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Erschienen in:
01.08.2015 | Original Article
The impact of intensified training with a high or moderate carbohydrate feeding strategy on resting and exercise-induced oxidative stress
Erschienen in: European Journal of Applied Physiology | Ausgabe 8/2015
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Purpose
This study investigated the impact of intensified training (IT) and carbohydrate (CHO) supplementation on resting and exercise-induced oxidative stress.
Methods
Male cyclists (n = 13, mean ± SD: age 25 ± 6 years; \(\dot{V}{\text{O}}_{2\hbox{max} }\) 72 ± 5 ml/kg/min) undertook two 9 day periods of endurance-based IT. In a counter-balanced, crossover and double-blinded study design, participants completed IT whilst ingesting high (H-CHO) or moderate (M-CHO) CHO beverages before (H-CHO: 24 g vs. M-CHO: 2 g), during (H-CHO: 60 g/h vs. M-CHO: 20 g/h) and after training sessions (H-CHO: 44 g vs. M-CHO: 10 g). Participants completed fasted performance trials without CHO on days 2, 6 and 10. Blood samples were taken before and immediately after exercise to assess plasma oxidative stress.
Results
Resting thiol (-SH) and catalase (CAT) activities decreased following 6 days of IT, independent of CHO condition [-SH (μM oxidised NADPH): H-CHO—14.0 ± 18.8, M-CHO—20.4 ± 20.3 and CAT (nmol/min/ml): H-CHO 12.5 ± 12.5, M-CHO 6.0 ± 4.5; all p < 0.05]. Resting total antioxidant capacity (TAC) was reduced after IT in M-CHO. All exercise bouts elicited significant increases in CAT, TAC, protein carbonylation (PC) and lipid hydroperoxides (LOOH), independent of CHO condition (p < 0.05). The magnitude of increase in PC and LOOH was greater on days 6 and 10 compared to day 2 in both conditions.
Conclusions
Short-term IT caused reductions in resting antioxidant capacity in trained cyclists. Exercise-induced increases in PC and LOOH were exaggerated as a result of IT; however, these responses were independent of carbohydrate intake before, during and after the preceding IT sessions.