title: Can supplementation with vitamin C and E alter physiological adaptations to strength training?
abstract: BACKGROUND
  Antioxidant supplementation has recently been demonstrated to be a double-edged sword, because small to moderate doses of exogenous antioxidants are essential or beneficial, while high doses may have adverse effects. The adverse effects can be manifested in attenuated effects of exercise and training, as the antioxidants may shut down some redox-sensitive signaling in the exercised muscle fibers. However, conditions such as age may potentially modulate the need for antioxidant intake. Therefore, this paper describes experiments for testing the hypothesis that high dosages of vitamin C (1000 mg/day) and E (235 mg/day) have negative effects on adaptation to resistance exercise and training in young volunteers, but positive effects in older men.
  
  
  METHODS
  We recruited a total of 73 volunteers. The participants were randomly assigned to receiving either vitamin C and E supplementation or a placebo. The study design was double-blinded, and the participants followed an intensive training program for 10-12 weeks. Tests and measurements aimed at assessing changes in physical performance (maximal strength) and physiological characteristics (muscle mass), as well as biochemical and cellular systems and structures (e.g., cell signaling and morphology).
  
  
  CONCLUSIONS
  Dietary supplements, such as vitamin C and E, are used by many people, especially athletes. The users often believe that high dosages of supplements improve health (resistance to illness and disease) and physical performance. These assumptions are, however, generally not supported in the scientific literature. On the contrary, some studies have indicated that high dosages of antioxidant supplements have negative effects on exercise-induced adaptation processes. Since this issue concerns many people and few randomized controlled trials have been conducted in humans, further studies are highly warranted.
  
  
  BACKGROUND
  ACTRN12614000065695.
authors: Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway ; Norwegian Olympic Sport Center, Oslo, Norway.
authors: Gøran
authors: G
authors: Paulsen
authors: Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
authors: Kristoffer T
authors: KT
authors: Cumming
authors: Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
authors: Håvard
authors: H
authors: Hamarsland
authors: University of Arkansas for Medical Sciences, Arkansas Children's Nutrition Center, Arkansas Children's Hospital Research Institute, Little Rock, Arkansas, USA.
authors: Elisabet
authors: E
authors: Børsheim
authors: Department of Public Health, Sport and Nutrition, Faculty of Health and Sport Sciences, University of Agder, Kristiansand, Norway.
authors: Sveinung
authors: S
authors: Berntsen
authors: Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway.
authors: Truls
authors: T
authors: Raastad
keywords: 1 repetition maximum; Antioxidants; Muscle mass; Muscle strength; Protocol paper