(2) LOWER BODY MUSCULOSKELETAL AND NEUROMUSCULAR PERFORMANCE IN NCAA DIVISION I TRACK AND FIELD AND CROSS-COUNTRY ATHLETES

Track and field and Cross-Country (TFXC) demand strenuous, frequent training to optimize musculoskeletal performance. Although beneficial, these chronic repetitive loading patterns contribute to a high incidence of lower extremity musculoskeletal stress injuries (MSIs). Research linking skeletal health, muscle morphology, force production, and excitation may provide insight to specific training adaptations and MSI etiology. PURPOSE: To compare lower extremity musculoskeletal characteristics between TFXC athletes and matched controls. METHODS: Thirty TFXC athletes (female n=21, male n=9) and controls, matched for sex, age (±2yrs), and weight (±5kg) who were physically active ≥3 days/wk provided voluntary informed consent, filled out injury and training frequency logs, and completed a total body and dual-hip Dual-energy X-ray Absorptiometry (DXA) scans allowing for regional assessments of bone and body composition measures. Real-time brightness mode ultrasonography assessed muscle thickness, pennation angle, and subcutaneous fat-corrected muscle echo intensity (mEI) of the vastus lateralis (VL) for each leg. Maximal voluntary isometric contractions were conducted to determine knee extensor peak force and spectral rate of force development (RFD) of each leg. Surface electromyographic amplitude (EMG_RMS) was recorded from the VL with bipolar sensors. Independent t-tests were used to compare group differences, with subsequent univariate analyses of bone and force metrics controlled for individual leg lean mass were ran. Cohen’s d effect sizes were calculated and α=0.050. RESULTS: Athletes’ lower extremity MSI incidence (3.3±2.8) was significantly greater than matched controls’ (1.1±1.5) (p=0.001; d=0.87). Athletes averaged 8.0±2.6 cardiovascular training sessions per week compared to controls 3.3±2.2 (p< 0.001; d=1.41), but controls resistance trained more frequently per week (3.4±1.5) than athletes’ (2.5±1.3) (p=0.017; d=0.61). Bilateral bone indices (all p< 0.001; d=0.47-1.00) and peak force (all p< 0.001; d=0.06-0.25) were superior in athletes after lean mass correction. Dominant leg RFD 50ms increments from 100-250ms were faster in controls (all p≤0.001; d=0.09-0.21) and EMG_RMS were similar between groups across all RFD time domains (50-250ms) (all p≥0.050; d=0.00-0.50). Athlete mEI (all p< 0.004; d=0.76-0.83) was better but muscle thickness (all p >0.050; d=0.31-0.34) and pennation angle (all p >0.050; d=0.06-0.20) were similar to controls. CONCLUSION: Despite athletes’ chronic training, superior force production and skeletal health indices are more associated with muscle quality than size and architecture, although force development and muscle excitation is not. PRACTICAL APPLICATIONS: Although frequent sport-specific training is developmentally essential and demonstrates superior skeletal health, muscle quality, and force production, variation in training may elicit adaptations to optimize force development capabilities, further benefitting performance and potentially reduce overuse injury risk.

Acknowledgements: None