The Acute Effect of Resistance Exercise in Individuals With Hypertrophic Cardiomyopathy: A Pilot Study

Resistance exercise in hypertrophic cardiomyopathy (HCM) remains underexplored. Yet, it has traditionally been restricted due to hypothesized deleterious effects. This single-center pilot study evaluated the acute effects of resistance exercise on left ventricular outflow tract (LVOT) gradient. One-repetition maximum (1RM) was determined for upright chest press and leg press exercises. In a subsequent session, patients completed 8 to 12 repetitions at 40%1RM and 2 repetitions at 80%1RM under 3 breathing conditions: no instructions, with Valsalva, and without Valsalva. LVOT gradients were measured at baseline, during, and immediately after exercise. Medication regimens were not altered. 24 patients (18 obstructive) were included. No individual with nonobstructive HCM developed obstruction during or immediately after resistance activity, even at higher intensities. Patients with obstructive HCM and baseline gradients <50 mmHg while on medical therapy exhibited only modest and likely clinically irrelevant increases in gradients during and after resistance efforts. Among those with higher resting gradients (≥50 mmHg), responses were variable depending on the type and intensity of exercise, but most did not experience significant increase in gradients. Importantly, no patient developed symptoms, drop in blood pressure, or arrhythmias during or after the exercises. There was also no consistent difference in gradient magnitude during versus immediately postexercise. Higher-intensity exercise with fewer repetitions did not produce larger increases in gradients. Different breathing instructions during lifting did not produce consistent changes in gradients. In conclusion, resistance exercise was not associated with clinically significant acute increases in LVOT gradient in patients with nonobstructive HCM and in most treated patients with obstructive HCM, including those with high resting gradients. Variability in individual responses supports the need for personalized exercise prescriptions.