title: Sympatho-vagal interaction in the recovery phase of exercise.
abstract: Reciprocal autonomic regulation occurs during incremental exercise. We hypothesized that sympatho-vagal interplay may become altered after exercise because of the differences in recovery patterns of autonomic arms. The cardiac vagal activity was assessed by measurement of beat-to-beat R-R interval oscillations using a Poincaré plot method (SD1), and muscle sympathetic nervous activity (MSNA) was measured from peroneus nerve by a microneurography technique during and after exercise in 16 healthy subjects. Autonomic regulation was compared between the rest and after exercise (3·5 ± 1·0 min after exercise) at equal heart rates (HR). SD1 was at the equal level at the recovery phase (40 ± 21 ms) compared to the resting condition (38 ± 16 ms, P = ns) at comparable HR (57 ± 10 for both). MSNA was higher at the recovery phase (40 ± 19 burst per 100 heartbeats) than at rest (25 ± 13 burst per 100 heartbeats, P<0·0001). The difference of MSNA activity between rest and late recovery phase had a strong positive correlation with the difference in SD1 (r = 0·78, P<0·001) at equal HRs. Subjects who have a higher sympathetic activity in the recovery phase of exercise have a more augmented cardiac vagal activity resulting in an accentuated sympatho-vagal outflow. The altered autonomic interaction observed here may partly explain the clustering of various cardiovascular events to the recovery phase of exercise.
authors.affiliation: Department of Exercise and Medical Physiology, Verve, Oulu, Finland. mikko.tulppo@verve.fi
authors.forename: Mikko P
authors.initials: MP
authors.lastname: Tulppo
authors.forename: Antti M
authors.initials: AM
authors.lastname: Kiviniemi
authors.forename: Arto J
authors.initials: AJ
authors.lastname: Hautala
authors.forename: Mika
authors.initials: M
authors.lastname: Kallio
authors.forename: Tapio
authors.initials: T
authors.lastname: Seppänen
authors.forename: Suvi
authors.initials: S
authors.lastname: Tiinanen
authors.forename: Timo H
authors.initials: TH
authors.lastname: Mäkikallio
authors.forename: Heikki V
authors.initials: HV
authors.lastname: Huikuri
mesh_terms: D000328:Adult; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D020127:Recovery of Function / Q000502:physiology*; D013223:Statistics as Topic; D013564:Sympathetic Nervous System / Q000502:physiology*; D014630:Vagus Nerve / Q000502:physiology*