TY - JOUR
T1 - Muscle activation and estimated relative joint force during running with weight support on a lower-body positive pressure treadmill
AU - Jensen, Bente Rona
AU - Hovgaard-Hansen, Line
AU - Cappelen, Katrine Louise
N1 - CURIS 2016 NEXS 230
PY - 2016/8
Y1 - 2016/8
N2 - Running on a lower-body positive-pressure (LBPP) treadmill allows effects of weight support on leg muscle activation to be assessed systematically, and has the potential to facilitate rehabilitation and prevent overloading. The aim was to study the effect of running with weight support on leg muscle activation and to estimate relative knee and ankle joint forces. Runners performed 6-min running sessions at 2.22 m/s and 3.33 m/s, at 100%, 80%, 60%, 40%, and 20% body weight (BW). Surface electromyography, ground reaction force, and running characteristics were measured. Relative knee and ankle joint forces were estimated. Leg muscles responded differently to unweighting during running, reflecting different relative contribution to propulsion and antigravity forces. At 20% BW, knee extensor EMGpeak decreased to 22% at 2.22 m/s and 28% at 3.33 m/s of 100% BW values. Plantar flexors decreased to 52% and 58% at 20% BW, while activity of biceps femoris muscle remained unchanged. Unweighting with LBPP reduced estimated joint force significantly although less than proportional to the degree of weight support (ankle). It was concluded that leg muscle activation adapted to the new biomechanical environment, and the effect of unweighting on estimated knee force was more pronounced than on ankle force.
AB - Running on a lower-body positive-pressure (LBPP) treadmill allows effects of weight support on leg muscle activation to be assessed systematically, and has the potential to facilitate rehabilitation and prevent overloading. The aim was to study the effect of running with weight support on leg muscle activation and to estimate relative knee and ankle joint forces. Runners performed 6-min running sessions at 2.22 m/s and 3.33 m/s, at 100%, 80%, 60%, 40%, and 20% body weight (BW). Surface electromyography, ground reaction force, and running characteristics were measured. Relative knee and ankle joint forces were estimated. Leg muscles responded differently to unweighting during running, reflecting different relative contribution to propulsion and antigravity forces. At 20% BW, knee extensor EMGpeak decreased to 22% at 2.22 m/s and 28% at 3.33 m/s of 100% BW values. Plantar flexors decreased to 52% and 58% at 20% BW, while activity of biceps femoris muscle remained unchanged. Unweighting with LBPP reduced estimated joint force significantly although less than proportional to the degree of weight support (ankle). It was concluded that leg muscle activation adapted to the new biomechanical environment, and the effect of unweighting on estimated knee force was more pronounced than on ankle force.
U2 - 10.1123/jab.2015-0075
DO - 10.1123/jab.2015-0075
M3 - Journal article
C2 - 26957520
SN - 1065-8483
VL - 32
SP - 335
EP - 341
JO - Journal of Applied Biomechanics
JF - Journal of Applied Biomechanics
IS - 4
ER -