Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double‐blind, randomised, controlled trial

Abstract

Key pointsr Recent studies have indicated that antioxidant supplementation may blunt adaptations to exercise, such as mitochondrial biogenesis induced by endurance training. However, studies in humans are sparse and results are conflicting.r Isolated vitamin C and E supplements are widely used, and unravelling the interference of these vitamins in cellular and physiological adaptations to exercise is of interest to those who exercise for health purposes and to athletes.r Our results show that vitamin C and E supplements blunted the endurance training-induced increase of mitochondrial proteins (COX4), which is important for improving muscular endurance.r Training-induced increases inV O 2 max and running performance were not detectably affected by the supplementation.r The present study contributes to understanding of how antioxidants may interfere with adaptations to exercise in humans, and the results indicate that high dosages of vitamins C and E should be used with caution.Abstract In this double-blind, randomised, controlled trial, we investigated the effects of vitamin C and E supplementation on endurance training adaptations in humans. Fifty-four young men and women were randomly allocated to receive either 1000 mg of vitamin C and 235 mg of vitamin E or a placebo daily for 11 weeks. During supplementation, the participants completed an endurance training programme consisting of three to four sessions per week (primarily of running), divided into high-intensity interval sessions [4-6 × 4-6 min; >90% of maximal heart rate (HR max )] and steady state continuous sessions (30-60 min; 70-90% of HR max ). Maximal oxygen uptake (V O 2 max ), submaximal running and a 20 m shuttle run test were assessed and blood samples and muscle biopsies were collected, before and after the intervention. Participants in the vitamin C and E group increased theirV O 2 max (mean ± S.D.: 8 ± 5%) and performance in the 20 m shuttle test (10 ± 11%) to the same degree as those in the placebo group (mean ± S.D.: 8 ± 5% and 14 ± 17%, respectively). However, the mitochondrial marker cytochrome c oxidase subunit IV (COX4) and cytosolic peroxisome proliferator-activated receptor-γ coactivator 1 α (PGC-1α) increased in the m. vastus lateralis in the placebo group by 59 ± 97% and 19 ± 51%, respectively, but not in the vitamin C and E group (COX4: −13 ± 54%; PGC-1α: −13 ± 29%; P ࣘ 0.03, between groups). Furthermore, mRNA levels of CDC42 and mitogen-activated protein kinase 1 (MAPK1) in the trained muscle were lower in the vitamin C and E group than in the placebo group (P ࣘ 0.05). Daily vitamin C and E supplementation attenuated increases in markers of mitochondrial biogenesis following endurance training. However, no clear interactions were detected for improvements inV O 2 max and running performance. Consequently, vitamin C and E supplementation hampered cellular adaptations in the exercised muscles, and although this did not translate to the performance tests applied in this study, we advocate caution when considering antioxidant supplemen...

Ryanodine receptor fragmentation and sarcoplasmic reticulum Ca 2+ leak after one session of high-intensity interval exercise

“…The induction of RyR1 fragmentation resulting in a long-lasting increase in resting [Ca 2+ ] i provides a mechanism for how a short session of HIIT exercise (≤3 min) can be highly effective in triggering muscle adaptations. Moreover, the ROS dependency of RyR1 modifications offers a tentative explanation as to why an effective antioxidant treatment hampers beneficial adaptations induced by endurance training (17)(18)(19). Finally, destabilized RyR1 has predominantly been linked to muscle weakness in several pathological conditions as well as in normal aging (8)(9)(10)(11)(12)(13), but here we show that RyR1 modifications can also have an integral role in physiological muscle adaptations.…”

“…Conversely, altered RyR1 function may also be beneficial by increasing the cytosolic free [Ca 2+ ] ([Ca 2+ ] i ) at rest, which can stimulate mitochondrial biogenesis and thereby increase fatigue resistance (14)(15)(16). Intriguingly, effective antioxidant treatment hampers beneficial adaptations triggered by endurance training (17)(18)(19), and this effect might be due to antioxidants preventing ROS-induced modifications of RyR1 (20).…”

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

“…Many athletes use antioxidant supplements [11] in the belief they could further protect against exercise induced stress and thus improve recovery. However, recent studies indicate that antioxidant supplementation have the ability to blunt training adaptations in skeletal muscle [12,13]. A proposed mechanism for the observed interference between antioxidant supplementation and training adaptations has been related to changes in redox status in the muscle, which in turn might affect cell signaling [14].…”

Ascorbic Acid and Performance: A Review

“…Interestingly, performance increased resistance to a greater extent in the animals treated with placebo compared with animals treated with Vitamin C. Thus, supplementation with high doses of vitamin C to decrease certain adaptations induced endurance training skeletal muscles [18]. In fact, high doses of isolated antioxidants should be used with caution in individuals who are simultaneously engaged in resistance training [19].…”