Key result
Sixteen weeks of high-intensity interval training in previously untrained men significantly increased left and right ventricular volume and mass, indicating balanced cardiac adaptation.
Why the study?
Does 16 weeks of high-intensity interval training induce detectable morphological cardiac changes in previously untrained men?
RCT (n=84)
randomly assigned
Does 16 weeks of high-intensity interval training induce detectable morphological cardiac changes in previously untrained men?
Sixteen weeks of high-intensity interval training in previously untrained men induces measurable, balanced physiological cardiac remodeling (increased ventricular volume and mass) detectable by cardiovascular magnetic resonance imaging.
Answers are grounded in this paper and cite their sources.
HIIT-associated CMR remodeling in untrained men should not yet change practice; leaves open long-term clinical relevance and need for outcome trials.
BACKGROUND: To prospectively evaluate whether short-term high-intensity (interval) training (HI(I)T) induces detectable morphological cardiac changes in previously untrained men in cardiovascular magnetic resonance imaging. METHODS AND RESULTS: Eighty-four untrained volunteers were randomly assigned to a HI(I)T group (n=42; 44.1±4.7 years) or an inactive control group (n=42; 42.3±5.6 years). HI(I)T focused on interval runs (intensity: 95%-105% of individually calculated heart rate at the anaerobic threshold). Before and after 16 weeks, all subjects underwent physiological examination, stepwise treadmill test with blood lactate analysis, and contrast-enhanced cardiovascular magnetic resonance imaging (cine, tagging, and delayed enhancement). Indexed left ventricular (LV) and right ventricular (RV) volume (LV, 77.1±8.5-83.9±8.6; RV, 80.5±8.5-86.6±8.1) and mass (LV, 58.2±6.4-63.4±8.1; RV, 14.8±1.7-16.1±2.1) significantly increased with HI(I)T. Changes in LV and RV morphological parameters with HI(I)T were highly correlated with an increase in maximal aerobic capacity (VO2max) and a decrease in blood lactate concentration at the anaerobic threshold. Mean LV and RV remodeling index of HI(I)T group did not alter with training (0.76 ±0.09 and 0.24±0.10 g/mL, respectively [P=0.97 and P=0.72]), indicating balanced cardiac adaptation. Myocardial circumferential strain decreased after HI(I)T within all 6 basal segments (anteroseptal, P=0.01 and anterolateral, P<0.001). There was no late gadolinium enhancement in any of the participants before or post HI(I)T. CONCLUSIONS: Sixteen weeks of HI(I)T lead to measurable changes in cardiac atrial and ventricular morphology and function in previously untrained men. This correlates with improvements in parameters of endurance capacity. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01406730.
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Scharf et al. (2015) conducted an RCT in Previously untrained men (n=84). High-intensity (interval) training (HI(I)T) vs. Inactive control group was evaluated on Morphological cardiac changes (indexed left and right ventricular volume and mass). Sixteen weeks of high-intensity interval training in previously untrained men significantly increased left and right ventricular volume and mass, indicating balanced cardiac adaptation.
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