Lifelong treadmill training improves muscle function detected by a modified grip strength test during aging in BALB/c mice

Abstract

Aims: The objective of this study was to establish a more accurate analytical model and method for grip strength test of mice and to investigate the beneficial effects of lifelong exercise training to prevent functional decline of muscle during aging.

Main methods: Fifty randomly selected adult male BALB/c mice (24-56 week age) were used in grip strength testing periodically with short periods (3 s). Such method was used to detect a modified grip strength test. Then sixty-four male BALB/c mice (6 week age) were assigned into groups Sedentary (n = 32), Exercise (n = 32, lifelong treadmill training 3 days per week and 30 min per day). The muscle strength and morphology parameters were measured at the ages of 6, 12, 30 and 64 weeks, respectively.

Key findings: The grip strength (peak value and endurance) of sedentary group monotonically decreased in adult BALB/c mice during aging, while that of exercise group remained a relatively high level even slightly increased at aged period. Meanwhile, lifelong exercise training could slow down the loss of gastrocnemius muscle mass, myofiber cross-sectional area, myonuclear number and myonuclear domain. The number of myofibers was relatively stable in adult mice.

Significance: Modified analytical method for grip strength testing, with improved accuracy and reliability, may be an efficient substitute for conventional method in measuring the strength and endurance of mice and investigating the effect of lifelong exercise on muscle loss. Lifelong exercise training helps prevent muscle loss and muscle defunctionalization while aging.

Keywords: Grip strength test; Lifelong exercise; Myonuclei; Sarcopenia; Training.