Exercise performance is affected by more than our bones, joints and muscles. Hormones, or chemicals produced by glands and essential to regulating bodily processes, also play a part. For instance, testosterone supports the anabolic (tissue-building) actions of protein synthesis, cortisol activates lipolysis (the burning of fat for energy) and epinephrine (adrenaline) brings about the burning of carbohydrates for energy. Read on for a primer on the impact hormones have on exercise and body composition. In particular, we’ll focus on sex hormones, most notably testosterone and estrogen, which are associated with anabolic actions.
Natural hormonal shifts
Our hormone levels are far from constant. Testosterone and cortisol tend to be at their highest in the morning and their lowest in the late evening and during the night, according to Anthony C. Hackney, Ph.D., professor of exercise physiology and nutrition at the University of North Carolina. Hormone levels also shift during the menstrual cycle, which, according to Stuart M. Phillips, Ph.D., American College of Sports Medicine fellow and a professor and director specializing in nutrition, exercise and health at McMaster University in Canada, can make “some women more or less likely to exercise.” Dr. Stephanie S. Faubion, medical director at the North American Menopause Society, adds that “there are hormonal influences (which are still understudied and not well-defined) that impact the risk of injury in women playing sports, for instance menstrual cycle alterations in knee-joint laxity.”
Amy Beckley, Ph.D., founder and CEO of Proov, which provides an at-home rapid-response urine progesterone test, explains how different types of exercise are best suited for specific times in the menstrual cycle. Estrogen and progesterone are low during the first phase, she says, making those days ideal for yoga and stretching. During days five through 15, estrogen surges, boosting circulation and strength, allowing women to push their hardest. During the last 12 days of the cycle, progesterone causes the gut to slow down and core temperature to increase. Endurance activities, such as longer sets, are recommended for those periods, Beckley says.
The stress of exercise also affects hormone levels, causing chemicals like human growth factor, epinephrine and insulin-like growth factor 1 to temporarily rise, according to Phillips. Since these hormonal shifts are relatively minor, though, scientific research has indicated that they do not impact body composition and workout performance in a significant way. “Strength is created by neuromuscular change—your brain talking to your muscle more efficiently—and changes at the muscle locally,” he explains. “These are processes that aren’t affected by the small variations in endogenous (body-produced) hormones to any great degree.”
It’s only if general levels are out of whack that problems can occur. For instance, a clinically low amount of testosterone in men is known as hypogonadism and is associated with sluggishness, Phillips says. True for all of us, aging causes a decline in sex hormones and hormones associated with anabolic actions, such as protein synthesis, Hackney explains. This leads to losses of muscle and bone and a tendency for gains in fat. For men, testosterone levels tend to plummet in the late 60s to early 70s (a process called andropause). While for women, estrogen levels drop notably around menopause (usually in the early 50s). Although natural, the side effects of these hormonal changes can negatively impact body composition and exercise performance.
Prescriptions for hormones
Supplementing with hormones can be effective and is fairly common: Anabolic hormones help build and prevent the loss of muscle and bone. Men with hypogonadism or age-related hormone drops sometimes undergo testosterone therapy.
Meanwhile, to cope with symptoms associated with menopause (such as hot flashes), women may opt for hormone replacement therapy (HRT), which tends to involve taking one or more of the following: estrogen, progesterone, DHEA and testosterone. “In HRT, estrogen might help with bones, progesterone with uterine health to prevent complications as you age, and testosterone might help you not become anemic,” Hackney explains. Phillips adds, “I think we’re seeing data now that shows that women experience a more rapid loss of muscle after menopause, and this can be offset with HRT.”
According to medical and legal guidelines, doctors should test patients’ hormone levels initially and continually and should determine valid medical reasons before writing prescriptions for hormone supplements or hormone replacement therapy. Both OB-GYNs and endocrinologists are qualified to assess hormonal levels and write such prescriptions.
Deciding whether to supplement is complex. After all, researchers are unsure about the long-term effects. They advise weighing the pros and cons carefully and undergoing shorter courses, if possible.
“In menopausal women who are in their 50s and within 10 years of menopause, the benefits of hormone therapy typically outweigh the risks,” Faubion says. “Risks are different depending on what formulation of hormone therapy is used, the dose and the route of administration.” As for those risks, hormone replacement therapy can up the chance that patients will experience a stroke or cancer.
Meanwhile, taking testosterone can cause many side effects, from increased risk of heart attack and stroke to acne and masculine traits in women. “We know that individuals who dope with testosterone or substances like it increase their risk of coronary and vascular disease, heart attack and stroke,” Hackney says. “They’ll be able to push harder physiologically, but they’re also upping the risks of serious health complications.” Further, men who supplement with testosterone stop producing it naturally, which could lead to fertility issues. If and when they decide to cease supplementation, they can suffer withdrawal effects.
Doctors also caution anyone with certain risk factors against hormone replacement therapy, testosterone therapy and supplementing with anabolic hormones—for instance, men with prostate issues and anyone at a higher risk of stroke. If you do decide to pursue hormone replacement therapy, experts are unanimously against compounded hormones, which are not regulated by the Food and Drug Administration. Finally, make sure you accompany estrogen with progesterone to avoid upping your risk of cancer. (This does not apply if you’ve had your uterus removed.)
Support your hormones without drugs
Even without supplementation, you can improve your hormonal balance and health. “Most men experiencing low testosterone with exercise training are suffering from an acute form of hypogonadism,” Hackney says. “This can be treated by increasing the amount of rest-recovery between exercise sessions, reducing the intensity of training and increasing food consumption to maintain caloric balance.”
In general, it’s a good idea to take in enough calcium and vitamin D to promote bone health. Exercise regularly, especially with weight-bearing regimens to maintain strength. Eat enough healthy foods (including protein) to support your workouts, avoid excess alcohol and sleep well.
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