Attention runners! Are you often injured? Do you avoid hilly races like the plague? Are you sore for weeks after the Imogene Pass Run? Are you embarrassed by your "runner's body"? If any or all of the above apply to you, strength training may be a big part of the cure for these problems.
Strength training for runners comes in many forms. The form I would like to discuss in this article is resistance or weight training. I can already hear the howls of protest from many within the running community. There has always been considerable debate about the benefits of weight training on running performance. Many distance runners and coaches have the mistaken impression that weight training is counterproductive to improved running performance. Running purists believe weight training will add unnecessary weight to a runner, thereby slowing a runner down. They argue it will cause a runner to become "muscle- bound", decreasing flexibility and joint mobility, which would ultimately be a detriment to running performance. Still others will argue that weight training goes against the principles of specificity of training, in other words, only training activities that mimic the running motion and use similar neuro- muscular pathways will improve running performance.

While there is some validity to the aforementioned points, lets look at some of the ways weight training can directly or indirectly improve a runner's performance.

Running is a repetitive activity that requires forward motion of one's own body weight against gravity. This activity not only requires a high degree of cardiovascular fitness and endurance but muscular strength and endurance as well. Lets look at muscular strength first. The stronger your muscles are, the greater the force you will be able to generate to accomplish a movement. There is not necessarily a linear relationship between force production and running performance. Running economy and efficiency also play a large role, meaning just because you are very strong and can produce a lot of force, that does not guarantee you will be a faster runner. In addition, stronger muscles help protect joints, ligaments, and connective tissue from the pounding of running. Ground reaction forces in running can be three to five times your body weight, causing your muscles to perform tremendous eccentric (shock absorbing) work in an effort to dissipate the stress to your connective tissue. The net effect: better distribution of the stresses that are typically the source of overuse injuries.

Overuse injuries are a very common problem in runners. Injury statistics among runners are difficult to quantify for several reasons. First of all, many runners who are injured simply continue to run until the pain is so great they are unable to do so. Running volume and intensities vary greatly among recreational and elite runners. My personal experience treating runners in Boulder has shown overuse injuries to be the primary reason runners are not able to train consistently. I may be stating the obvious but runners who are injured less often are able to train more consistently. More consistent training allows for greater potential improvement. Is weight training starting to make more sense now?

Now lets discuss the benefits of improved muscular endurance that occur with weight training. Increased muscular endurance allows runners to go progressively longer with less fatigue, enabling them to tolerate increased training volumes and intensities. Improved endurance in the muscles of the lower body is critical to powering up long, steep inclines while muscles of the upper body are essential for maintaining arm swing and rhythm when the legs start to fatigue. Muscular endurance helps maintain running efficiency and economy, reducing oxygen consumption. Reduced oxygen consumption theoretically allows a runner to run faster.

Weight training offers numerous benefits to the aging runner. Older runners start to lose lean muscle mass beginning at age 30 and declining approximately five percent per decade. Weight training helps maintain lean muscle mass, which raises our resting metabolic rate, helping the body burn more calories at rest. A higher resting metabolic rate helps control body composition by eliminating or controlling excess body fat. A leaner runner has less weight to move against gravity. Weight training has also been shown to be beneficial in improving bone density and strength and may help reduce osteoporosis. Are you heading for the gym yet?

If weight training offers all these benefits, why are more runners not doing it? I often hear runners say they are afraid of adding too much muscle bulk, thereby slowing them down. This fear has little validity to it. A well designed resistance training program for endurance athletes can target the aerobic, slow-twitch fibers, which do not enlarge as quickly as the anaerobic, fast-twitch fibers typically seen in sprinters or body builders. The increased power output you gain offsets the minimal weight gain associated with a properly designed weight- training program for runners. Think of it as adding more horsepower to your "engine".

Another argument I often hear is that weight training does not adhere to the specificity of training principles discussed earlier. Studies have shown that with as little as ten weeks of weight training, a runner will experience an improvement in running economy (defined as oxygen consumption for a standardized running speed). As running economy improves, you should be able to run further and/or faster because of the reduced oxygen consumption.

A third argument I hear from many runners is that weight training is too time intensive. Let face it - most runners want to simply run, and the thought of adding two to three weight training sessions to their already busy training schedule is often a deterrent. Recent studies have shown that runners can benefit from as little as two 20 to 30 minute sessions per week. Isn't that a small price to pay for improved performance and less injuries?

Now that I hopefully have you hooked on the idea, what should your program include? You are probably expecting a sample weight training program, but because there is such variation among runners let's talk in more global terms in regards to program design. Just like any good training program design, it should address your individual needs and be sport specific. A body builder's weight training program offers little benefit to a runner. If you have little or no experience with weight training, seek someone who has experience working with runners. Ideally, this person's background should include education or certification in strength and conditioning, exercise physiology and sports medicine. Program design should include the major muscle groups of the upper body, lower body, and core muscles. Exercises should be performed to replicate running-specific muscular contraction. Progressive increases in training resistances are the key to building muscular strength while increases in repetitions will help build muscular endurance. Training volume and intensity should be manipulated to fit in- season and off-season schedules for maximum results and injury prevention. And as with all training programs, consistency is the key to achieving the best results.

Jeff Guerra is a Physical Therapist, Certified Strength and Conditioning Specialist, and USA Triathlon Expert Level Coach at the Boulder Center for Sports Medicine. His legs are still sore from the 2004 Imogene Pass Run.