Warm-up stretching: time for a chain reaction

Although many athletes frequently integrate stretching into their pre-exercise warm-up routines, the actual benefits on subsequent performance, and the most appropriate type of stretching, remain far from clear - even controversial^(1,2). This is perhaps understandable; the numerous studies conducted on stretching to date have included many variables such as the type of stretching used (see box 1), the timing and duration of the stretching and the fitness levels of the subjects studied^(3-5).

Static vs. dynamic

One of the main areas of confusion is about which stretching type (see box 1) produces the greatest benefits. For example, some research evidence has highlighted that static stretching protocols may be less effective, and that stretches longer than 60 seconds per muscle–tendon unit can actually cause performance impairments rather than performance gains, while dynamic stretches of under four minutes’ duration per muscle group are likely to be much more effective⁽⁶⁾. And while static stretching can improve range of movement in joints, which has been associated with a decrease in injury risk⁽⁷⁾, some studies have concluded that static stretching, when used as an injury prevention strategy for endurance athletes, is unable to reduce the prevalence of musculoskeletal injuries⁽⁸⁾.

Box 1: Common modes of stretching

The term stretching covers a number of different techniques for maintaining and developing flexibility. The four most common modalities are listed below:

• Dynamic range of motion stretching - often employed in warm ups where the major muscles are moved rhythmically in gentle repetitive motions within their full but normal range of movement.
• Static stretching –The muscles/joints are moved slowly and steadily into the stretch position and held static without bouncing, then released - widely acknowledged as a relatively safe technique for stretching novices and useful for increasing range of movement.
• Ballistic Stretching – an extension of dynamic stretching movement, where the muscle is taken to end of its range of motion then slightly over-stretched by ‘bouncing’. Only well-conditioned athletes, whose sport requires explosive and ballistic movements, are recommended to use this kind of stretching.
• Proprioceptive neuromuscular facilitation (PNF) – a sophisticated technique combining static stretching with added resistance (usually provided by a partner) against which the stretched muscle group works. PNF can improve further flexibility in those already accustomed to static stretching.

Compared to static stretching, dynamic stretching has been proposed as a superior warm-up stretching mode. However, even here the evidence is still quite mixed. Some studies have concluded that pre-exercise dynamic stretching can improve power, sprint and jump performance, and enhance range of motion - generating a similar, or greater, increase in flexibility than static stretching⁽⁹⁾. That said, other studies have found that pre-exercise dynamic stretching produces no gains in running performance or on exercise efficiency^(10,11).

In a 2021 study on runners, researchers compared pre-running static stretching, dynamic stretching and no stretching on running economy (how efficiently the runners were able to use oxygen to sustain a given pace), time to exhaustion and perceived exertion (RPE) in a subsequent running challenge⁽¹²⁾. This research found that:

·        Running economy improved equally in the static and dynamic stretching warm ups compared to no stretching. In simple terms, the runners who stretched using either mode as part of their warm up were able to utilize oxygen more efficiently in their running.

·        Compared to no stretching, the runners’ levels of perceived exertion at the end of the session were significantly and equally reduced following the dynamic and static stretch warm ups (see figure 2).

·        The runners’ times to exhaustion in the intense task at the end of the session were NOT improved following either of the stretch warm up – ie here, there seemed to be no benefits from stretching in the warm up.

Figure 2: Perceived rate of exertion during submaximal running