Time-efficient physical training for enhancing cardiovascular function in midlife and older adults: promise and current research gaps

Abstract

Cardiovascular diseases (CVD) remain the leading cause of death in developed societies, and "midlife" (50-64 yr) and older (65+) men and women bear the great majority of the burden of CVD. Much of the increased risk of CVD in this population is attributable to CV dysfunction, including adverse changes in the structure and function of the heart, increased systolic blood pressure, and arterial dysfunction. The latter is characterized by increased arterial stiffness and vascular endothelial dysfunction. Conventional aerobic exercise training, as generally recommended in public health guidelines, is an effective strategy to preserve or improve CV function with aging. However, <40% of midlife and older adults meet aerobic exercise guidelines, due in part to time availability-related barriers. As such, there is a need to develop evidence-based time-efficient exercise interventions that promote adherence and optimize CV function in these groups. Two promising interventions that may meet these criteria are interval training and inspiratory muscle strength training (IMST). Limited research suggests these modes of training may improve CV function with time commitments of ≤60 min/wk. This review will summarize the current evidence for interval training and IMST to improve CV function in midlife/older adults and identify key research gaps and future directions.

Keywords: aging; inspiratory muscle strength training; interval training.

Conflict of interest statement

No conflicts of interest, financial or otherwise, are declared by the authors.

Figures

Fig. 1.

Age-related cardiovascular dysfunction increases risk for clinical disorders. Continuous aerobic exercise can prevent or reverse cardiovascular dysfunction. High-intensity interval training and inspiratory muscle strength training may have beneficial cardiovascular effects.

Fig. 2.

Representative duration and intensity of sprint interval training (SIT), high-intensity interval training (HIIT), and moderate-intensity continuous training (MICT) aerobic exercise protocols.

Fig. 3.

Likely mechanisms through which interval training improves cardiovascular function. SIT, sprint interval training; HIIT, high-intensity interval training; ROS, reactive oxygen species.

Fig. 4.

Improvement in vascular endothelial function, assessed via brachial artery flow-mediated dilation (FMD), following 6 wk of either moderate-intensity continuous training (MICT) or low-volume sprint interval training (SIT) in patients with coronary artery disease. Data are means ± SE. *P < 0.05 compared with baseline. Data are from Currie et al. (21).

Fig. 5.

Research gaps and future directions for interval training research. RCT, randomized controlled trial; CV, cardiovascular; CVD, cardiovascular diseases; PM, postmenopausal; TM, treadmill.

Fig. 6.

A: representative duration and intensity of high- and low-resistance inspiratory muscle strength training (IMST) protocols. B: inspiratory pressures associated with various physical activities. High-resistance IMST is a novel form of physical activity requiring inspiratory pressures much greater than other activities. PIMAX, maximal inspiratory pressure; MI, moderate intensity.

Fig. 7.

A: resting brachial artery systolic blood pressure (SBP) before and after 6 wk of time-efficient inspiratory muscle strength training (IMST). B: absolute change in resting SBP following 6 wk of time-efficient IMST or low-resistance sham training. Subjects were either young adults or midlife/older patients with obstructive sleep apnea (OSA). Data are means ± SE. *P < 0.05 compared with baseline. Data are from Vranish and Bailey (124), DeLucia et al. (24), and Vranish and Bailey (125).

Fig. 8.

Hypothesized acute and chronic physiological changes associated with inspiratory muscle strength training. SBP, systolic blood pressure; NO, nitric oxide.

Fig. 9.

Research gaps and future directions regarding high-resistance inspiratory muscle strength training research. RCT, randomized controlled trial; IMST, inspiratory muscle strength training; CR, cardiorespiratory; CV, cardiovascular; PM, postmenopausal.