound images quantified quadriceps and hamstrings muscle cross-sectional area (CSA) in 27 study participants (14 women, age, 24 ± 4 years; 13 men, age, 25 ± 6 years). Peak torque (PT) was taken from maximal voluntary isometric contractions (MVICs) and isokinetic leg extension and flexion contractions from 60° to 300° s^-1. Independent samples t-tests examined differences in CSA and HTQ from CSA. Mixed-factorial ANOVAs examined differences in PT and HTQ from PT.

Results: Men had larger CSA and PT than women for leg extension and flexion across velocity (P < .01). There were no sex-based differences in the HTQ from CSA or PT across velocity (P ≥ .11). For both groups, leg extension PT decreased from MVIC to 300° s^-1 (P ≤ .04). For women, leg flexion PT was the same from MVIC to 60° s^-1 (P > .98), decreased from 60° to 180° s^-1 (P < .01), and plateaued from 180° to 300° s^-1 (P ≥ .07). For men, leg flexion PT decreased from MVIC to 300° s^-1 (P ≤ .03). For both groups, HTQ increased from MVIC to 60° s^-1 (P < .01), then plateaued from 60° to 300° s^-1 (P > .98).

Conclusion: Both groups had similar patterns of response for leg extension PT and HTQ across velocity, with no sex-based differences for HTQ. Factors other than HTQ may account for the potential sex-based difference in knee injury risk.

Clinical relevance: Increased knee injury predisposition for women compared with men may be due to neuromuscular control or anatomy rather than HTQ.

Background: Diminished corticospinal excitability is theorized to contribute to poor quadriceps function after anterior cruciate ligament (ACL) reconstruction. Operant conditioning of the motor evoked torque (MEP_TORQUE) is a promising approach capable of improving corticospinal excitability. However, it is unknown whether increasing corticospinal excitability can improve quadriceps function after a short-term operant conditioning intervention in patients with reconstructed ACL.

Hypothesis: After ACL reconstruction, patients would demonstrate increases in quadriceps strength, voluntary activation, and corticospinal excitability after a 2-week operant conditioning intervention.

Study design: Randomized controlled clinical trial.

Level of evidence: Level 1.

Methods: A total of 22 patients with reconstructed ACL were randomized into 1 of 2 groups: group 1 received 2 weeks of operant conditioning training on the reconstructed leg to improve their transcranial magnetic stimulation (TMS)-elicited MEP_TORQUE responses (COND); group 2 received 2 weeks of TMS only (SHAM-COND). Quadriceps strength, voluntary activation, and corticospinal excitability on the reconstructed leg were evaluated before and after the 2-week intervention. Within-session changes in corticospinal excitability were also evaluated during the training sessions.

Results: The COND group demonstrated a significantly higher within-session percent increase in MEP_TORQUE during training compared with the SHAM-COND group, paralleled by a significant increase in corticospinal excitability after the 2-week intervention. In addition, quadriceps strength and voluntary activation improved on the reconstructed leg after the 2-week intervention, regardless of group.

Conclusion: Operant conditioning training can elicit improvements in corticospinal excitability after ACL reconstruction; however, improvements in quadriceps strength and voluntary activation seem not to be attributed solely to operant upconditioning training.

Clinical relevance: Operant conditioning is a promising approach to improve corticospinal excitability after ACL reconstruction. However, optimizing the delivery of operant conditioning protocols by potentially increasing the dosage of operant conditioning and intervening earlier after surgery may be needed to translate these changes to improvements in quadriceps function.

Background: Verbal feedback (knowledge of results [KR]) and listening to music are common ergogenic strategies used to boost athlete performance during resistance exercise. No previous research has explored their effects when both strategies are combined in the same exercise session (KR+music). This study aimed to examine the impact of providing KR, listening to music, and their combined effects on: (1) mechanical responses (number of repetitions, fastest velocity, and average velocity in a set), and (2) perceptual responses (feeling scale [FS], rating of perceived exertion [RPE], and rate of perceived discomfort [RPD]) when a determined percentage of velocity loss (%VL) is prescribed.

Hypothesis: Providing KR or listening to music would provide an ergogenic effect on these outcomes whereas KR+music can compromise mechanical performance.

Study design: Cross-sectional study.

Level of evidence: Level 3.

Methods: Fifteen recreational resistance-trained men were tested on 5 occasions separated by a 48 to 72 hour washout period. The first session was used to determine the bench press 1-repetition maximum (1RM) strength. The 4 experimental sessions were identical (4 sets at 70% 1RM with a 20%VL during bench press exercise) except for the intervention (ie, control, KR, music, and KR+music) used randomly on each session.

Results: The findings revealed that: (1) mechanical performance was significantly greater for the music condition (from 5.7% to 20.4%), followed by the KR+music (from 4.9% to 15.4%) and KR (from -0.4% to 8.1%) condition, and (2) greater FS values were found for music compared with control condition, while no significant differences were reported for RPE or RPD.

Conclusion: Listening to music enhances bench press performance and mood; adding KR does not compromise these benefits.

Clinical relevance: Recreational athlete performance may benefit from listening to music, and KR+music does not compromise this effect. However, athlete preference should take priority when implementing these ergogenic strategies.

Background: Radiographic evaluations are commonly used to determine calcaneal ossification staging throughout pediatric development. Sonographic imaging may offer a less expensive, noninvasive, clinically feasible option for calcaneal developmental assessments. Here, we assessed (1) inter-rater agreement of radiographic and sonographic calcaneal ossification staging of children and adolescent patients with Sever's disease and (2) agreement between radiographic and sonographic calcaneal ossification staging scores.

Hypothesis: There would be substantial agreement of radiographic and sonographic calcaneal ossification staging across raters, and between imaging measures.

Study design: Retrospective cohort study.

Level of evidence: Level 3.

Methods: Adolescent patients (<18 years of age) with physician-diagnosed Sever's disease who had complete calcaneal sonographic and radiographic imaging available on a retrospective chart review were included. Three independent reviewers with advanced training in musculoskeletal ultrasound each separately assessed radiographic and sonographic imaging data and assigned calcaneal calcification stages (0-5) to blinded images based on established criteria. Fleiss' Kappa analyses were used to determine inter-rater staging agreement for both imaging approaches. Cohen's Kappa analyses were used to determine the agreement between radiographic and sonographic staging. Absolute agreement, and relative agreement within each stage were assessed for both analyses.

Results: Data from 19 patients (13 female, 6 male; 12.2 ± 2.3 years) were included. Absolute inter-rater agreement for radiographic and sonographic calcaneal ossification staging was comparable across the 3 raters (radiographs, κ = 0.692, z = 9.02; P < .01; sonographs, κ = 0.713, z = 7.95; P < .01), and perfect relative agreement (κ = 1.0, z = 10.6; P < .01). Consensus scores for radiographic and sonographic staging had moderate (κ = 0.535, z = 4.2; P < .01, and perfect relative (100% relative agreement, z = 6.22; P < .01) agreement.

Conclusion: Sonographic evaluations of calcaneal ossification staging was comparable across assessors, and similar to radiographic staging.

Clinical relevance: Clinicians may consider incorporating ultrasound imaging for calcaneal ossification staging for young patients.

Background: Adipose tissue is an endocrine organ that produces various bioactive molecules known as adipokines, including resistin, which is be highly expressed in people with obesity and cardiovascular disease (CVD). The effects of supramaximal high intensity interval training (HIIT) and moderate-intensity interval training (MIIT) on serum levels of resistin and various cardiometabolic health indices, were investigated.

Hypothesis: Supramaximal and moderate interval training induce comparable effects on serum resistin levels and cardiometabolic health indices.

Study design: Cohort study.

Methods: Thirty overweight adult women were assigned to 1 of 3 groups: HIIT (2 sets of 8 intervals, each with 30 seconds exercise at 100%-110% maximal aerobic speed [MAS] followed by 30 seconds rest at 50% MAS; for 6 weeks with 3 sessions per week), MIIT (2 sets of 8 intervals, each with 30 seconds exercise at 70%-80% MAS followed by 30 seconds rest at 50% MAS; for 6 weeks with 3 sessions per week), or a control group.

Results: Triglyceride levels were significantly higher in the control group compared with both the HIIT and MIIT groups (P = .02 and .01, respectively). High-density lipoprotein levels were also elevated significantly in the experimental groups compared with the control group (P = .04 and .03, respectively). Serum resistin increased significantly from pretest levels in the control group (P < .01). Between-group comparisons showed that resistin levels were significantly higher in the control group than in the experimental groups (P < .01 and .01, respectively).

Conclusion: Six weeks of HIIT can reduce resistin levels and improve cardiometabolic health indicators in nonpostmenopausal women. Although 6 weeks of MIIT does not reduce resistin, it does decrease systolic blood pressure and obesity-related factors in nonmenopausal women.

Clinical relevance: Supramaximal interval training may be recommended to control bioactive molecules produced from adipose tissue that are linked to CVD.

Background: Women's participation in all football codes (including Australian Football [AF]) is increasing rapidly. To guide injury prevention strategies, the authors aimed to describe the current and lifetime prevalence of significant musculoskeletal injuries and concussions for women and girls playing community AF.

Hypothesis: Women will have high rates of injury associated with playing AF.

Study design: Cross-sectional survey.

Level of evidence: Level 3.

Methods: Participants were Victorian community AF players from 165 participating teams (<16 years, <18 years, senior women's). Demographics, injury prevalence, and health outcomes are reported descriptively. To explore relationships between sociodemographic factors and anterior cruciate ligament (ACL) injury history, the authors fitted univariate logistic regression models. Independent variables were age, body mass index, number of career AF games, sport experience, location (metropolitan/regional), and socio-economic index.

Results: A total of 2435 players (95% of players enrolled in the trial), aged 24 ± 7 years completed the survey. One-quarter (n = 619, 25%) reported a current injury, and half (n = 1238, 51%) reported a previous significant injury. The most common injury sites were knee (n = 160 26% current, n = 403 33% previous), ankle (n = 130 21% current, n = 427 35% previous), and hand/fingers (n = 100 16% current, n = 317 26% previous). Self-reported previous ACL injury (n = 139, 6%) and concussion (n = 1335, 55%) were also prevalent. Increasing age (odds ratio [OR], 1.07; 95% CI, 1.05-1.09) and more career games (OR, 2.22; 95% CI, 1.24-3.97) were associated with ACL injury history.

Conclusion: Women and girls playing community AF reported high rates of significant injury. Injury prevention programs should target the most prevalent injury sites: head (concussion), ankle, knee, and hand/fingers.

Clinical relevance: These findings highlight high injury rates for women playing AF and will be invaluable in shaping injury prevention strategies.

Background: Acute caffeine ingestion can improve exercise performance. Interplay between caffeine habituation and training status on the performance-enhancing effect of caffeine is unknown.

Hypothesis: Habitual caffeine consumption and training status affect the ergogenicity of pre-exercise caffeine intake on exercise performance.

Study design: Double-blind, placebo-controlled, counterbalanced experimental design.

Level of evidence: Level 3.

Methods: Eighty physically inactive men were randomized into 1 of 4 groups: caffeine supplementation (CAF), caffeine supplementation + exercise training (CAFEXE), placebo (PLA), and placebo + exercise training (PLAEXE); high-intensity interval training and caffeine were administered for 9 and 8 weeks, respectively. Data were collected pre-test, mid-test, post-test, and delayed post-test, each including 2 experiment sessions (3 mg/kg caffeine or placebo), with an additional experiment session post-test (6 mg/kg caffeine). In each experiment session, 45-min after consuming a placebo or caffeine, a 3-km running test and a Wingate power test were performed.

Results: Pre-exercise ingestion of 3 mg/kg caffeine improved 3-km running time and mean power output (MPO) in all groups at all stages (P < 0.05); this effect was higher in trained than in untrained volunteers (P < 0.05). Habitual caffeine consumption reduced the ergogenic effect of caffeine in both aerobic and anaerobic trials (P < 0.05); 6 mg/kg caffeine enhanced this decrease only in CAFEXE (P < 0.05). Short-term caffeine withdrawal augmented the reduced ergogenic effect of caffeine on 3-km running performance and MPO in CAF and CAFEXE (P < 0.05).

Conclusion: Habituation to caffeine and training status could partially influence the ergogenic effects of caffeine on exercise performance.

Clinical relevance: Regular caffeine consumption leads to some degree of tolerance and decreases its ergogenicity. A pre-exercise increase in caffeine dosage in trained people and short-term caffeine withdrawal in both trained and untrained people could compensate for the reduced caffeine ergogenicity in young men.