The Effect of One-Stage Global Fatigue on Coordination and Variability of Joints and Electrical Activity of Selected Lower-Limb Muscles of Elite Rowers: A Trauma Approach

Abstract

Introduction: Muscle fatigue due to exhaustive exercise is a common phenomenon that occurs during exercises and causes impaired motor function. The aim of the present study was to investigate the effect of one-stage global fatigue on the coordination and variability of joints and electrical activity of selected lower-limb muscles of elite rowers. Methods and Materials: A total of 14 rowers of the national men's rowing team participated in this quasi-experimental study. A rowing ergometer was used to induce global fatigue due to exhausting exercise. First, to measure mean power (MP), the subjects performed the 2000-m ergometer test. Fatigue protocol was performed after one week, (three 2-minute continuous tests with 60%, 90%, and 120% of MP). Electrical data of selected muscles were measured by electromyography and kinematic data were measured by IMU in 15 consecutive strokes at the beginning and end of the fatigue protocol. Shapiro-Wilk test was used to determine the normality of data distribution and dependent t-test was utilized to compare the dependent variables. P-value ≤0.05 was considered as the significant level in all tests. Results: The results showed a significant increase in the mean level of activity of biceps femoris, tibialis anterior, gastrocnemius medialis, and rectus femoris between pre-test and post-test (P≤0.05). The results also indicated a significant decrease in the coordination of ankle-knee and ankle-thigh joints in the sagittal plane and a significant increase in variability between ankle-knee joints in the sagittal plane and ankle-thigh joints in the sagittal and horizontal planes (P<0.05). Conclusion: Overall, fatigue seems to have a large effect on the mean activity and maximum activity of the muscles of the lower limbs in the sagittal and horizontal planes. Increased variability of the lower-limb joints following fatigue may be due to a decrease in strength or flexibility of the muscles in this area, which can adversely affect the performance of professional rowers and increase the risk of injury due to overactive musculoskeletal system.