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Twible, Bryce Daniel Lawrence

University of British Columbia

Inter-limb asymmetry (ILA) refers to an imbalance between contralateral limbs due to anatomical or physiological variations. With proposed links to injury risk, physical development, and athletic performance, ILA can significantly influence neuromuscular function. Investigating factors, such as neuromuscular fatigue, that can influence ILA is critical for optimizing training programs, injury rehabilitation, and sport-specific performance. PURPOSE: To determine if a single bout of hockey-specific exercise creates or exacerbates lower limb ILA, and to investigate if a dose-response relationship exists between the intensity of on-ice training and the extent of change to lower limb ILA. METHODS: Before and after an on-ice training session, 33 youth ice-hockey athletes (14.9±1.7 years; 11 females) performed three repetitions of a maximal vertical countermovement jump (CMJ), eccentric hamstring contraction, and maximal isometric hip adduction and abduction. Force- and power- related variables were analyzed to determine neuromuscular function, and ILA was calculated as: ILA = [(Stronger Limb – Weaker Limb) ÷ Stronger Limb)] × 100%). RESULTS: The fatiguing on-ice training session elicited reductions in maximal isometric hip adduction (left: −7.3±10.3%; right: −9.5±9.6%) and abduction (left: −4.9±6.9%; right: −5.0±8.1%) force. There were no reductions (p≥0.10) in CMJ performance metrics (jump height, relative peak power, braking duration, total duration). The ILA was greater (p<0.05) following the on-ice training session compared to pre-training for CMJ propulsive impulse (6.3±2.9% vs 5.1±2.6%), CMJ braking rate of force development (19.3±7.6% vs 15.2±6.4%), and peak isometric hip adduction force (6.7±5.5% vs 6.1±4.1%). Relative peak force ILA during the CMJ was greater for the females only (5.5±3.9% vs 4.1±2.6%). There were no pre- and post-training session differences detected in ILA for CMJ braking impulse (pre: 9.4±5.5%; post: 10.1±6.8%), peak isometric hip abduction force (6.4±3.8% vs 5.9±3.5%) or peak eccentric hamstring force (7.8±5.3% vs 9.3±5.8%). There was no significant relationship between the magnitude of ILA change and on-ice training intensity (p≥0.09). CONCLUSION: Inter-limb asymmetry is increased in youth hockey athletes following an on-ice training session, presumably owing to neuromuscular fatigue. These findings indicate that youth athletes may experience increased ILA to maintain bilateral task performance when fatigued.

Text

2023-07-11

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/85225

Health and Exercise Sciences

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/