Muscle oxygenation is associated with bilateral strength asymmetry during isokinetic testing in sport teams

Objectives. - Muscle oxygenation capacity is a metabolic component that can influence the bilateral strength asymmetry. This study measured the muscle oxygen saturation (SmO2) during a protocol of high-intensity isokinetic fatigue (FAT) and its relationship with the body composition (BD) at the local level of the vastus lateralis. Methods. - Twenty-two rugby players (age 22.5 & PLUSMN; 4.6 years, weight 89.8 & PLUSMN; 12.6 kg, height 176.4 & PLUSMN; 7.8 cm) performed a FAT test to obtain the peak moments (PM) torque of the knee muscle flexors and extensors. SmO2 dynamics was evaluated using a portable NIRS, where muscle oxygen consumption, critical oxygenation, muscle oxygen extraction and recovery curves were obtained. The localized thigh BD was evaluated with dual-energy absorptiometry (DEXA). The tests were evaluated by dominant leg (DL) and non-dominant leg (not DL). Results. - Greater average peak torque were found in the DL of the knee extensor muscles (DL: 157 +/- 28 vs. NDL: 148 +/- 25; P = 0.028). Similarly, a SmO2 difference (DL: 11.7 +/- 10.1 vs. NDL: 16.3 +/- 13.2; P = 0.044) and critical oxygenation (DL: 20.8 +/- 10.1 vs. NDL: 26.3 +/- 12; P = 0.049) isassociated with greater bilateral strength asymmetry (r = 0.618 P = 0.01 and r = 0.447 P = 0.03). Also, a greater muscle mass showed an association with a better muscle oxygen extraction. Conclusions. - This study highlights the use of SmO2 dynamics as a complement to isokinetictests in order to identify muscle metabolism and muscle imbalances in team sports such asrugby. (c) 2023 Elsevier Masson SAS. All rights reserved.