Physiological Response Differences between Run and Cycle High Intensity Interval Training Program in Recreational Middle Age Female Runners.

The aim of this investigation was to compare the changes in endurance running performance and physiological variables after a four-week period of high intensity interval training (HIIT) in either running or cycling in female athletes. Fourteen recreational female runners (age = 42 10 yr, height = 1.67 0.06 m, body mass = 61.6 10.4 kg, body mass index (BMI) = 22.2 3.4 kg.m) were randomly allocated to one of two HIIT training groups: running (HIIT) or cycling (HIIT). Each group performed two HIIT sessions per week for 4 weeks, which consisted of 6 x 2 min at 95% of maximal heart rate (HR) and 4 x 1 min all out efforts. Maximal oxygen consumption (VO) in treadmill running increased significantly after the HIIT (p < 0.01, ES = 0.6) but remained unchanged in HIIT. However, HIIT improved average velocity in a 10 km running time trial (TT) (p < 0.05, ES = -0.4), whereas, no changes were found for the HIIT group. Analysing the first and last HIIT sessions, for HIIT only the average rate of perceived exertion (RPE) increased significantly, whereas, performance variables such as average heart rate (HR) and average pace (pace) remained unchanged. HIIT enhanced significantly the average speed of HIIT sets (speed) and the peak power output (PPO) of the session, as well as, the RPE and delayed onset muscle soreness immediately after HIIT session (DOMS) were increased significantly. A regime of HIIT in cycling may evoke increases in female recreational runners' power, which may be related with improvements in a 10 km TT independent of changes in aerobic capacity. This may be advantageous in order to avoid overuse running related injuries.