What happens if you do cardio BEFORE lifting weights?

4 Jul 2026 · 1 min

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In this brief instructional video, Eric Roberts explains that performing high‑intensity or long‑duration cardio before a weight‑training session depletes the muscle glycogen (carbohydrate) stores that are needed for strength work. As a result, lifters may be unable to lift as heavy, experience reduced performance, and face a higher risk of injury due to compromised form. Roberts advises that when cardio and weight training are done on the same day, the optimal sequence is to lift weights first and then perform cardio afterward, and he encourages viewers to share this advice with anyone who does the reverse.

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Here's what happens if you do cardio before you lift weights. Your muscles store carbs and use those carbs as energy for your workouts. If you do high-intensity or long-duration cardio before lifting, your muscles will use all of those carbs, which means when you go to lift weights, you won't be able to lift as heavy and you'll increase your risk of injury because it'll be harder to maintain proper form. This is This is why if you're gonna do cardio and weights on the same day, always lift weights first and then do cardio after. Share this with someone who's been doing it backwards.