The effects of tocotrienol supplementation on exercise-induced lipid peroxidation and endurance performance in the heat

Singh, Harbindar Jeet (2004) The effects of tocotrienol supplementation on exercise-induced lipid peroxidation and endurance performance in the heat. Singh. (Submitted)

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INTRODUCTION: The increase in oxygen consumption during endurance exercise leads to free radical (FR) production and subsequent lipid peroxidation (LIPOX). Raised body temperature has also been reported to increase the rate of FR production. This oxidative stress may impair endurance performance since FRs can cause cell damage and has been implicated in muscular fatigue. Vitamin E supplementation has been shown to attenuate FR-induced LIPOX. It is however unclear if vitamin E supplementation could decrease LIPOX and improve endurance running performance of heat-adapted recreational athletes in the heat. PURPOSE: This study examined the effects of tocotrienol (Palm Vitee) supplementation on exercise-induced LIPOX and endurance performance in the heat. METHODS: 18 healthy, male recreational athletes (aged: 24.9 ± 1.4 yrs; body weight: 59.6 ± 1.5 kg; V02max: 57.7 ± 1.5·1.min"1 ) completed two endurance running trials until exhaustion on a motorised treadmill at 70°/o V02max on two separate occasions following a 6-week supplementation of either vitamin E (E) or placebo (P). Both trials were conducted at an ambient temperature of 31°C and a 70°/o RH. During the trials, rectal temperature (T rec), skin temperature (Tsk). heart rate (HR) and ratings of perceived exertion (RPE) were recorded at 1 0-min intervals while oxygen uptake (V02) was recorded every 20 min. Blood samples were collected every 20 min during the running trials for the determination of plasma volume changes (PVC), lactate (LAC), glucose (GLU), free fatty acid (FFA), triglyceride (TRI), malondialdehyde (MDA), creatine kinase (CK), total antioxidant status (TAS) and vitamin E. RESULTS: No significant differences were evident in T rec• T Skt HR. RPE, vo2 or in the time to exhaustion between the E and P trials (81.1 ± 4.5 vs 76.9 ± 4.5 min respectively). Similarly, PVC, CK, LAC, GLU, FFA, TRI and TAS were also not different between the two trials. Vitamin E supplementation, however, resulted in a significantly higher (p<0.001) mean serum vitamin E concentration at rest and during post-exercise compared to that in the placebo tnal. Resting plasma MDA concentration in the E trial was significantly lower than that in the P trial (0.38 vs 0.46 pmol.l" 1 ; p<0.05). At exhaustion. plasma MDA was higher than the resting values in both trials and it was higher in the P trial compared to the E trial although the difference did not reach statistical significance (p=0.090). CK activity at exhaustion, 1 h and 24 h post-exercise was not different during the two trials but was significantly higher {p<0.001) than the corresponding resting values in both trials. CONCLUSION: Vitamin E supplementation decreased lipid peroxidation at rest and, to some extent, during exercise in the heat as evident from the lower MDA levels. It however, does not enhance endurance running performance or prevent exercise-induced muscle damage during exercise in the heat. In addition, vitamin E supplementation did not influence the changes of some of the physiological parameters (e.g. PVC, LAC, GLU, FFA, TRI, CK and TAS) that occurred during exercise in the heat.

Item Type: Article
Uncontrolled Keywords: Endurance running performance
Subjects: R Medicine
Divisions: Kampus Kesihatan (Health Campus) > Pusat Pengajian Sains Perubatan (School of Medical Sciences) > Article
Depositing User: Mr Abdul Hadi Mohammad
Date Deposited: 08 Oct 2019 03:55
Last Modified: 08 Oct 2019 03:55

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