NEW YORK (Reuters Health) – Interrupting sedentary time with brief activity breaks may be particularly important for less fit individuals, new findings show.
“Individuals with lower fitness (which reflect the majority of the population), experience exaggerated rises in postprandial (post-meal) glucose during prolonged sedentary time,” Matthew McCarthy, a PhD student at the University of Leicester and the study’s first author, told Reuters Health by email. “In turn, individuals with lower fitness experience greater glycemic benefit from breaking up this sedentary time with light-intensity activity breaks.”
More time spent being sedentary has been linked to metabolic syndrome, diabetes and cardiovascular disease (CVD), McCarthy and his team note in their report, online June 8 in Medicine and Science in Sports and Exercise. But there is evidence, they add, that the ill effects of sedentary time may be lower in more fit individuals.
The researchers compared postprandial glycemia in 34 non-obese individuals under two 7.5-hour experimental conditions: prolonged sitting or sitting for 30 minutes alternating with five-minute walks.
Blood glucose incremental Area Under the Curve (iAUC) averaged 3.89 mmol/Lxh with prolonged sitting and 2.51 mmol/Lxh with walking breaks, while insulin iAUC went from 241 to 156 mU/Lxh (both p<0.02).
Higher cardiorespiratory fitness (CRF) was associated with a lower blood glucose response, but there was no association between CRF and insulin iAUC. For men in the 25th centile for CRF, blood glucose iAUC went from 5.80 to 2.98 mmol/Lxh in the sedentary and walking-break conditions, respectively. For men in the 75th CRF centile, blood glucose iAUC went from 1.99 to 1.78 mmol/Lxh. The pattern was similar for women.
“Given that postprandial glucose has been implicated in the development of chronic metabolic diseases such as T2DM, CVD and obesity, this emphasizes the clinical importance of breaking up prolonged sedentary time with light-activity breaks for the majority of the population,” McCarthy said.
“Although the benefits of moderate to vigorous physical activity (MVPA) or exercise are indisputable, adherence rates remain low. Engaging in light-intensity activity breaks may provide an additional, potentially more appealing, strategy to protect metabolic health that overcomes common barriers to exercise adherence,” he said. “As a rule of thumb, we would advise individuals (particularly those with low fitness) to break up their prolonged sitting time as often as possible, especially during the postprandial period.”
Future research should look at whether breaking up sedentary stretches with activity has long-lasting benefits, and whether ethnicity or body mass index have modifying effects, McCarthy said.
SOURCE: http://bit.ly/2tVS2v9
Med Sci Sports Exerc 2017.
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