Abstract
Although angina pectoris in patients with coronary heart disease often occurs when their forearms are in an elevated position for a prolonged period, and sympathetic activation is a major cause of this condition, little is known about the physiological effects of forearm elevation on sympathetic activity during forearm exercise. We hypothesized that forearm elevation augments sympathetic activation during the static handgrip exercise in humans. A total of 10 healthy male volunteers performed 2 min of static handgrip exercise at 30% of maximal voluntary contraction followed by 2 min of post-exercise muscle ischaemia (PEMI; specific activation of the muscle metaboreflex) with two forearm positions: the exercising forearm was elevated 50 cm above the heart (forearm-elevated trial) or fixed at the level of the heart (heart-level trial). Muscle sympathetic nerve activity (MSNA), blood pressure and heart rate were monitored. MSNA increased during handgrip exercise in both forearm positions (P < 0.001); the increase was 51% greater in the forearm-elevated trial (516±99 arbitrary units) than in the heart-level trial (346±44 units; P < 0.05). The increase in mean blood pressure was 8.4 mmHg greater during exercise in the forearm-elevated trial (P < 0.05), while changes in heart rate were similar in both forearm positions. The increase in MSNA during PEMI was 71% greater in the forearm-elevated trial (393±71 arbitrary units/min) than in the heart-level trial (229±29 units/min; P < 0.05). These results support the hypothesis that forearm elevation augments sympathetic activation during handgrip exercise. The excitatory effect of forearm elevation on exercising MSNA may be mediated primarily by increased activation of the muscle metaboreflex.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 295-301 |
| Number of pages | 7 |
| Journal | Clinical Science |
| Volume | 103 |
| Issue number | 3 |
| State | Published - Sep 2002 |
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Keywords
- Cardiovascular system
- Microneurography
- Muscle reflex
- Muscle sympathetic nerve activity
- Static exercise
- Sympathetic nervous system
ASJC Scopus subject areas
- Medicine(all)
Cite this
Forearm elevation augments sympathetic activation during handgrip exercise in humans. / Michikami, Daisaku; Kamiya, Atsunori; Fu, Qi; Niimi, Yuki; Iwase, Satoshi; Mano, Tadaaki; Suzumura, Akio.
In: Clinical Science, Vol. 103, No. 3, 09.2002, p. 295-301.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Forearm elevation augments sympathetic activation during handgrip exercise in humans
AU - Michikami, Daisaku
AU - Kamiya, Atsunori
AU - Fu, Qi
AU - Niimi, Yuki
AU - Iwase, Satoshi
AU - Mano, Tadaaki
AU - Suzumura, Akio
PY - 2002/9
Y1 - 2002/9
N2 - Although angina pectoris in patients with coronary heart disease often occurs when their forearms are in an elevated position for a prolonged period, and sympathetic activation is a major cause of this condition, little is known about the physiological effects of forearm elevation on sympathetic activity during forearm exercise. We hypothesized that forearm elevation augments sympathetic activation during the static handgrip exercise in humans. A total of 10 healthy male volunteers performed 2 min of static handgrip exercise at 30% of maximal voluntary contraction followed by 2 min of post-exercise muscle ischaemia (PEMI; specific activation of the muscle metaboreflex) with two forearm positions: the exercising forearm was elevated 50 cm above the heart (forearm-elevated trial) or fixed at the level of the heart (heart-level trial). Muscle sympathetic nerve activity (MSNA), blood pressure and heart rate were monitored. MSNA increased during handgrip exercise in both forearm positions (P < 0.001); the increase was 51% greater in the forearm-elevated trial (516±99 arbitrary units) than in the heart-level trial (346±44 units; P < 0.05). The increase in mean blood pressure was 8.4 mmHg greater during exercise in the forearm-elevated trial (P < 0.05), while changes in heart rate were similar in both forearm positions. The increase in MSNA during PEMI was 71% greater in the forearm-elevated trial (393±71 arbitrary units/min) than in the heart-level trial (229±29 units/min; P < 0.05). These results support the hypothesis that forearm elevation augments sympathetic activation during handgrip exercise. The excitatory effect of forearm elevation on exercising MSNA may be mediated primarily by increased activation of the muscle metaboreflex.
AB - Although angina pectoris in patients with coronary heart disease often occurs when their forearms are in an elevated position for a prolonged period, and sympathetic activation is a major cause of this condition, little is known about the physiological effects of forearm elevation on sympathetic activity during forearm exercise. We hypothesized that forearm elevation augments sympathetic activation during the static handgrip exercise in humans. A total of 10 healthy male volunteers performed 2 min of static handgrip exercise at 30% of maximal voluntary contraction followed by 2 min of post-exercise muscle ischaemia (PEMI; specific activation of the muscle metaboreflex) with two forearm positions: the exercising forearm was elevated 50 cm above the heart (forearm-elevated trial) or fixed at the level of the heart (heart-level trial). Muscle sympathetic nerve activity (MSNA), blood pressure and heart rate were monitored. MSNA increased during handgrip exercise in both forearm positions (P < 0.001); the increase was 51% greater in the forearm-elevated trial (516±99 arbitrary units) than in the heart-level trial (346±44 units; P < 0.05). The increase in mean blood pressure was 8.4 mmHg greater during exercise in the forearm-elevated trial (P < 0.05), while changes in heart rate were similar in both forearm positions. The increase in MSNA during PEMI was 71% greater in the forearm-elevated trial (393±71 arbitrary units/min) than in the heart-level trial (229±29 units/min; P < 0.05). These results support the hypothesis that forearm elevation augments sympathetic activation during handgrip exercise. The excitatory effect of forearm elevation on exercising MSNA may be mediated primarily by increased activation of the muscle metaboreflex.
KW - Cardiovascular system
KW - Microneurography
KW - Muscle reflex
KW - Muscle sympathetic nerve activity
KW - Static exercise
KW - Sympathetic nervous system
UR - http://www.scopus.com/inward/record.url?scp=0036713843&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0036713843&partnerID=8YFLogxK
M3 - Article
C2 - 12193155
AN - SCOPUS:0036713843
VL - 103
SP - 295
EP - 301
JO - Clinical Science
JF - Clinical Science
SN - 0143-5221
IS - 3
ER -