6-week High-intensity Interval Training (HIIT) of the Lower Extremities Improves VO2max of the Upper Extremities

High intensity interval training (HIIT) is widely used to improve VO_2max. The purpose of this study was to examine if lower extremity HIIT resulted in improved maximal oxygen uptake (VO_2max) and peak power output (PPO) of the upper extremities. Twenty healthy and trained participants (11 female and 9 male, VO_2max 3160±1175 ml/min) underwent a 6-week HIIT program of the lower extremities on a cycle ergometer. Before and after the training period a maximal cycle ergometry (CE) and a maximal hand crank ergometry (HCE) were conducted to determine VO_2max and PPO. Additionally, hematological parameters were determined. Increases in VO_2max of the lower extremities (3160±1175 to 3449±1231 ml/min, p<0.001, η²p=0.779) as well as of the upper extremities (2255±938 to 2377±1015 ml/min, p=0.010, η²p=0.356) from pre- to post-test were found. PPO of the lower extremities increased (243±95 to 257±93 W, p<0.001, η²p=0.491), whereas it remained unchanged for the upper extremities (103±50 to 108±54 W, p=0.209, η²p=0.150). All hematological parameters increased. The results demonstrate that VO_2max of the upper extremities increased after 6-weeks of cycling HIIT. However, upper body PPO was unchanged.