September 1, 1994Journal of Applied Physiology
Arm muscle sympathetic nerve activity during preparation for and initiation of leg-cycling exercise in humans
Why the study?
Does leg-cycling exercise reduce arm muscle sympathetic nerve activity in healthy young subjects?
Population
11 healthy young subjects
Comparison
1 min of leg-cycling exercise at one or more… vs Upright seated rest (control)
Follow-up
1 minute
Authors
Discussion
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Implication
May indicate anticipatory sympathetic withdrawal before low-intensity leg exercise; leaves open applicability to patients or higher workloads.
Key Points
- To determine whether muscle sympathetic vasoconstrictor nerve activity in nonactive skeletal muscle suppresses immediately prior to and during the initiation of upright dynamic leg exercise.
- Radial nerve muscle sympathetic nerve activity (MSNA) was recorded in 11 healthy young subjects during upright seated rest and 1 minute of leg cycling across workloads ranging from 33 to 266 W (10–80% peak power output).
- MSNA was evaluated across four phases: control rest, preparation (prior to pedaling), initiation (pedaling onset to target workload), and the initial 60 seconds at target power.
- MSNA decreased abruptly (P < 0.05) to 19 ± 4% of baseline control levels during the preparation phase before starting a 33-W load.
- MSNA remained suppressed during the cycling initiation phase in 8 of 11 subjects, increasing only in 3 subjects whose diastolic arterial pressure fell below control levels.
- Arm MSNA stayed at or below control levels throughout 1 minute of cycling at 33–166 W, exceeding baseline levels only during the latter portion of cycling at workloads ≥60% of peak power output.
Structured PICO
Does leg-cycling exercise reduce arm muscle sympathetic nerve activity in healthy young subjects?
P
Population
11 healthy young subjects
I
Intervention
1 min of leg-cycling exercise at one or more submaximal workloads (range 33-266 W; approximately 10-80% of peak power output)
C
Comparator
Upright seated rest (control)
O
Outcome
Muscle sympathetic nerve activity (MSNA) from the radial nerve in the armsurrogate
Sympathetic vasoconstrictor nerve activity to nonactive skeletal muscle decreases immediately before and remains suppressed during the initiation of upright dynamic exercise.
Cite This Study
Callister et al. (1994) studied this question.