Endurance of Lower Paraspinals and Gluteal Muscles Using Surface EMG on Healthy Subjects During Performance of Common Lumbar Stabilization Exercises




Smith, Susan M.

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Low back pain (LBP) has become a major problem in the western world. It is a concern in worker's compensation cases and the reason for many lost work days. In order to effectively rehabilitate persons with LBP, physical therapists need to provide proven methods to improve muscular stability. Lumbar stabilization exercises which train muscles for endurance in a biomechanically safe posture are routinely part of the rehabilitation process. No established time or protocol to train the muscles for endurance exists. The length of training time and number of repetitions of an exercise per rehabilitation session must be determined to safely and effectively strengthen the postural muscles of the lumbar spine and pelvis. The purpose of this study was to establish an ideal number of prone and quadruped lumbar stabilization exercises with superimposed extremity movements which produced fatigue. The subjects were twenty 20 to 40 year old females physical therapy students (mean 27.25 ±_ 4.56) trained in lumbar stabilization exercises. Fatigue was studied in the left and right lower paraspinals and left and right gluteal muscles. Surface EMG was used to measure fatigue via a median frequency shift of the power spectrum to the low end of the frequency continuum and an increase in EMG activity in the same area of the spectrum. Fatigue would have taken place when EMG activity increased and median frequency shifts to the left in the power spectrum due to the concentration of the motor unit action potentials. A median frequency of 20 to 50% was considered as fatigue. Surface EMG measures are more advantageous than traditional fatigue measures because it eliminates subjective fatigue which occurs when a subject consciously decides to end the exercise. One subject reached fatigue in all four muscle groups and one other reached fatigue in three of the four groups. No significant difference in workload existed between the left and right sides of the body. Significance existed between the paraspinal and gluteal workloads in the first prone lumbar stabilization exercise only (t = 0.007). The ratio of paraspinal to gluteal work was 1 to 0.7114.



back muscles, spine muscles, buttocks muscles, muscle strength, electromyography, backache, exercise therapy


Smith, S.M. (1997-05). Endurance of lower paraspinals and gluteal muscles using surface EMG on healthy subjects during performance of common lumbar stabilization exercises (Unpublished thesis). Southwest Texas State University, San Marcos, Texas.


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