Downhill running, especially FAST downhill running, can subject runners to higher stresses on the legs due to eccentric force, which is a major cause of delayed-onset muscle soreness, or "DOMS."
The common misconception that DOMS is caused by "lactic acid in the muscles" is completely wrong. DOMS in the leg muscles is caused by eccentric force, where the muscles are doing two things at once: (1) acting like “shock absorbers” to absorb the impact forces of landing on your foot, while at the same time (2) lengthening like a spring to propel the body forward. The end result is that the muscles are pulled in two different directions at the same time, which results in microscopic tearing of the muscle fibers. The muscle damage triggers an inflammatory response by the body, resulting in swelling, stiffness, and tenderness in the muscles. The good news is that most of the symptoms of DOMS, which fade in a few days, are a result of the body’s inflammatory response, not damage to the muscles themselves.
The best way to reduce the effects of increased eccentric force in a downhill race is to train using what is known as “repeated bout effect.” This training effect occurs when a session of running downhill in a workout (a “bout”) provides a protective effect in subsequent workouts of the same nature. After recovering from normal muscle damage and soreness from a downhill session, runners can recover faster, and experience less DOMS, after subsequent workouts.
This doesn’t mean that the best way to build “downhill running ability” is to go out for a couple of downhill runs a few weeks before your race. The “repeated bout effect” regimen should follow a measured and meaningful schedule that allows time to recover and adapt from one session before the next one. Moreover, the intensity of the downhill workouts should be very light in the early sessions, and with short distances. Over time, the intensity and distance gradually increase. Meanwhile, ensuing workouts should take into consideration the need for short recovery from the downhill intensity. Your body will need a little extra time for the inflammation and repair process to take place before you attempt any other type of intensity in a “hard” run.
All totaled, a proper training schedule for a downhill race should incorporate two major elements to maximize the gains from a downhill course, while minimizing the effects of eccentric force: (1) repeated bout effect sessions over a number of weeks, with gradually increasing intensity and distance; and (2) regular practice of using proper downhill form. With both of these training elements in your training regimen, you should be well prepared for any downhill race.
Paul Carmona is the Online REVEL Coach who has designed trainling plans specifically for REVEL downhill courses. He is an 11-time REVEL Marathon Finisher and run multiple Boston Qualifiers on every REVEL course!