Isometric handgrip training improves cardiac systolic function and ventricular-arterial coupling regardless of sex in young adults

BACKGROUND: Isometric handgrip (IHG) is a time-efficient, low-cost, home-based intervention that rivals the blood pressure-lowering effects of traditional training modalities. The resultant reduction in arterial load contributes to the increase in cardiac systolic function observed often, but not universally, after IHG. Moreover, few IHG studies have evaluated how changes in ventricular-arterial coupling influence cardiac training adaptations, or whether these responses differ by sex. PURPOSE: To determine if IHG improves systolic function and ventricular-arterial coupling due to reductions in arterial load, and whether these adaptations are sex-specific in young adults. METHODS: Twelve normotensive females and twelve males (18–29 years) completed a baseline visit, a 4-week home-based IHG program (3 days/week; 4 × 2-min at 30% MVC; ~89% adherence), and a 4-week non-exercise period in a randomized crossover design. Modified Simpson’s -derived cardiac volumes and systolic function were obtained from echocardiographic four-chamber views. Carotid end-systolic pressure (ESP), calibrated to brachial mean pressure, was estimated from ECG-gated tonometry measurements. Heart–vessel interactions were quantified via the arterial (ESP/stroke volume) to ventricular elastance (ESP/end-systolic volume) ratio (Ea/Ees). Ventricular-arterial parameters were allometrically scaled to body surface area (BSA). IHG effects were tested with linear mixed models. RESULTS: There were no sex differences in stroke volume and Ea after scaling for BSA. After IHG, both sexes showed similar increases in scaled stroke volume (interaction p=0.594; mean difference (ΔIHG–BAS): 9 mL, 95% CI: 2–15 mL, p=0.004) and ejection fraction (interaction p=0.564; ΔIHG–BAS: 3.1%, 95% CI: 1.2–4.9%, p< 0.001), driven by higher end-diastolic volume (condition, p< 0.001). IHG induced similar ESP reductions across sex (interaction, p=0.192, condition, p=0.003). The coupling ratio decreased in both sexes (interaction p=0.505; ΔIHG–BAS: –0.06, 95% CI: –0.10 to –0.03, p=0.003), reflecting reduced Ea (interaction p=0.286; ΔIHG–BAS: –0.24 mmHg/mL, 95% CI: –0.34 to –0.13 mmHg/mL, p< 0.001), while Ees remained unchanged (p=0.505). CONCLUSIONS: IHG training reduces arterial load, resulting in increased systolic function and optimized ventricular-arterial coupling regardless of sex. Even in normotensive young adults with favorable ventricular–arterial coupling reflected by unopposed and energetically efficient blood ejection, heart–vessel interactions remain amendable to optimization via IHG, possibly enhancing reserve against future cardiac disease. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.