One of the biggest mistakes people make when weight training is to use momentum to lift the weight. Many aren’t even aware they’re doing it, but it works against them when it comes to strength-building. It can also increase the risk of injury. Momentum takes tension off the muscle being worked and makes it easier to lift the weight up. Look around the gym, and you’ll see people bouncing heavy weights around. Sure, they’re happy they can lift so much, but take the momentum out of the equation, and see if they can move it.
To Build Strength, Take Momentum Out of the Picture
If you want to build maximal strength, it’s important to use proper form, and that means taking the momentum out of your workout. There are certain types of exercise where momentum is appropriate. If you’ve done a kettlebell workout, you know that momentum is a necessary part of the movements. You’re using multiple muscle groups simultaneously in a dynamic fashion to lift the kettlebells across several planes. Kettlebell workouts are designed to build functional strength while burning calories, but they aren’t best for building maximum strength or size.
When lifting weights to build muscle, unlike kettlebells, the less momentum you use the better. You can lift more weight using momentum, but you won’t get better results. It’s more effective to decrease the amount of weight you use and really concentrate on form. Force yourself to lift the weight slowly through the full range of motion of the exercise. Stop to pause at the top for two seconds before slowly lowering it back down. If you’ve used momentum in the past, you’ll find you won’t be able to lift as heavy or as long when you take the momentum out of your movements. On the other hand, you want the muscles to do all of the work if you’re going to build strength.
Time Under Tension
If your goal is to build muscle (hypertrophy) it is important that you understand a principle known as “Time Under Tension”. This principle says that in order for an exercise to be effective as far as building muscle goes, you need to perform the exercise for at least 45 seconds without rest at a very challenging weight. This is why it just so happens that 10 reps at a normal steady cadence has historically been one of the most preferred rep ranges for bodybuilders who are mainly interested in building muscles.
Using momentum not only uses muscles not related to the those you’re trying to work, but also speeds up each rep reducing the time under tension to well under 45 seconds. This means you will not get the full benefit of the exercise and if your goal is hypertrophy you will not be very successful.
Another way to reduce momentum is to use resistance bands or to combine weights and bands together. The force on a band remains consistent regardless of whether you use momentum. Resistance bands are another good way to add variety to a strength workout.
The Bottom Line?
Momentum is appropriate when you’re doing a kettlebell type workout, but not when you’re using weights to build muscle. Lower the amount of weight you’re using, slow down your movements and concentrate on form, and you’ll maximize the strength training benefits you get.
On Fitness Magazine. September/October 2010. “The Use and Misuse of Momentum”