Characteristics of quadriceps fatigue induced by continuous maximal knee extension among young and elderly adult men with different levels of physical activity
Affiliations: [a] Yuanpei College, Shaoxing University, Zhejiang, China | [b] Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai, China | [c] Department of Kinesiology and Health, Georgia State University, GA, USA | [d] Chinese Medicine Integrated with Western Medicine College, Fujian University of Traditional Chinese Medicine, Fujian, China | [e] Teacher Education College, Shaoxing University, Zhejiang, China
Note: [1] Sihong Zhou and Xini Zhang contributed equally.
Abstract: BACKGROUND: Skeletal muscle strength can be impacted by various factors. However, the possible effects of different forms of exercises on the elderly’s muscle strength remain unknown. Furthermore, whether the level of physical activity influences the effects of an exercise-based training also remains unclear. OBJECTIVE: To investigate the characteristics of fatigued quadriceps by continuous maximum knee extension movements among different male groups under different physical conditions. METHODS: A total of 36 male participants (24 elderly and 12 youth) were divided into three groups, namely, young male group, and two groups of elderly participants: physically active and physically inactive. All groups underwent two sets of fatigue procedures. They initially finished 30 isokinetic maximum knee extension contractions at 60∘/s. Three days later, they completed 50 isokinetic maximum knee extension at 180∘/s. Then, their muscle strength characteristics were assessed. RESULTS: During the 60∘/s fatigue test the total work of the dominant and non-dominant quadriceps in the two elderly groups was significantly lower than that of the young male group (p< 0.05). Moreover, the total work of dominant quadriceps in physically active elderly male group was significantly higher than physically inactive male group in the middle (71.1 ± 12.0 vs. 52.0 ± 18.5 J) and the last third (60.9 ± 8.6 vs. 44.4 ± 15.4 J, p< 0.05). During the 180∘/s fatigue test the total work of dominant and non-dominant quadriceps in young male group was significantly higher than their elderly counterparts (p< 0.05). Moreover, the total work of dominant quadriceps in physically active elderly male group was significantly higher than in the physically inactive male group in the first (48.9 ± 4.6 vs. 31.7 ± 6.3 J), the middle (41.2 ± 4.8 vs. 26.1 ± 3.5 J), and the last third (33.3 ± 7.0 vs. 20.3 ± 3.1 J, p< 0.05). CONCLUSION: Exercise is associated with improved function and fatigue resistance of the quadriceps in elderly people. Moreover, the implications of the bilateral quadriceps’ imbalance in this group may be of functional importance and should thus be clinically considered.
