Cardio-protection afforded by β-blockade is maintained during resistance exercise

Area of Science:

• Cardiovascular Physiology
• Exercise Science
• Pharmacology

Background:

• The cardio-protective effects of beta-adrenergic blockade are well-established at rest.
• However, its efficacy during resistance exercise, particularly isometric contractions, remains less understood.

Purpose of the Study:

• To systematically evaluate if the cardio-protective effects of beta-blockade are retained during various isometric resistance exercises.
• To compare the effects of a selective beta1-blocker (atenolol) and a non-selective beta-blocker (propranolol) against a placebo.

Main Methods:

• Eleven healthy young males participated in a randomized, double-blinded, repeated-measures study.
• Participants performed isometric hand-gripping, single-leg extension, and double-leg dead-lift exercises at 30% maximal voluntary contraction under placebo, atenolol, and propranolol conditions.
• Key cardiorespiratory parameters including heart rate, blood pressure, and cardiac output were measured.

Main Results:

• A graded pressor response was observed with increasing exercise intensity across all conditions.
• Both atenolol and propranolol similarly attenuated the rise in heart rate and systolic blood pressure.
• A significant interaction effect showed the greatest reduction in rate-pressure product with the dead-lift exercise under beta-blockade.

Conclusions:

• Beta-adrenergic blockade preserves its cardio-protective effect during isometric resistance exercise.
• This protective effect is even enhanced when heart rate exceeds 100 beats per minute during exercise.