The two second stretch is replacing the old method of stretching. Muscle fibers contract when a stretch is held for thirty seconds. Holding a stretch for just two seconds prevents the stretch reflex from kicking in. The new approach of two second stretching is a fundamental element of Active Isolated Stretching. 30 second stretching is used by older more traditional methods of stretching. Traditional stretching is the tried and failed method. AIS stretching is the optimized method of stretching. Conventional stretching emphasizes stretch and hold for thirty seconds. Active Isolated Stretching (AIS) promotes a repetition pattern of stretching where the hold is only for two seconds. The stretching method you choose will only reflect the effectiveness of that type of stretching. If you chose traditional stretching you will emphatically be able to claim that conventional stretching is not working, but if you chose Active Isolated Stretching you will understand that new stretching techniques are essential for repairing physical pain, preventing injuries, and preparing for athletic activities.
How long should I hold a stretch?
The conventional form of stretch and hold for thirty seconds is what everyone knows. The problem with holding a stretch for thirty seconds (or ten seconds) is that an automatic stretch reflex will kick in after two seconds and prevent the target muscle from lengthening. Therefore by holding a stretch for thirty seconds, the automatic stretch reflex prevents the target muscle from lengthening to its potential.
Considering this fact, Active Isolated Stretching uses a two second stretch. Rather than holding one long time, AIS emphasizes holding a stretch for two seconds and doing 6 to 8 repetitions to the same target muscle. Each repetition goes slightly more than the previous rep. Always holding for a maximum of two seconds and only increasing the stretch two or three degrees more than the previous repetition. The increase in the stretch is gradual. If you consistently increase the range of motion one to three degrees through each rep, than in a series of repetitions you can increase the range of motion twenty percent from its original state.
AIS stretching avoids maximum effort because overloading the stretch can cause microtears to a target muscle. Gentle and gradual opening is part of the AIS method.
When we lift weights for strength training, we do repetitions to get the maximum benefit to the target muscle. Similarly, AIS states that a repetition pattern to stretching will be most beneficial to lengthen target muscles.