The Secrets of Springs

Why does Pilates equipment use springs for resistance instead of weights?

by Christine Romani-Ruby

The most defining feature of Pilates equipment is its use of springs for resistance. In fact, if you replaced the springs with weights, Pilates apparatus would be no different than some of the other equipment found in a fitness center. Springs are truly essential to getting the great results possible from equipment-based Pilates exercises. Here are the key reasons why:


Springs provide both assistance and resistance.

A spring has the ability to provide resistance in one direction and assistance in the opposite direction. This is most evident on the Reformer, which has a moving carriage resisted by springs. When doing footwork, the quadriceps and gluteus contract when you push the carriage out, stretching the springs. Your hamstrings then contract to gently return the carriage and are assisted by the recoiling of the springs. As the carriage closes, the quadriceps continue contracting to fight the pull of both the hamstrings and the springs. These movements must be very precise, some say rhythmical, to keep this opposition in check and prevent a loss of control of the carriage. (This is why your Pilates instructor corrects you when you slam the carriage closed.)

Springs encourage eccentric muscle activity.

An eccentric contraction happens when you lengthen a muscle while actively working it, like the lengthening that happens in your biceps when you extend your arm after a curl. On the Reformer, as you return the carriage to its starting position, some of your muscles must contract eccentrically to avoid giving in to the spring and slamming the carriage closed. This eccentric work is where Pilates gets its reputation for being a great way to both lengthen and strengthen muscles in fitness and in rehabilitation. It has also been proven to be a great method of strengthening for older adults.

Springs provide an active, flowing stretch.

Muscles have mechanisms that can protect us from overstretching them, but that can sometimes limit our ability to gain flexibility. On the Reformer, the spring tricks this system of inhibition and allows muscles to gently stretch more effectively. When you return the carriage, the spring recoils and decreases its pull or tension, causing the muscle to relax. This allows the joint to go into a position of stretch for that same muscle. This technique works because muscles stretch more readily immediately after contraction.

Springs require slow, controlled movements.

The eccentric resistance provided by the spring is very unpredictable. It is unlike the pull of gravity that the body is accustomed to. The further a spring is stretched, the more resistance it provides and the more concentration it takes to accommodate. As the muscles adapt, they must exhibit a great deal of control to keep the carriage movement smooth and the body in alignment. This slow, controlled activity is highly recommended for older adults who are trying to stay strong for the activities of daily living. It can be used to reteach a normal movement pattern or to retrain a muscle that is not being used appropriately.

Springs offer protection during advanced activities.

Springs protect you when you're practicing many of the more advanced planking and balancing exercises, such as the long stretch, down stretch and arabesque. Imagine that the Reformer carriage would be as slippery as ice without the springs, but with them it has a coating of sand or gravel to control the movement. By changing the tension of the spring, the amount of protection can be varied. This decreases the risk of injury and lets beginners start higher-level exercises safely, and with confidence. With a lower level of protection (lighter spring) your core will need to be more involved.

Christine Romani-Ruby, MPT, ATC, is co-founder and chief executive officer of PowerHouse Pilates, a company in Monongahela, Pennsylvania, that offers Pilates training for fitness and rehabilitation professionals.