Cardiovascular disease is a leading cause of morbidity and mortality in males and females in the United States and globally. Cardiac rehabilitation (CR) is recommended by the American Heart Association/American College of Cardiology for secondary prevention for patients with cardiovascular disease. CR participation is associated with improved cardiovascular disease risk factor management, quality of life, and exercise capacity as well as reductions in hospital admissions and mortality. Despite these advantageous clinical outcomes, significant sex disparities exist in outpatient phase II CR programming. This article reviews sex differences that are present in the spectrum of care provided by outpatient phase II CR programming (ie, from referral to clinical management). We first review CR participation by detailing the sex disparities in the rates of CR referral, enrollment, and completion. In doing so, we discuss patient, health care provider, and social/environmental level barriers to CR participation with a particular emphasis on those barriers that majorly impact females. We also evaluate sex differences in the core components incorporated into CR programming (eg, patient assessment, exercise training, hypertension management). Next, we review strategies to mitigate these sex differences in CR participation with a focus on automatic CR referral, female-only CR programming, and hybrid CR. Finally, we outline knowledge gaps and areas of future research to minimize and prevent sex differences in CR programming.

It is currently unknown whether sex differences exist in the cardiovascular consequences of the inspiratory muscle metaboreflex. We hypothesized that the activation of the inspiratory muscle metaboreflex will lead to less of an increase in mean arterial pressure (MAP) and limb vascular resistance (LVR) and less of a decrease in limb blood flow (Q̇_L) in women compared with men. Twenty healthy men ( n = 10, 23 ± 2 yr) and women ( n = 10, 22 ± 3 yr) were recruited for this study. Subjects performed inspiratory resistive breathing tasks (IRBTs) at 2% or 65% of their maximal inspiratory mouth pressure (PI_MAX). During the IRBTs, the breathing frequency was 20 breaths/min with a 50% duty cycle. At rest and during the IRBTs, MAP was measured via automated oscillometry, Q̇_L was measured via Doppler ultrasound, and LVR was calculated. EMG was recorded on the leg to ensure no muscle contraction occurred. The 65% IRBT led to attenuated increases ( P < 0.01) from baseline in women compared with men for MAP (W: 7.3 ± 2.0 mmHg; M: 11.1 ± 5.0 mmHg) and LVR (W: 17.7% ± 14.0%; M: 47.9 ± 21.0%), as well as less of a decrease ( P < 0.01) in Q̇_L (W: −7.5 ± 9.9%; M: −23.3 ± 10.2%). These sex differences in MAP, Q̇_L, and LVR were still present in a subset of subjects matched for PI_MAX. The 2% IRBT resulted in no significant changes in MAP, Q̇_L, or LVR across time or between men and women. These data indicate premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with age-matched men.

With inspiratory muscle metaboreflex activation, we hypothesized that, compared with their younger counterparts, older men and women would exhibit greater 1) increases in mean arterial pressure (MAP) and limb vascular resistance (LVR) and 2) decreases in limb blood flow (Q̇_L) but 3) no sex differences would be present in older adults. Sixteen young adults [8 young men (YM) and 8 young women (YW), 18–24 yr] and 16 older adults [8 older men (OM) and 8 older women (OW), 60–73 yr] performed inspiratory resistive breathing tasks (IRBTs) at 2% and 65% of their maximal inspiratory pressure. During the IRBTs, breathing frequency was 20 breaths/min with a 50% duty cycle. At baseline and during the IRBTs, MAP was measured via automated oscillometry, Q̇_Lwas determined via Doppler ultrasound, and LVR was calculated. The 65% IRBT led to significantly greater increases in MAP in OW (15.9 ± 8.1 mmHg) compared with YW (6.9 ± 1.4 mmHg) but not ( P > 0.05) between OM (12.3 ± 5.7 mmHg) and YM (10.8 ± 5.7 mmHg). OW (−20.2 ± 7.2%) had greater ( P < 0.05) decreases in Q̇_Lcompared with YW (−9.4 ± 10.2%), but no significant differences were present between OM (−22.8 ± 9.7%) and YM (−22.7 ± 11.3%) during the 65% IRBT. The 65% IRBT led to greater ( P < 0.05) increases in LVR in OW (48.2 ± 25.5%) compared with YW (19.7 ± 15.0%), but no differences ( P > 0.05) existed among OM (54.4 ± 17.8%) and YM (47.1 ± 23.3%). No significant differences were present in MAP, Q̇_L, or LVR between OM and OW. These data suggest that OW exhibit a greater inspiratory muscle metaboreflex compared with YW, whereas no differences between OM and YM existed. Finally, sex differences in the inspiratory muscle metaboreflex are not present in older adults.NEW & NOTEWORTHY Premenopausal women exhibit an attenuated inspiratory muscle metaboreflex compared with young men; however, it is unknown whether these sex differences are present in older adults. Older women exhibited a greater inspiratory muscle metaboreflex compared with premenopausal women, whereas no differences were present between older and younger men.