Biomechanics of lower limb raising from the supine position.
OBJECTIVE
This study analyses the kinematics of the lower limb raising movement from the supine position and the electromyography activity of the muscles involved.


METHODS
Twenty healthy right hand subjects performed the right lower limb raising from the supine position, starting from the clinical bed plane and up to a 70 degrees inclination of the thigh over the horizontal plane, while the knee was kept flexed at 120 degrees by a soft splint. The same exercise was executed with no resistance and with 2 kg and 8 kg respectively applied to the ankle. The kinematics was recorded utilising an optoelectronic system, whereas the electromyography activity was recorded by a surface electromyography (EMG) applied to the following muscles: right rectus femoris, left biceps femoris, rectus abominalis from both sides and dorsal major from both sides.


RESULTS
In all the cases the pelvis performed a backwards rotation retroversion. The highest increase of EMG activation was recorded on the right rectus femoris as well as on the left biceps femoris; the increase was lower in the right rectus abdominis and in the right dorsal major, whereas it was minimum in the left rectus abdominis and in the left dorsal major. A great variability in the activation times was reported in the various muscles of the different subjects, regardless of the trials. The only muscle anticipating the right rectus femoris activation was the left biceps femoris.


CONCLUSIONS
The research has shown how the simple movement under study is more complex than what is usually described by the text books, both in regard to the kinematics and to muscles' actions. Even the individual variability in utilising the agonist and stabilisation muscles can be of relevance for a more rational utilisation of the physical exercise in motor re-education.
Gatti
R
R
Laboratory of Movement Analysis, School of Physiotherapy Vita-Salute San Raffaele University, Via Olgettina 58, 20132 Milan, Italy. gatti.roberto@hsr.it
Corti
M
M
Cervi
P
P
Pulici
L
L
Boccardi
S
S
D000328:Adult; D001696:Biomechanical Phenomena; D004576:Electromyography; D005260:Female; D006801:Humans; D035002:Lower Extremity / Q000502:physiology*; D008297:Male; D009068:Movement / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D012399:Rotation; D018709:Statistics, Nonparametric; D016683:Supine Position / Q000502:physiology*