Effect of Body-Weight-Support Running on Lower-Limb Biomechanics

Abstract

Study Design Controlled laboratory study. Background Body-weight-support (BWS) running is increasing in popularity, despite limited evidence of its effects on running mechanics. Objectives To determine the effect of increasing BWS on lower-limb biomechanics during lower-body positive-pressure (LBPP) treadmill running. Methods Fourteen male recreational runners completed 15 randomized trials on an LBPP treadmill at 5 levels of BWS and 3 velocities (1-minute trials with 3-minute recovery). Knee and ankle kinematic data were recorded continuously via electrogoniometry. Synchronous in-shoe plantar-pressure data identified stride onset and quantified foot-segment forces. Data were recorded during the final 30 seconds of each trial and averaged over 10 consecutive stride cycles. Results Higher levels of BWS resulted in significantly (P<.001) increased stride duration, reduced stride frequency, and reduced ground contact time (GCT). In addition, normalized GCT (GCT/stride duration) was significantly reduced (P<.001), indicating increased flight time. Increasing BWS resulted in significant reductions (P<.001) in peak knee flexion and dorsiflexion and reduced overall knee and ankle range of motion during the stance phase. Conclusion Running on an LBPP treadmill alters lower-limb kinematics, resulting in reduced ankle and knee joint range of motion. In addition, increased BWS alters stride characteristics, resulting in shorter GCT and longer flight time. Clinicians must be aware of lower-limb kinematic alterations to provide safe and effective parameters for rehabilitation involving LBPP treadmills. J Orthop Sports Phys Ther 2016;46(9):784-793. doi:10.2519/jospt.2016.6503.

Physiological and Biomechanical Responses of Highly Trained Distance Runners to Lower-Body Positive Pressure Treadmill Running

“…Both the current data and those of previous studies [ 12 , 22 , 28 , 29 ] are in disagreement with the work of Mercer and Chona [ 39 ] who reported no effects on stride length with increased BWS. We found small to moderate increases in stride length with each 10% incremental increase in BWS.…”

“…Sainton et al [ 26 ] described this pattern of movement as similar to the gait patterns adopted by astronauts on the Moon as defined by Minetti et al [ 38 ]. Studies are in agreement that unweighing-induced changes in flight time increase with increasing levels of BWS [ 12 , 13 , 26 , 29 ]. In our study, flight time was less affected by higher running speeds but was significantly affected by BWS.…”

“…Results are also conflicting regarding stride characteristics while running on LBPPT [ 10 , 12 , 22 , 26 , 28 , 29 ]. Several studies have reported stride rate decreased with unweighting [ 10 , 12 , 26 , 29 ], whereas Gojanovic et al [ 22 ] found stride rate increased in males and remained unchanged in females at different absolute velocities. Grabowski and Kram [ 10 ] reported an increase in contact time, whereas Raffalt et al [ 12 ] and Neal et al [ 29 ] reported decreased contact time, and Sainton et al [ 26 ] reported no change in contact time.…”

“…Several studies have reported stride rate decreased with unweighting [ 10 , 12 , 26 , 29 ], whereas Gojanovic et al [ 22 ] found stride rate increased in males and remained unchanged in females at different absolute velocities. Grabowski and Kram [ 10 ] reported an increase in contact time, whereas Raffalt et al [ 12 ] and Neal et al [ 29 ] reported decreased contact time, and Sainton et al [ 26 ] reported no change in contact time. However, studies are in agreement that stride length and flight time increase with unweighting [ 12 , 13 , 22 , 28 , 29 ].…”

“…Grabowski and Kram [ 10 ] reported an increase in contact time, whereas Raffalt et al [ 12 ] and Neal et al [ 29 ] reported decreased contact time, and Sainton et al [ 26 ] reported no change in contact time. However, studies are in agreement that stride length and flight time increase with unweighting [ 12 , 13 , 22 , 28 , 29 ]. Sometimes, runners may do a portion of their run on LBPPT and the remainder overground.…”