Why You Should Always Put Weight Training Before Cardio

lifting weights — Rachael Vanderwal and Azania Stewart (right) of Britain's women's basketball team lift weights during a training camp prior to the London 2012 Olympic Games in Guildford, southern England, on May 25, 2012. REUTERS

One of the biggest fitness questions is whether cardio should be done before or after you lift weights. Most advise to do it in whatever order feels best for you, but this new video from PictureFit explains the science behind which is better.

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As the video explains, your body performs better when you start with lifting. Our bodies have glycogen, which is a stored form of glucose that is used as energy. If you don’t have enough glycogen, your workout will take a beating.

While both cardio and weightlifting use glycogen, lifting weights takes only about a third of it, however resistance training is the most affected if you don’t have enough. Weightlifting uses quick bursts of energy which is provided by glyocgen, while cardio is slow and steady and burns fat in addition to glyocogen. PictureFit says that you can also train your body to adapt to cardio workouts with less glycogen.

Another reason to lift before cardio is because of two proteins in the body, mTOR and AMPK. The protein mTOR is important for muscle growth and is elevated after we lift weights. AMPK, on the other hand, is activated from exercises like cardio and actually can stop the mTOR signal, which means your muscle growth will suffer. However, this is only a theory that many believe to be true, says the narrator.

The biggest reason PictureFit says you should put resistance training before cardio is because of fatigue. The main point of lifting weights is to overload your muscles, which means you’ll increase resistance from exercise to exercise. If you do cardio first, you’ll already have fatigued muscles, which will lower the muscle force production from weight training. Plus, your heart will be tired, you’ll have less energy and you might be mentally fatigued.

Of course lifting first can also impact your cardio workout, but as PictureFit explains, cardio performed at a steady rate isn’t as demanding.

If your schedule is pretty tight, go ahead and get both workouts in on one visit, but PictureFit advises splitting up your cardio and resistance training on different days for optimal results.