Warm-Up and Stretching: What the Evidence Actually Says

A warm-up is the short period of preparation before the main part of a workout. Its purpose is to gradually raise body and muscle temperature, increase blood flow, and rehearse the movements that are about to be loaded, so the body is ready to work and the session feels smoother. The idea is widely accepted across exercise guidance, and most people sense it intuitively: jumping straight into a hard effort cold feels worse than easing in.

The more contested question is what kind of stretching belongs in a warm-up. A popular and oversimplified version of the science says that static stretching, holding a muscle in a lengthened position for a sustained time, should never be done before exercise because it weakens the muscle. The fuller picture is more nuanced and more useful. Research shows that any performance cost from static stretching is duration-dependent: it is trivial for the short holds people typically use and only becomes meaningful with long holds right before strength or power efforts. Static stretching also keeps a genuine role for flexibility and range of motion. This guide lays out what a good warm-up looks like, what the evidence actually says about static versus dynamic stretching, and when each one fits. It is general and educational, not a personal training plan.

The essentials at a glance

• A warm-up that primes performance is built as submaximal aerobic activity, then large-amplitude dynamic stretching, then sport-specific dynamic drills (Behm and Chaouachi, 2011).
• Dynamic stretching has been shown either to have no effect or to slightly improve subsequent performance, which is why it suits a warm-up (Behm and Chaouachi, 2011; Behm et al., 2016).
• Any performance cost from static stretching is duration-dependent. Short holds under 60 seconds per muscle produce a trivial change of roughly 1-2% (around -1.1% in pooled estimates), while long holds of 60 seconds or more produce a larger deficit of roughly 4.6% to 7.5% in strength and power (Kay and Blazevich, 2012; Behm et al., 2016).
• Within a full warm-up that includes dynamic activity after the stretch, short static stretching does not impair subsequent strength and power performance (Chaabene et al., 2019).
• Static stretching keeps a real role for flexibility and range of motion, and stretching within a warm-up that adds post-stretch dynamic activity is recommended for increasing joint range of motion and may help reduce muscle injuries (Behm et al., 2016).
• The popular claim that one should never static-stretch before exercise is an oversimplification: the cost is small for short holds and static stretching has value when timing and duration are sensible (Kay and Blazevich, 2012; Chaabene et al., 2019).

What a good warm-up looks like

The clearest guidance on structuring a warm-up comes from a review by Behm and Chaouachi published in 2011. Its conclusion is direct: a warm-up to minimize impairments and enhance performance should be composed of a submaximal-intensity aerobic activity, followed by large-amplitude dynamic stretching, and then completed with sport-specific dynamic activities. That sequence is a practical template rather than a rigid rule.

The first part, a few minutes of easy aerobic movement such as a brisk walk, light jog, or easy cycling, raises body and muscle temperature and increases blood flow. The second part, dynamic stretching, means moving the joints through a controlled range of motion rather than holding a stretch still: leg swings, walking lunges, arm circles, and similar movements that take the muscles through the motions they are about to perform under load. The third part narrows in on the specific activity ahead, rehearsing the actual movement patterns at a lighter intensity, for example a few progressively heavier warm-up sets before a working set of squats.

The logic running through all three stages is to move from general to specific and from easy to harder, so the body arrives at the main effort warm, mobile, and rehearsed. A beginner does not need a complicated routine; a short, sensible warm-up that follows this general shape is enough. For people building a first resistance-training session around compound movements, the guide on strength training for beginners describes the movement patterns that the specific part of a warm-up can rehearse.

Static stretching: the duration-dependent nuance

Static stretching means holding a muscle in a lengthened position for a sustained period. The headline that traveled furthest from the research is that static stretching weakens the muscles and should be avoided before exercise. The more careful reading of the evidence is that the effect depends heavily on how long the stretch is held.

A 2012 systematic review by Kay and Blazevich is the clearest source on this dose-response. Pooling many studies, it found that static stretches held for short durations produced only trivial changes in performance, with a pooled estimate of about -1.1% for holds under 30 seconds and about -1.9% for holds of 30 to 45 seconds. Its conclusion was that shorter durations of stretch, under 60 seconds, can be performed in a pre-exercise routine without compromising maximal muscle performance. Only when holds reach 60 seconds or more per muscle does a meaningful reduction become likely, on the order of about 7.5% in measures of muscle strength. A 2016 systematic review by Behm and colleagues reached the same shape of result, reporting that holds of 60 seconds or more per muscle group substantially inhibit strength and power, with a decline of about 4.6%, while total static stretching of 60 seconds or less is much less harmful, with a change of about 1.1%.

Two practical points follow. First, the durations that produce real impairment, a minute or more held on a single muscle, are longer than what most people actually do in a warm-up, so the everyday cost of a few short stretches is small. Second, timing and what surrounds the stretch matter. A 2019 review by Chaabene and colleagues concluded that when short static stretching is included in a full warm-up that adds dynamic activity afterward, it does not impair subsequent strength and power performance, and the authors argued that blanket recommendations against pre-exercise static stretching should be updated. The honest summary is that long static holds immediately before a maximal strength or power effort can briefly reduce output, while short holds, especially when followed by dynamic movement, carry little or no cost.

Dynamic versus static: when each one fits

Dynamic and static stretching are tools for different jobs, and the useful question is not which is better but when each one fits. Dynamic stretching, controlled movement through a range of motion, is the better fit immediately before training because the evidence shows it either has no effect on subsequent performance or slightly improves it. That is why the standard warm-up template places large-amplitude dynamic stretching after the easy aerobic part and before the main effort.

Static stretching is the better tool for building flexibility and joint range of motion over time. Both the 2016 Behm review and the 2019 Chaabene review found that static stretching increases range of motion, and the 2016 review recommended stretching within a warm-up that adds post-stretch dynamic activity for increasing joint range of motion, noting it may also help reduce muscle injuries while leaving athletic performance essentially unaffected. So static stretching is not something to avoid; it simply has a clearer home either separately from a workout, after the main session when raising output is no longer the goal, or in short holds inside a fuller warm-up.

For most people who are not chasing a one-rep maximum or an explosive jump, the distinction is fairly academic: a sensible warm-up that gets the body moving and a little flexibility work fit comfortably together. The duration-dependent finding matters most for those doing maximal strength or power work, where it is reasonable to keep any long static holds out of the few minutes right before the heaviest effort and save longer flexibility stretching for afterward. Recovery tools such as foam rolling are sometimes used alongside stretching as part of a warm-up or cool-down; the guide on foam rolling covers what the evidence does and does not support there.

Frequently asked questions

Should I stretch before or after a workout?

Both can have a place, but the type of stretching matters more than a strict before-or-after rule. Before a workout, dynamic stretching (controlled movement through a range of motion) suits a warm-up because it does not impair, and may slightly improve, performance. Longer static-stretch holds aimed at flexibility are often better saved for after the session or for a separate time, especially before maximal strength or power efforts. Short static holds before exercise are not a problem, particularly when followed by dynamic movement (Behm and Chaouachi, 2011; Kay and Blazevich, 2012; Chaabene et al., 2019).

Is static stretching bad before lifting?

Not as a blanket rule. The performance cost of static stretching is duration-dependent. Short holds under 60 seconds per muscle produce only a trivial change (around 1-2%), while long holds of 60 seconds or more can reduce strength and power by roughly 4.6% to 7.5% in the minutes immediately afterward. So before heavy lifting it is sensible to avoid long static holds right before the working sets, but a few short stretches, especially followed by dynamic movement, are not a problem. This is a duration question, not a reason to never static-stretch (Kay and Blazevich, 2012; Behm et al., 2016; Chaabene et al., 2019).

What is a good warm-up?

A warm-up that primes performance generally follows three stages: a few minutes of easy, submaximal aerobic activity to raise body temperature and blood flow; then large-amplitude dynamic stretching that moves the joints through a controlled range of motion; then sport-specific dynamic drills that rehearse the movements about to be done, such as lighter warm-up sets before heavy lifts. The principle is to progress from general to specific and from easy to harder, so the body arrives at the main effort warm and rehearsed (Behm and Chaouachi, 2011).

Is dynamic stretching better than static stretching?

Neither is better in general; they suit different purposes. Dynamic stretching is the better fit immediately before exercise because it does not impair, and may slightly improve, subsequent performance. Static stretching is the better tool for building flexibility and joint range of motion, which research shows it does effectively, and it fits well separately from a session, after a workout, or in short holds within a fuller warm-up. The useful question is not which wins but when each one fits (Behm and Chaouachi, 2011; Behm et al., 2016).

How long should I warm up before exercise?

There is no single fixed number that fits everyone, because the right length depends on the activity, the intensity ahead, and the individual. The sourced guidance describes the structure rather than a stopwatch figure: a few minutes of easy aerobic activity to raise temperature, then dynamic stretching, then activity-specific rehearsal that builds up to the working intensity. The general principle is that a warm-up should be long enough to leave the body warm, mobile, and rehearsed, and should be built up gradually and matched to current fitness rather than rushed (Behm and Chaouachi, 2011).

Does stretching prevent injury?

The evidence is suggestive rather than conclusive. A 2016 systematic review by Behm and colleagues recommended stretching within a warm-up that adds post-stretch dynamic activity, noting it can help reduce muscle injuries and increase joint range of motion while leaving performance essentially unaffected. That points to stretching as part of a fuller warm-up, not stretching on its own, and the injury-reduction benefit is best described as plausible rather than guaranteed. A complete warm-up that raises temperature and rehearses the movement is the more clearly supported practice; specific injury-prevention needs for a particular sport or condition are a question for a qualified professional (Behm et al., 2016).

Do I really need to warm up before every workout?

A warm-up is widely recommended because it raises body and muscle temperature, increases blood flow, and rehearses the movements ahead, which helps the body work better and the session feel smoother. For harder or higher-intensity efforts a warm-up matters more, while for very light activity it can be shorter and gentler. It need not be long or complicated: a few minutes of easy aerobic movement, some dynamic stretching, and a little activity-specific rehearsal is enough for most people. Building it up gradually and matching it to the effort ahead is the sensible approach (Behm and Chaouachi, 2011).

How does this fit with the rest of a training plan?

A warm-up is one piece of a larger picture. It sets up each session, while the session itself, how often to train and how to add load over time, is covered elsewhere: the guide on strength training for beginners describes the compound movements a warm-up rehearses, the guide on progressive overload explains how to add stress gradually so training keeps working, and the guide on how much exercise adults need each week covers the overall weekly activity target. A sensible warm-up is the on-ramp to those sessions rather than a substitute for them (Behm and Chaouachi, 2011).

References

1. 1Behm DG, Chaouachi A. A review of the acute effects of static and dynamic stretching on performance. Eur J Appl Physiol. 2011;111(11):2633-2651 (PubMed 21373870) · European Journal of Applied Physiology (via PubMed, National Library of Medicine). Accessed 2026-06-14.
2. 2Kay AD, Blazevich AJ. Effect of acute static stretch on maximal muscle performance: a systematic review. Med Sci Sports Exerc. 2012;44(1):154-164 (PubMed 21659901) · Medicine & Science in Sports & Exercise (via PubMed, National Library of Medicine). Accessed 2026-06-14.
3. 3Behm DG, Blazevich AJ, Kay AD, McHugh M. Acute effects of muscle stretching on physical performance, range of motion, and injury incidence in healthy active individuals: a systematic review. Appl Physiol Nutr Metab. 2016;41(1):1-11 · Applied Physiology, Nutrition, and Metabolism (Canadian Science Publishing). Accessed 2026-06-14.
4. 4Chaabene H, Behm DG, Negra Y, Granacher U. Acute Effects of Static Stretching on Muscle Strength and Power: An Attempt to Clarify Previous Caveats. Front Physiol. 2019;10:1468 (PMC6895680) · Frontiers in Physiology (via PMC, National Library of Medicine). Accessed 2026-06-14.