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 (HIIT) on endurance, running economy and change of direction economy in female soccer players. Nineteen sub-elite female soccer players were randomised to two groups: HIIT (10 HIIT sessions over 13 days) or HIIT (4 HIIT sessions over 13 days) interventions. Endurance performance was evaluated through the 30-15 intermittent fitness test (30-15); 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. HIIT significantly improved 30-15 scores compared to baseline (+4.4%, p=0.009; =0.96) and 30-15 scores relative to HIIT (p=0.002; =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 (=0.93) an moderate (=0.53) changes observed for the HIIT over the two distances, respectively. HIIT may be more effective than HIIT to improve 30-15 over shorter training periods but may not affect running economy and change of direction economy.