High-intensity Interval Training Shock Microcycle Improves Running Performance but not Economy in Female Soccer Players

This study aimed to evaluate the effect of high-intensity interval training shock microcycles (HIITSM) on endurance, running economy and change of direction economy in female soccer players. Nineteen sub-elite female soccer players were randomised to two groups: HIITSM (10 HIIT sessions over 13 days) or HIITTRAD (4 HIIT sessions over 13 days) interventions. Endurance performance was evaluated through the 30–15 intermittent fitness test (30–15IFT); running economy over a 5-min treadmill run; and change of direction economy over two conditions: (1) 5-min 20m shuttle run, and (2) 5-min 10m shuttle run. HIITSM significantly improved 30–15IFT scores compared to baseline (+4.4%, p=0.009; d=0.96) and 30–15IFT scores relative to HIITTRAD (p=0.002; d=2.01). There was no significant interaction (group×time) for running economy and change of direction economy. Pre- to post- intervention there was a significant main time effect for blood lactate over 20m and 10m shuttle runs (p<0.001 and p=0.037, respectively), with large (d=0.93) and moderate (d=0.53) changes observed for the HIITSM over the two distances, respectively. HIITSM may be more effective than HIITTRAD to improve 30–15IFT over shorter training periods but may not affect running economy and change of direction economy.