Isometric stretches involve voluntary contractions of the muscles against a stretch to switch off the stretch reflex, allowing you to get deeper into a stretch.
The following pictures illustrate the concept when used with a side split.
First, you slide down to your maximum stretch. Next, you tense against the stretch by attempting to squeeze the legs together. Finally, you relax the tension and within 2 seconds slide further into the stretch.
There are infinite variations on the length of tensions and the number of repetitions performed, but all variations fall in to one of two methods:
For more information see:
- Isometric Stretching
- Stretching Scientifically by Tom Kurz
- Relax Into Stretching by Pavel Tsatsouline