Many runners now accept that they'll perform and feel better if they do more than just run. That's especially true for people who took up the sport as adults and whose non-running hours include a lot of sitting. Regular strength training, including for your legs, can help to correct muscle imbalances and weaknesses that are common in modern life.

At the same time, many runners struggle with how to schedule their various workouts. After all, strength training is supposed to help, not detract from your running. New research out of Australia offers guidance on how best to combine mile repeats and repetitions in the gym.

Fifteen runners of a wide range of ability and average weekly mileage did different strength-training sessions on three occasions. One workout was a high-intensity whole-body session, one high-intensity but for legs only, and one was low-intensity, whole-body. Six hours after each workout, they did a treadmill test of 10 minutes running at 70% of  ventilatory threshold pace (easy), then 10 minutes at 90% of threshold pace (roughly, close to half marathon pace), and then as long as possible at 110% of threshold pace. The runners also did the treadmill test at the outset of the study, to get a benchmark for how they would perform when fresh.

The high-intensity strength workouts significantly lessened the runners' time to exhaustion at the end of the treadmill test. In the benchmark test, they'd lasted an average of close to 5 minutes at 110% of threshold pace. After each of the high-intensity strength sessions, time to exhaustion was almost a minute less, suggesting that the hard weight workouts six hours earlier had dramatically decreased the runners' ability to sustain fast running.

The lead researcher, Kenji Doma, Ph.D., of James Cook University, toldRunner's World Newswire his findings have practical implications for how runners should arrange their workouts.

First, Doma advises, don't schedule a hard running workout later in the day of a weight session. "Running at maximal effort is impaired six hours [after] lower-extremity resistance training, and therefore trained to moderately trained runners will need more than that to recover for running sessions set at high intensities," he says.

In addition, "running at maximal effort is still impaired 24 hours after lower-extremity resistance training," Doma says. "Therefore, in the case of trained and moderately trained runners undertaking high-intensity running sessions after lower-extremity resistance training, they may need more than one day to recover."

Second, Doma found that running performance at lower intensities was unaffected by the weight workouts. "Runners could undertake strength training and running sessions on the same day six hours apart as long as the running session is set at submaximal intensities," Doma says.

If possible, Doma says, try to arrange your schedule so that on days that you run and lift, running comes first.

"I found that lower-extremity resistance training performed six hours prior to running sessions at moderate to high intensities cause carryover effects of fatigue the next day to a greater extent than the reverse sequence," he says. "Therefore, if undertaking lower-extremity resistance training and running sessions on the same day, it is best to undertake a running session before a strength-training session, for example, running in the morning before work and lower-extremity resistance training in the evening after work."

In this scenario, it would make sense to have that morning run be one of your harder workouts of the week. Your workout the following day would then be an easy recovery run, which would be warranted even without the evening lifting, but is that much more called for on the basis of Doma's research. This sequence would also mesh with many coaches' recommendation to have great discrepancy between your hard and easy days, so that you can better recover from your toughest workouts, instead of including hard elements of non-running training on your easy running days.