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Knee extensor muscle oxygen consumption in relation to muscle activation.
Eur J Appl Physiol. 2006 Dec; 98(6):535-45.EJ

Abstract

Recently, fatigability and muscle oxygen consumption (mVO(2)) during sustained isometric contractions were found to be less at shorter (30 degrees knee angle; 0 degrees = full extension) compared to longer knee extensor muscle lengths (90 degrees) and, at low torques, less in the rectus femoris (RF) muscle than in the vastus lateralis and medialis. In the present study we hypothesized that these findings could be accounted for by a knee angle- and a muscle-dependent activation respectively. On two experimental days rectified surface EMG (rsEMG) was obtained as a measure of muscle activation in nine healthy young males. In addition, on day 1 maximal torque capacity (MTC) was carefully determined using superimposed nerve stimulation on brief high intensity contractions (> 70%MVC) at 30, 60 and 90 degrees knee angles. On day 2, subjects performed longer lasting isometric contractions (10-70%MTC) while mVO(2) was measured using near-infrared spectroscopy (NIRS). At 30 degrees , maximal mVO(2) was reached significantly later (11.0 s +/- 6.5 s) and was 57.9 +/- 8.3% less (average +/- SD, across intensities and muscles) than mVO(2) at 60 and 90 degrees (p < 0.05). However, rsEMG was on average only 18.0 +/- 11.8% (p = 0.062) less at the start of the contraction at 30 degrees . At 10%MTC at all knee angles, maximal mVO(2) of the RF occurred significantly later (28.8 +/- 36.0 s) and showed a significantly smaller increase in rsEMG compared to both vasti. In conclusion, it is unlikely that the tendency for less intense muscle activation could fully account for the approximately 60% lower oxygen consumption at 30 degrees , but the later increase in RFmVO(2) seemed to be caused by a less strong activation of the RF.

Authors+Show Affiliations

Institute for Fundamental and Clinical Human Movement Sciences, Vrije Universiteit, Van der Boechorststraat 9, 1081, BT, Amsterdam, The Netherlands. Ronald.Kooistra@fbw.vu.nlNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

17089159

Citation

Kooistra, R D., et al. "Knee Extensor Muscle Oxygen Consumption in Relation to Muscle Activation." European Journal of Applied Physiology, vol. 98, no. 6, 2006, pp. 535-45.
Kooistra RD, Blaauboer ME, Born JR, et al. Knee extensor muscle oxygen consumption in relation to muscle activation. Eur J Appl Physiol. 2006;98(6):535-45.
Kooistra, R. D., Blaauboer, M. E., Born, J. R., de Ruiter, C. J., & de Haan, A. (2006). Knee extensor muscle oxygen consumption in relation to muscle activation. European Journal of Applied Physiology, 98(6), 535-45.
Kooistra RD, et al. Knee Extensor Muscle Oxygen Consumption in Relation to Muscle Activation. Eur J Appl Physiol. 2006;98(6):535-45. PubMed PMID: 17089159.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Knee extensor muscle oxygen consumption in relation to muscle activation. AU - Kooistra,R D, AU - Blaauboer,M E, AU - Born,J R, AU - de Ruiter,C J, AU - de Haan,A, Y1 - 2006/11/07/ PY - 2006/08/23/accepted PY - 2006/11/8/pubmed PY - 2007/5/15/medline PY - 2006/11/8/entrez SP - 535 EP - 45 JF - European journal of applied physiology JO - Eur J Appl Physiol VL - 98 IS - 6 N2 - Recently, fatigability and muscle oxygen consumption (mVO(2)) during sustained isometric contractions were found to be less at shorter (30 degrees knee angle; 0 degrees = full extension) compared to longer knee extensor muscle lengths (90 degrees) and, at low torques, less in the rectus femoris (RF) muscle than in the vastus lateralis and medialis. In the present study we hypothesized that these findings could be accounted for by a knee angle- and a muscle-dependent activation respectively. On two experimental days rectified surface EMG (rsEMG) was obtained as a measure of muscle activation in nine healthy young males. In addition, on day 1 maximal torque capacity (MTC) was carefully determined using superimposed nerve stimulation on brief high intensity contractions (> 70%MVC) at 30, 60 and 90 degrees knee angles. On day 2, subjects performed longer lasting isometric contractions (10-70%MTC) while mVO(2) was measured using near-infrared spectroscopy (NIRS). At 30 degrees , maximal mVO(2) was reached significantly later (11.0 s +/- 6.5 s) and was 57.9 +/- 8.3% less (average +/- SD, across intensities and muscles) than mVO(2) at 60 and 90 degrees (p < 0.05). However, rsEMG was on average only 18.0 +/- 11.8% (p = 0.062) less at the start of the contraction at 30 degrees . At 10%MTC at all knee angles, maximal mVO(2) of the RF occurred significantly later (28.8 +/- 36.0 s) and showed a significantly smaller increase in rsEMG compared to both vasti. In conclusion, it is unlikely that the tendency for less intense muscle activation could fully account for the approximately 60% lower oxygen consumption at 30 degrees , but the later increase in RFmVO(2) seemed to be caused by a less strong activation of the RF. SN - 1439-6319 UR - https://www.unboundmedicine.com/medline/citation/17089159/Knee_extensor_muscle_oxygen_consumption_in_relation_to_muscle_activation_ L2 - https://dx.doi.org/10.1007/s00421-006-0298-2 DB - PRIME DP - Unbound Medicine ER -