For those who are seeking weight loss, cardio should come first, but if gaining muscle mass is the goal, it's time to hit the weight room first.
"Doing cardio first will induce fatigue that may compromise technique and possibly increase risk of injury," explains Fabio Comana, director of Continuing Education for the National Academy of Sports Medicine. Exhausting one with a big run right before weights and resistance training doesn't just up the risk of injury; it also means you'll have less energy to throw into a really good weight training session.
On the other hand, if you're looking to lose fat, try doing interval cardio training before getting started on weights. The cardio will deplete your body's supply of glycogen, the stored form of glucose in muscle cells and a primary material in our energy storage. Once glycogen is depleted, the body turns to more long-term storage sources, like fat.
If your goal is strictly to have a lean body, not to be strongest, or most powerful, but achieve maximal leanness; try high-intensity interval training at the beginning of each workout.
But that doesn't mean weights aren't important for fat loss. In fact, when it comes to analyzing the percentage weight loss that's comprised of fat versus lean tissue like muscle, weights have cardio beat overall.
There may be other reasons for doing cardio first. If you have Type 2 diabetes or hypertension prevention and treatment is the priority, then do cardio over resistance. Some diseases are better managed with cardio first, then introducing resistance training.
It's important to get the opinion of a doctor and Certified Personal Trainer before proceeding. If you're exercising, no matter the order, you aren't doing anything wrong. Depending on your goal, you may want to choose one type of exercise over the other. Of course, you could alternate days and avoid the question entirely.
