Acute high-intensity resistance exercise caused transient load-dependent carotid stiffening in middle-aged (mean difference -46.6; 95% CI -71.3 to -21.8; p=0.002) and young females.
Observational (n=28)
Does acute high-intensity resistance exercise elicit different load-dependent and structural carotid stiffening in young versus middle-aged females?
High-intensity resistance exercise causes only transient, load-dependent carotid stiffening in females regardless of age, suggesting it does not increase the immediate risk of vascular damage in healthy middle-aged females.
Effect estimate: mean difference -46.6 (95% CI -71.3 to -21.8)
p-value: p=0.002
BACKGROUND: Aging stiffens the common carotid artery due to pressure load-dependent and structural remodelling mechanisms. In older females, these effects are partly exacerbated by the endocrine menopausal transition. Acute high-intensity resistance exercise (RE) elicits a more exaggerated pressor response in older females, which plausibly leads to greater acute load-dependent arterial stiffening compared to young females. However, whether such a hypertensive stimulus also elicits acutely alters structural stiffening, and whether aging amplifies these responses remains unknown. PURPOSE: To determine how load-dependent and structural components contribute to carotid stiffness following an acute hypertensive stimulus (RE), in both young and middle-aged females. METHODS: Fifteen young (18-34 years) and 13 largely middle-aged (50-68 years) females completed an acute bout of high-intensity unilateral isokinetic knee flexion/extension exercise. Beat-to-beat BP was measured via finger photoplethysmography. Distensibility of the common carotid and brachial arteries was obtained from ultrasonic echo-tracking to estimate pulse wave velocity (PWV) as an indicator of local arterial stiffness. Structural (using fixed pressures, carotid: 112/80 mmHg) and load-dependent PWVs were estimated from the Bramwell-Hill equation with Peterson’s elastic modulus (PEM), using a participant-specific exponential model with a non-linear stiffness parameter. Measurements were obtained at baseline and immediately, 5-min, and 30-min post-RE, with changes analyzed using a two-way repeated measures ANOVA. RESULTS: Total carotid PEM was elevated in the middle-aged group at baseline and remained elevated across testing (mean difference (d) = 191, 95% CI: 131 to 251, p < 0.001). Load-dependant PEM was not significantly different between groups at baseline (d = 14.0, 95% CI: -13.1 to 41.1, p = 0.297). Immediately post-RE, load-dependent PEM increased in middle aged (d = -46.6, 95% CI: -71.3 to -21.8, p = 0.002) and young (d = -21.0, 95% CI: -38.7 to -3.26, p = 0.024) females before returning to baseline at 5-min post- RE. While structural PEM was elevated in the middle-aged group at baseline (d = 177.2, 95% CI: 113.1 to 241.2, p < 0.001), neither group showed structural changes across testing. CONCLUSION: High-intensity leg-kicking causes transient carotid stiffening exclusively attributed to load dependent mechanisms irrespective of age in females. These findings suggest that acute blood pressure increases during resistance exercise do not increase immediate risk of vascular damage or adverse events in healthy middle-aged females. 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.
Fitzpatrick et al. (Fri,) conducted a observational in Healthy females (n=28). Acute high-intensity unilateral isokinetic knee flexion/extension exercise vs. Baseline and young females was evaluated on Change in load-dependent Peterson's elastic modulus (PEM) immediately post-exercise (mean difference -46.6, 95% CI -71.3 to -21.8, p=0.002). Acute high-intensity resistance exercise caused transient load-dependent carotid stiffening in middle-aged (mean difference -46.6; 95% CI -71.3 to -21.8; p=0.002) and young females.