While it may not be the most obvious choice, strength training is in fact a great way to improve endurance performance. Strength training can involve weight lifting, strength- building movements, core training and plyometrics. The aim is to build up strength in the smaller muscles that are neglected through endurance workouts alone and correct muscle imbalances. A significant effect of strength training is seen in running economy, one of the big three determinants of endurance performance.

Reduces Muscle Fatigue

Better running economy means using less oxygen to power muscles so that the athlete can keep going for longer. Whether running, cycling, swimming or performing another endurance activity, the athlete can go farther and faster without experiencing muscle fatigue. For example, just a one percent improvement to running economy can take off 20 seconds from a 10k run time, according to fitness site Peak Performance.

Perhaps a bit ironically, strength training is one of the best ways to improve running economy without actually running.

As reported in sports and recreation directory Active, Erik Taylor, a National Academy of Sports Medicine certified trainer, recommends strength training to provide additional protection against injuries. Taylor suggests a minimum of two strength training sessions per week for endurance athletes: one using heavy weights, and the other a circuit session with lighter weights and no rest between exercises in order to keep the heart rate high. The amount of weight and number of repetitions should be periodically increased to continue challenging the body, but only to a point where exercises can be executed with good form.

Improves Endurance Performance

One example of how strength training leads to improved endurance performance was carried out in a 10-week study conducted by the University of New Hampshire. Athletes who participated in a strength training program showed a 24% increase in upper body strength, and 34% increase in lower body strength. In comparison, those who exercised purely by running made no improvement in strength. Further, the strength-trained group saw a drop in average heart rate when running, while the control group experienced no change.

The most significant change found by the study, however, was the improvement in running economy. By the end of 10 weeks, the strength-trained athletes were using 4% less oxygen to run at a 10k race pace; that translated to an improved running time of 6:17 minutes per-mile on average, down from 6:30 minutes per-mile, without the feeling of increased effort. In addition, none of the strength-trained athletes saw an increase in body mass.

Possible Factors

Peak Performance cites a few possible reasons why strength training may increase running economy. The first suggestion is that strength training improves the individual cells in leg muscles. As fewer fibers need activating during running, oxygen demand is lowered. Second, body parts may become more stable through strength training. This reduces unnecessary motion that requires oxygen without propelling the body forward. Finally, improvement in running economy may result from the positive effect strength training has on the efficient coordination of muscle activity in athletes’ nervous systems.

Whatever the reason, there is increasingly-strong evidence supporting the notion that strength training leads to better running economy, and therefore improved endurance performance, in athletes.