Effects of intensity and training on cardiovascular responses to the Valsalva maneouvre.

Objectives: To establish the effect of intensity of effort during Valsalva's manoeuvre (VM) on blood pressure and heart rate responses.

Methods: Fourteen participants consisting of eight powerlifters and six controls completed four 15-s VMs at 30 and 50% maximum expiratory pressure. Expiratory pressure (EP), systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were recorded continuously during manoeuvres and response amplitudes were related to well-established phases (I-IV).

Results: For all participants, SBP and DBP responses during Phase I were significantly higher at 50% EP than 30% EP. Phase II responses were significantly higher at 50% EP than 30% EP for HR (39.9 ± 24.3 vs. 24.5 ± 12.5 bpm), SBP (43.6 ± 24.6 vs. 35.3 ± 18.3 mm Hg) and DBP (26.7 ± 7.1 vs. 21.1 ± 7.4 mm Hg). For Phase IV, only the HR response was affected significantly by intensity. These intensity-dependent effects were similar between powerlifters and controls. Powerlifters had significantly greater Phase II responses (HR, SBP and DBP), but in the whole group these cardiovascular responses were also significantly correlated with expiratory pressure (mm Hg) at 30% EP (r=0.59-0.84) and 50% EP (r=0.53-0.82) which was higher in powerlifters than controls.

Conclusions: This study demonstrates that heart rate and blood pressure responses during Phase II are affected by the relative intensity of VM, whereas during Phase IV only heart rate is affected. The higher Phase II responses in powerlifters can be attributed to the higher expiratory pressures they developed.