You've got a decision to make: Press snooze. . .or pop out of bed and exercise? Hit the gym after work. . .or hit happy hour?
In these moments when you're staring down your sneakers, you're trying to rouse your left prefrontal cortex (PFC), the area of the brain where your elements of willpower reside. Regular exercisers have an advantage: Their brains can anticipate the positive perks of a sweat session. "When you have positive reinforcement, you're much more likely to do something," says John J. Ratey, M.D., an associate clinical professor of psychiatry at Harvard Medical School and author of Spark: The Revolutionary New Science of Exercise and the Brain.
Power up: If this is where you typically derail, solicit external assistance--schedule a workout with a friend or register for a race--rather than relying on willpower alone, says Ratey. Still slacking? Use nonexercise activities and daily chores (like making your bed every morning) to get your PFC operating optimally. "You can build your willpower like you would a muscle," says mind-body health expert David Yaden of the Community Biofeedback Clinic in Phoenixville, Pennsylvania. "Your willpower becomes stronger even when you're practicing doing little things."
The First Step
Within minutes of getting moving, your brain lights up like a neon sign, says brain chemistry researcher David Glass, Ph.D., a professor in the department of biological sciences at Kent State University. First comes a rush of serotonin and dopamine, the feel-good hormones that also improve memory and learning. "It sets off your reward circuitry," says Glass. "That's what makes exercise rewarding and possibly addictive."
Just like your hardworking muscles, the brain perks build with each rep or stride. As your heart rate rises, blood flow increases, and over time more capillaries develop in the brain. As your nerve cells fire, they boost the creation of proteins such as brain derived neurotrophic factor (or BDNF, which plays a role in the positive thoughts you attribute to working out) as well as compounds that promote new brain-cell formation. The result: You increase the production of neurons--literally building your brain over a period of weeks by creating new nerve cells, says Brian R. Christie, Ph.D., director of the neuroscience program at the University of Victoria in Canada.
Power up: Try something fresh--like Zumba or a new form of yoga--that forces both your brain and your body to work in unaccustomed ways, says Christie. "Cognitively complex tasks can have benefits for the brain, so it makes sense that combining physical and mental exercise provides the most benefits."
The High Point
As your muscles grow weary, the temptation to pull the plug grows stronger. But if you keep going--for a total of 20 minutes or more--your natural opioid system kicks into high gear, flooding your brain with painkilling chemicals like endorphins. (According to one study, these endorphins attach to the same brain regions that light up when you're sexually aroused.) Other researchers credit a chemical called cannabinoids for the high (yep, it's from the same family of chemicals that gives marijuana smokers their buzz). It could be that the body releases these substances to cope with the stress of exercise, says lead researcher Arne Dietrich, Ph.D., of the American University of Beirut. "If you give your body time to release these chemicals, you may feel much better during and after exercise," he says. And not just physically: A study published in the British Journal of Sports Medicine reported that exercisers scored significant mental-health perks after just 20 minutes.
Thankfully, your brain does have a safety brake. It constantly meters out your efforts based on your training, previous experience, the duration ahead, and information it's gathering from your heart and muscles. It's what South African exercise physiologist Timothy Noakes, M.D., calls the "central governor" theory of fatigue. If your brain doesn't like what it's feeling, it signals that you're fatigued. In fact, research shows that even when endurance athletes quit from seemingly insurmountable fatigue, they still have glycogen (fuel) in their muscle stores and untapped muscle fibers at their disposal. Their brain has just told them it's time to stop.
Power up: Make high-intensity intervals--say, alternating one-minute all-out effort and one-minute recovery--a part of your weekly routine. "They teach your central governor that going harder won't do you any harm," says Noakes. For workouts longer than 90 minutes, make sure you have at least 30 to 60 grams of glucose an hour (such as fruit or sports drinks) and get plenty of fluids so you don't feel fuzzy-headed by the time you finish.
The cranial perks of your sweat session are still in play long after you've hit the shower. Researchers in Ireland had students perform brain-taxing tests, then had half the group ride stationary bikes for 30 minutes while the others chilled out. They then repeated the test, and the students who exercised did significantly better, while the ones who lazed about showed no improvement. The likely reason: The pedalers had much higher blood levels of BDNF. Because it's most active in the hippocampus, cortex, and basal forebrain--areas vital to learning, memory, and higher thinking--surges of the protein may contribute to why adults who exercise display sharper memory skills, higher concentration levels, more fluid thinking and reasoning, and greater problem-solving than those who stay sedentary.
Power up: Even if you're lying in a pool of your own sweat, barely able to move, try to think positive. Focus on how good your workout made you feel, even if that's stretching the truth. Over time, it could help your brain adhere to those thoughts and make you less resistant to lacing up.
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