Why a planned weekly rest day should be part of every marathon training plan or triathlon training program

Want to reap all the benefits you can from that tough workout you did today? Then make sure you follow it up with some rest. That’s because the cellular changes that ultimately increase your fitness level actually occur during the period of relative inactivity after the workout—not during the workout itself. If you don’t allow for this post-workout muscle recovery period and you do another hard workout too soon, chances are your body will not have the opportunity to recover from and adapt to the first workout.

Consequently, every endurance athlete, whether in 10-K training, marathon training, or Ironman training, should have one designated rest day per week. When planning your rest day, keep in mind that the whole point of it is simply to subject your body to much less training stress than usual. So maybe you’ll do a super light workout, try a cross-training session, or actually take a zero for your rest day. It all depends on how much you normally train on non-rest days.