Unilateral Fatiguing Exercise And Its Effect On Relative, Percent Change Differences Between Vastus Lateralis Muscles

Abstract

: Relative, percent change differences between homologous vastus lateralis muscles across different resting muscular lengths have not previously been reported following the cessation of unilateral fatiguing aerobic exercise. PURPOSE: The purpose of the present study was to compare contralateral cross-over adaptations following unilateral fatiguing exercise, between different aerobically trained populations, across resting postural positions (RPPs) that incorporated different hip and knee joint angles. METHODS: Twenty healthy, college-aged men (mean ± SD; age = 22.9 ± 3.5 years and 22.8 ± 2.6 years; height = 181 ± 7.5 cm and 180 ± 5.9 cm; weight = 87.2 ± 10.7 kg and 85.2 ± 10.5 kg; BMI = 26.6 ± 3 kg/m2 and 26.2 ± 2.2 kg/m2; dominant thigh skinfold thickness = 15.1 ± 4.6 mm and 14.55 ± 5.3 mm; non-dominant thigh skinfold thickness = 15.55 ± 3.5 mm and 15.2 ± 3.8 mm; and VO2 peak 25.1 ± 4.3 ml/kg/min and 44.7 ± 3.7 ml/kg/min, for the 10 novice and 10 advanced trained participants, respectively) exercised on an upright cycle ergometer, using only their dominate limb, for 30 minutes at 60% of their VO2 peak. Resting surface electromyographic (sEMG) and mechanomyographic (MMG) signals were measured prior to and following exercise. RESULTS: The results indicated that the relative, percent change difference of the normalized MMG amplitude values were 7.6% and 4%; 9.1% and 7.5%; 5.7% and 3.9%; and 3.7% and 2%; while the results for the relative, percent change difference of the normalized MMG mean frequency values were 4.7% and 5.7%; 8.4% and 7.4%; 4.2% and 3.2%; and 2.7% and 3.7% (for the upright sitting position with legs extended 180° [1]; upright sitting position with legs bent 90° [2]; lying supine position with legs extended 180° [3]; and lying supine with legs bent 90° [4], respectively), for the novice and advanced groups, respectively. CONCLUSION: Our results provide further evidence to the concept that muscles are capable of possessing MMG activity post-exercise, despite a lack of sEMG signals. Additionally, our results suggest that there may be multiple neural and mechanical mechanisms concurrently contributing to the contralateral cross-over adaptations observed across the post-exercise recovery time course.