Torque-velocity and power-velocity relationships during isokinetic trunk flexion and extension.

BACKGROUND

No study has reported the possibility of establishing torque-velocity and power-velocity relationships for both flexor and extensor trunk muscles. The present study therefore sought to assess these relationships during isokinetic exercise.

METHODS

Nine healthy male subjects performed series of isokinetic trunk flexions and extensions at six different velocities ranging from 45 degrees s(-1) to 120 degrees s(-1). Trunk flexor and extensor muscles were, respectively, assessed on two separate days. All experiments used a Biodex dynamometer.

FINDINGS

Torque-velocity relationships were significantly well described by a linear relationship for both trunk flexor (P<0.01; r=0.92-0.99) and extensor muscles (P<0.05; r=0.82-0.97) in all subjects. Power-velocity relationships exhibited a parabolic shape for all subjects (P<0.05; r=0.96-0.99) for both muscle groups.

INTERPRETATION

Results showed that trunk muscle torque- and power-velocity relationships can be assessed during isokinetic exercise. The findings were in agreement with previous studies of lower and upper limbs. This kind of measurement can therefore be applied in assessing low-back pain patients during rehabilitation.