Myth: Cardio (treadmill, elliptical trainer, stationary bicycle) should be done first at the gym to warm up before weight training.
Reality: A cardio workout should not be done before exercising with weights or resistance training. Your aim is to use the body’s fuel – glucose (sugar in the blood) – during the workout to provide energy. Most peoples’ goals in coming to a gym include wanting to lose or maintain weight so they often do cardio first because that is their first priority. But doing cardio first will burn much, if not all, of the glucose in your blood (how much you have to burn depends on the amount of carbs eaten before the workout).
If you deplete the fuel and then weight train, you may no longer have enough glucose to lift the weights. Because your body needs to obtain energy from somewhere to be able to do the exercise, it will break down the muscle tissue you have already built to gain what it needs to lift the new weight. This is obviously not the goal.
Glucose should help with the heavy workload. You still need to warm up properly, which can include five minutes of light cardio, and then use the energy stores to lift weights and build muscle. This completed, your body will be in fat-burning mode with glucose stores depleted, and then you do cardio — at the end when you will burn fat for fuel. The level of fat-burning depends on your nutrition prior, during and after the workout, and your exercise intensity level.
Kyle Bruce, NASM certified personal trainer and former pro hockey player, is a specialist in functional movement assessment and functional strength conditioning for sports and rehabilitation. He is assistant fitness manager at Steve Nash Fitness World Kitsilano, Vancouver.