The effects of strenuous isokinetic eccentric exercise on neuromuscular and sensorimotor performance of the knee flexors in adults and children
Thesis or dissertation
University of Exeter
The main concern of this thesis was to evaluate the effects of strenuous eccentric exercise on specific indices of neuromuscular and sensorimotor performance. The effects and symptoms of exercise-induced muscle damage (EIMD) have been very well documented in adult populations. They include impairments in muscle function (isometric and dynamic strength, power and rate of force development and flexibility), an increase in the release of muscle proteins (e.g. creatine kinase), delayed onset muscle soreness and an increase in perceived exertion. However, very little research has focussed on the effects of EIMD on electromechanical delay and sensorimotor performance. Even less attention has focussed on the effects of strenuous eccentric exercise on children populations. To date, only four studies have investigated the effects of EIMD in children, although these studies did not assess the effects of EIMD on sensorimotor performance. This thesis comprises six chapters: • Chapter 1: Introduction • Chapter 2: Review of Literature • Chapter 3: Reproducibility and Single Measurement Reliability of Indices of Neuromuscular and Sensorimotor Performance of the Knee Flexors in Adults and Children. • Chapter 4: Evaluation of the Effects of two bouts of strenuous isokinetic eccentric exercise on Sensorimotor and Neuromuscular Performance of the knee flexors in Men and Women. • Chapter 5: Evaluation of the effects of a bout of strenuous eccentric exercise on sensorimotor and neuromuscular performance of the knee flexors in young athletes. • Chapter 6: Further thoughts, conclusions and limitations. Chapter 3 examined the single-measurement reliability and reproducibility of selected indices of neuromuscular and sensorimotor performance that were deployed in the subsequent chapters of this thesis in adults and children. The results demonstrated no statistically significant differences (P > 0.05) between groups (males, females, boys and girls), which suggested that considerations regarding the testing protocols could be made on the same basis for all the selected groups. Similarly, no significant differences were observed between legs (preferred, non-preferred) in any of the involved groups. Furthermore, the findings demonstrated that single-trial protocols are not powerful enough for the accurate discrimination of intra-session differences in performance capabilities especially during intra-individual assessments and moreover are insufficient for the correct interpretation of neuromuscular and sensorimotor performance between days. Chapter 4 assessed the effects of two bouts of exercise-induced muscle damage on neuromuscular and sensorimotor performance of the knee flexors of both legs in males and females. The eccentric exercise protocols were associated with impaired peak force, elevated soreness, decreased passive flexibility, prolonged electromechanical delay and preserved sensorimotor performance. However, no significant differences between men and women were observed. Interestingly, the prolonged electromechanical delay and the preserved sensorimotor performance were the novel and most important findings of this study and were contrary to previous observations. Finally chapter 5 assessed the effects of a strenuous eccentric exercise protocol on neuromuscular and sensorimotor performance of the knee flexors of both legs in boys and girls (aged 11-14 years) who were members of the Exeter Tennis Centre. The eccentric exercise protocol was associated with impaired peak force, elevated soreness, decreased passive flexibility, and preserved electromechanical delay and sensorimotor performance. Interestingly, all impaired indices of muscle function returned to baseline 72 hours after the damaging protocol. Moreover, there were no significant sex differences. Further analysis revealed that boys and girls experienced milder symptoms of muscle damage than men and women, with the adult participants demonstrating higher levels of peak force decrease and of delayed onset muscle soreness.
Eston, Roger G
PhD in Sport and Health Sciences