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Electromyographic analysis of exercise resulting in symptoms of muscle damage.
J Sports Sci. 2000 Mar; 18(3):163-72.JS

Abstract

Surface electromyographic (EMG) signals were recorded from the hamstring muscles during six sets of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions. The EMG per unit torque increased during eccentric (P < 0.01) but not during concentric exercise. Similarly, the median frequency increased during eccentric (P < 0.01) but not during concentric exercise. The EMG per unit torque was lower for submaximal eccentric than maximum isometric contractions (P < 0.001), and lower for submaximal concentric than maximum isometric contractions (P < 0.01). The EMG per unit torque was lower for eccentric than concentric contractions (P < 0.05). The median frequency was higher for submaximal eccentric than maximum isometric contractions (P < 0.001); it was similar, however, between submaximal concentric and maximum isometric contractions (P = 0.07). Eccentric exercise resulted in significant isometric strength loss (P < 0.01), pain (P < 0.01) and muscle tenderness (P < 0.05). The greatest strength loss was seen 1 day after eccentric exercise, while the most severe pain and muscle tenderness occurred 2 days after eccentric exercise. A lower EMG per unit torque is consistent with the selective recruitment of a small number of motor units during eccentric exercise. A higher median frequency during eccentric contractions may be explained by selective recruitment of fast-twitch motor units. The present results are consistent with the theory that muscle damage results from excessive stress on a small number of active fibres during eccentric contractions.

Authors+Show Affiliations

School of Sport, Health and Physical Education Sciences, University of Wales, Bangor, Gwynedd, UK. mchugh@nismat.orgNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Clinical Trial
Comparative Study
Journal Article

Language

eng

PubMed ID

10737267

Citation

McHugh, M P., et al. "Electromyographic Analysis of Exercise Resulting in Symptoms of Muscle Damage." Journal of Sports Sciences, vol. 18, no. 3, 2000, pp. 163-72.
McHugh MP, Connolly DA, Eston RG, et al. Electromyographic analysis of exercise resulting in symptoms of muscle damage. J Sports Sci. 2000;18(3):163-72.
McHugh, M. P., Connolly, D. A., Eston, R. G., & Gleim, G. W. (2000). Electromyographic analysis of exercise resulting in symptoms of muscle damage. Journal of Sports Sciences, 18(3), 163-72.
McHugh MP, et al. Electromyographic Analysis of Exercise Resulting in Symptoms of Muscle Damage. J Sports Sci. 2000;18(3):163-72. PubMed PMID: 10737267.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Electromyographic analysis of exercise resulting in symptoms of muscle damage. AU - McHugh,M P, AU - Connolly,D A, AU - Eston,R G, AU - Gleim,G W, PY - 2000/3/29/pubmed PY - 2000/4/15/medline PY - 2000/3/29/entrez SP - 163 EP - 72 JF - Journal of sports sciences JO - J Sports Sci VL - 18 IS - 3 N2 - Surface electromyographic (EMG) signals were recorded from the hamstring muscles during six sets of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions. The EMG per unit torque increased during eccentric (P < 0.01) but not during concentric exercise. Similarly, the median frequency increased during eccentric (P < 0.01) but not during concentric exercise. The EMG per unit torque was lower for submaximal eccentric than maximum isometric contractions (P < 0.001), and lower for submaximal concentric than maximum isometric contractions (P < 0.01). The EMG per unit torque was lower for eccentric than concentric contractions (P < 0.05). The median frequency was higher for submaximal eccentric than maximum isometric contractions (P < 0.001); it was similar, however, between submaximal concentric and maximum isometric contractions (P = 0.07). Eccentric exercise resulted in significant isometric strength loss (P < 0.01), pain (P < 0.01) and muscle tenderness (P < 0.05). The greatest strength loss was seen 1 day after eccentric exercise, while the most severe pain and muscle tenderness occurred 2 days after eccentric exercise. A lower EMG per unit torque is consistent with the selective recruitment of a small number of motor units during eccentric exercise. A higher median frequency during eccentric contractions may be explained by selective recruitment of fast-twitch motor units. The present results are consistent with the theory that muscle damage results from excessive stress on a small number of active fibres during eccentric contractions. SN - 0264-0414 UR - https://www.unboundmedicine.com/medline/citation/10737267/Electromyographic_analysis_of_exercise_resulting_in_symptoms_of_muscle_damage_ L2 - http://www.tandfonline.com/doi/full/10.1080/026404100365063 DB - PRIME DP - Unbound Medicine ER -