Everyone’s seen it: A gym-goer working hard to crush it but instead is standing in their own way. How? They’re using momentum to complete the reps instead of the power of their own muscles. We raise our eyebrows when we see someone swinging their body during bicep curls, but the truth is, you, too, might be using momentum without even knowing it.
And it’s not even entirely your fault. Newton’s second law of motion, the Law of Acceleration, states that “the rate of change in the momentum of a body is proportional to the applied force and takes place in the direction in which the force acts (Enoka 1994)” . This means that if you “cheat” by using a body part other than the one you’re focusing on, the momentum of the moving weight may be greater than your muscle’s ability to slow it down and stop it.
For example, if you begin lat pull downs by pulling the bar down explosively, momentum begins building during the exericse. Your muscles are working less and your spine and joints more. By the time you’re done with the set you need to let the weights drop just to control the momentum!
So unless you’re a powerlifter, strength training needs to be slow and deliberate – especially at the beginning of the movement – or momentum will easily take over. The heavier the weight, the greater the risk of momentum.
The good news is that you can stop using momentum and get more out of your workouts.
You can inadvertently use momentum during any exericse. But the most common culprits are standing bicep curls, seated machine or cable rows, triceps pushdowns, and back extensions. The best strategy is to assume that unless you consciously control it, you are using momentum. Then take an analytical approach (via IDEA Health and Fitness) with these steps:
- Set up. When you get into position, check your alignment – are your spine and joints in neutral position and your abdominal muscles pulled in to your spine?
- Define the start, middle, and end. Every exercise has a start, middle, and end, with the end position the same as the start position. To prevent swinging and bouncing during the repetition, know where these points are. Treat each point as its own distinct movement instead of one movement blurred together.
- Contract at the peak. At the midpoint of the repetition, always pause and contract the right muscles. This will stop you from using momentum and recruit more motor units to increase force.
- Control the speed. Slower repetitions build less momentum than faster ones. I’m not saying you should avoid fast, powerful concentric phases; sometimes you do want to train forcefully to generate power. Just be aware that when you rush through reps you’re more likely to rely on momentum, so slow down and practice awareness through each rep.
Tips for Specific Exercises
Here are some common exercises and variations to cut down on momentum. You’ll most likely have to lower the weight to do these with good form.
Standing Bicep Curls. Stand against a wall with your upper back and glutes touching the wall. You can also do preacher curls and seated curls for less momentum.
Bent-over Rear Delt Raise. Stand behind an incline bench and adjust it so that when you bend at the waist and place your head on the end of the seat, your upper body is parallel to the floor. Remember to keep your back flat and pull in your abdominal muscles to avoid back strain. See it here.
Pull ups. To avoid swinging during pull ups, do not jump up to the bar – use a box to get to the dead-hang position (arms straight). Cross your ankles and pull your belly button into your spine to stabilize yourself. Perform each pull up slowly, with two counts up, a pause at the top, and two counts down.
Seated Rows and Lat Pull downs. Keep the resistance at a weight that allows you to pull your elbows back and retract your shoulder blades without moving the rest of your body. You shouldn’t lean too far forward or too far back during each rep – keep your spine neutral. Also try chest-supported rows to isolate the back muscles.
Triceps Pushdowns. If your gym has a back pad at the cable station, that’s the way to go. When I do pushdowns this way I have to drop the weight 40 percent! If you can’t do pushdowns against a pad, I suggest you skip pushdowns and do lying triceps extensions, narrow-grip bench presses, or diamond pushups instead.
And finally, two more tips: (1) You’re less likely to use momentum during prone and supine positions; and (2) it’s usually fine to use leg drive to transfer force from your lower body to your upper body (such as with bench presses and lying triceps extensions on the floor).
Once you become aware of the power of momentum, your results will become much more productive. Enjoy!
The article originally appeared on www.workoutnirvana.com.