How Exercise Changes Your Body Chemistry
The powers of a good sweat are well-documented: Regular physical activity can help lower your blood pressure and cholesterol levels, help you achieve and maintain a healthy weight, and reduce your risk of depression, heart disease, stroke, and cancer.
While weight loss and blood sugar control are two reasons for these benefits, there’s another one that most people don’t know about: When you move, your muscles release hormones. Here are three you’re producing every time you work up a sweat.
The hormone: Irisin
What it is: Exercise causes it to break off into your bloodstream and circulate throughout your body. Hence its nickname: the “exercise hormone.”
How it works: One recent study found that irisin reprograms fat cells to burn energy instead of storing it, which explains how working out boosts your metabolic rate and helps you shed flab. Another recent U.K. study discovered that people with higher levels of irisin in their blood are more likely to have longer telomeres—caps at the end of chromosomes that shorten as you age. Many health issues—including cancer, heart disease, and Alzheimer’s—are associated with shorter telomere length.
Maximise the benefits: “Focus on the large muscle groups since they contain more individual muscle cells,” says study author James Brown, Ph.D.
The hormone: Testosterone
What it is: The primary male sex hormone secreted in your testicles that powers sex drive and fuels bone, hair, and muscle growth.
How it works: Following a workout, levels of testosterone rise for 15 minutes to an hour depending on your age, fitness level, and how intensely you exercised. Your body uses circulating testosterone to build muscle mass.
Low T levels may contribute to heart disease including blood clots and an abnormal heart rhythm, as well as type 2 diabetes and metabolic syndrome.
Maximise the benefits: Start with aerobic exercise then turn to weights: Participants registered a 41.4 percent increase in testosterone when they exercised on a bike then performed a weight-lifting routine of bench presses, squats, lat pull-downs, and knee extensions, according to research in The Journal of Strength and Conditioning Research. Guys who exercised in the reverse order only increased their testosterone by 3.3 percent after their workout. One theory: Since strength training raises testosterone more than aerobic exercise, when you start with cardio and finish with lifting, the hormone maintains a steady rise throughout your workout and beyond. When you exercise in the reverse order, it may fall back down while you’re panting on the treadmill.
The hormone: Peptide YY
What it is: A hormone secreted in your gut that acts on areas of the brain to reduce appetite and increase fullness after a meal.
How it works: While researchers aren’t entirely sure how it happens, exercise does increases levels of peptide YY, which may make you less hungry after a workout. That’s one step in the right direction: A recent report in the American Journal of Public Health found that obesity accounts for nearly 18 percent of all deaths in the U.S.
Maximise the benefits: Aerobic exercise seems to have the edge in boosting PYY levels compared to strength training. According to a 2013 study in the journal Appetite, weight-bearing exercise, like jumping rope, has a greater effect on PYY than non-weight bearing activities, such as cycling or swimming.