Examining Change in Gait and Impact Forces on a Lower Body Positive Pressure Treadmill at 60% VO2peak Original Research

Abstract

Introduction: Running is one of the most popular forms of physical activity in the world providing many health benefits but also leads to an increase in overuse and tendinopathy injuries. Lower body positive pressure treadmills (LBPPT) reduce body-weight (BW) impact, benefiting individuals with musculoskeletal conditions or undergoing rehabilitation. Previous research indicates LBPPT could be a potential training alternative or reintroducing exercise sooner in rehabilitation process.  The purpose of this study was to examine average impact force and accumulated impact force over the course of a 5-km run at 60% of VO_2peak at various % BW to examine if there is a potential alternative to over-ground running.

Methods: In total, 20 aerobically fit individuals completed a VO_2peak and 5 counterbalance trials at 100% BW on a regular treadmill and 100%, 90%, 80% and 70% BW on a LBPPT. A linear mixed-effect model was used for all insole data and repeated-measures analysis of variance (ANOVA) tests of within-subject’s effects was performed for each variable.

Results: The results showed a significant difference in the time it took to run the 5-km as the BW decreased (100% RT: 33.8 ±  1.1 min; 100% LBPPT: 31.8 ± 0.9 min; 90%: 30.3 ±  1.0 min; 80%: 28.0 ±  1.0 min; 70%: 24.6 ± 0.7 min; p < 0.05). Average impact force per step did not differ between conditions (p > 0.05), but the accumulated impact over the course the 5-km did significantly decrease as BW decreased (100% RT: 8283.5 ± 342.7 kN; 100% LBPPT: 8203.8 ± 326.2 kN; 90%: 6953.9 ± 348.6 kN vs. 80%: 6953.9 ± 270.0 kN; p < 0.001).

Conclusions: In conclusion, the LBPPT treadmill provides a possible alternative to runners to maintain the same aerobic intensity while accumulating less force and stress on the lower extremity over a fixed distance.