Received August 29, 2005
Revised September 23, 2005
Accepted after revision October 5, 2005
Human/environmental and exercise physiology
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Effects of rhythmic muscle compression on cardiovascular responses and muscle oxygenation at rest and during dynamic exercise in humans
Takeshi Nishiyasu 1*,
Tsuyoshi Maekawa 2,
Ryoko Sone 3,
Nobusuke Tan 3,
Narihiko Kondo 4
1 University of Tsukuba
2 School of Medicine, Yamaguchi University
3 Faculty of Education, Yamaguchi University
4 Faculty of Developmental Sciences, Kobe University
* To whom correspondence should be addressed. E-mail: nisiyasu{at}taiiku.tsukuba.ac.jp.
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Abstract |
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We examined the way in which the duration of rhythmic muscle compressions affects cardiovascular responses and muscle oxygenation at rest and during dynamic exercise. Measured were the mean arterial pressure (MAP), heart rate (HR) and oxygenation of the vastus lateralis muscle (by near-infrared spectroscopy) in eight healthy subjects at rest and during supine bicycle exercise (50 and 100W at 60 rpm) while applying pulsed compressions at 1000-ms intervals. Compression pressure and durations were 150 mmHg and 300, 600, 900 and 1000 ms (1000 ms, actually being static compression), respectively. During exercise, the pulsed leg compression was synchronized to each thigh extensor muscle contraction. The observed changes in muscle oxygenation were dependent on compression duration (increased at 300 ms, no change at 600 ms, decreased at 900 or 1000 ms) and were different from those seen at rest (increases at < 1000 ms, decrease at 1000 ms). This suggests that the effects of external pulsed muscle compression may have a duration threshold below which muscle-pumping counteracts the obstruction to flow caused by the compression, and that the threshold is set at a shorter compression duration during exercise than at rest. Although HR and MAP did not change during pulsed compression at rest, during exercise they both increased progressively as compression duration increased. Thus, while exercising the increased MAP and HR seen during the compression could be due to the combination and interaction among mechanical effects and the muscle mechanoreflex and/or metaboreflex.
Key Words:
Cardiovascular, Exercise, Sympathetic nervous system
