Tips on running downhill for those in 10K training, half-marathon training, or marathon training
 
The most famous feature of the Boston Marathon racecourse is Heartbreak Hill, a climb of 88 feet over 0.6 miles that begins just past the 20-mile mark of the race. (See my previous blog Time to Climb with tips on uphill training.) But the most challenging feature of the Boston course is probably its extensive downhill sections, including a 150-foot plummet in the first mile.

While running downhill generally feels easier and is less taxing on the metabolic and cardiovascular systems than level or uphill running, it subjects the tissues of the lower extremities to significantly more strain. This strain causes muscle damage, soreness, and neuromuscular fatigue that can cripple runners later in a run or race. Runners who enter races that have extensive downhill sections without including specific preparation for this challenge in their 10K training, half-marathon training, or marathon training seldom run as well as they hope to run.

The Downside of Downhills

The specific nature of the strain imposed by downhill running is called eccentric loading. An eccentric load occurs when an outside force tries to stretch a muscle as the muscle itself tries to resist that stretch by contracting. Eccentric loading takes place every time your foot makes contact with the ground when you run. The quadriceps muscles on the front of the thigh are subjected to the greatest eccentric loading. When your foot strikes the ground, impact forces try to make your knee buckle. Unconsciously, you contract your quadriceps to stabilize your knee and remain upright. But your knee does flex and your quads do stretch a bit when you land, so those muscles are essentially pulled in two directions simultaneously. This strain causes microscopic trauma to the muscle fibers. While eccentric loading occurs on all gradients, it is much greater when you are running downhill.

There are two consequences of the strain of running downhill. First, it limits performance and causes fatigue to occur more quickly in runners who are unaccustomed to downhill running. A recent French study found that runners were able to sustain 97 percent of their maximum 60-meter sprint speed in a set of 10 sprints on a neutral gradient, but only 95 percent of their maximum 60-meter sprint speed in a set of 10 sprints on a 4.7 percent downhill gradient. The reason appears to be that the greater eccentric loading associated with sprinting downhill triggered a protective neuromuscular inhibition—in other words, the brain refused to drive the muscles as hard as it could have to protect the legs from excessive strain.

The second consequence of the strain associated with running downhill is delayed-onset muscle soreness (DOMS). Indeed, when exercise physiologists wish to study exercise-induced muscle damage and DOMS, they almost always use downhill running to cause damage and soreness, because it does so more effectively than most other kinds of exercise.

Practice Makes Perfect

Fortunately, it’s been shown that including downhill running in your 10K training, half-marathon training, or marathon training will greatly increase both fatigue resistance and eccentric loading tolerance. In fact, a single downhill run that is extreme enough to cause significant soreness provides a protective effect that lasts up to two months.

But you need more than just one downhill workout to improve downhill running efficiency and to overcome the neuromuscular inhibition that limits downhill running performance. So, when preparing for Boston, or any downhill course, include downhill training in your weekly long run. Start with just a mile or so of downhill running in your first long run and include at least 10 total miles of downhill running in your “peak” long run two to three weeks before race day.

Finding routes that accommodate this type of training may be a challenge in itself. One option is to organize a point-to-point run that starts high and ends low. U.S. Olympian Rod DeHaven used to prop up the back end of a treadmill and run as long as 16 straight miles downhill while preparing for the 2001 Boston Marathon, in which he finished sixth in 2:12:41.