(14) SEASONAL CHANGES IN COUNTERMOVEMENT JUMP AND ISOKINETIC TESTING PERFORMANCE IN WOMEN COLLEGIATE LACROSSE ATHLETES

Background: Neuromuscular (NM) fatigue level can be monitored using countermovement jump (CMJ) via force plates. Concurrently, adequate training load must be prescribed to improve muscular strength, which can be monitored via isokinetic testing. Limited data exist regarding NM fatigue experienced by collegiate women athletes.

Purpose: To investigate seasonal changes in lower body strength and power performance in women collegiate lacrosse athletes.

Methods: National Collegiate Athletic Association Division I women lacrosse athletes (n=9, mean ± SD; age=19.1±0.9 years, hheight=168.4±6.8 cm, body mass=69.0±7.8 kg) participated. Testing took place four times across the macrocycle: pre-season start (time 1), preseason end (time 2), in-season start (time 3), and off-season end (time 4). Following a standardized dynamic warm-up, athletes performed 3 CMJ on a force plate (1600 Hz sampling rate). CMJ metrics included: reactive strength index modified (RSImod), jump height, relative values of unloading force (UF), braking force (BF), peak power (PP), peak propulsive force (PPF), and landing force (LF). Following CMJ, in the same session, isokinetic strength testing for dominant (D) and non-dominant (ND) legs was conducted and consisted of knee flexion/extension at 60°/s (5 concentric & eccentric repetitions (reps) and 300°/s (7 concentric & eccentric reps). Relative peak torques within the isokinetic phase from each testing mode, speed, and leg were used for analysis. Metrics were post-processed using personalized MATLAB scripts. Repeated measures analysis of variance (ANOVA) assessed changes in strength and power across time (p < 0.05). Post-hoc analysis included Bonferroni corrections.

Results: Measures across time points 1-4 are presented in Figure 1. For measures of CMJ performance, decreases in RSImod (p=0.03), PPF (p=0.006), and BF (p=0.004) occurred between time 1 and 4. Isokinetic strength variables at 60°/s decreased from time 1 to 2 (p < 0.001) except for D leg concentric hamstring strength. Quadriceps and hamstring strength variables increased from time 2 to 3 (p < 0.001). D and ND eccentric, ND concentric quadriceps strength, and D leg hamstring strength increased from time 3 to 4 (p < 0.001). However, ND concentric quadriceps strength decreased from time 3 to 4 (p < 0.001). No changes were observed in isokinetic strength at 300°/s.

Conclusion: No change in NM fatigue level (i.e., CMJ) was observed due to the competitive season; however, off-season training decreased CMJ performance. Lower body strength at 60°/s was improved during the competitive season. PRACTICAL APPLICATION: Findings from the current study indicate in-season power performance can be maintained with appropriate exercise selection and adequate stimuli. However, high-intensity training in the off-season may cause accumulation of fatigue and a subsequent decrease in performance assessment, which highlights the importance of using periodization to elicit positive training adaptations.


Acknowledgements: None