Intra‐arterial blood pressure traits during and after heavy resistance exercise in healthy males

Effect of Acute Resistance Exercise and Resistance Exercise Training on Central Pulsatile Hemodynamics and Large Artery Stiffness: Part I

Background

Engaging in habitual resistance exercise training (RET; also known as strength training) causes systemic health effects beyond those caused by aerobic/endurance exercise training alone. Despite the resoundingly favorable effect of habitual RET on measures of cardiovascular disease risk, controversy still exists regarding the vascular health effects of this exercise modality largely because some studies find increases in large artery stiffness and central pulsatile hemodynamics with RET. In this two-part series, we examine the effect of acute resistance exercise (RE) and RET on large artery stiffness and pulsatile hemodynamics. We perform a historical overview of seminal/classic studies and report on key findings that have shaped the field. We provide personal commentary on the studies and potential implications of findings related to the acute effects of RE on large artery stiffness and central pulsatile hemodynamics. For part one of this two-part series, we perform a detailed analysis of the hemodynamic signature produced during RE and discuss the sub-acute effects on short-term modulation of large artery stiffness and central pulsatile hemodynamics.

Summary

Acute RE elicits marked ("extreme") elevations in arterial pressure, mediated primarily by increases in vascular resistance and intrathoracic pressure (ITP). Vascular compression from muscular contraction contributes to increases in afterload via increased vascular resistance and pressure from wave reflections. However, as a result of the higher ITP associated with breath holds (Valsalva maneuver) during high relative efforts (>80%), the change in pressure across the aortic wall (transmural pressure) is less than the change in intra-arterial pressure.

Key Messages

The high arterial pressures during some heavy weight lifting exercises are associated with positive swings with ITP related to the Valsalva maneuver and elevations in vascular resistance. The pressure oscillations lead to marked stress within the vascular wall and likely contribute to elevations in large artery stiffness over the subsequent hour.

Diastolic function and dysfunction in athletes

Cardiac remodelling is often most profound in male athletes and in athletes with the greatest volumes of endurance training and is characterized by chamber enlargement and a mild-to-modest hypertrophy. The diastolic filling of the left ventricle (LV) is a complex process including the early recoil of the contracted LV, the active relaxation of the myocardium, the compliance of the myocardium, the filling pressures, and heart rate. Echocardiography is the cornerstone for the clinical assessment of LV diastolic function. LV diastolic function is usually enhanced in elite endurance athletes characterized by improved early filling of the ventricle, while it is preserved or enhanced in other athletes associated with the type of training being performed. This allows for the high performance of any endurance athlete. Typical findings when using resting echocardiography for the assessment of LV diastolic function in endurance athletes include a dilated LV with normal or mildly reduced LV ejection fraction (EF), significantly enlarged left atrium (LA) beyond the commonly used cut-off of 34 mL/m2, and a significantly elevated E/A ratio. The early-diastolic mitral annular velocity and the E-wave peak velocity are usually normal. Importantly, interpretation of the echocardiographic indices of LV diastolic function should always consider the clinical context and other parameters of systolic and diastolic functions. In the absence of an underlying pathology, single measurements outside the expected range for similar athletes will often not represent the pathology.

Older females but not males exhibit increases in cerebral blood velocity, despite similar pulsatility increases after high-intensity resistance exercise

Sex differences in resting cerebral hemodynamics decline with aging. Given that acute resistance exercise (RE) is a hypertensive challenge, it may reveal sex-dependent abnormalities in cerebral hemodynamics. Thus, we hypothesized that cerebral blood velocity and pulsatility responses to RE would be sex-dependent in older adults. Fourteen older females and 11 males (50-68 yr) completed a high-intensity unilateral isokinetic knee flexion/extension exercise. Measurements were collected at baseline, immediately, 5- and 30-min post-RE. Blood pressure was measured via finger photoplethysmography. Mean middle cerebral artery blood velocity (MCAv) and pulsatility were assessed via transcranial Doppler ultrasound. Carotid pulsatility was obtained via duplex ultrasound. MCAv increased immediately after RE in older females [mean difference (d) = 6.02, 95% CI: 1.66 to 10.39 cm/s, P < 0.001] but not in males (d = -0.72, 95% CI: -3.83 to 5.27 cm/s, P = 0.99), followed by similar reductions 5-min post-RE in older females (d = -4.40, 95% CI: -8.81 to -0.10 cm/s, P = 0.045) and males (d = -6.41, 95% CI: -11.19 to -1.62 cm/s, P = 0.003). MCAv pulsatility increased similarly in older females (d = 0.24, 95% CI: 0.11 to 0.40, P < 0.001) and males (d = 0.38, 95% CI: 0.20 to 0.53, P < 0.001), persisting 5-min post-RE. Older females showed smaller increases in carotid pulsatility immediately after RE (d = 0.18, 95% CI: 0.03 to 0.38, P = 0.01) than males (d = 0.48, 95% CI: 0.26 to 0.68, P < 0.001). An exercise-mediated hypertensive stimulus revealed differential sex responses in MCAv and carotid pulsatility but not in cerebral pulsatility. Cerebral pulsatility findings suggest a similar sex susceptibility to cerebrovascular abnormalities following exercise-mediated hypertensive stimulus in older adults.NEW & NOTEWORTHY Sex differences in resting cerebral hemodynamics decline with advancing age as females experience larger reductions in cerebral blood velocity and steeper pulsatility increases than males. However, an exercise-mediated hypertensive stimulus might reveal sex differences in cerebral hemodynamics not apparent at rest. Following high-intensity resistance exercise, older females but not males exhibit increases in cerebral blood velocity, despite similar increases in cerebral pulsatility. The susceptibility to cerebrovascular abnormalities following exercise-mediated hypertensive stimulus appears similar between sexes.