| Abstrakt: |
Problem statement: Changes in the neuromuscular system owing to aging can decrease strength and muscle power. Additionally, muscle architecture and quality are affected by the natural aging process. However, it has been suggested that lifelong physical exercise may attenuate or even prevent age-related decline in physical function. Nevertheless, it is still uncertain to what extent chronic and predominantly aerobic physical training delays age-related decreases in neuromuscular function, architecture, and muscle quality. Purpose: This study was designed to compare the muscle architecture, muscle quality, and neuromuscular function of the knee extensor muscles between middle-aged runners (MR, N = 25; 53.9 ± 2.5 y, 76.5 ± 12.3 kg) and older runners (OR, N = 16; 64.4 ± 3.5 y, 70.5 ± 9.8 kg). Approach: Measures of muscle architecture were: cross-sectional area, pennation angle, fascicle length, and muscle thickness of the vastus lateralis muscle. Echo intensity of the vastus lateralis muscle was used as a marker of muscle quality, while isometric absolute and relative peak torque, rate of torque development, voluntary activation level, peak twitch torque, contraction time, and half-relaxation time of the knee extensor muscles were used as markers of neuromuscular function. Results: The OR group presented lower cross-sectional area, pennation angle, muscle thickness, absolute peak twitch torque, 100–200 ms rate of torque development, and greater echo intensity. There were no other significant differences between OR and MR groups. Conclusions: These findings suggest that though older runners have approximately 20 years of running training, they presented lower values for some markers of muscle architecture and neuromuscular function, as well as lower muscle quality compared to middle-aged runners. [ABSTRACT FROM AUTHOR] |
