Squats Match Exercise Echo for Provoking Heart Obstruction in Hypertrophic Cardiomyopathy

For patients with obstructive hypertrophic cardiomyopathy, the choice of bedside maneuver used to unmask dangerous left ventricular outflow tract obstruction may matter less than clinicians have assumed.

Hypertrophic cardiomyopathy is the most prevalent genetic heart muscle disease, with an estimated prevalence between 1 in 200 and 1 in 500. It is defined by left ventricular wall thickening of at least 15 millimeters that cannot be attributed to other conditions such as hypertension, aortic valve stenosis, or storage disease. In roughly 70 percent of patients, the left ventricular outflow tract becomes obstructed, with Doppler-measured peak gradients of at least 30 millimeters of mercury defining the obstructive form of the disease.

The Leipzig team enrolled consecutive ambulatory outpatients with obstructive hypertrophic cardiomyopathy between October 2024 and September 2025. All 20 participants were myosin inhibitor-naive, had no mobility-limiting conditions, and were examined in the departmental echo laboratory by board-certified cardiologists using a standardized protocol starting at 7:30 in the morning. To standardize conditions, all patients fasted for three hours before testing, since recent food intake has been shown to increase outflow tract gradients. Continuous wave Doppler in the apical three-chamber view captured gradients at rest and then during each provocation in a fixed sequence: Valsalva, handgrip at 50 percent and 30 percent of maximal hand force, squats, and finally semi-supine bicycle exercise stress echocardiography, with rest intervals until heart rate and blood pressure returned to baseline.

The results were striking in their symmetry. The mean resting gradient was 38.9 plus or minus 31.4 millimeters of mercury, already indicating obstruction at rest in the cohort. Handgrip exercise at 30 percent of maximal force produced a mean gradient of 34.35 plus or minus 22.81, and at 50 percent a mean of 42.30 plus or minus 29.96, neither significantly different from rest. By contrast, the Valsalva maneuver drove the mean gradient to 98.9 plus or minus 52.8, squats to 120.3 plus or minus 68.8, and bicycle exercise to 83.4 plus or minus 43.3, all highly significant compared with rest. Yet the three effective maneuvers did not differ significantly from one another, and no single technique dominated: squats produced the highest gradient in 10 of 20 patients, the Valsalva maneuver in 6, and bicycle exercise in only 4.

A subtler finding concerned timing. During bicycle exercise, gradients measured in the early recovery period, within 30 seconds after stopping, were significantly higher than those at peak exercise, 83.40 versus 78.26 millimeters of mercury, and in 18 of 20 patients the early-recovery value exceeded the peak-exercise value. Because gradients after squats and bicycle exercise were assessed in early recovery rather than during exertion, the authors caution that these values reflect both exercise-induced and early-recovery-induced obstruction, a nuance that matters when comparing modalities whose measurement windows differ.

The study also quantified the practical cost of each test. Bicycle exercise stress echocardiography averaged 15 minutes and 54 seconds of pure examination time, with patients reaching a maximal workload of 107.5 plus or minus 48.05 watts. Squats took an average of 1 minute and 23 seconds, with patients performing 27.5 plus or minus 9.32 repetitions at a pace of roughly one squat every three seconds until subjective exhaustion, and the Valsalva maneuver, conservatively estimated at 15 seconds, was the shortest of all. Both bedside maneuvers were significantly faster than bicycle exercise, and the authors note that the true time burden of the ergometer test is likely underestimated because setup and dismantling of equipment were not counted.

For the subgroup of patients whose resting gradient was below 30 millimeters of mercury, 9 of the 20 participants, the stepwise protocol showed how often each maneuver first unmasked significant obstruction. A gradient of at least 30 was first provoked by the Valsalva maneuver in 8 of these 9 patients and by squats in the remaining one. A gradient of at least 50 was first elicited by Valsalva in 6 patients and by squats in 2, while in one patient no maneuver reached the 50-millimeter threshold. Among the 3 patients whose gradient stayed below 50 during Valsalva, 2 subsequently crossed that threshold during both squats and bicycle exercise, illustrating why a second bedside maneuver can spare some patients a full exercise test.

The failure of handgrip exercise fits the underlying physiology. Isometric handgrip primarily increases afterload while leaving preload and contractility largely unchanged, whereas elevations of the outflow tract gradient are driven mainly by reductions in preload and afterload; the increased afterload during handgrip actually reduces left ventricular stroke volume and ejection velocity. The authors conclude that handgrip, despite its growing use as a simple stressor in echocardiography, particularly for assessing mitral regurgitation, is not a suitable method for provoking outflow tract obstruction in this population. The mechanism behind the success of squats is different: the squatting phase raises both preload and afterload, and the sudden transition to standing and then semi-supine positioning abruptly drops both, further augmenting obstruction through repetitive preload and afterload swings that are also easier to standardize than a patient-dependent Valsalva effort.

The findings align with prior work but add context. Peng and colleagues reported higher gradients with squats than Valsalva in 109 patients with hypertrophic cardiomyopathy, while Joshi and colleagues found treadmill exercise provoked significantly higher gradients than Valsalva, a discrepancy the Leipzig authors attribute in part to posture, since upright treadmill exercise reduces venous return more than semi-supine cycling and recruits greater muscle mass. Reant and colleagues similarly reported lower gradients during semi-supine bicycle exercise than treadmill exercise. The study has clear limitations: the single-center cohort of 20 patients makes the analyses primarily exploratory, the population was heterogeneous in age, NYHA class, and medication use, the fixed maneuver sequence could have introduced fatigue effects, and the repetitive squat-to-exhaustion protocol differs from the simpler squat-to-stand maneuver described in guidelines. Because all participants already had obstructive disease, the study assessed gradient provocation rather than diagnostic specificity, which would require validation in non-obstructive patients and controls. With those caveats, the authors suggest that squats, being simple, rapid, and inexpensive, may serve as a practical adjunct to the Valsalva maneuver before resorting to the more time-consuming and technically demanding exercise stress echo, while noting that equivalence for diagnostic classification and treatment decisions remains to be established.

Subject of Research: Comparison of provocation maneuvers for left ventricular outflow tract gradients in obstructive hypertrophic cardiomyopathy

Article Title: The effect of different exercise modalities on the maximal left ventricular outflow tract gradient in patients with obstructive hypertrophic cardiomyopathy

Article References: Möbius-Winkler, M. N., Hagendorff, A., Stöbe, S., Gaier, M., Kogel, A., Antoniadis, M., Laufs, U., Metze, M., Lenk, K., & Kandels, J. (2026). The effect of different exercise modalities on the maximal left ventricular outflow tract gradient in patients with obstructive hypertrophic cardiomyopathy. Echo Research & Practice, 13(1), Article 39. https://doi.org/10.1186/s44156-026-00141-3

Image Credits: AI Generated

DOI: 10.1186/s44156-026-00141-3

Keywords: hypertrophic cardiomyopathy, left ventricular outflow tract obstruction, exercise stress echocardiography, Valsalva maneuver, squats, handgrip exercise, echocardiography, Doppler gradient, cardiac imaging, bedside maneuvers, effect, different