Running on a lower-body positive pressure treadmill: VO2max, respiratory response, and vertical ground reaction force

This study investigated maximal oxygen consumption (VO2max) and time to exhaustion while running on a lower-body positive pressure treadmill (LBPPT) at normal body weight (BW) as well as how BW support affects respiratory responses, ground reaction forces, and stride characteristics.

Twelve runners performed VO2max tests on a regular treadmill and an LBPPT. Furthermore, they performed steady-state running (10km/hr, 14 km/hr, and 18 km/hr) and high-speed running (20km/hr and 22 km/hr) at four different BWs on the LBPPT. VO2, heart rate, ventilation, and breathing frequency as well as vertical ground reaction force (vGRF) and stride characteristics were measured.

VO2max could be obtained on both treadmills, although time to exhaustion was 34.5% longer on the LBPPT. VO2, ventilation, and heart rate decreased linearly with increasing BW support at steady-state running, while breathing rate remained unaffected by increasing BW support. Ground reaction force was markedly reduced with increasing BW support. The contact time decreased and flight time increased with increasing BW support. The step frequency decreased and step length increased to some extent with increasing BW support.

VO2max can be achieved on an LBPPT at 100% BW with an incline-running protocol. The LBPPT is a suitable training device for athletes and allows training at high running speeds and high aerobic stimuli with the benefit of low vGRF and a near-normal movement pattern, although manipulation of gravitational weight causes some adaptations in locomotion.