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Muscle activation and force production during bilateral and unilateral concentric and isometric contractions of the knee extensors in men and women at different ages.
Electromyogr Clin Neurophysiol. 1997 Apr-May; 37(3):131-42.EC

Abstract

In experiment I ten young men (29 +/- 3 yrs; M30), 12 middle-aged men (50 +/- 4 yrs; M50) and 12 women (48 +/- 5 yrs; W50), 12 elderly men (67 +/- 4 yrs; M70) and 12 women (68 +/- 4 yrs; W70) volunteered for subjects for examination of maximal 1 RM strength and electromyographic activity of the knee extensor muscles during the bilateral and unilateral concentric contraction on a variable resistance knee extension dynamometer. In experiment II 10 young (Y) men (29 +/- 5 yrs) and 10 older (O) men (61 +/- 4 yrs) were examined for their maximal voluntary isometric force and force-time curves and electromyographic activity of the knee extensor muscles during the bilateral and unilateral contractions. The bilateral 1 RM of 165.5 +/- 25.5 kg in M30 was greater (p < 0.01) than that of 127.7 +/- 24.5 kg recorded for M50 the latter being also greater (p < 0.05) than that of 109.0 +/- 17.7 kg recorded for M70. The bilateral value of 87.4 +/- 13.4 kg in W50 was greater (p < 0.05) than that of 69.9 +/- 15.0 kg recorded for W70. The bilateral 1 RM values were slightly greater than the summed unilateral 1 RM values in all groups M50, W50 and W70 showing a significant (p < 0.05) difference. All groups showed slightly (ns.) greater mean maximal integrated EMG values during the bilateral conditions in comparison to that of the corresponding unilateral condition. The maximal isometric forces in Y men were 25% greater (p < 0.001) than in O men. In both groups the bilateral forces were somewhat greater (p < 0.05) than the summed unilateral forces and the bilateral IEMG values slightly (ns.) greater than the corresponding unilateral IEMG values. The early forces on the force-time curve were much greater (p < 0.05-0.001) in Y than O men in both conditions. The present findings suggest that both maximal voluntary isometric and concentric force, and especially explosive strength of the knee extensors decrease greatly with increasing age probably due to selective muscle atrophy and/or possible decreases in the amount or rate of voluntary activation of the muscles. However, no bilateral deficit could be found indicating that the central nervous system in a simple single joint isometric and maximal 1 RM concentric force production of the knee extensors was capable of activation of the two bilateral muscle groups simultaneously independent of age and sex of the subject. To which extent the activation and force production of the muscles would be different in terms of the bilateral deficit during various multijoint exercises utilizing isometric and higher velocity concentric, eccentric and various stretch shortening cycle exercise needs to be examined in the future.

Authors+Show Affiliations

Department of Biology of Physical Activity, University of Jyväskylä, Finland.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

9187864

Citation

Häkkinen, K, et al. "Muscle Activation and Force Production During Bilateral and Unilateral Concentric and Isometric Contractions of the Knee Extensors in Men and Women at Different Ages." Electromyography and Clinical Neurophysiology, vol. 37, no. 3, 1997, pp. 131-42.
Häkkinen K, Kraemer WJ, Newton RU. Muscle activation and force production during bilateral and unilateral concentric and isometric contractions of the knee extensors in men and women at different ages. Electromyogr Clin Neurophysiol. 1997;37(3):131-42.
Häkkinen, K., Kraemer, W. J., & Newton, R. U. (1997). Muscle activation and force production during bilateral and unilateral concentric and isometric contractions of the knee extensors in men and women at different ages. Electromyography and Clinical Neurophysiology, 37(3), 131-42.
Häkkinen K, Kraemer WJ, Newton RU. Muscle Activation and Force Production During Bilateral and Unilateral Concentric and Isometric Contractions of the Knee Extensors in Men and Women at Different Ages. Electromyogr Clin Neurophysiol. 1997 Apr-May;37(3):131-42. PubMed PMID: 9187864.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Muscle activation and force production during bilateral and unilateral concentric and isometric contractions of the knee extensors in men and women at different ages. AU - Häkkinen,K, AU - Kraemer,W J, AU - Newton,R U, PY - 1997/4/1/pubmed PY - 1997/4/1/medline PY - 1997/4/1/entrez SP - 131 EP - 42 JF - Electromyography and clinical neurophysiology JO - Electromyogr Clin Neurophysiol VL - 37 IS - 3 N2 - In experiment I ten young men (29 +/- 3 yrs; M30), 12 middle-aged men (50 +/- 4 yrs; M50) and 12 women (48 +/- 5 yrs; W50), 12 elderly men (67 +/- 4 yrs; M70) and 12 women (68 +/- 4 yrs; W70) volunteered for subjects for examination of maximal 1 RM strength and electromyographic activity of the knee extensor muscles during the bilateral and unilateral concentric contraction on a variable resistance knee extension dynamometer. In experiment II 10 young (Y) men (29 +/- 5 yrs) and 10 older (O) men (61 +/- 4 yrs) were examined for their maximal voluntary isometric force and force-time curves and electromyographic activity of the knee extensor muscles during the bilateral and unilateral contractions. The bilateral 1 RM of 165.5 +/- 25.5 kg in M30 was greater (p < 0.01) than that of 127.7 +/- 24.5 kg recorded for M50 the latter being also greater (p < 0.05) than that of 109.0 +/- 17.7 kg recorded for M70. The bilateral value of 87.4 +/- 13.4 kg in W50 was greater (p < 0.05) than that of 69.9 +/- 15.0 kg recorded for W70. The bilateral 1 RM values were slightly greater than the summed unilateral 1 RM values in all groups M50, W50 and W70 showing a significant (p < 0.05) difference. All groups showed slightly (ns.) greater mean maximal integrated EMG values during the bilateral conditions in comparison to that of the corresponding unilateral condition. The maximal isometric forces in Y men were 25% greater (p < 0.001) than in O men. In both groups the bilateral forces were somewhat greater (p < 0.05) than the summed unilateral forces and the bilateral IEMG values slightly (ns.) greater than the corresponding unilateral IEMG values. The early forces on the force-time curve were much greater (p < 0.05-0.001) in Y than O men in both conditions. The present findings suggest that both maximal voluntary isometric and concentric force, and especially explosive strength of the knee extensors decrease greatly with increasing age probably due to selective muscle atrophy and/or possible decreases in the amount or rate of voluntary activation of the muscles. However, no bilateral deficit could be found indicating that the central nervous system in a simple single joint isometric and maximal 1 RM concentric force production of the knee extensors was capable of activation of the two bilateral muscle groups simultaneously independent of age and sex of the subject. To which extent the activation and force production of the muscles would be different in terms of the bilateral deficit during various multijoint exercises utilizing isometric and higher velocity concentric, eccentric and various stretch shortening cycle exercise needs to be examined in the future. SN - 0301-150X UR - https://www.unboundmedicine.com/medline/citation/9187864/Muscle_activation_and_force_production_during_bilateral_and_unilateral_concentric_and_isometric_contractions_of_the_knee_extensors_in_men_and_women_at_different_ages_ L2 - https://medlineplus.gov/olderadulthealth.html DB - PRIME DP - Unbound Medicine ER -