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Neural activation after maximal isometric contractions at different muscle lengths.
Med Sci Sports Exerc. 2006 May; 38(5):937-44.MS

Abstract

PURPOSE

To investigate i) whether neural activation dependence on muscle length is preserved with neuromuscular fatigue and ii) whether fatigue induced by a maximal isometric exercise is muscle length dependent.

METHODS

Twelve male subjects performed two fatiguing quadriceps muscle exercises: FS is the fatigue carried out at short muscle length (S) (S = 40 degrees of knee flexion) and FL is the fatigue at long muscle length (L) (L = 100 degrees). Before and after each fatiguing exercise (i.e., three maximal isometric contractions maintained until 80, 60, and 40% of the initial maximal torque, respectively), activation level (AL, assessed by means of twitch interpolation technique), EMG activity (RMS), and peak doublet torque (Pd) were measured at the two lengths (S and L).

RESULTS

First, AL was greater (P < 0.05) at L compared with S before and after both exercises. Second, despite a similar decrease in maximal voluntary torque (approximately 21% of the initial value) after the two exercises, AL and RMS were significantly reduced after FS (P < 0.05) but remained unchanged after FL, whereas the Pd decrease was more pronounced after FL than FS (P < 0.05). Nevertheless, after a given fatiguing exercise (i.e., FS or FL), AL, RMS, and Pd changes were similar at both postexercise test lengths (S and L).

CONCLUSION

These results clearly demonstrate that i) the neural activation dependence on quadriceps muscle length is maintained with fatigue, and ii) neuromuscular fatigue after maximal isometric contractions is dependent on the muscle length at which the exercise is performed: short length preferentially induces neural activation impairment, whereas long length leads to higher contractile failure.

Authors+Show Affiliations

INSERM/ERIT-M Motricity-Plasticity, Faculty of Sport Science, University of Burgundy, Dijon, France. kevin.debrosses@inrs.frNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

16672848

Citation

Desbrosses, Kévin, et al. "Neural Activation After Maximal Isometric Contractions at Different Muscle Lengths." Medicine and Science in Sports and Exercise, vol. 38, no. 5, 2006, pp. 937-44.
Desbrosses K, Babault N, Scaglioni G, et al. Neural activation after maximal isometric contractions at different muscle lengths. Med Sci Sports Exerc. 2006;38(5):937-44.
Desbrosses, K., Babault, N., Scaglioni, G., Meyer, J. P., & Pousson, M. (2006). Neural activation after maximal isometric contractions at different muscle lengths. Medicine and Science in Sports and Exercise, 38(5), 937-44.
Desbrosses K, et al. Neural Activation After Maximal Isometric Contractions at Different Muscle Lengths. Med Sci Sports Exerc. 2006;38(5):937-44. PubMed PMID: 16672848.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Neural activation after maximal isometric contractions at different muscle lengths. AU - Desbrosses,Kévin, AU - Babault,Nicolas, AU - Scaglioni,Gil, AU - Meyer,Jean-Peerre, AU - Pousson,Michael, PY - 2006/5/5/pubmed PY - 2006/10/13/medline PY - 2006/5/5/entrez SP - 937 EP - 44 JF - Medicine and science in sports and exercise JO - Med Sci Sports Exerc VL - 38 IS - 5 N2 - PURPOSE: To investigate i) whether neural activation dependence on muscle length is preserved with neuromuscular fatigue and ii) whether fatigue induced by a maximal isometric exercise is muscle length dependent. METHODS: Twelve male subjects performed two fatiguing quadriceps muscle exercises: FS is the fatigue carried out at short muscle length (S) (S = 40 degrees of knee flexion) and FL is the fatigue at long muscle length (L) (L = 100 degrees). Before and after each fatiguing exercise (i.e., three maximal isometric contractions maintained until 80, 60, and 40% of the initial maximal torque, respectively), activation level (AL, assessed by means of twitch interpolation technique), EMG activity (RMS), and peak doublet torque (Pd) were measured at the two lengths (S and L). RESULTS: First, AL was greater (P < 0.05) at L compared with S before and after both exercises. Second, despite a similar decrease in maximal voluntary torque (approximately 21% of the initial value) after the two exercises, AL and RMS were significantly reduced after FS (P < 0.05) but remained unchanged after FL, whereas the Pd decrease was more pronounced after FL than FS (P < 0.05). Nevertheless, after a given fatiguing exercise (i.e., FS or FL), AL, RMS, and Pd changes were similar at both postexercise test lengths (S and L). CONCLUSION: These results clearly demonstrate that i) the neural activation dependence on quadriceps muscle length is maintained with fatigue, and ii) neuromuscular fatigue after maximal isometric contractions is dependent on the muscle length at which the exercise is performed: short length preferentially induces neural activation impairment, whereas long length leads to higher contractile failure. SN - 0195-9131 UR - https://www.unboundmedicine.com/medline/citation/16672848/Neural_activation_after_maximal_isometric_contractions_at_different_muscle_lengths_ L2 - http://dx.doi.org/10.1249/01.mss.0000218136.58899.46 DB - PRIME DP - Unbound Medicine ER -