Effect of fatigue on hamstring coactivation during isokinetic knee extensions

• Published in: European journal of applied physiology Vol. 78; no. 6; pp. 555 - 559
• Main Authors: WEIR, J. P, KEEFE, D. A, EATON, J. F, AUGUSTINE, R. T, TOBIN, D. M
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.11.1998
• Subjects: Adult; Biological and medical sciences; Electromyography; Female; Femoral Nerve - physiology; Fundamental and applied biological sciences. Psychology; Humans; Knee Joint - physiology; Male; Muscle Contraction - physiology; Muscle Fatigue - physiology; Muscle, Skeletal - innervation; Muscle, Skeletal - physiology; Striated muscle. Tendons; Vertebrates: osteoarticular system, musculoskeletal system; Extension; Knee; Human; Electrophysiology; Lower limb; Calf(anatomy); Quadriceps muscle; Fatigue; Activation; Electromyography; Striated muscle; Muscle contraction
• ISSN: 0301-5548; 1439-6319; 1432-1025; 1439-6327
• DOI: 10.1007/s004210050460

We examined the effect of fatigue of the quadriceps muscles on coactivation of the hamstring muscles and determined if the response is different between two isokinetic speeds in ten males and ten females with no history of knee pathology. Electromyographic data were recorded from the vastus lateralis and biceps femoris muscles during 50 maximal knee extensions at isokinetic speeds of 1.75 rad x s(-1) (100 degrees x s(-1)) and 4.36 rad x s(-1) (250 degrees x s(-1)). A greater degree of coactivation was apparent at the higher speed, but the increase in coactivation of the hamstring muscles was similar at both speeds. The results revealed that: (1) coactivation is greater at a higher isokinetic speed, and (2) coactivation increases during fatigue, but the rate of increase is independent of contraction velocity.