The difference in one table
| Isotonic | Isometric | |
|---|---|---|
| What happens | The muscle changes length and the joint moves | The muscle produces force but the joint does not move |
| Load | Usually a constant external load (weight, bodyweight) | Held against a fixed object or a held position |
| Everyday word | Dynamic | Static |
| Examples | Squat, push-up, biceps curl | Plank, wall sit, pushing against a wall |
Isotonic contractions have two phases. A concentric phase shortens the muscle while it lifts the load (standing up from a squat). An eccentric phase lengthens it under control while lowering the load (sitting back down).
Isotonic exercise examples
- Squats and lunges
- Push-ups and bench press
- Pull-ups and rows
- Biceps curls and triceps extensions
- Overhead presses
- Step-ups
- Cycling, rowing and swimming strokes, which repeat dynamic movements
Most traditional strength training is isotonic. If you want single-joint options, see our examples of single-joint exercises.
Isometric exercise examples
- Plank and side plank
- Wall sit
- Glute bridge hold
- Dead hang from a bar
- Paused or held mid-range squat
- Pushing or pulling against an immovable object, such as a doorframe
- Holding a weight still at arm’s length
What about isokinetic exercise?
Isokinetic exercise moves a joint at a constant speed, regardless of the effort you apply. It generally requires specialized machines, and is more common in rehabilitation and research settings than in a typical gym.
Is walking isometric or isotonic?
Walking is mainly isotonic, because your leg muscles lengthen and shorten as the joints move. Some muscles, such as those that stabilize the trunk, work more isometrically to keep you upright.
Good isometric holds for strength training
- Plank: builds trunk endurance. Start with short sets, such as 20 to 30 seconds, and progress gradually.
- Wall sit: loads the quadriceps without joint movement.
- Dead hang: challenges grip and shoulders.
- Bottom-position squat hold: useful for learning positions.
- Glute bridge hold: works the glutes and hamstrings.
- Mid-range press or pull against a fixed bar: a classic strength method that needs good setup and care.
Isometrics can be useful when joints are sensitive to movement (as in the isometric bicep curl), when you are building tolerance to a position, or when you have little equipment. They tend to strengthen muscle most at or near the joint angle being trained, so using varied angles may help.
Using both
Isotonic work forms the base of most programs. Isometric holds fit well as warm-up activation, as finishers, or in rehab-style sessions. Adding a pause at the hardest point of an isotonic lift combines the two. For recovery after a hard day, see our post-gym muscle recovery guide.
Safety
Holding your breath while straining can temporarily raise blood pressure. Mayo Clinic and other health sources advise people with high blood pressure or heart conditions to talk with their doctor before doing intense isometric exercise. Breathe steadily during holds, build up duration gradually, and stop if you feel pain, dizziness or chest discomfort.