Jan 29, 2015
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Mixing Exercise Is Okay

There’s a school of thought that athletes should not mix aerobic exercise and strength training work on the same day. The idea is that due to exercise antagonism, also known as muscle interference, aerobic exercise reduces the ability of muscles to strengthen, while weight work hurts the endurance training response. However, two recent studies found no such connection between the two forms of exercise.

A Swedish study looked at college-age men who exercised regularly. Researchers had the subjects pedal a stationary bike with one leg for 45 minutes for aerobic exercise. Six hours later, they performed strenuous double-leg extension exercises for strength work. This way, one leg was working aerobically and strengthening, while the other leg was subjected only to strength training.

According to The New York Times, researchers saw no performance differences between the legs. And muscle biopsies taken before and after each session showed no physiological evidence of any negative effects from doing aerobic exercise before the strength work.

“Aerobic exercise can precede resistance exercise on the same day without compromising” muscle building, the researchers reported. The study, titled “Aerobic Exercise Alters Skeletal Muscle Molecular Responses to Resistance Exercise,” appeared online in advance of its publication in Medicine & Science in Sports & Exercise in March.

A second study, which was published in the April issue of the Journal of Applied Physiology, used sedentary middle-age Canadian men as subjects and found similar results. Subjects completed 40 minutes of stationary cycling one day, eight sets of strenuous leg extensions another day, and four sets of leg extensions followed by 20 minutes of cycling on the third day. “Our hypothesis had been that we would see a greater response to each exercise individually,” Stuart Phillips, PhD, a professor of kinesiology at McMaster University who oversaw the Canadian study, told the Times. “We saw no indications of interference.”

The study, titled “Concurrent Resistance and Aerobic Exercise Stimulates Both Myofibrillar and Mitochondrial Protein Synthesis in Sedentary Middle-Aged Men,” also found little difference in muscle response between the single-exercise sessions and multi-exercise sessions, even though the loads of aerobic and strength work were cut in half. “In our study, the men were doing only 50 percent as much,” Phillips told the Times. “But their muscles couldn’t tell the difference.”

The abstract of the Swedish study can be found by searching its title at: journals.lww.com/acsm-msee. The abstract of the Canadian study can be found by searching the study title at: jap.physiology.org.

Ankle-Knee Connection?

Although there has been some concern that wearing protective ankle braces could leave athletes more susceptible to knee injuries because restrictions to the ankle could cause problems elsewhere in the kinetic chain, a recent study suggests otherwise. Giselle Aerni, MD, a primary care sports medicine fellow at the University of Connecticut, presented a research project titled “The Effect of Lace-Up Ankle Bracing on Knee Biomechanics During a Jump Landing” at the 21st American Medical Society for Sports Medicine (AMSSM) Annual Meeting in Atlanta in April.

“Ankle braces are common in the sport community and there has been concern that stabilizing the ankle joint might alter biomechanics further up the kinetic chain,” Aerni said in an AMSSM press release. “Our research showed that knee biomechanics known to be risk factors for ACL injury did not appear to be negatively impacted by wearing a lace-up ankle brace.”

Boosting the Immune System Athletes have long contended with the fact that strenuous exercise can compromise the immune system, leaving them more susceptible to illness or infection. But a new study indicates that using a form of beta-glucan (which is found in baker’s yeast) as a supplement may reduce immunosupression.

The study was led by Brian McFarlin, PhD, Associate Professor at the University of Houston, and published in the British Journal of Nutrition. It studied the effects of 10 days of supplementation with Wellmune WGP, a natural carbohydrate that contains beta-glucan.

The subjects were active men and women who completed 50-minute bouts of cycling daily in hot and humid conditions over two 10-day periods that were separated by a seven-day washout period allowing the supplement or placebo to be cleared from their bodies. Subjects were blindly assigned to two groups. One used a supplement with beta-glucan during the first period and rice flour as a placebo during the second. The other used the placebo during the first 10-day period and the beta-glucan supplement during the second.

Researchers compared blood collected before, and two hours after, the cycling bouts. They found that when the subjects used the beta-glucan supplement, there were significantly greater levels of total and pro-inflammatory white blood cells, known as monocytes, that play a role in immune function.

The abstract for “Baker’s Yeast Beta-Glucan Supplementation Increases Monocytes and Cytokines Post-Exercise: Implications for Infection Risk?” can be found by going to the British Journal of Nutrition Web site at: :http://bit.ly/LfR0mm.

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