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The Rundown

Rise and Shine. Sleep is an important part of fitness and a new study from Rutgers University has found that people who stay up late may be at greater risk of type 2 diabetes and heart disease.

The researchers wanted to investigate if late-nighters have fundamental metabolic differences to those who like to get an early start so they recruited fifty-one volunteers split between night owls and early birds. They were all in their mid 50s, free of diabetes or cancer, had relatively sedentary lifestyles and presented with symptoms including high blood pressure, elevated fasting glucose or increased waist circumference.

After monitoring the group for a week to track physical activity, the researchers sent them to the lab for metabolic tests designed to measure how the body processes fat and carbohydrates into energy.

The results were that morning people were more insulin sensitive and more successful at using fat for energy compared to the late-nighters who relied more on processing carbohydrates for energy and showed signs of insulin resistance.

Study author Steven Malin notes that the differences in fat metabolism between early birds and night owls “shows that our body’s circadian rhythm (wake/sleep cycle) could affect how our bodies use insulin and a sensitive or impaired ability to respond to the insulin hormone has major implication for our health.”

The metabolic differences may make night owls more susceptible to heart disease and type 2 diabetes but there are some limitations to the study.

The activity tracking found that early risers were more physically active overall than night owls. So, are the metabolic differences between the two groups a result of differences in physical activity? Or is exercise more beneficial metabolically when done in the morning versus the evening?

While the answers are still unclear, the researchers suggest that those who like to stay up late should be aware that they face a higher risk for cardiovascular and metabolic disease.

Cold Swim. A new scientific review published in the International Journal of Circumpolar Health suggests that taking a dip in icy water may reduce “bad” body fat in men and the risk of diabetes.

The authors of the review looked at 104 studies and say that many of them showed significant effects from cold water swimming, including on “good” fat, which helps burn calories.

There are some caveats. Namely, the review was inconclusive overall on the health benefits of cold-water bathing. In addition, much of the available research involved small numbers of participants, usually of one gender and there were differences in water temperature and salt composition. It’s also unclear whether swimmers are naturally healthier.

However, the review did offer insights into positive links between cold water swimming and brown adipose tissue (BAT), a type of “good” body fat activated by cold. BAT burns calories to maintain body temperature (as opposed to “bad” white fat, which stores energy).

The review also found that cold exposure in water or air seems to increase the production of adiponectin by adipose tissue. This is a protein that plays an important role in protecting against insulin resistance, diabetes and other diseases.

More education is needed on the health risks connected to taking an icy plunge, say the authors, including hypothermia and heart and lung issues that may be related to the shock from the cold.

Replay

This week’s vintage moment in sports culture is brought to you by the nosebleed section. University of Pittsburgh students look down on Forbes Field from the top of their campus's Cathedral of Learning as the Pirates are winning their first World Series in 35 years against the Yankees. October 13, 1960. Photo: George Silk/Time Life Pictures.