The area of a muscle correlates to the amount of force it can produce; bigger muscles produce greater force. Resistance training can increase the size of the muscle--but it can also enhance the nervous system's ability to coordinate the contraction of muscle fibers, which also contributes to greater force. In runners, the goal is greater force without increased muscle size, or developing a big engine in a light chassis. Training duration, volume, and intensity are all variables that determine whether this desired outcome is achieved.
Most runners will benefit from two resistance train sessions per week, using dumbbells in a variety of ways. In keeping with the sport-specific principle of resistance training, favor exercises that stabilize the core. Contrary to common belief, this does not mean favoring only abdominal and back exercises. For example, the alternate standing shoulder press, during which you "punch" a dumbbell above your head with one hand, then lower it as you raise the dumbbell in the other hand, demands of the core muscles that they stabilize the body while you perform these exercises. By contrast, an isolated single-joint exercise like the bicep curl may provide little benefit, as these muscles are rarely used in isolation during running.
Similarly, while back exercises are certainly running-appropriate, remember to achieve muscle balance by training the muscles of the chest and shoulders, which provide opposite antagonistic actions to the muscles of the upper back. Limiting muscle imbalances in the way limits injury. Unilateral upper body exercises are more specific to running than bilateral exercises like the traditional bench press; running simply does not involve both limbs moving in the same direction simultaneously.
Reviewing the key principles of any resistance training program, in addition to specificity we find progressive overload, individuality, and reversibility.
Increase the load in your dumbbell exercises by two to four pounds every couple of weeks to ensure progressive overload and therefore continued gains in muscle strength. Research suggests that after eight weeks and up to three or so years, strength gains are primarily due to gains in muscle size, not the neurological coordination of muscle fibers seen in the earlier stages of resistance training. This might be considered a complicating factor for runners, who generally don't want bigger upper-body muscles to carry across the finish line. Note that this phenomenon attenuates, however, after about three years of regular strength training, when a ceiling is reached in terms of muscle hypertrophy, and neural factors again seem to take over as the main supplier of greater force.
Most running-specific resistance training sessions should involve 12 to 15 reps per set, with a load allowing for a 12- to 15-repetition maximum. Perform three sets, with 45 seconds to a minute rest in between. You can work through a routine in as little as 30 minutes if you perform "supersets," alternating the exercises of two opposing muscle groups such that the rest for one group occurs during the exercise of the opposing group. Perform large muscle group exercises before small, and compound exercises before single-joint.
Individuality simply means that each athlete adapts differently to training according to experience, history of injury, biomechanics, genetics, and other factors. Additional considerations involve your specific goals, and include weighing the importance of improved endurance versus strength versus power (traditionally, the product of strength and speed). Resistance training is a unique form of training because you can elicit a wide variety of adaptations by carefully manipulating the repetitions, loads, rest periods, and number of sets to suit your exact needs. As skills and experience improve, there are always ways of performing advanced variations of the exercises, as well, for example while balancing on a stability ball or in a lunge position.
And finally, remember that reversibility follows a predictable pattern as well. If you had a 20% improvement in muscle strength after six weeks, it would take approximately six weeks without training to lose this gain.
An effective twice-a-week upper-body resistance training regimen for runners might look like this.
Three 12-rep sets of each (load = 12RM), with 45 seconds rest in between:
Performed seated at a weight machine with knees under pad and a grip on the bar wider than shoulder-width.
Alt. Dumbbell Chest Presses
Performed prone on a weight bench, pushing weights up one hand at a time.
Cable Seated Rows
Seated with legs straight out and knees slightly flexed, bring the pulley handles toward your trunk with both hands. Squeeze the shoulder blades together and down, keeping arms close to the body.
Alt. Standing Shoulder Presses
Lift dumbbells one at a time above your head from a standing position.
Dumbbell Side Delt Abduction
Standing and holding weights at sides, bring both arms up parallel to the floor.
Run Strong ed. by Kevin Beck, Human Kinetics, Champaign, IL, 2005,"Gaining Ground Through Upper-Body Strength" by Michael Leveritt, PhD,CSCS, pp. 83-99
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