In the Journals

Brief, high-intensity exercises improve heart function, diabetes control

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September 10, 2015

Short periods of intense physical activity, in between periods of low activity or rest, can improve heart structure and diabetes control, according to research in Diabetologia.

Sophie Cassidy, a PhD student at Newcastle University, United Kingdom, and colleagues analyzed data from 28 adults with type 2 diabetes controlled with diet or metformin who were randomly assigned to high-intensity intermittent training for 12 weeks (n = 12) or standard care (n = 11). Participants in the exercise group were assigned to intense cycling sessions 3 days per week on nonconsecutive days at a local gym, completing repeated, intense cycling intervals that gradually increased to 3 minutes 50 seconds. There were 3-minute “recovery periods” between each interval, which included 90 seconds of passive recovery, 60 seconds of band-resistance upper body exercises and 30 seconds to prepare for the next interval.

Only the first session was supervised; participants’ remaining sessions were guided by voice commands on an MP3 device. Participants wore multisensory armbands, received weekly phone calls and completed exercise diaries to allow researchers to monitor performance.

Researchers measured cardiac structure and function using functional MRI, as well as liver and visceral fat, body composition and glycemic control at both baseline and 12 weeks.

Participants in the exercise group experienced structural cardiac changes, according to researchers, with a 12% increase in ventricular wall mass (P < .05) and increased end-diastolic blood volume (P < .01) during the 12-week period. In addition, exercise group participants showed improvements in systolic function and left ventricular ejection fraction (P < .05). Those in the exercise group also experienced a 39% reduction in liver fat (6.9% to 4.2%; P < .05). High-intensity exercise sessions had no effect on fasting glucose or fasting insulin; however, researchers found that changes in liver fat correlated with changes in HbA1c and 2-hour glucose.

“This study demonstrates, for the first time, that exercise can begin to reverse some of the early cardiac changes that are commonly found in people with type 2 diabetes,” the researchers said in a press release. “Interestingly, the data also suggest that this type of high-intensity intermittent exercise benefits both the heart and diabetes control, but the benefits appear to be greatest in the heart. The strong, positive effect of exercise on the heart is, although completely logical, a message that needs to be communicated to people with type 2 diabetes more clearly.” – by Regina Schaffer

Disclosure: The researchers report no relevant financial disclosures.

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