Among athletes, endurance is one of the key elements to victory. In addition to
training, athletes normally used supplement to prevent fatigue during the event. With
prolonged and intense activity, our body started to experience decrease in muscle
performance due to several factors such as oxidative stress, dehydration and
accumulation of lactic acid in the body fluids. The free radicals generated during
intense exercise will expose the cells to oxidative damages. In the event of
dehydration, there will be significant losses of water and functional electrolytes during
intense exercise which affected the body fluid balance. Fatigue will also occur during
reduced oxygen in aerobic metabolism which later caused accumulation of lactic acid
in the muscle. This will change the pH balance toward more acidic and caused the
muscles to lose contractile efficiency. In addition, fatigue can also be studied using rats
as model organism. Results from this activity can be useful to analyse cellular
metabolism and physiology effects of the tested rats toward physical exercise.
Therefore, this review aims to discuss the causes of fatigue through oxidative stress,
dehydration and lactic acid accumulation. In addition, the effectiveness of using rats as
a model system in measuring fatigue is also included in illustrating examples on fatigue
assessment in vivo.