Scientists have made great progress in discovering what doesn’t cause soreness after exercise. It’s not a low-grade persistent muscle spasm, and it’s not an accumulation of lactic acid. Instead, most researchers now agree with a theory first proposed over a century ago that blames post-exercise soreness on microscopic “tears” in your muscles. But that leaves an important mystery: if muscle damage is the cause, why does the pain peak 24 to 48 hours after you stop exercising? You may know from bitter experience that the harder you work out, the more likely you are to be sore afterwards. But intensity isn’t the only factor, as numerous experiments with hill running and stair climbing have shown.
For example, Swedish researchers compared three groups of volunteers who ran for 45 minutes on a treadmill, either on an uphill slope of four degrees, a downhill slope of four degrees, or a downhill slope of eight degrees. Even though the uphill group had to work the hardest to maintain pace, it was only the downhill groups that developed “delayedonset muscle soreness,” or DOMS. The reason is that downhill running involves “eccentric” muscle contractions, which occur when the muscle is trying to shorten but is being forced by an external load to lengthen.
Typical examples include lowering the weight in a biceps curl or the braking action of your quadriceps (front upper leg) muscle as you run downhill. During eccentric contractions, your muscle filaments are stretched to their limits—and sometimes beyond. The resulting damage effectively weeds out the weakest links in your muscles, so that they will be stronger once they’re repaired. Ironically, it’s the repair process, rather than the damage itself, that is thought to cause pain in the day or two after exercise. The body sends
cells called neutrophils and macrophages to clear out the damaged tissue and mobilizes a host of other types of cells to begin the rebuilding process.
The outer membranes of nearby muscle cells get damaged in the process, allowing fluid to rush in and cause the muscles to swell. Meanwhile, another substance called bradykinin is released by the damaged muscle, which, after a delay of about 12 hours, causes an increase in
levels of “nerve growth factor” that lasts for about two days. Nerve growth factor, which is associated with chronic pain conditions, makes your nerve endings more sensitive—so that any movement of your inflamed muscles presses against these hypersensitive nerves and causes pain. Recent studies in Japan and elsewhere have suggested that nerve sensitivity caused by bradykinin is enough to explain the delayed response of DOMS, and any inflammation is purely coincidental. This debate hasn’t yet been resolved. Still, the practical message is clear: once you’ve done the crime, you’ll have to serve the time.
The pain results from muscle damage, and once the workout is over you can’t “undamage” the muscles, despite the promises of various lotions, creams, and pills. The good news, though, is that the damaged muscle comes back stronger once it’s repaired. In fact, without this damage-repair cycle, you wouldn’t get any benefit from training— so ideally, you want your workout to fall in that sweet spot where you’re doing enough microscopic damage to stimulate adaptation, without doing so much damage that you have to skip the next few workouts. As you weed out the weak muscle fibers, you’ll become less and less susceptible to DOMS. And you don’t have to suffer the full effects of DOMS to get this protective
Running uphill is tough on the lungs, and running back down is tough on the legs. Either way, hills can derail an otherwise pleasant run if you’re notprepared for them. Fortunately, a team of Australian researchers armed with the latest technology has come up with some valuable guidance. In a 2010 study, they sent a group of runners out on a hilly six-mile course while wired with a portable gas analyzer to measure oxygen consumption, a GPS receiver to measure speed and acceleration, a heart rate monitor, and an “activity monitor” to measure stride rate and stride length. The results suggest that most runners make two key mistakes: they try to run too fast on the uphills, and they don’t run fast enough on the downhills.
When you’re running on flat terrain, your speed is generally limited by the ability of your heart and lungs to transport oxygen to the muscles in your legs. If you try to maintain the same speed while hauling your body up a hill, you’ll quickly notice that you’re breathing harder because you’re consuming more oxygen.
The problem with this approach is that, once you get to the top of the hill, you’ll need time to recover from this extra effort. In the study, runners took an extra 78 seconds on average to regain their initial speed after cresting a hill—a delay that wipes out the benefit of pushing hard up the hill, lead researcher Andrew Townshend of the Queensland University of Technology says. “Based on our results, we suggested that a small decrease in speed on the uphill may be more than compensated for by a quicker return to faster running speeds on the subsequent level section,” he says. Surprisingly, the opposite was true on downhill sections.
Because of the jarring impacts involved in running downhill, most of us simply can’t run fast enough downhill to be limited by oxygen. The practical tip: when you get to the bottom of a hill, focus on maintaining your momentum (and higher speed) until your breathing forces you to slow down again. The downhill results were much less consistent among subjects than the uphill and level sections of the experiment. Some people were able to run far closer to their aerobic limits than others, gaining valuable time without getting significantly more tired. This suggests that downhill running is a skill you can acquire through practice. Of course, there’s a reason we tend to back off when running down hills: it’s hard on the legs and raises injury risk. For that reason, it’s best to limit downhill training to short sprints on a fairly gentle grade—a technique that’s also used by sprinters and football players to improve their sprint
speed.
A 2008 study from Marquette University found that a 10 percent grade (5.7 degrees) is the ideal gradient to maximize your speed in 40- yard sprints. While these simple tips—slow down on the ups, speed up on the downs—should help you distribute your effort more evenly during runs, you’ll need to try them out to find the right balance for yourself. “The best I can suggest is that runners should practice varying their degree of effort on hills that they frequently use in training, to determine how much they should slow down to reap an overall time benefit,” Townshend says. “An experiment of n=1 for all to try!”
Let’s start with one incontrovertible fact: you can’t fulfill your ultimate potential as both a weightlifter and a marathoner at the same time. Too many hours sweating on the elliptical will hinder your ability to put on muscle, and pumping too much iron will slow your endurance gains. But most of us don’t want Olympic medals in both events. We just want some combination of reasonable cardiovascular fitness and non-vanishing muscles—a desire shared by many elite athletes. Top basketball players, for instance, need strength and explosiveness but also have to last for a full 40 to 60 minutes on the court.
New techniques now allow researchers to directly measure which specific proteins are produced in muscles after different types of exercises. It turns out that the sequence of cellular events that leads to bigger muscles is determined in part by the same “master switch”—an enzyme called AMP kinase —that controls adaptations for better endurance. But you can’t have it both ways: the switch is set either to “bigger muscles” or to “better endurance,” and the body can’t instantly change from one setting to the other. How you start your workout determines which way the switch will be set for the session.
So if your goal is beach muscles, your weights routine should come first. If you’re preparing for an upcoming 5K race, do your full cardio
workout before tacking on weights at the end. And if you’re looking for the best of both worlds, Hansen suggests
For many people, heading out for a run or a bike ride offers a mental break—a chance to think about the events of the day, or about nothing at all,
while the legs navigate on autopilot. But for those who are looking to lower their best race times, a growing body of research suggests that what’s
going on in your head during training sessions can make a big difference in how effective those sessions are. “It’s not just physical intensity that
counts, it’s mental intensity,” says Joe Baker, a researcher at York University in Toronto.
Over the past few decades, psychologists have reached the remarkable conclusion that your level of achievement in fields ranging from sports
to music to science depends less on natural talent than on the number of hours you spend doing “deliberate practice,” a term coined by Florida
State University cognitive psychologist Anders Ericsson. In one of his seminal studies, Ericsson found that the virtuosos at major philharmonics had
averaged 7,400 hours of deliberate practice by the age of 18; typical professionals had averaged 5,300 hours; and those who ended up teaching
violin instead of performing had spent only 3,400 hours.
Not all practice is “deliberate” practice. Rather than simply repeating tasks over and over, it involves setting specific goals and monitoring how
well you perform, constantly adjusting and improving your technique. This seems like the opposite of most training for endurance sports—heading
out the door and running for an hour at a comfortable pace, say, with no specific goals, minimal feedback, and no thought about technique.
But top endurance athletes rely on a number of training techniques that do fit the definition of deliberate practice. In a study of the training
practices of elite runners by University of Ottawa researchers Bradley Young and John Salmela, what separated the highest-performing group from
their less accomplished peers was how much they incorporated elements like interval training, tempo runs, and time trials, all of which require
ongoing attention to pace and other feedback. “High quality and high intensity, rather than long slow distance, is at the heart of deliberate practice,”
Baker says.
Traditionally, researchers have divided the mental strategies used by endurance athletes into “associative” and “dissociative.” When you’re
associating, you’re concentrating on the task at hand: your breathing, your pace, and so on. When you’re dissociating, you’re thinking about
anything but the task at hand: the weather, or last night’s TV show. A series of studies over the past few decades has demonstrated that faster
runners have more associative thoughts during competition than their slower rivals, who have more dissociative thoughts. “But there’s an important
message,” Baker notes. “No one has suggested that top runners associate all the time.”
Similarly, psychologists don’t suggest that you try to make all your training deliberate. Even the virtuoso violinists, famed for spending 10 or
more hours a day practicing, managed to average only a few hours a day of deliberate practice. For most people, the majority of exercise time
should remain relaxed, a mental diversion. But adding a segment of deliberate practice a few times a week could make a big difference in your
race performance. And there may be an added bonus. Young and Salmela’s study of elite runners produced one very unexpected result: they found
that the types of training that took the most effort and concentration—the most deliberate, in other words—were rated as the most enjoyable
sessions by the runners. So deliberate practice may be hard, but it’s satisfying—especially on game day.
The key word here is “maintain,” since 95 percent of your mature skeleton is already in place by the age of 17 for girls and 19 for boys. Once you
reach adulthood, it’s basically one long fight against the slow but inexorable weakening of your bones. According to conventional wisdom, the key
to that fight is engaging in weight-bearing activities—those in which you’re standing and supporting your own weight rather than being seated. But
the latest research shows strength training can also play a key role—and in fact, lifting weights may be even more effective than some weightbearing
activities like elliptical training.
“Over the past decade, people have realized that bone is more dynamic than we thought. It’s actually a pretty responsive tissue,” says Heather
McKay, a professor in the faculty of medicine at the University of British Columbia and the director of the Centre for Hip Health and Mobility. It turns
out that training your bones has more in common with training your muscles than previously thought: if you stress them, they’ll get stronger. How
much stronger depends on what your body is currently used to, how big a load you apply, and how you apply it. Recent studies by McKay’s team
have found that short bursts of intense activity separated by brief rest periods—anything from jumping on the spot to squats in the weight room—
build bone more effectively than continuous, less intense activities.
This means that weight bearing, on its own, is a bit overrated. It’s true that the skeleton gets a bit of a workout from gravity whenever you’re
standing up, but you can stress your bones in a more targeted manner by training with weights. “Any time you’re increasing your muscle mass, the
tension of the muscles on the bone creates a ‘bending moment’ that stimulates your bones,” McKay explains. Lifting weights also allows you to
target vulnerable areas like your wrists, which get no benefit from your hours on the elliptical.
Another study by McKay’s group found that schoolchildren who jumped up and down between 5 and 15 times, three times a day (at the
morning, noon, and end-of-school bells) significantly increased their bone density. Since a quarter of your adult skeleton is laid down during early
puberty, it’s important to make sure children are doing the kinds of activities that build strong bones—and this study confirms that even small
amounts of intense, jarring activities like jumping are more effective than simply standing or walking around.
Numerous studies over the years have found that strength-trained athletes have greater bone mineral density than endurance-trained athletes,
lending support to the idea that building muscle is better for bones than weight-bearing activities like running. But a 2009 article in the Journal of
Strength and Conditioning Research showed that the differences aren’t that simple. Pamela Hinton and her colleagues at the University of
Missouri compared runners, cyclists, and strength-trained men. They did find that the strength group had the greatest bone density, but that was
only because they had the biggest bodies. The runners were leaner, but their bones were just as strong relative to their body size.
There was, however, a significant difference between the bone density of runners and cyclists, which suggests that it’s the repeated, jarring
impacts of running that produce stronger bones compared to cycling. As a result, Hinton recommends that those who engage in activities such as
cycling, swimming, and rowing consider adding a dose of either strength training or a higher-impact activity like running to their regimen. That also
means that elliptical trainers, which many people turn to precisely for their softer landing, suffer from the same shortcoming. “There’s no impact
force, as the steps of the machine move with you,” Hinton says
Imagine crossing the finish line of a 10K running race—or a bike ride or any other activity that pushes you to your limits. You’re out of breath, and
your heart is thumping. Your legs are burning, you’re overheating and dripping sweat, and you feel as though your fuel gauge is on empty. All these
factors contribute to your sense of fatigue, but which was the one that actually prevented you from going faster or farther? Scientists have been
pursuing the answer to this question for the last century. But according to a radical theory that has been gaining momentum in the last few years,
there is no answer—because it’s the wrong question.
Researchers test the limits of endurance by putting athletes on a treadmill and gradually increasing the speed until they’re forced to stop (or fall
off the back of the treadmill). But compare this to what happens in real-life athletic contests. While running a race, you never reach a point where
you simply keel over (unless something goes badly wrong). Instead, you’re constantly adjusting your effort with the goal of running as fast as you can
while ensuring that you complete the distance. So whatever “failure” causes you to fall off the treadmill at the end of a maximal test can’t be the
same thing that prevents you from running faster over 10K.
What’s been missing here is the role of the brain. Instead of our limits being dictated by “peripheral” fatigue—a failure somewhere in the
muscles of your legs, the beating of your heart, or the pumping of your lungs—South African researcher Tim Noakes has proposed that a “central
governor” in the brain regulates our physical exertions. This governor integrates physiological information from throughout the body—core
temperature, blood oxygenation, muscle signals, and so on—along with other data based on previous experience and knowledge of how long you
expect to continue. Operating beyond conscious control, it regulates how much muscle you’re able to activate, with the goal of holding you back
before you reach a state that could damage your heart or other organs.
This doesn’t mean that fatigue is imaginary. Your body really does have physical limits—but, if the central governor theory is correct, your brain
rarely permits your body to actually reach them. The simplest example of this phenomenon is the finishing sprint that is a nearly universal
phenomenon across endurance sports, from novices to world-record holders. No matter how hard you thought you were going, you suddenly find as
you approach the finish that your legs can move faster after all. Nothing has changed physiologically—but your central governor allows you to speed
up now that the finish line is in sight.
In contrast, if you put subjects in a hot room and ask them to pedal an exercise bike as hard as they can, their power output will be lower than in
cool conditions—right from the first pedal stroke. The slowdown happens long before any of the physical effects of heat could be relevant—further
evidence that the brain is quietly enforcing a safe “maximal” effort.
This debate between peripheral and central models of fatigue is perhaps the most controversial topic in current exercise physiology. No
definitive conclusions are in sight, but there’s broad recognition that the brain plays a larger role than previously acknowledged. This role is
unconscious, so you can’t simply “decide” to push through to your true physical limits—which is probably a good thing. What you can do, though, is
gradually teach your brain what your body is capable of. For example, training at your goal race pace not only increases fitness, but also allows your
mind to become familiar with the accompanying physiological feedback. You can’t turn your central governor off—but with patience you can adjust
its settings.
• “RICE” (rest, ice, compression, elevation) is important immediately after soft-tissue injury, but after acute swelling has passed switch to
“MICE” (mobilization, ice, compression, elevation) to avoid scar tissue build-up.
• Ice baths may help speed recovery from muscle soreness, using bouts lasting at least five minutes and temperature of 50°F (10°C).
• Heat packs can loosen tight or injured muscles, but only if they’re near the surface. Use heat before exercise to aid warm-up, not after.
• Massage doesn’t flush away lactic acid but may speed recovery from muscle soreness. Use a practitioner who specializes in sports
massage.
• Anti-inflammatory drugs like aspirin and ibuprofen are not suitable for chronic, nagging injuries or to prevent pain before it happens. They
carry health risks and may interfere with the effects of training. However, they’re suitable for acute injuries.
• After an extreme event like a marathon, your body will return to normal within about a week, but neuromuscular fatigue can persist for
several weeks.
• “Platelet-rich plasma” is a component of your own blood, injected to speed healing of tendon injuries. Recent clinical trials suggest it’s
not a “miracle cure,” but it may speed healing in some patients.
• The best way to keep your bones strong enough to avoid stress fractures is to strengthen the muscles around them. Shortening your
running stride may also help.
• For “above-the-neck” symptoms like a runny nose or a sore throat, exercising with a cold appears to have no ill effects, and may even
speed recovery slightly.
• Having a few drinks won’t affect your next day’s workout, but more than four or five (depending on your weight) can slow muscle recovery
and displace other needed nutrients.
