Effect of local blood circulation and absolute torque on muscle endurance at two different knee-joint angles in humans

Citation
Ho. Hisaeda et al., Effect of local blood circulation and absolute torque on muscle endurance at two different knee-joint angles in humans, EUR J A PHY, 86(1), 2001, pp. 17-23
Citations number
30
Categorie Soggetti
Physiology
Journal title
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY
ISSN journal
14396319 → ACNP
Volume
86
Issue
1
Year of publication
2001
Pages
17 - 23
Database
ISI
SICI code
1439-6319(200111)86:1<17:EOLBCA>2.0.ZU;2-M
Abstract
The effects of the local blood circulation and absolute torque on muscle en durance at different knee-joint angles were determined. The rate of muscle deoxygenation (using near-infrared spectroscopy), and the rate of muscle fa tigue (using the slope of integrated electromyography. iEMG) were evaluated concurrently. Nine healthy subjects performed submaximal (50% maximal volu ntary contraction. MVC) static knee extension at 50 degrees (extended posit ion, EXT) and 90 degrees (flexed position, FLEX) joint angles until the tar get torque could no longer be maintained: that time was measured as the end urance time. They exercised with the circulation occluded (OCCL), and witho ut (FREE) to study the possible effects of the local circulation. Although MVC torque was independent of joint angle [mean (SID) FLEX 250.6 (51.7) N(. )m and EXT 246.5 (46.6) N(.)m], significantly shorter (P < 0.01) endurance time in FLEX [FREE 71.1 (10) s and OCCL 63.1 (8.8) s] than at EXT [FREE 115 .3 (30) s and OCCL 106.7 (29.1) s] were obtained in both circulatory condit ions. The iEMG-time slope was significantly greater in FLEX at the proximal and distal portion (P < 0.05) in both circulatory conditions. Muscle deoxy genation rate in OCCL was significantly greater (P < 0.05) at FLEX [20.8 (8 .0)%] than EXT [10.9 (4.0)%]. The results would suggest that different knee -joint angle affects muscle endurance even if the local circulation is cont rolled. Circulatory disturbance would further reduce muscle endurance in EX T, but not in FLEX. Because of the greater muscle internal force in FLEX. l ocal blood flow might be already limited even with a free circulation. The greater muscle deoxygenation and muscle fatigability would be related to th e shorter muscle endurance in FLEX.