When Should Runners Lift Weights?

In endurance sports, high energy demands are met by increased oxygen consumption as well as augmented anaerobic metabolism. The cardiovascular and respiratory systems become highly active. Athlete performance is limited by the central systems of circulation, respiration, and heat dissipation rather than peripheral muscle function alone.

When heavy strength training is combined with high-intensity endurance training, strength gains are diminished. Therefore, care must be taken when combining endurance training with strength training.

When strength training and endurance training are done concurrently it is difficult for an organism to adapt simultaneously to the conflicting demands.

A same-day running session followed by a strength training session impedes strength gains.

Similarly, a same-day strength training session followed by a running session impedes endurance adaptations.

Knowing this, when should runners lift weights?

Answer: As the first training session/activity on days designated as running recovery days.

Here’s why: The desired training effect of running recovery days is recuperation from prior running-focused training stressors (stimuli). Running performed on recovery days is purposely non-demanding and aimed to provide a restitution load, not a training load. Strength training stimulates different biological systems than running training and produces different enzyme signaling. The fatigue accumulated from strength training is mostly central (neurological) fatigue not peripheral (metabolic) fatigue. Recovery from central fatigue happens much more rapidly, sometimes overnight, than recovery from peripheral fatigue.

Therefore, on a running recovery day, a runner is in a metabolic pre-fatigue state. Strength training results in heavy neurological stress and little, if any, metabolic stress. Performing a recovery run immediately after a strength training session will force the runner to run at a more appropriate (slower) pace due to pre-existing metabolic fatigue and the newly introduced neurological fatigue. The effect of this cumulative fatigue will result in a slow running pace which is desirable on recovery runs, as a common mistake by most runners is making their easy runs too stressful by running them too fast.

Reference: Science and Practice of Strength Training, Zatsiorsky, Kraemer, Fry, Chp. 11