January 1, 2013Open Access

Moderate intensity supine exercise causes decreased cardiac volumes and increased outer volume variations: a cardiovascular magnetic resonance study

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Healthy volunteers (n=26). Intervention: Moderate intensity supine exercise vs. Rest. Primary outcome: Total heart volume variation (THVV) (p=<0.001).

Key Result

Moderate intensity supine exercise in healthy volunteers decreased total heart volume by 4% and increased total heart volume variation from 5.9% to 9.7%.

Study Design

Type

Observational (n=26)

Multicenter

Structured PICO

Does moderate intensity supine exercise alter cardiac volumes and pumping mechanisms in healthy volunteers?

Population

26 healthy volunteers (6 women), mean age 30±8 years (range 19-59), with no signs of cardiac disease.

Intervention

Moderate intensity supine exercise using one-legged knee extensions on a custom-built MR-compatible ergometer, targeting a heart rate approximately 40 bpm higher than resting.

Comparator

Resting state (baseline measurements prior to exercise).

Outcome

Changes in left ventricular (LV), right ventricular (RV), and total heart volumes (THV), as well as cardiac pumping mechanisms (longitudinal and radial contribution to stroke volume) measured by cardiovascular magnetic resonance (CMR).surrogate

Moderate intensity supine exercise decreases total heart volume due to reduced right ventricular volume, while increasing radial pumping contribution to stroke volume.

Main Result

Absolute Event Rate: 9.7% vs 5.9%

p-value: p=<0.001

Limitations

Exercise heart rate only increased by approximately 40 bpm over resting HR
Small subpopulation (n=6) for reproducibility tests
Performed in the supine position, limiting interpretation to supine exercise or microgravity

Abstract

BACKGROUND: The effects on left and right ventricular (LV, RV) volumes during physical exercise remains controversial. Furthermore, no previous study has investigated the effects of exercise on longitudinal contribution to stroke volume (SV) and the outer volume variation of the heart. The aim of this study was to determine if LV, RV and total heart volumes (THV) as well as cardiac pumping mechanisms change during physical exercise compared to rest using cardiovascular magnetic resonance (CMR). METHODS: 26 healthy volunteers (6 women) underwent CMR at rest and exercise. Exercise was performed using a custom built ergometer for one-legged exercise in the supine position during breath hold imaging. Cardiac volumes and atrio-ventricular plane displacement were determined. Heart rate (HR) was obtained from ECG. RESULTS: HR increased during exercise from 60±2 to 94±2 bpm, (p<0.001). LVEDV remained unchanged (p=0.81) and LVESV decreased with -9±18% (p<0.05) causing LVSV to increase with 8±3% (p<0.05). RVEDV and RVESV decreased by -7±10% and -24±14% respectively, (p<0.001) and RVSV increased 5±17% during exercise although not statistically significant (p=0.18). Longitudinal contribution to RVSV decreased during exercise by -6±15% (p<0.05) but was unchanged for LVSV (p=0.74). THV decreased during exercise by -4±1%, (p<0.01) and total heart volume variation (THVV) increased during exercise from 5.9±0.5% to 9.7±0.6% (p<0.001). CONCLUSIONS: Cardiac volumes and function are significantly altered during supine physical exercise. THV becomes significantly smaller due to decreases in RVEDV whilst LVEDV remains unchanged. THVV and consequently radial pumping increases during exercise which may improve diastolic suction during the rapid filling phase.

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