Quick Answer: Springs lose tension gradually with use as the steel takes a small permanent set, so an old red spring genuinely provides less resistance than a new one of the same color. Studios typically replace springs on a schedule, and the change is most noticeable in exercises where you work at the end of the spring’s stretch. Expect to drop a setting for a few weeks after a replacement, and treat that as recalibration rather than lost strength.

Your footwork felt fine on Tuesday and heavy on Thursday, on the same machine at the same setting. If the studio changed the springs between those two sessions, that is your answer.

Do springs really lose tension over time?

Yes, through a process that is gradual and mostly invisible until it is replaced.

A coil spring stores energy by elastically deforming. Within its designed range, it returns exactly to its original shape. Over thousands of cycles, particularly cycles that approach the upper end of its range, a small amount of that deformation becomes permanent. The spring takes what engineers call a set, meaning its resting length increases slightly and its resistance at a given stretch decreases.

Add environmental factors. Heat and humidity affect the steel and any coating over years. Uneven use matters too: the springs on the ends of the gear bar often get used more than the middle ones in studios where clients grab the nearest one, so they age unevenly.

The result is a set of springs that all look identical and all read the same color but do not all deliver the same resistance.

This is why studios replace springs on a schedule rather than waiting for something to look wrong, and why a well-run studio replaces the whole set at once rather than one at a time. Mixed-age springs on the same machine produce inconsistent resistance depending on which ones you choose, which is confusing for everyone.

The amount of loss over a spring’s service life is modest in absolute terms and very noticeable in practice, because Pilates work is precise and you are attuned to small differences on movements you have done hundreds of times.

Where does the difference show up most?

In three specific situations, which is why it feels inconsistent rather than uniformly harder.

At the end range of the spring’s stretch. Spring resistance increases as it extends, so a long-carriage movement loads the spring most at the far end. That is where a fresh spring’s extra tension is most apparent, and where the last few inches of footwork or long stretch suddenly feel different.

In eccentric control. Returning the carriage slowly against the spring is where you feel resistance most consciously. A new spring pulls harder on the return, which makes controlled returns feel more demanding even when the concentric phase seems unchanged.

In exercises where you are near your limit. If a movement was already at the edge of your control, a small resistance increase pushes it over. This is why advanced exercises reveal the change before basic ones do.

Where it shows up least: short-range work close to the stopper, and exercises where your body weight dominates the load rather than the spring.

The practical consequence: the exercises you use to judge how strong you feel are exactly the ones most sensitive to spring age. That is a measurement problem rather than a strength problem.

Myth vs Fact: Reformer Springs

Myth: Spring colors mean the same thing at every studio. Fact: color coding varies by manufacturer. A red spring on one brand of reformer is not the same resistance as a red spring on another, which is why moving studios can feel disorienting and why cue sheets do not transfer.

Myth: More springs always means harder. Fact: it depends entirely on the exercise. In many movements more springs provide more support and make the exercise easier, which is one of the genuinely counterintuitive features of the reformer. Elephant and long stretch are classic examples where lighter is harder.

Myth: Springs should be replaced when they look worn. Fact: visual inspection catches corrosion and damage but not tension loss, which is invisible. Replacement is scheduled by usage hours, not by appearance.

Myth: You should always use the setting your instructor calls out. Fact: the call is a starting point for an average client on that machine. If the movement quality breaks down, changing the spring is the correct response, and good instructors expect it.

Myth: Old springs are dangerous. Fact: tension loss is a performance issue, not a safety one. Safety issues are broken hooks, damaged coils, and corrosion, all of which are visible and all of which mean the spring comes off the machine immediately.

The one that reframes the whole thing: the spring setting is not a score. Reformer work is about the quality of the movement at whatever resistance allows you to do it well. Chasing heavier springs the way one chases heavier dumbbells misunderstands what the apparatus is for, and it is the single most common source of frustration for people coming from a weight room background.

How should you adjust after a spring change?

Recalibrate deliberately over two or three sessions rather than pushing through.

Drop one setting for the first session or two on the exercises where you feel the difference most. This is not a step backward, it is matching the resistance to what you were actually working against before.

Prioritize movement quality over the setting. If the carriage is jerking, the return is uncontrolled, or you are recruiting the wrong areas to manage the load, the spring is too heavy regardless of what the label says.

Tell your instructor. They usually know the springs were changed and can adjust cues for the class. They also want the feedback, because it tells them how the new set is landing across different clients.

Expect it to normalize in two to four weeks. New springs bed in slightly, and your own calibration adjusts, and the difference stops being noticeable.

Use the change as a data point rather than a judgment. If you found the new springs difficult in exactly the exercises you had been sloppy on, that is useful information about where control was marginal.

This is general information, not medical advice. Sharp joint pain, pinching, or pain that persists after class is a reason to stop the exercise and speak to your instructor or a health professional, regardless of spring setting.

FAQ: Reformer Spring Questions, Answered

How often should studios replace springs?

Most manufacturers give guidance based on usage hours, and busy studios often work on an annual or biennial cycle for the full set. A studio that can tell you its replacement schedule is a studio paying attention.

Can I tell if a spring is old just by feel?

With enough experience on one machine, yes, especially if you compare the same-colored springs against each other on the same exercise. It is not reliable enough to be a maintenance method, though.

Should my home reformer springs be replaced on the same schedule?

No, because usage is far lower. Home machines used a few times a week will go considerably longer than a studio machine used many hours daily. Follow the manufacturer’s hour-based guidance rather than a calendar.

TL;DR:

• Springs take a small permanent set over thousands of cycles, so old springs genuinely give less resistance
• The difference is most obvious at end range, on controlled returns, and in exercises near your limit
• Spring colors are not standardized across manufacturers, and more springs often makes an exercise easier
• Drop a setting for a couple of weeks after a replacement and prioritize movement quality over the number

Ask your studio when the springs were last replaced. It explains more about your last few classes than you would expect.