How Hard Should Strength Training Be?

Every now and then a runner asks me if he or she should do P90X or CrossFit. Usually I advise runners not to do them. I have nothing against either program, but they’re extremely taxing. While I’m a big believer in strength training for runners, I don’t think a runner’s hardest workouts should be anything other than runs. You can only put so much energy into strength training before it starts to take away from running.

A study that appeared in the European Journal of Applied Physiology last year supports the idea that a little bit of strength training can go a long way for runners. Thirty-seven male runners between the ages of 21 and 45 participated in the study, which was conducted at the University of Jyväskylä, Finland. All of the subjects ran three to four times a week throughout the study, which lasted eight weeks. Eleven of the subjects also did maximal strength-building workouts once or twice a week. Ten others did explosive power-building workouts instead. Another nine subjects did a mix of maximal strength-building and explosive power workouts. The remaining seven subjects did lighter circuit training.

The researchers in charge of the study put all of the subjects through a number of tests to determine the effects of the different types of strength training on both strength parameters and running performance parameters. Of course, the latter are all that matter to runners, but knowing the effects of each type of strength training on strength itself would help the researchers understand how it benefited running performance if it did.

The results? Maximal strength-building workouts, explosive strength training and a mix of the two produced equal improvements in dynamic strength, jump height, and maximal muscle activation. None of these protocols improved isometric strength (yoga would have been better for that) or rate of force development (or how quickly the muscles respond to the brain’s commands). Circuit training did not improve muscle activation, jump height, rate of force development, or isometric strength, and maximum strength actually decreased over the second half of the circuit-training program.

If strength training improves running performance by increasing strength and power, you would think that circuit training — considering that it failed to increase strength and power — also failed to improve running performance in this study. In fact, circuit training improved more running parameters than the more intense strength-training protocols. Specifically, members of the circuit training group saw gains in maximum running speed, speed at the ventilatory threshold (or the pace at which one starts to breathe heavily), and VO2 max. Runners on the other three strength-training programs also increased their maximum running speed and speed at the ventilatory threshold but experienced no improvement in VO2 max. Running economy did not improve on any of the strength-training programs.

If this were the first study on the effects of strength training on running performance that had ever been done, we might conclude from these results that strength training actually impedes improvement in running performance and that circuit trainers improved their running more because their strength training was less intense and thus impeded their improvement less. But past studies have shown that a program that combines running with strength training improves running performance more than a program of running only.

What this study shows is that a minimalist approach to strength training can be effective for runners, and it even suggests that a less intense approach to strength training may be better for runners than hardcore iron pumping. Just one or two strength workouts a week were enough to improve running performance for all of the subjects, and the least intense of these four minimalist strength-training programs improved the most running parameters.

The most effective way to improve as a runner is to run a lot, run hard a couple of times a week, and always have plenty of energy to handle a heavy running load. You’ll improve even more if you complement your running with some strength training, but just be sure that you don’t lift weights so much or so hard that you don’t have plenty of energy left for your running.