Received January 10, 2008
Revised February 18, 2008
Accepted after revision March 17, 2008
Exercise training in late middle aged male F344BN rats improves skeletal muscle aerobic function
Andrew C Betik 1*,
David J Baker 1,
Daniel J Krause 1,
Marina J McConkey 1,
Russell T Hepple 1
1 University of Calgary
* To whom correspondence should be addressed. E-mail: abetik{at}kin.ucalgary.ca.
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Abstract |
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The Fisher 344BN-hybrid rat has become an increasingly popular and useful strain for studying age related declines in skeletal muscle function because this strain lives long enough to experience significant declines in muscle mass. Since exercise is often considered a mechanism to combat age-related declines in muscle function, determining the utility of this strain of rat for studying the effects of exercise on the aging process is necessary. The purpose of this study was to evaluate the plasticity of skeletal muscle aerobic function in late middle aged male rats following 7 weeks of treadmill exercise training. Training consisted of 60 min per day, 5 days per week with velocity gradually increasing over the training period according to the capabilities of individual rats. The final 3 weeks involved 2 min high intensity intervals to increase the training stimulus. We used in situ skeletal muscle aerobic metabolic responses and in vitro assessment of muscle mitochondrial oxidative capacity to describe the adaptations of aerobic function from the training. Training increased running endurance from 11.3 ± 0.6 to 15.5 ±0.8 min, an improvement of approximately 60%. Similarly, distal hindlimb muscles from trained rats exhibited a higher maximal oxygen consumption in situ (23.2 ± 1.3 µmol·min-1 versus 19.7 ± 0.8 µmol·min-1 for trained versus sedentary, respectively) and greater citrate synthase and complex IV enzyme activities in gastrocnemius (29% and 19% respectively) and plantaris (24% and 28% respectively) muscles compared to age-matched sedentary controls. Our results demonstrate that skeletal muscles from late middle aged rats adapt to treadmill exercise by improving skeletal muscle aerobic function and mitochondrial enzyme activities. This rat strain seems suitable for further investigations using exercise as an intervention to combat aging-related declines of skeletal muscle aerobic function.
Key Words:
Ageing, Exercise, VO2,max
