The impact of 2 years of high‐intensity exercise training on a model of integrated cardiovascular regulation

Abstract

Key points Heart rate variability, a common and easily measured index of cardiovascular dynamics, is the output variable of complicated cardiovascular and respiratory control systems. Both neural and non‐neural control mechanisms may contribute to changes in heart rate variability. We previously developed an innovative method using transfer function analysis to assess the effect of prolonged exercise training on integrated cardiovascular regulation. In the present study, we modified and applied this to investigate the effect of 2 years of high‐intensity training on circulatory components to tease out the primary effects of training. Our method incorporated the dynamic Starling mechanism, dynamic arterial elastance and arterial–cardiac baroreflex function. The dynamic Starling mechanism gain and arterial–cardiac baroreflex gain were significantly increased in the exercise group. These parameters remained unchanged in the controls. Conversely, neither group experienced a change in dynamic arterial elastance. The integrated cardiovascular regulation gain in the exercise group was 1.34‐fold larger than that in the control group after the intervention. In these previously sedentary, otherwise healthy, middle‐aged adults, 2 years of high‐intensity exercise training improved integrated cardiovascular regulation by enhancing the dynamic Starling mechanism and arterial–cardiac baroreflex sensitivity. Abstract Assessing the effects of exercise training on cardiovascular variability is challenging because of the complexity of multiple mechanisms. In a prospective, parallel‐group, randomized controlled study, we examined the effect of 2 years of high‐intensity exercise training on integrated cardiovascular function, which incorporates the dynamic Starling mechanism, dynamic arterial elastance and arterial–cardiac baroreflex function. Sixty‐one healthy participants (48% male, aged 53 years, range 52–54 years) were randomized to either 2 years of exercise training (exercise group: n = 34) or control/yoga group (controls: n = 27). Before and after 2 years, subjects underwent a 6 min recording of beat‐by‐beat pulmonary artery diastolic pressure (PAD), stroke volume index (SV index), systolic blood pressure (sBP) and RR interval measurements with controlled respiration at 0.2 Hz. The dynamic Starling mechanism, dynamic arterial elastance and arterial–cardiac baroreflex function were calculated by transfer function gain between PAD and SV index; SV index and sBP; and sBP and RR interval, respectively. Fifty‐three participants (controls: n = 25; exercise group: n = 28) completed the intervention. After 2 years, the dynamic Starling mechanism gain (Group × Time interaction: P = 0.008) and the arterial–cardiac baroreflex gain (P = 0.005) were significantly increased in the exercise group but remained unchanged in the controls. There was no change in dynamic arterial elastance in either of the two groups. The integrated cardiovascular function gain in the exercise group increased 1.34‐fold, whereas there was no change in the control...

Mid‐life crisis or mid‐life gains: 2 years of high‐intensity exercise is highly beneficial for the middle‐aged heart

“…The use of an integrated three‐component cascade model by Hieda et al . () builds upon previous work from their group (Shibata et al . ), providing a more comprehensive assessment of the CV and respiratory control mechanisms on integrated CV function by building in the dynamic Starling mechanism.…”

“…Thus, it would be interesting to apply the three‐component cascade model of integrated CV regulation developed by Hieda et al . () to high‐level endurance athletes with orthostatic hypotension as this finding suggests there may be a disconnect between steady‐state and non‐steady‐state responses to haemodynamic stressors such as central hypovolaemia. Nonetheless, it is clear that application of the three‐component cascade model beyond steady‐state conditions requires further study.…”

“…Taken together, these findings provide novel insight into the individual and combined effects of exercise training on the integrated regulation of CV, suggesting high-intensity training augments total CV function in middle-aged adults through enhancements in LV compliance and arterial baroreflex sensitivity. The use of an integrated three-component cascade model by Hieda et al (2019) builds upon previous work from their group (Shibata et al 2006), providing a more comprehensive assessment of the CV and respiratory control mechanisms on integrated CV function by building in the dynamic Starling mechanism. This was an important and necessary adaptation of their previous model, given the gain of the relationship between LVEDP and sBP is dependent on LV output (i.e.…”

“…These studies would be particularly relevant given many high-level endurance athletes experience central hypovolaemia, orthostatic hypotension and an attenuation of arterial-cardiac baroreflex sensitivity during orthostatic stress (Ogoh et al 2003), which would be contradictory to the finding of enhanced dynamic arterial-cardiac baroreflex gain at steady-state in response to high-intensity training in the current study. Thus, it would be interesting to apply the three-component cascade model of integrated CV regulation developed by Hieda et al (2019) to high-level endurance athletes with orthostatic hypotension as this finding suggests there may be a disconnect between steady-state and non-steady-state responses to haemodynamic stressors such as central hypovolaemia. Nonetheless, it is clear that application of the three-component cascade model beyond steady-state conditions requires further study.…”

“…Nonetheless, it is clear that application of the three-component cascade model beyond steady-state conditions requires further study. The study of Hieda et al (2019) is not without its limitations, but it is clear that the authors could use this as an opportunity to refine the model moving forward. As the authors note, measurements of augmentation index and pulse wave velocity would have been more appropriate and sensitive to study changes in dynamic arterial elastance and, more importantly, central and peripheral adaptations to 2 years of vigorous endurance training using their three-component cascade model.…”