 Study Protocol: Two testing sessions, on nonconsecutive days, will occur at least 72 hours prior to the start of the training period. The same testing protocols will be repeated at the end of the 4-week training period. Testing protocols include performance testing VO2peak, lactate threshold, critical power, anaerobic working capacity and neuromuscular economy and anthropometric measures physiological cross-sectional area and muscle quality. The training protocol for individuals in the experimental groups will consist of 4-weeks of high intensity interval training with three sessions per week on an electronically braked cycle ergometer. Individual work -loads will be calculated based on the outcomes from each participants preliminary testing. 