The effect of load intensity on back muscle oxygenation in static muscle work

Abstract

Any muscle fatigue during static contraction is important; previous studies suggest that fatigue is associated with musculoskeletal injury and low back pain. Among local factors that affect muscle fatigue are blood perfusion of the muscle and level of its oxygenation. To investigate the effect of load intensity on the low back muscle during repeated static work, 11 young male subjects aged between 23-27 years old and no history of low back pain during the last 12 months participated. Subjects held a load in their hands whilst sustaining trunk flexion at 30° which was equal to 10 and 40% of their maximal voluntary force till they felt tired in the low back region. The task was repeated for 12 times with resting time between each task. Oxyhemoglobin (Oxy-hb) and deoxy-hemoglobin (Deoxy-hb) of the erector spinae muscle (ESM) at the third level of the vertebral column was evaluated using near infrared spectroscopy. As a result Oxy-hb showed significantly larger decreases by repetition in 40% MVC than in 10% MVC. On the contrary Deoxy-hb showed significantly larger increases by repetition in 40% MVC than in 10% MVC. © 2012 Taylor & Francis Group, London.