I have searched and searched but I cannot find the scientific source for any notion around glycogen depletion and timing of weight training vs. cardio. There are tons of bloggers who repeat the concept but nobody quotes any official source. They all seem to be echoing each other. And there are contrarians out there too.

Now, as I’ve mentioned in previous posts, there is a lot of science supporting the idea of cardio post weight lifting. The articles I cite though don’t mention glycogen.

So some facts
- glycogen is reduced after weight training; but it may not be “depleted”
- interval training, especially HIIT, also reduces glycogen
- drinking protein after weight training and before cardio will help prevent muscle loss from steady-state cardio; I do not know how that affects glycogen

In the end, it is consistency over time that gets results, so if you are at the upper-end of the fitness elite, you’ll have to experiment for several weeks with each option.

But for 90% of you reading this, you can ignore these details. You simply need to get your butt to the weight room on a regular basis, add in cardio after your workouts, and avoid packaged/processed foods.

Darrin – I think the advice was do a protein shake first. Then do weigh training. Do not eat or drink anything. Jump directly on the treadmill for Steady state cardio, approx 30 mins. After cardio then drink the post workout protein shake with some ground almonds and stevia (insulin boost). Hope you are able to reserach this soon.

@ John, Joe – Yes, there is scientific evidence to support what John mentioned. I’ve referenced several reasons over the past months about the advantages of doing cardio after weight training, but the glycogen issue is an interesting one that is also supported (somewhat) by science. I’ll have to look it up when I get back but I think you do need to be careful about too much depletion. For example, if you are doing HIIT (usually 10 to 20 minutes) or a short SS cardio (like 30 min or less) then just protein after your weight training is fine. But if you are doing a 45 minute or longer cardio, then you need some carbs to sustain and reduce burning muscle.

@ Tyson – HIIT 3x per week? Plus SS cardio 3x a week? That’s extreme! I do SS cardio 3x per week, and at most do HIIT 1x per week (because doing HIIT right is nearly a puke-fest because it is so intense). I think 99% of the science out there would indicate that doing that much would inhibit muscle growth (primarily because of the lack of rest days). Are you an exception to the general rule on this one? Are you able to do that without losing muscle? If so, please share your secrets!