Abstract
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; V˙ O2max 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.
Original language | English |
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Pages (from-to) | 1757-1767 |
Number of pages | 11 |
Journal | European Journal of Applied Physiology |
Volume | 115 |
Early online date | 31 Mar 2015 |
DOIs | |
Publication status | Published - Aug 2015 |
Keywords
- Overtraining
- Antioxidant
- Reactive oxygen species
- Glucose
- Performance