Whey protein supplementation accelerates satellite cell proliferation during recovery from eccentric exercise

Abstract

Human skeletal muscle satellite cells (SCs) are essential for muscle regeneration and remodeling processes in healthy and clinical conditions involving muscle breakdown. However, the potential influence of protein supplementation on post-exercise SC regulation in human skeletal muscle has not been well investigated. In a comparative human study, we investigated the effect of hydrolyzed whey protein supplementation following eccentric exercise on fiber type-specific SC accumulation. Twenty-four young healthy subjects received either hydrolyzed whey protein + carbohydrate (whey, n = 12) or iso-caloric carbohydrate (placebo, n = 12) during post-exercise recovery from 150 maximal unilateral eccentric contractions. Prior to and 24, 48 and 168 h post-exercise, muscle biopsies were obtained from the exercise leg and analyzed for fiber type-specific SC content. Maximal voluntary contraction (MVC) and serum creatine kinase (CK) were evaluated as indices of recovery from muscle damage. In type II fiber-associated SCs, the whey group increased SCs/fiber from 0.05 [0.02; 0.07] to 0.09 [0.06; 0.12] (p < 0.05) and 0.11 [0.06; 0.16] (p < 0.001) at 24 and 48 h, respectively, and exhibited a difference from the placebo group (p < 0.05) at 48 h. The whey group increased SCs/myonuclei from 4 % [2; 5] to 10 % [4; 16] (p < 0.05) at 48 h, whereas the placebo group increased from 5 % [2; 7] to 9 % [3; 16] (p < 0.01) at 168 h. MVC decreased (p < 0.001) and muscle soreness and CK increased (p < 0.001), irrespective of supplementation. In conclusion, whey protein supplementation may accelerate SC proliferation as part of the regeneration or remodeling process after high-intensity eccentric exercise.

Protein Supplementation Does Not Affect Myogenic Adaptations to Resistance Training

“…Olsen et al first demonstrated that chronic resistance exercise training (RET) with protein supplementation may provide a slight enhancement of the satellite cell pool compared to RET alone (32). Based on basic science and pre-clinical findings, we anticipated that protein supplementation would enhance satellite cell activity and content through mTORC1 (17, 40) and particularly on MHC II fibers (1, 11). Instead, we demonstrated similar increases in satellite cell content between treatments, which were driven primarily through increases in MHC II fibers.…”

“…Our hypothesis is that physiological adaptation may best explain the insensitivity to protein supplementation typically seen in chronic exercise studies. Farup and colleagues demonstrated that whey protein supplementation following eccentric exercise accelerated the satellite cell pool expansion compared to consumption of carbohydrate placebo (11). However, by 168 hr post exercise (11) and after 12 weeks of training (12) the satellite cell pool was identical between treatments.…”

“…Farup and colleagues demonstrated that whey protein supplementation following eccentric exercise accelerated the satellite cell pool expansion compared to consumption of carbohydrate placebo (11). However, by 168 hr post exercise (11) and after 12 weeks of training (12) the satellite cell pool was identical between treatments. For novice exercisers, peak satellite cell activity occurs after 2 weeks of RET (18).…”

“…Recently, Farup and colleagues have expanded upon these findings by demonstrating that this effect is muscle fiber-type-specific, as reported in results from both acute (11) and chronic studies (12). These findings in human skeletal muscle have been supported by basic and pre-clinical approaches demonstrating that nutrient provision (in particular the leucine metabolite HMB) enhances myogenic proliferation via mTORC1 signaling (27, 40).…”

Exercise and Stem Cells

“…Type II fiberassociated enhancement of satellite cell content and activation (as reflected by DLK1 expression) has been observed in young recreationally active men 1-3 days following an acute bout of maximal unilateral isolated eccentric exercise or traditional resistance-type exercise. [112][113][114][115] Resistance exercise training can also increase satellite cell content in young and aged men and women, 113,[116][117][118][119] and the increase has been demonstrated to be specific to type II fibers in elderly men and correlated with fiber size or muscle volume in young and aged men. 120,121 The strong relationship between satellite cell content and muscle fiber size postexercise would suggest a role for the satellite cell in growth, yet myonuclear accretion and/or new fiber synthesis are not consistently observed posttraining.…”