Professionals within the fitness industry are used to lively debate. We are accustomed to hearing researchers argue dynamic vs. static stretching. We have heard many opinions about the best ways to build muscle: low weight, high reps or heavy weight, low reps. And the debates continue. One such controversy involves the use of particular weight lifting machines common to many gyms: leg extension machines. Are these machines a good use of your time and energy? Can some of these machines actually be a detriment to your health and fitness?

You can still sculpt your legs without using leg extension machinesLeg extension machines are a controversial weight machine. These machines have a seat and a padded bar that rest at the juncture of the leg and foot. As you lean back in the seat, you lift the legs up until they are nearly straight and then slowly let the legs back down. The amount of weight your legs lift can be adjusted.

If you use this type of machine, you are focusing your lifting efforts on your quadriceps (the large muscles of your front thigh area)-namely the vastus medialis, vastus lateralis, vastus intermedius, and the rectus femoris. Interestingly, this machine lets the hamstring muscles completely relax as the quadriceps do all of the work. Many avid lifters are attracted to this particular machine because they feel that this isolation really helps them emphasize each of the four muscles in the quadriceps. And of course, if you get judged on your physique while posing, you want some major muscle definition. They’re right about this isolation, but are leg extension machines a good weightlifting choice for the average person?

I think not. Of course, as is to be expected with any controversy or debate, there are various schools of thought regarding leg extensions. Some say these machines are hard on knees. Others say the machine has a common rehabilitative method for knee injury or knee surgery is the leg extension machine. How can both be true? I would suggest that using leg extensions in a rehab atmosphere works because light weight is used to correct muscular imbalances. But if we are talking about the typical person doing leg extensions on the machine at my gym, they are not lifting five or 10 pounds. Rather, they’re lifting much more weight. Such a difference in weight makes a tremendous difference in terms of how the knee is affected.

Other common criticisms of the leg extension machine:

But you might be thinking, “What can I do in place of the leg extension machine?” Squats, when done correctly, are the absolute best exercise for leg strengthening. Squats are the king of leg exercises. Don’t go for isolation while you ignore other muscles. Squats are also a functional exercise. This means that they mimic natural movements that people use throughout their everyday lives.

Use your gym time wisely. Work all of those leg muscles at once by doing squats. Leave the leg extension machines to the professional bodybuilders.