Vitamin C supplementation does not alter high-intensity endurance training-induced mitochondrial biogenesis in rat epitrochlearis muscle

Effect of high-dose vitamin C and E supplementation on muscle recovery and training adaptation: a mini review

PURPOSE

This review aimed to investigate the effects of high-dose vitamins C and E supplementation combined with acute or chronic exercise on muscle recovery and training adaptation.

METHODS

We used PubMed, Web of Science, and Wiley Online Library databases to perform a literature search based on the keywords 'vitamin C, vitamin E, antioxidants, muscle recovery, training adaptation, and oxidative stress'.

RESULTS

Vitamin C or E supplementation has been reported to contribute to a reduction in oxidative stress and muscle damage; however, there is currently inadequate evidence of their positive effects on muscle recovery. Long-term vitamin C or E supplementation can have negative effects on physiological phenomena required for training adaptation, such as strength, muscle hypertrophy, and endurance. Numerous studies emphasized that an adequate diet consisting of fruits and vegetables is a more appropriate way of consuming antioxidants than supplementation.

CONCLUSION

The effects of high-dose vitamin C and E supplementation on post-exercise muscle recovery remain unclear and ambiguous, although there is evidence of potential negative effects on training adaptation.

Chronic administration of plasma from exercised rats to sedentary rats does not induce redox and metabolic adaptations

The present study aimed to investigate whether endurance exercise-induced changes in blood plasma composition may lead to adaptations in erythrocytes, skeletal muscle and liver. Forty sedentary rats were randomly distributed into two groups: a group that was injected with pooled plasma from rats that swam until exhaustion and a group that was injected with the pooled plasma from resting rats (intravenous administration at a dose of 2 mL/kg body weight for 21 days). Total antioxidant capacity, malondialdehyde and protein carbonyls were higher in the plasma collected from the exercised rats compared to the plasma from the resting rats. Νo significant difference was found in blood and tissue redox biomarkers and in tissue metabolic markers between rats that received the "exercised" or the "non-exercised" plasma (P > 0.05). Our results demonstrate that plasma injections from exercised rats to sedentary rats do not induce redox or metabolic adaptations in erythrocytes, skeletal muscle and liver.

Inhibition of Oxidative Stress by Antioxidant Supplementation Does Not Limit Muscle Mitochondrial Biogenesis or Endurance Capacity in Rats

The objective of the present study was to analyze the activation and expression patterns of upstream and downstream factors of PGC-1α to determine whether antioxidant (AO) supplementation inhibits mitochondrial biogenesis in skeletal muscles as an adaptation to endurance training, as well as to analyze changes in endurance capacity based on such findings. For this objective, 24 male Sprague-Dawley (SD) rats were allocated into 4 groups (vehicle-sedentary, V-Sed; vehicle-exercise, V-EX; antioxidant-sedentary, AO-Sed; antioxidant-exercise, AO-EX) of 6 rats each. The rats were then treated with vitamin C (500 mgkg^-1 body weightd^-1) or a placebo for 8 wk, and a swimming program was implemented in some rats during the last 4 wk of this period. Immediately after the last training session, blood was collected from the tail of each rat, and TBARS was measured to test the effect of vitamin C as an AO. As a result, increased oxidative stress from exercise was inhibited by vitamin C supplementation. Analysis of whether reduced oxidative stress by vitamin C supplementation also inhibited mitochondrial biogenesis within skeletal muscles showed that phosphorylation of p38 MAPK and AMPK, along with levels of PGC-1α, NRF-1, mtTFA, and mitochondrial electron transport enzymes, increased after endurance training in spite of vitamin C supplementation. Moreover, running time, distance, and total work increased significantly in the exercise group as compared to those in the sedentary group, regardless of vitamin C supplementation. These results indicate that mitochondrial biogenesis and endurance capacity increase as a result of endurance training, regardless of AO supplementation.

Moderate dependence of reactive oxygen species production on membrane potential in avian muscle mitochondria oxidizing glycerol 3-phosphate

Mitochondria are a major source of reactive oxygen species production in cells, and the production level is sensitive to the magnitude of the membrane potential (ΔΨ). The present study investigated the level of superoxide production in mitochondria oxidizing glycerol 3-phosphate (GP) and its dependence on ΔΨ in isolated avian muscle mitochondria. The levels of superoxide produced in mitochondria oxidizing GP were lower than those obtained with succinate and were similar to those obtained with NADH-linked substrates (glutamate/malate/pyruvate). The dependence of superoxide production on ΔΨ in mitochondria oxidizing GP was lower than that of mitochondria oxidizing succinate, and a weak dependence of GP-supported superoxide production on ΔΨ was observed in the presence of NADH-linked substrates or succinate. These results suggest that the levels of superoxide generated in response to GP are quantitatively low, but they are unsusceptible to changes in ΔΨ in avian muscle mitochondria.