Investigation Into Lower Extremity Accommodation During Lbppt Submaximal Running

Lower Body Positive Pressure Treadmills (LBPPT) have gained popularity in clinical and research environments for their ability to reduce the runners’ bodyweight, consequently lowering the GRFs. The combination of repetitive vertical ground reaction forces (vGRF) impacting the lower extremities and factors such as biomechanics contributes to running injury risk and LBPPT present a training opportunity for potential injury prevention and injury rehabilitation. Running in a LBPPT is novel to most runners and it is not yet known if time is needed to adapt to this new running experience. PURPOSE: The purpose of this study was to investigate whether there is an accommodation period present during LBPPT submaximal running in vGRF or stance time. METHODS: Participants (n = 14; 8 males, 6 females; age: 27 ± 6 years; mass: 73.12 ± 16.52 kg; height: 1.74 ± 0.10 m) were recruited to complete three 15-minute bodyweight support (BWS) running conditions at 100%, 80%, and 60% of their total bodyweight. Loadsol insoles were used to collect v GRF during running. Peak vGRF, and stance time were compared by 3 (BWS: 0%, 20%, 40%) x 8 (Time: t1, t2, t3, t4, t5, t6, t7, t8) repeated measures ANOVAs (p < .05). RESULTS: There was no interaction effect for BWS and time for peak vGRF (p = 0.78) or stance time (p = 0.27). Peak vGRF was different for BWS (F = 57.26, p < 0.001, η2 = 0.93) but not for time (F = 0.80, p = 0.503, η2 = 0.06). Peak vGRF was higher for 0% (1570.26 + 337.47 N) BWS than 20% (1465.45 + 340.07 N, p < 0.001) and 40% (1148.15 + 337.47 N, p < 0.001). Mean stance time was different for BWS (F = 26.16, p < 0.001, η2 = .59) and time (F = 2.82, p = 0.07, η2 = 0.18). On average, mean stance time was longer at minute 15 when compared to minute 1 (p = 0.04). CONCLUSIONS: Although we did not observe an accommodation period for vGRF we did observe one for stance time. This highlights the importance of providing participants time to adjust to this novel running condition prior to data collection and analysis.