Stretching has a clear, well-supported effect on flexibility, but that effect is already achieved with little time (10 minutes per week). For performance, dynamic stretching as a warm-up is smarter than static stretching. The claim that stretching prevents injuries is not supported by the available studies. For low back complaints, there is reasonable evidence that stretching the hip muscles is beneficial.
Stretching works excellently if you want to become more flexible, but the amount matters less than most people think. A large meta-analysis of 189 studies involving more than 6,600 adults shows that a single stretching session already produces a noticeable improvement in mobility1. Anyone who keeps that up weekly achieves a large effect with just 10 minutes of stretching per week. Doing more after that point provides no additional benefit. Someone who is already flexible has less to gain than someone who starts out stiff.
For people who play sports and want to warm up, the choice of stretching does matter. Static stretching lasting 60 seconds or longer per muscle group immediately before a competition or training session temporarily reduces strength and explosiveness by an average of around 4 to 5 percent2,3. Brief static stretching (less than 60 seconds) has hardly any negative effect, and if a few minutes of active movement follow afterwards, the disadvantage largely disappears. Dynamic stretching, in which the muscles are taken through their full range of motion with swinging movements, tends to have a small positive effect on performance and is therefore the better warm-up choice4,2,3. Fast-bouncing, ballistic stretching exercises produce less predictable results and are not recommended as preparation.
One of the most overrated claims about stretching is that it prevents injuries. Studies show no convincing evidence that static or PNF stretching (a technique in which the muscle is alternately contracted and released) reduces the overall risk of injury2,5. Anyone wanting to prevent hamstring injuries is far better off with eccentric strength training, such as the Nordic hamstring exercise: randomised studies show a reduction of 57 to 70 percent with that approach5. Stretching is therefore not a substitute for targeted strength exercises as injury prevention.
For specific complaints, stretching can be worthwhile. People with non-specific low back pain demonstrated measurably less pain, fewer limitations, and better balance after six weeks of stretching the hip muscles three times per week compared with a sham treatment, as shown by a randomised controlled trial6. For tendon problems of the shoulder, flexibility exercises appear to offer more benefit than for tendon problems of the knee or ankle, but the underlying studies are of low quality and a physiotherapist is the appropriate person to consult here7.
Finally, it is worth knowing that greater flexibility is not automatically better for sports performance. In runners, a certain degree of muscle stiffness is associated with a more efficient running technique: the muscles then store more energy with each stride8. The value of stretching therefore depends strongly on the goal: increasing flexibility (yes, it works), warming up for sport (dynamic stretching works best), preventing injuries (stretching does not work for that; strength training does), or addressing a specific complaint (depends on the complaint).
Based on one large meta-analysis (189 RCTs, n=6654) for mobility, multiple systematic reviews for sports performance and injury prevention, one RCT for low back pain, and one network meta-analysis for shoulder tendon disorders. The injury prevention claim is based on limited observational evidence.