Changes in paraspinal electromyographic spectral analysis with exercise: Two studies

It has been suggested, but not substantiated, that electromyographic (EMG) power spectrum (PS) analysis of the paraspinal muscles could be a useful method of evaluating low back pain treatment outcome. The use of PS analysis to measure paraspinal muscle adaptations was investigated in two studies: Study 1, involving previously sedentary healthy women who participated in a 12-week fitness class program, and Study 2, involving low back pain sufferers who participated in a 10-week back-care exercise program. All subjects underwent assessments of physical fitness (aerobic capacity, back strength, and flexibility) and EMG PS analysis of the multifidus and iliocostalis muscles (during a constant force contraction), before and after the experimental period. The results in both studies indicated that the EMG PS measures were sensitive to adaptive changes, with findings of (a) decreases in multifidus initial median frequency (IMF) and fatigue (FTG) of the fitness class participants and (b) an increase in multifidus IMF and decreases in multifidus and iliocostalis FTG of the back-care participants. The results are discussed with regard to possible links between spectral changes and alterations in muscle fiber characteristics and functioning, and the need for further research to substantiate such links.