Kiew, Oii Foong
(2010)
Effects of eurycoma longifolia jack
supplementation on recreational athletes'
running performance and physiological
responses in the heat.
Effects of eurycoma longifolia jack supplementation on recreational athletes' running performance and physiological responses in the heat.
Abstract
This study investigated the effects of Eurycoma longifolia Jack supplementation on
recreational athletes' endurance running capacity and physiological responses in the heal
Twelve healthy male recreational athletes (Age: 23.3 (3.7) years old; V021nax: 45.1 (8.1)) ml.kg"
1.min-1
) were recruited in this double blind, placebCH:ontrolled, cross-over study. Subjects
completed two endurance running trials in the heat (31°C, 70% relative humidity), perfonned on
separate days, after consuming either 2 capsules of Eurycoma longifolia Jack (75 mg per
capsule) or placebo per day for 7 days before and one hour prior to the experimental trial. On the
trial day, after 5 minutes warm-up at 50% V021nax, subjects were requested to run on the treadmill
at 60% V021nax for 60 minutes. This was immediately followed by a 20 minutes time trial for
detennining endurance running capacity. Blood samples were taken before warm-up, after warmup,
and every 20 minutes during the trial. Statistical analysis was perfonned using two-way
ANOVA with repeated measures. Results show that endurance running capacity was not
significantly different (P<0.05) between Eurycoma longifolia Jack (EL) and placebo (P) trials.
Similarly, oxygen uptake, heart rate, skin temperature, tympanic temperature, ratings of perceived
exertion, haemoglobin concentration, haematocrit level, plasma glucose concentration, and
plasma free fatty acid concentration were not significantly different between the trials. These
findings suggest that supplementation of Eurycoma longifo/ia Jack with a dosage of 150 mg.day''
for 7 days did not elicit beneficial effects on endurance running capacity and physiological
responses of recreational athletes in the heat. Higher dosage and longer duration of
supplementation of Eurycoma longifolia jack is warranted to elicit the positive effects during
endurance exercise.
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