Vitamin C and E supplementation alters protein signalling after a strength training session, but not muscle growth during 10 weeks of training

Abstract

Key pointsr Although antioxidant supplements are generally believed to give health benefits, recent experiments show that they may adversely affect adaptations to endurance exercise.r This study is the first to investigate the effects of high dosages of vitamins C and E on the cellular and physiological adaptations to strength training in humans.r Here we report that vitamin C and E supplementation interfered with exercise-induced signalling in muscle cells after a session of strength training, by reducing the phosphorylation of p70S6 kinase and mitogen-activated protein kinases p38 and ERK1/2. r The vitamin C and E supplement did not significantly blunt muscle hypertrophy during 10 weeks of training; however, some measurements of muscle strength revealed lower increases in the supplemented group than the placebo group.r Even though the cellular events are not clearly reflected in physiological and performance measurements, this study implies that redox signalling is important for inducing skeletal muscle adaptations to strength training and that vitamin C and E supplements in high dosages should be avoided by healthy, young individuals engaged in strength training.Abstract This study investigated the effects of vitamin C and E supplementation on acute responses and adaptations to strength training. Thirty-two recreationally strength-trained men and women were randomly allocated to receive a vitamin C and E supplement (1000 mg day −1 and 235 mg day −1 , respectively), or a placebo, for 10 weeks. During this period the participants' training involved heavy-load resistance exercise four times per week. Muscle biopsies from m. vastus lateralis were collected, and 1 repetition maximum (1RM) and maximal isometric voluntary contraction force, body composition (dual-energy X-ray absorptiometry), and muscle cross-sectional area (magnetic resonance imaging) were measured before and after the intervention. Furthermore, the cellular responses to a single exercise session were assessed midway in the training period by measurements of muscle protein fractional synthetic rate and phosphorylation of several hypertrophic signalling proteins. Muscle biopsies were obtained from m. vastus lateralis twice before, and 100 and 150 min after, the exercise session (4 × 8RM, leg press and knee-extension). The supplementation did not affect the increase in muscle mass or the acute change in protein synthesis, but it hampered certain strength increases (biceps curl). Moreover, increased phosphorylation of p38 mitogen-activated protein kinase, Extracellular signal-regulated protein kinases 1 and 2 and p70S6 kinase after the exercise session was blunted by vitamin C and E supplementation. The total ubiquitination levels after the exercise session, however, were lower with vitamin C and E than placebo. We concluded that vitamin C and E supplementation interfered with the acute cellular response to heavy-load resistance exercise and demonstrated tentative long-term negative effects on adaptation to strength training.

Vitamin C and E supplementation does not affect heat shock proteins or endogenous antioxidants in trained skeletal muscles during 12 weeks of strength training

“…Despite an increase in muscle mass over 10 weeks of training, we have reported that vitamin C and E supplementation blunted hypertrophy related signaling to the strength training session investigated in the present study [25]. Based on these results, we hypothesized that vitamin C and E supplementation would be able to blunt the stress induced by exercise, measured as reduced activation of NFκB pathway, and expression of HSPs (CRYAB and HSPB1) or antioxidant enzymes (SOD2 and GPx1).…”

“…Contrary to our initial hypothesis, vitamin C and E supplementation did not blunt the IκBα response or the concomitant changes in HSP (CRYAB and HSPB1) and endogenous antioxidant (SOD2 and GPx1) mRNA levels in response to a session of heavyload strength exercise. Despite an increase in muscle strength and mass in upper-and lower body exercises in both groups [25], no changes were observed in protein levels in the investigated HSPs (αB-crystallin, HSP27 or HSP70) or endogenous antioxidants (GPx1 and mnSOD) after 10 weeks of heavy load strength training.…”

“…Results on muscle mass and more strength measurements have been published previously [25]. In a randomized double blinded manner, participants were allocated to receive either a vitamin C and E or a placebo supplement based on baseline maximal strength tests (1RM) and sex.…”

New strategies in sport nutrition to increase exercise performance

“…In terms of a supplemental dose, the EFSA have recently stated that 4000iU is the maximum dose that should be used which we have also shown to be an effective dose in correcting deficiencies [146]. Recent work from our group [147] This is best exemplified by the notion that decreasing reactive oxygen species (ROS) generation with nutritional antioxidants, attenuates exercise-induced redox signalling, and thereby blunts exercise adaptation [150,151]. Over the last decade research has therefore somewhat switched focus from looking at exercise-induced ROS generation as being damaging at all times with nutrition focused on prevent any increase in ROS production…”

Effects of exercise on alterations in redox homeostasis in elite male and female endurance athletes using a clinical point-of-care test

“…Initially, RNOS were thought to be detrimental to athlete recovery, but it is now clear that RNOS are important for adaptation to endurance training (Finaud et al 2006, Ristow et al 2009, Powers et al 2010a, skeletal muscle hypertrophy and protein signaling (Makanae et al 2013, Paulsen et al 2014). Nonetheless, a critical balance (captured in the theory of hormesis; Radak et al, (2008) exists between the sufficient or "optimal" dose of RNOS to drive adaptation, and the overproduction of RNOS that could lead to apoptosis, immunosuppression, excessive fatigue and reduced performance (Levada-Pires et al 2008, Lewis et al 2015 The monitoring of elite athletes is widespread with considerable resources devoted to improving performance (Davison et al 2009).…”