Muscle tone and weight control. For the past decade, these benefits have topped the list of reasons why we exercise, according to the Sporting Goods Manufacturers Association’s annual report on the fitness industry. They consistently edge out others—like “feeling good after” and “increased energy"—we can’t see in a mirror.
That doesn’t mean we don’t care about the stuff we can’t see. We assume, for instance, that the effort to break a sweat leads to better cardiovascular health and a lower cancer risk. And extra energy and happiness are still key benefits.
But the breadth of invisible boons goes even further, affecting everything from our dating lives to our bowel movements. So the next time you’re stressing about a few stubborn pounds or a less-than-cut quad, focus on these six invisibly awesome effects of your efforts. We’ll start with your pain tolerance.
1. You Feel No (or at Least Less) Pain
Think of pain in one of two ways: pain threshold, when you begin to feel it, and pain tolerance, the max amount of pain you can sustain. Dr. Jonas Tesarz led a study that found athletes have higher pain tolerances than average folk. He suggests that there are objective differences in central pain processing between athletes and non-athletes, though he’s uncertain if athletes acquire the ability to tolerate pain through training, or if they train because they already tolerate the pain well. What he does know: “Higher pain tolerance may be an important step for outstanding performance” in your sport.
That heightened pain tolerance helps far beyond a workout or sports competition. Because of it, says Sims, smaller pain-inducers like day-to-day stress will have less of an impact on your life. It comes down to the mind-body connection. “Athletes ‘push’ their way through exertional pain and their brains learn suppression under stress,” says Sims. “Moreover it is the mental strategies employed that aren't even conscious—positive self talk or competitive pushing—that lead to less perceived pain due to the want of the better outcome,” she adds. Those skills transfer to other stressful encounters in life—like traffic jams or conflicts at work.
2. Your Brain Gets Super-Charged
When compared to less-fit peers, athletes have larger brain volumes in the basal ganglia and hippocampus, areas associated with thought, action, behavior, decision-making, and memory, says Sims.
That doesn’t necessarily mean you can exercise your way into Mensa. The relationship between brain volume and intelligence is hotly debated. While brain volume hasn’t been directly tied to intelligence (if it were, sperm whales would rule the world), smaller brain volume has been linked to disorders like Alzheimer’s, depression, and even schizophrenia, leading some to believe bigger is truly better, at least in health. And growing your hippocampus, studies have found, can improve spatial memory, or the memory of one’s environment, like the layout of your house or hometown.
One of the ways it grows is through endurance exercise, research shows. Exercise can trigger the growth of new nerves and synapses—the junction points between different nerves. A stronger network in your noggin means a better functioning brain.
How much do you need to workout to see those benefits? Not as much as you think. One study found that 40 minutes of moderate-intensity aerobic exercise (60 to 75 percent of max heart rate) three days a week in older people increased brain volume by 2 percent. Another performed in older adults with mild memory impairments found that twice weekly, hour-long sessions of aerobic activity, like a brisk walk, increased hippocampal volume.
3. You’re Sexier—No Six-Pack Needed
Men’s sweat contains the odorless pheromone called androstadienone, a chemical believed to boost a woman’s mood and levels of cortisol, a hormone linked to sexual arousal. “As it is derived from testosterone, it is a strong attractant for women,” says exercise physiologist Stacy Sims. In fact, a 2007 study found that women who were exposed to androstadienone before a speed-dating event rated men as more attractive than those who weren’t exposed to the pheromone.
Women also give off a pheromone called estratetraenol. Researchers believe it works in a similar manner, enhancing men’s mood and arousal, though the effects are less noticeable.
Beyond pheromones, the improved circulation and cardiovascular function that come with exercise can lead to better sex. More testosterone means stronger erections too—and increased physical activity has been linked with better sexual function in men—including protection from erectile dysfunction. A studydone on women taking antidepressants (known for dampening libido) at the University of Texas at Austin found that ladies were 169 percent more turned on watching an erotic film when they spun on a stationary bike for 20 minutes beforehand than they were watching the movie without exercise.
4. You Crave Healthier Food
“Most people know that exercise affects appetite, but many don't know that it also affects food choices—in a good way,” says Matt Fitzgerald, sports nutritionist and author of Diet Cults. Studies like this one in The American Journal of Clinical Nutrition have found that an intense workout, like an hour of running at 70 percent maximum aerobic capacity, reduces the desirability of high-calorie foods.
Researchers believe the result may have to do with thirst. The brain may lower-calorie fare as being more water-dense, so that’s what it craves when we’re dehydrated after a workout.
It could also be that training—coupled with daily intense exercise—helps regulate blood sugar and hormonal hunger controls. “There is also a large body of scientific evidence to show that athletes are also more aware of their bodies than sedentary folks,” says Sims. They can distinguish things like muscle fatigue more easily and determine when hunger is really hunger, rather than, say, boredom.
5. Your Bowels Flow Freely
You can thank your workout for keeping your GI tract unclogged. During exercise, your intestines actually experience reduced blood flow, which slows motility. But the extra oxygenation and blood flow you experience post-workout keeps everything moving through your system, says Sims.
Why that matters: Poop problems are more than just embarrassing. Constipation can mean everything from hard-to-pass stools to vomiting. (Or rectal prolapse—when part of your intestine pushes out. Don’t Google image that.) But the exercise benefits don’t stop at fending off a stomachache or an emergency bathroom run. “The movement associated with running increases the transit rate of digested foods through the lower bowels, decreasing risk of colon cancer,” says sports physiologist Dr. Allen Lim.
Just remember: You need to pair your exercise with healthy fiber and fluid intake. The recommended fiber intake for adults under 50 is 38 grams for men, and 25 grams for women. For men and women over 50, it’s 30 and 21 grams per day, respectively. To put that in perspective, the average apple has between 4 and 5 grams of fiber.
When it comes to water, the Institute of Medicine recommends women drink approximately 2.7 liters (91 ounces) a day, while men should aim for approximately 3.7 liters (125 ounces).
“A dehydrated athlete who sits on a bike can get really constipated,” says Lim. So drink up.
6. You Become Unbreakable
You build muscle by creating micro-tears in those tissues when you work out. While you’re resting, your body repairs those tears, ultimately building your muscles back stronger, and sometimes bigger. The same goes for bones. When you’re forced to work against gravity, your muscles pull on your bones, forcing them to remodel and become stronger. The result: you’re less prone to fracture—or to getting hurt going about your day-to-day tasks.
Having stronger muscles can even prevent you from breaking a bone. A noteworthy Australian study found that calf circumference was linked to tibia pain—in fact, each 10 millimeter reduction in calf circumference increased the risk of tibial stress fracture fourfold. It could be that the electric properties of leg muscle tissue, combined with lean muscle mass, allows those muscles to dampen impact forces when your feet strike the ground, which helps keep you injury-free.
So hike. Run. Dance. Jump. It’s never too late to start working on your muscles and bones. In a recent study, researchers from Copenhagen found that 70-year-old men who played soccer for one hour twice a week for four months improved muscle function by 30 percent—and bone mineral density by two.