Influence Of Resistance Exercise Intensity On Post-exercise Hypotension, Hemodynamics And Sympathetic Activation

Introduction
Although extensively demonstrated after aerobic exercise, the occurence of post-exercise hypotension after resistance
exercise is still controversial. The aim of this study was to evaluate the effect of different resistance exercise intensities
on blood pressure and its hemodynamic and autonomic mechanisms in the post-exercise period.

Methods
Seventeen normotensive subjects were submitted, in a randon order, to 3 experimental sessions: control (C - with no
exercise), low-intensity resistance exercise (LI - 40% of 1 repetition maximal - RM), and high intensity resistance
exercise (HI - 80% of RM). In all sessions, blood pressure (BP - auscultatory and tonometric methods), heart rate (HR
- ECG), and cardiac output (CO - CO2 rebreathing) were measured. Autonomic regulation was evaluated by the
spectral analysis of HR and BP variabilities. All measurements were taken at baseline and for 90 minutes after rest (C)
or exercise (LI and HI).

Results
Systolic BP decreased after both exercise sessions (LI=-6±1 and HI=-8±1 mmHg, P<0.05). Diastolic BP decreased after
LI exercise, increased in C session, and did not change after HI session. This response was different between LI and the
other sessions (LI=-4±1 vs. C=+5±1 and HI=0±1 mmHg, P<0.05). CO decreased similarly in all sessions (marginal
value=-0.4±0.2 l/min, P<0.05), while systemic vascular resistance (SVR) increased in C (+7±2 U, P<0.05), did not
change in LI (+1±1 U), and increased in HI (5±2 U, P<0.05) session, and this behavior was significantly different
between sessions. Stroke volume decreased (LI=-11±2 and HI=-17±2 ml/beat, P,0.05), while HR increased (LI=+17±2
and HI=+21±2 bpm, P,0.05) in both exercise sessions, and these responses were greater after HI exercise. In regard to
autonomic regulation of the heart, high-frequency normalized component of HR variability decreased (LI=-22±3, and
HI=-23±3%, P,0.05), while low-frequency component (LI=+22±3 and HI=+23±3%, P,0.05) increased after both
exercise sessions. Low frequency component of systolic and diastolic BP variability did not change in any session.

Discussion/ Conclusions
Resistance exercise of low and high intensity causes post-exercise hypotension, which is greater for diastolic BP after
low-intensity exercise. BP fall was due to CO decrease that is not completely compensated by SVR increase. Moreover,
BP fall was accompanied by an increase in sympathetic activation of the heart, with no change in sympathetic
vasomotor tone.
Financial Support: FAPESP (01/01952-8) and CAPES (Demanda Social)

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