The Technology That Could Replace Weights Forever

Limitations of Traditional Free Weights and Machines00:03

For decades, people have used chunks of steel to lift weights and build muscle. However, there are specific elements of hypertrophy and athletic training where traditional free weights and even machines fall short. The first issue is tension in the stretch. When performing dumbbell lateral raises, the most theoretically stimulative part of the range of motion is the bottom third, but gravity only points downward, making this the exact place where dumbbells exert the least tension on the delts—the opposite of ideal.

The second limitation is the opposite problem: some free weight movements where constant tension is desired only have tension during a portion of the lift. For athletic function training requiring strength in every range of motion, movements like dumbbell flies and pullovers kick out completely at the top, meaning the load doesn't apply to the pecs in the upper end of the ROM.

Third, while machines can solve the problem of constant tension, they introduce their own limitation. Lying hamstring curls would ideally be tougher at the bottom and easier at the top to accommodate the strength curve and maximize hypertrophy. Hamstrings are way stronger at the stretch than near full contraction, and since tension under stretch is most important for hypertrophy, not having the hams more challenged at the stretch is a significant downside of most leg curl machines.

Fourth, traditional weights—especially dumbbells—have loading increments that can be inappropriately large. If someone can do 20+ repetitions with 10-lb dumbbells for bicep curls and wants to progress, they typically must jump to 15-lb dumbbells since most gyms don't have 12.5-lb options. This represents the same progression jump as going from 200 to 300 lbs on the leg press in one session.