Some exercises, like Spanish and goblet squats as well as reverse lunges, are kinder to ailing joints than others.

But if you want to train the range of motion (ROM) of your joints, as well as your flexibility and strength, “isotonic training” might help.

“Isotonic”, which has its origins in Ancient Greek, roughly translates to “same tension”.

The idea is that you keep the muscle at roughly the same tension throughout the movement.

It involves the “rhythmic muscular contractions”, most often using little force. It is sometimes also called “dynamic” movement,

Another type of exercise, isometric (or “static”) training, does the opposite: lots of load, and very little change to the length of the muscle.

Most exercises involve a combination of isometric and isotonic movements, though some tend more towards one then the other.

Some exercises that mostly, or entirely, use isotonic movement are:

• squats
• pushups
• pullups
• bench presses
• deadlifts
• jogging
• crunches
• sit-ups
• Russian twists
• reverse crunches
• burpees
• cross-country skiing
• swimming.

A 2022 review found that isotonic exercise helped to improve the strength of participants’ hamstring muscles.

“These exercises, when performed at low intensity, but with high repetition, can be used by the healthy general population to prepare for training and daily exercise,” it read.

And in another 2022 study, isotonic training was found to be a more efficient way to improve muscle strength, flexibility, and endurance more than isometric movement.

Healthline explained that isometric training targets the ROM of joints. It may help with functional movement (like lifting things from a shelf or crouching to pick something up), and mobility, too.

If you have existing joint or heart conditions, are injured, or have other medical concerns, though, it may be worth speaking to a doctor before taking up any new exercise.