Abstract
Aging is associated with a loss of muscle mass and functional capacity. Present study was designed to compare the impact of specific dairy proteins on muscular function with or without a low-intensity physical activity program on a treadmill in an aged rat model. We investigated the effects of nutritional supplementation, five days a week over a 2-month period with a slow digestible protein, casein or fast digestible proteins, whey or soluble milk protein, on strength and locomotor parameters in sedentary or active aged Wistar RjHan rats (17–19 months of age). An extensive gait analysis was performed before and after protein supplementation. After two months of protein administration and activity program, muscle force was evaluated using a grip test, spontaneous activity using an open-field and muscular mass by specific muscle sampling. When aged rats were supplemented with proteins without exercise, only minor effects of different diets on muscle mass and locomotion were observed: higher muscle mass in the casein group and improvement of stride frequencies with soluble milk protein. By contrast, supplementation with soluble milk protein just after physical activity was more effective at improving overall skeletal muscle function in old rats compared to casein. For active old rats supplemented with soluble milk protein, an increase in locomotor activity in the open field and an enhancement of static and dynamic gait parameters compared to active groups supplemented with casein or whey were observed without any differences in muscle mass and forelimb strength. These results suggest that consumption of soluble milk protein as a bolus immediately after a low intensity physical activity may be a suitable nutritional intervention to prevent decline in locomotion in aged rats and strengthen the interest to analyze the longitudinal aspect of locomotion in aged rodents.
Highlights
Sarcopenia is the involuntary decline in lean muscle mass, strength, and function that occurs with aging [1,2,3]
One randomized control trial (RCT) has demonstrated that an increase in dietary protein (i.e. 30 g/day/week during 24 weeks) combined with twiceweekly progressive resistance training in a frail elderly population induced an average increase of 1.3 kg in lean body mass compared with exercise alone, there was no effect of protein intake on strength or physical performance, with both the supplemented and the un-supplemented group experiencing a similar degree of improvement [16]
The present study was designed to compare the impact of specific dairy protein supplementations on muscular function with or without a low-intensity physical activity program in a rodent model of aging
Summary
Sarcopenia is the involuntary decline in lean muscle mass, strength, and function that occurs with aging [1,2,3]. One randomized control trial (RCT) has demonstrated that an increase in dietary protein (i.e. 30 g/day/week during 24 weeks) combined with twiceweekly progressive resistance training in a frail elderly population induced an average increase of 1.3 kg in lean body mass compared with exercise alone, there was no effect of protein intake on strength or physical performance, with both the supplemented and the un-supplemented group experiencing a similar degree of improvement [16]. Another RCT in non-frail elderly subjects who underwent resistance training has reported a significant additional beneficial effect on muscle strength of a cysteine-rich whey versus casein protein supplementation [17]. These studies have underscored the importance of the nature of the proteins selected for the nutritional strategy, and their digestibility rate (i.e. rapidly versus slowly digested proteins) [26], as well as their amino-acid composition [27]
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