Relationship between erector spinae muscle oxygenation via in vivo near infrared spectroscopy and static endurance time in healthy males.

The purpose of the study was to confirm the trends in right and left side muscle blood volume (Mbv) and muscle oxygenation (Mox) during the Biering-Sorensen muscular endurance (BSME) test, compare right and left side Mbv and Mox responses, and predict BSME time via Mox variables. Research suggests that during moderate intensity (approximately 20% of maximal volitional contraction) muscle contraction blood flow will decrease as a result of increased intramuscular pressure. Moreover, decreased muscle oxygenation is believed to be associated with diminished musculoskeletal endurance time, but until the development of near infrared spectroscopy (NIRS) it was not possible to non-invasively monitor these changes in erector spinae muscle. Nineteen healthy males completed the BSME in a prone position. The NIRS probes were placed on the left and right erector spinae muscle at the third lumbar vertebra level. The test protocol was: 2 min resting baseline, BSME to volitional fatigue, and 4 min recovery. The results indicated Mbv initially increased reaching asymptote before returning to baseline at termination. The Mox increased then declined systematically until BSME termination, returning to near baseline in recovery. No significant difference between sides was noted for Mbv or Mox. Mox best predicted BSME time. In conclusion, Mbv increased and then reaches asymptote as indicated in previous research, and oxygen availability was associated with the duration of erector spinae static contraction. Thus, prolonged static postures using the erector spinae muscles may diminish muscle oxygenation increasing susceptible to fatigue and injury.