Every week, we’re bringing you a roundup of the latest health and wellness news to hit the wire. This week, we look at a downside to overload training, why cardiovascular exercise makes for a healthier gut, and a new and improved Army fitness plan.

Overdoing it with overload training

Many endurance athletes use overload training to try to reach a personal best. However, a new first-of-its-kind study of triathletes and cyclists by the University of Guelph in Canada suggests that this method could actually hinder performance by altering firing in the body’s sympathetic nerve fibers.

“The theory behind overload training is that you train to the point of complete exhaustion so that when you rest and recover, you will be able to perform at a higher level than before,” says Alexandra Coates, a Ph.D. student in human health and nutritional science and lead author of the study. “But that may not be entirely correct.”

Muscle sympathetic nerve activity, which constricts the muscle’s blood vessels and indicates stress in the body, increases in overtrained athletes, according to the study in the journal Medicine & Science in Sports & Exercise. Coates and her team believe that the three weeks of overload training in the study altered the nervous system of the athletes—and not in a good way. The overloaded athletes’ sympathetic nerve activity at rest, measured by a needle inserted into a nerve in the lower leg, showed a high level of activity, while healthy athletes typically show a low level of sympathetic nerve activity at rest.

Meanwhile, athletes who followed a consistent training program and didn’t overload at 150 percent of their regular training load showed improvements in their overall fitness and other markers of cardiovascular health.

It appears the overtraining negated some of the beneficial effects of the regular training, Coates says.

Exercise for a better gut?

Sure, you know a probiotic can improve gut health, but could exercise help do the trick, too?

A small study by San Francisco State University researchers, published recently in the International Journal of Sport Nutrition and Exercise Metabolism, found a link between better gut health and good cardiovascular fitness.

Participants were put through a series of treadmill and body composition tests, food logs and stool samples. After studying the results, researchers found that those with better cardiovascular fitness had a higher ratio of a type of bacteria called Firmicutes in their gut, relative to another category called Bacteroides.

The Firmicutes phylum of bacteria are associated with metabolic byproducts that help prevent gut bacteria from leaking into the body. “These metabolic byproducts help strengthen the intestinal lining and help prevent leaky gut syndrome,” says lead researcher Ryan Durk. He says this research reinforces the idea of “exercise as medicine” and could eventually be used to create exercise prescriptions to improve gut and overall health.

“When we say that phrase, we think of it as meaning that exercise will help people stay healthier and live longer. But you don’t think about your gut bacteria,” Durk says. “We now know that exercise is crucial for increasing beneficial bacteria in the gut.”

Forget swimsuit-ready—is your body combat-ready?

The Army has developed a much more comprehensive (and tougher) test to determine whether its recruits are ready for combat.

A new combat-style trial rolling out in 2020 will replace the existing Army Physical Fitness Test, which has been used for four decades and consists solely of push-ups, sit-ups and a 2-mile run.

The new test has movements designed to mimic the actions soldiers will use in the field, such as lifting heavy equipment and pulling someone to safety. It includes strength moves like deadlifts, medicine-ball throws, hand-release push-ups, 90-pound sled pushes and leg tucks for core strength. No minimum performance requirement has currently been established for the test.

Curious about how you’d fare? You can check out the full list of exercises in Stars and Stripes.

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