Effects of Standing Back Extension Exercise on Lumbar Erector Spinae Hemodynamics and Muscle Activity After Prolonged Lumbar Flexion.

OBJECTIVE

This study aimed to explore the hemodynamic effects of standing back extension exercise (SBEE) on the lumbar erector spinae (LES) after adoption of the lumbar flexion position.

METHODS

Hemodynamics and activities of the LES were measured in 16 asymptomatic adults (8 men and 8 women; mean age, 20.3 ± 0.5 years) using near-infrared spectroscopy of oxygenated hemoglobin and myoglobin (Hb + Mb) levels and surface electromyography in resting prone and Biering-Sørensen test positions to evaluate both resting and contraction states of the LES before and after 5 minutes of adopting the lumbar flexion position. After adopting the lumbar flexion position, all participants randomly performed two 3-second repetitions of SBEE and maintained a relaxed sitting position (control [CON]) separated by at least a 1-day interval.

RESULTS

After participants had assumed the lumbar flexion position, compared with SBEE, CON was significantly associated with more positive changes in the deoxygenated[Hb + Mb] levels in the prone position (P = .028, w = 0.76, power = 0.99). Deoxygenated[Hb + Mb] levels in the prone (P = .026, d = 0.71, power = 0.73) and Biering-Sørensen test positions (P = .036, d = 0.32, power = 0.22) were significantly lower for SBEE than for CON.

CONCLUSION

Compared with CON, SBEE resulted in lower deoxygenated[Hb + Mb] levels in the LES at rest and during sustained muscle contraction after participants adopted the lumbar flexion position. These results suggest that the physiological effects of using SBEE on low back pain are caused by partial ischemia of the LES due to maintaining a flexed trunk posture.