Research - Validation Studies 

Back and hip extensor fatigability in chronic low back pain patients and controls. 

Year: 1998  Country: Finland   Study Population: 20 chronic low back pain patients/15 healthy controls

Kankaanpää M, Taimela S, Laaksonen D, Hänninen O, Airaksinen O. Back and hip extensor fatigability in chronic low back pain patients and controls. Archives of Physical Medicine and Rehabilitation 1998;79(4):412-417.


To investigate the difference in lumbar paraspinal and gluteus maximus muscle fatigability between chronic low back pain (CLBP) patients and healthy controls during a back extension endurance using electromyographic (EMG) spectral analysis. 


Maximal voluntary isometric back extensions (MVC) was performed at 30° flexion. A 50% MVC load was used in isometric endurance test. 

Outcome measures: pain intensity (VAS), functional disability (ODI), average EMG (aEMG%), and initial spectral median frequency (MFinit) and change over time (MFslope) from lumbar paraspinal muscles (L3-L4, L5-S1) and gluteus maximus muscles.


CLBP patients had higher pain intensity and functional disability as well as lower MVC and time to endurance compared to healthy controls (p<0.05). Similar muscle activity levels (aEMG%) and MFinit indicated similar muscle loading in both groups at the beginning of the endurance test. MFslope indicated that lumbar paraspinal muscle fatigability was similar in both groups but, the gluteus maximus fatigued faster in CLBP patients compared to controls (p<0.05). However, the shorter endurance time indicated greater fatigability in the CLBP patient group in general (p<0.05).