The effects of tocotrienol supplementation on exercise-induced \nlipid peroxidation and endurance performance in the heat
Year: 2004
Type: article
Abstract: INTRODUCTION: The increase in oxygen consumption during endurance \nexercise leads to free radical (FR) production and subsequent lipid peroxidation (LIPOX). \nRaised body temperature has also been reported to increase the rate of FR production. \nThis oxidative stress may impair endurance performance since FRs can cause cell \ndamage and has been implicated in muscular fatigue. Vitamin E supplementation has \nbeen shown to attenuate FR-induced LIPOX. It is however unclear if vitamin E \nsupplementation could decrease LIPOX and improve endurance running performance of \nheat-adapted recreational athletes in the heat. PURPOSE: This study examined the \neffects of tocotrienol (Palm Vitee) supplementation on exercise-induced LIPOX and \nendurance performance in the heat. METHODS: 18 healthy, male recreational athletes \n(aged: 24.9 ± 1.4 yrs; body weight: 59.6 ± 1.5 kg; V02max: 57.7 ± 1.5 ml.kg·1.min"1 \n) \ncompleted two endurance running trials until exhaustion on a motorised treadmill at 70°/o \nV02max on two separate occasions following a 6-week supplementation of either vitamin E \n(E) or placebo (P). Both trials were conducted at an ambient temperature of 31°C and a \n70°/o RH. During the trials, rectal temperature (T rec), skin temperature (Tsk). heart rate \n(HR) and ratings of perceived exertion (RPE) were recorded at 1 0-min intervals while \noxygen uptake (V02) was recorded every 20 min. Blood samples were collected every \n20 min during the running trials for the determination of plasma volume changes (PVC), \nlactate (LAC), glucose (GLU), free fatty acid (FFA), triglyceride (TRI), malondialdehyde \n(MDA), creatine kinase (CK), total antioxidant status (TAS) and vitamin E. RESULTS: No \nsignificant differences were evident in T rec• T Skt HR. RPE, vo2 or in the time to exhaustion \nbetween the E and P trials (81.1 ± 4.5 vs 76.9 ± 4.5 min respectively). Similarly, PVC, \nCK, LAC, GLU, FFA, TRI and TAS were also not different between the two trials. Vitamin \nE supplementation, however, resulted in a significantly higher (p<0.001) mean serum \nvitamin E concentration at rest and during post-exercise compared to that in the placebo \ntnal. Resting plasma MDA concentration in the E trial was significantly lower than that in \nthe P trial (0.38 vs 0.46 pmol.l" 1 \n; p<0.05). At exhaustion. plasma MDA was higher than \nthe resting values in both trials and it was higher in the P trial compared to the E trial \nalthough the difference did not reach statistical significance (p=0.090). CK activity at \nexhaustion, 1 h and 24 h post-exercise was not different during the two trials but was \nsignificantly higher {p<0.001) than the corresponding resting values in both trials. \nCONCLUSION: Vitamin E supplementation decreased lipid peroxidation at rest and, to \nsome extent, during exercise in the heat as evident from the lower MDA levels. It \nhowever, does not enhance endurance running performance or prevent exercise-induced \nmuscle damage during exercise in the heat. In addition, vitamin E supplementation did \nnot influence the changes of some of the physiological parameters (e.g. PVC, LAC, GLU, \nFFA, TRI, CK and TAS) that occurred during exercise in the heat.
Author: Singh, Harbindar Jeet
Language: English
Subfield: Physiology (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7018834397