LEG INTRAMUSCULAR PRESSURES DURING LOCOMOTION IN HUMANS

To assess the usefulness of intramuscular pressure (IMP) measurement f or studying muscle function during gait, IMP was recorded in the soleu s and tibialis anterior muscles of 10 volunteers during treadmill walk ing and running by using transducer-tipped catheters. Soleus IMP exhib ited single peaks during late-stance phase of walking [181 +/- 69 (SE) mmHg] and running (269 +/- 95 mmHg). Tibialis anterior IMP showed a b iphasic response, with the largest peak (90 +/- 15 mmHg during walking and 151 +/- 25 mmHg during running) occurring shortly after heel stri ke. IMP magnitude increased with gait speed in both muscles. Linear re gression of soleus IMP against ankle joint torque obtained by a dynamo meter produced linear relationships (n = 2, r = 0.97 for both). Applic ation of these relationships to IMP data yielded estimated peak soleus moment contributions of 0.95-1.65 N . m/kg during walking, and 1.43-2 .70 N . m/kg during running. Phasic elevations of IMP during exercise are probably generated by local muscle tissue deformations due to musc le force development. Thus profiles of IMP provide a direct, reproduci ble index of muscle function during locomotion in humans.