Stretching is a technique used to improve flexibility and increase the functional range of motion in joints. Active Isolated Stretching (AIS), developed by kinesiotherapist Aaron Mattes, distinguishes itself through a specific protocol. Unlike traditional stretching that relies on sustained, passive holds, AIS employs active movement and short-duration holds to achieve lengthening. This system is designed to work with the body’s natural neurological and circulatory mechanisms, promoting soft tissue health and injury prevention.
The Foundation of Active Contraction
The primary feature of Active Isolated Stretching is the requirement for the individual to actively initiate the movement. This technique involves contracting the muscle opposite the one being stretched, known as the antagonist muscle. For example, to stretch the hamstring, the quadriceps must be actively engaged to lift the leg through the range of motion. This active contraction moves the limb to the point of a stretch, ensuring the targeted muscle is isolated and prepared for lengthening.
The stretch is then held for a brief period, typically 1.5 to 2 seconds, before the muscle is immediately released. This short duration prevents the nervous system from triggering a protective reflex that would resist the stretch. The process is repeated multiple times, usually 8 to 10 repetitions per set, to progressively increase the range of motion with each cycle. This repetitive action, coupled with the brief hold, makes the process feel more like a controlled, slow-motion movement than a traditional static stretch.
Leveraging Reciprocal Inhibition
The neurological mechanism that makes the active contraction effective is called reciprocal inhibition. This is a reflex where the nervous system causes a muscle to relax when its opposing muscle is contracted.
AIS uses this reflex to its advantage, allowing the targeted muscle to achieve a greater degree of lengthening. By actively contracting the opposing muscle, AIS bypasses the protective stretch reflex, or myotatic reflex. The myotatic reflex causes the muscle being stretched to contract and resist the force when it is held in a stretched position for too long, often around three seconds or more. The two-second hold in AIS specifically avoids activating this reflex, permitting effective lengthening of the muscle fibers over multiple repetitions.
Distinctions from Static Stretching
Active Isolated Stretching differs significantly from traditional static stretching. The most noticeable contrast is the time spent in the stretched position: AIS uses a short hold of two seconds, whereas static stretching requires holding a stretch for 30 seconds or more. This difference in hold time is directly linked to avoiding the body’s natural protective response that resists sustained tension.
The nature of the movement also contrasts sharply; AIS is active, requiring the individual to use their own muscle power to initiate and perform the stretch. Static stretching is often passive, relying on external forces like gravity, body weight, or a partner to hold the muscle in an elongated state. Furthermore, AIS promotes circulation to the area through rhythmic repetition, typically involving 8 to 10 repetitions. Static stretching is aimed at achieving deep, sustained tissue lengthening, often performed with only one to three long-held repetitions.
Optimal Usage Scenarios
Active Isolated Stretching is suited for scenarios where increasing circulation and preparing muscles for activity are the primary goals. Due to its dynamic nature, it is used as a component of a dynamic warm-up before exercise or athletic performance. The repetitive, short-duration stretching helps to increase the temperature of the muscles and connective tissue, enhancing their readiness for movement.
The technique is also incorporated into post-exercise recovery and rehabilitation protocols, such as physical therapy, because it can target specific muscles and restore free movement. By promoting blood flow and increasing the range of motion gradually, AIS assists in the repair process and helps to prevent the formation of adhesive scar tissue. Conversely, static stretching is reserved for the cool-down phase of an exercise session, where the objective is to relax and lengthen already-warmed muscles to alleviate stiffness.