Trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise.
METHODS
Experimental laboratory study.


OBJECTIVE
To examine how a change in trunk position influences the kinematics, kinetics, and muscle activity of the lead lower extremity during the forward lunge exercise.


BACKGROUND
Altering the position of the trunk during the forward lunge exercise is thought to affect the muscular actions of the lead lower extremity. However, no studies have compared the biomechanical differences between the traditional forward lunge and its variations.


METHODS
Ten healthy adults (5 males, 5 females; mean age +/- SD, 26.7 +/- 3.2 years) participated. Lower extremity kinematics, kinetics, and surface electromyographic (EMG) data were obtained while subjects performed 3 lunge exercises: normal lunge with the trunk erect (NL), lunge with the trunk forward (LTF), and lunge with trunk extension (LTE). A 1-way analysis of variance with repeated measures was used to compare lower extremity kinematics, joint impulse (area under the moment-time curve), and normalized EMG (highest 1-second window of activity for selected lower extremity muscles) among the 3 lunge conditions.


RESULTS
During the LTF condition, significant increases were noted in peak hip flexion angle, hip extensor and ankle plantar flexor impulse, as well as gluteus maximus and biceps femoris EMG (P<.015) when compared to the NL condition. During the LTE condition, a significant increase was noted in peak ankle dorsiflexion and a significant decrease was noted in peak hip flexion angle (P<.015) compared to the NL condition.


CONCLUSIONS
Performing a lunge with the trunk forward increased the hip extensor impulse and the recruitment of the hip extensors. In contrast, performing a forward lunge with the trunk extended did not alter joint impulse or activation of the lower extremity musculature.


METHODS
Therapy, level 5.
Farrokhi
Shawn
S
Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA 90089-9006, USA.
Pollard
Christine D
CD
Souza
Richard B
RB
Chen
Yu-Jen
YJ
Reischl
Stephen
S
Powers
Christopher M
CM
D000328:Adult; D000843:Ankle Joint / Q000502:physiology; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006621:Hip Joint / Q000502:physiology; D006801:Humans; D007700:Kinetics; D007719:Knee Joint / Q000502:physiology; D007866:Leg / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D016059:Range of Motion, Articular / Q000502:physiology; D012016:Reference Values; D012129:Respiratory Function Tests / Q000379:methods*