Downhill Bracer

May 2, 2004
Outside Magazine
Outside magazine, October 1996

Downhill Bracer

For runners, hikers, and skiers in training, the best offense is a good descent
By Andrew Tillin

When Bill McDermott crests the hill near the 23-mile mark of his beloved Catalina Marathon, he approaches the long, final descent not so much as a respite as an opportunity. While others gingerly coast to the finish, nursing sore hips, tired hamstrings, and spent quads, McDermott kicks into overdrive. Heart pounding and legs churning, the man sometimes called the Human Shock Absorber gets serious. "I think of downhill running as something unto itself," says McDermott, a 45-year-old aerospace engineer who's become a local endurance icon after winning the California island race a dozen times. "Going uphill just requires conditioning," he continues. "But to go down, you need conditioning and skill."

How hard can it be to plant one foot lower than the other? Most athletes think of going downhill as a chance to rest, mop your brow, swap high fives. Heed the ascent, we've been taught, because uphill training forges stronger lungs, demands more calories, toughens the athletic psyche. But downhill training offers its own benefits: Not only will it improve your running performance, it also will prepare your muscles for the workout they'll get when you start skiing again. Indeed, downhill running is key to the off-season training regimen of the U.S. Ski Team.

Thanks to the laws of physics, a 160-pound runner who can average eight-minute miles on level ground can easily achieve seven-minute miles on a ten-degree downslope. This boost in speed not only is invigorating, but also has genuine physiological impacts. It forces you to hone your balance, and it's a great power workout: Each time you plant your foot on said downslope, you place up to four times as much force on your leg muscles as when running an ascent. "Going downhill is the way to do leg-strength training while you run," says Mitchell Craib, an exercise physiologist specializing in running mechanics and a professor at Guilford College in Greensboro, North Carolina. He adds that regular downhill running hurts muscles at first, but that they adapt surprisingly well the more you do it. Such a routine is the best way to avoid the soreness that typically accompanies your first few days of skiing or backpacking.

Eccentric Habits
Running downhill taxes your muscles in the same way as lowering a barbell after curling it or returning your upper body to the mat following a torso crunch. To perform any of these actions, the muscle must lengthen--a movement that's called an eccentric contraction. Such contractions don't require nearly as much effort as their opposite, the concentric contraction. "You have to use as much as four times the amount of energy to curl a weight upward," says John Faulkner, a physiologist specializing in muscle mechanics at the University of Michigan in Ann Arbor.

So we arrive at the eccentric-contraction conundrum: How do we build muscles that are already so powerful when lengthening? Running uphill or on the flats won't work, because although any stride comprises both eccentric and concentric contractions, neither of those challenges emphasizes the eccentric contraction. Instead you have to put the pressure on by tilting your workout downhill, where gravity increases the force on your lengthening muscles.

But most of us don't do downhill work often enough, which is why our muscles become so thoroughly fatigued after a long day of bump skiing or when, in getting back into shape, we do countless sit-ups. "You get the kind of soreness that you see in exhausted marathoners and mountaineers," Faulkner says. "Their quads can be damaged enough that they have to walk backward down stairs."

Chalk up this soreness to the physiology of eccentricity. When you overdo lengthening contractions, tiny links--called crossbridges--that connect proteins within your muscles get stretched too far. Suddenly these proteins, which generate muscle power in moving back and forth, can't function smoothly, if at all. The process is a little like a misfiring car engine: The proteins are pistons, and when the crossbridges get overstretched, it's as if you've thrown a rod. The pistons no longer fire in line, damaging the surrounding muscle tissue--and causing pain. Worse, this pain gets more severe before you heal, a phenomenon known as delayed-onset muscle soreness, or DOMS. Cells affected in eccentric-contraction overload become free radicals and damage the already tender muscle tissue. Encounter enough downhills on day one of your backpacking trip and you may have difficulty getting off your Therm-a-Rest pad.

Fortunately, if you concentrate on training your muscles eccentrically, you can prevent soreness. The best way, in fact, to keep your proteins in line and avoid DOMS is to adapt your muscles to making such movements.

Contractional Agreement
Start your downhill routine by tackling only short and gentle grades. "You don't have to perform as many lengthening contractions as you would in a marathon or backpacking trip for the training to be effective," Faulk-ner says. That's why members of the U.S. Ski Team's alpine squad, who spend entire winters performing muscle-lengthening contractions as they barrel down mountains, devote a slice of off-season training time to bounding down grassy hills. As for technique, it's best to pretend you're running on a level surface. "If you're tentative--landing with straight legs, holding your torso bolt-upright--you're going to slow yourself down," says Steve Johnson, an exercise physiologist and director of science and education for the U.S. Ski Team. "Be aggressive and flexible."

Catalina marathoner McDermott, who once clocked a sub-four-minute mile down a dirt road in training, stresses economy of movement. "You don't want your arms or legs flailing," he says. "You know you've gotten pretty good when you can run down a rocky path as fast as if it were pavement." Like the elite skiers, McDermott prefers rough trails where he has to pick his way down rapidly, as if he were following the fall line on a black-diamond run, always looking several feet ahead for the next obstacle.

Unfortunately, Johnson says, rigorous downhill training borders on the treacherous. "If you overdo this kind of work, it can be destructive to your muscles as well as your joints and connective tissue," he says. "It's so easy to turn an ankle, so we also use a controlled environment." Enter the weight room, where Johnson's skiers have greater command over the fate of their muscles and tendons. Studies have shown that resistance-training programs with specific focus on eccentric motions will make you more fit (see "AprŠs Ski). Proper eccentric training also helps you maintain strength during exercise layoffs of up to four weeks. "The beauty of this work is that our athletes emerge more robust," says Johnson.

Of course, the average outdoor athlete doesn't need world-class robustness. Still, both McDermott and Johnson recommend downhill-specific training once or twice a month--especially leading up to ski season. The rest of the time, try to work lengthening contractions into your everyday routine. Because in the end, perhaps the greatest advantage of downhill training may be that it's enjoyable.

"I tell people to take to the roller-coaster courses," McDermott says. With that philosophy, and 75,000 miles behind him, he's training yet again for Catalina. "I'm not ready to concede that race," he says, though he hasn't won the last two years. "Why should I? If I've lost a step, it's in my ability to run up."

Andrew Tilin, a former senior editor of Outside, is getting his muscles in order for ski season.

More at Outside

Elsewhere on the Web