Maximal expiratory pressure and Valsalva manoeuvre do not produce similar cardiovascular responses in healthy men

Cardiovascular responses to low-intensity isometric handgrip exercise in coronary artery disease: effects of posture

BACKGROUND

Coronary artery disease (CAD) lead to cardiovascular autonomic control disfunctions that can worsen exercise and/or posture adjustments.

OBJECTIVES

To verify the cardiovascular responses to low-intensity isometric handgrip exercise performed in different postures in CAD patients. This study tested the hypothesis that the posture influences the cardiovascular responses during isometric handgrip exercise and that the presence of CAD leads to greater cardiovascular stress during this type of exercise.

METHODS

We investigated cardiovascular responses to isometric handgrip exercise in 15 CAD patients (CADG) and 15 health matched-control (CG). The subjects performed isometric handgrip exercise at 30% of maximum voluntary contraction until exhaustion in SUPINE, SITTING and STANDING positions. Systolic arterial pressure, diastolic arterial pressure, mean blood pressure, heart rate, peripheral vascular resistance, cardiac output, stroke volume and double product were measured during rest (baseline), exercise (peak value) and recovery in the 1st minute (REC1). Delta PB (ΔPB, peak minus baseline) and PR1 (ΔPR1, peak minus REC1) were calculated.

RESULTS

Higher ΔPB and ΔPR1 of systolic and mean arterial pressure and double product were observed in STANDING when compared to SITTING and/or SUPINE. CADG showed higher ΔPB of systolic and mean arterial pressure in all postures and higher ΔPR1 of strove volume in the SITTING.

CONCLUSION

We concluded that the posture during isometric handgrip exercise influences the cardiovascular responses with STANDING leading to higher cardiovascular stress. CAD promoted higher arterial pressure responses however these responses were physiological and expected due to the presence of disease and type of exercise.

Is cardiac autonomic modulation during upper limb isometric contraction and Valsalva maneuver impaired in COPD patients?

PURPOSE

To evaluate the heart rate variability (HRV) indices and heart rate (HR) responses during isometric contraction (IC) and Valsalva maneuver (VM) in COPD patients.

METHODS

Twenty-two stable moderate to severe COPD patients were evaluated. R-R intervals were recorded (monitor Polar^® S810i) during dominant upper limb IC (2 minutes). Stable signals were analyzed by Kubios HRV^® software. Indices of HRV were computed in the time domain (mean HR; square root of the mean squared differences of successive RR intervals [RMSSD] and HRV triangular index [RR tri index]) and in the frequency domain (high frequency [HF]; low frequency [LF] and LF/HF ratio). The HR responses were evaluated at rest, at the peak and at the nadir of the VM (15 seconds). The Valsalva index was also calculated.

RESULTS

During IC: time domain indices (mean HR increased [P=0.001], RMSSD, and RR tri index decreased [P=0.005 and P=0.005, respectively]); frequency domain indices (LF increased [P=0.033] and HF decreased [P=0.002]); associations were found between forced expiratory volume in 1 second (FEV₁) vs RMSSD (P=0.04; r=-0.55), FEV₁ vs HR (P=0.04; r=-0.48), forced vital capacity (FVC) vs RMSSD (P=0.05; r=-0.62), maximum inspiratory pressure (MIP) vs HF (P=0.02; r=0.68). FEV₁ and FVC justified 30% of mean HR. During VM: HR increased (P=0.01); the nadir showed normal bradycardic response; the Valsalva index was =0.7.

CONCLUSION

COPD patients responded properly to the upper limb IC and to the VM; however, HR recovery during VM was impaired in these patients. The severity of the disease and MIP were associated with increased parasympathetic modulation and higher chronotropic response.