High intensity exercise been shown to produce different acute exercise responses when compared to moderate intensity. Manipulating the rate of muscle contraction to alter intensity has received limited research. The primary purpose of this PhD was to investigate the potential mechanism that produces the acute differences observed when comparing high and moderate intensity exercise. Altering exercise intensity will be achieved through increased force and rate of contraction, as well as increased contraction rate alone. Methods In study 1, twelve recreationally active male participants completed 3 trials in random order consisting of 7x30second sprint cycles at 130%peak power output (PPO)(SIE), 60 minutes at 55% PPO (MICE), and a rest trial where no exercise was performed. In study 2 a separate nineteen recreationally active male participants cycled for 1-hr at 55% PPO at either 65-rpm or 95-rpm. In study 3 a separate eighteen recreationally active males completed a replica study similar to study 2 but with the addition of a 41minute submaximal trial at 95rpm at 55% PPO. Indirect calorimetry was used to measure a number of metabolic variables during exercise. Muscle biopsies were performed as part of study 1 and 3. Results Study 1: Significantly lower glycogen (94±24 vs 108±30 vs 125±31 mmol/kg/wt p=<.001) and increased insulin sensitivity (0.28±0.05 vs 0.25±0.04 vs 0.22±0.04 GIR p=<0.05) were observed 24 hours post SIE when compared to MICE. Study 2: Significantly greater carbohydrate utilisation (2.48±0.2 vs 1.97±0.2g/min p=<.01) was observed when exercising at 95rpm vs 65rpm at 55%PPO. Study 3: Greater total glycogen use per contraction was observed (-0.008±0.002 vs -0.006±0.002 mmol/kg/min p=<.05) at 95vs65rpm. xix Conclusions There were no fibre specific differences in glycogen use between trials. Increased glycogen use observed following SIE exercise is also observed following MICE at an increased contraction rate. The increase in glycogen use was not shown to occur as a result of increased type 2 fibre recruitment alone.