Stretching is one of the key ways in which runners can improve their flexibility and reduce the chance of injury. Done correctly, stretching can also help improve performance. There's lots of conflicting information on stretching, such as when to do it, how often to do it, how long to do it for, and what exactly to do. In this article we explain some basic principles and provide some general guidelines for the runner.
Benefits of Stretching
Stretching comes with several benefits.
Improved Range of Motion
When taking part in any physical activity it's important to ensure that the muscles can comfortably extend to the ranges of movement required to perform that activity.
When the limits of a muscle group's movement is reached, the muscles, tendons, and ligaments associated with the movement are put under stress. As well as increasing the risk of injury, this means they are less able to work effectively. An increased range of motion simply means that this limit is much less likely to be reached.
Stretching increases the length of the muscles. And when the muscles can contract over a greater length more force can be generated.
There is an optimum position in which each body part must be placed in order to generate an optimum amount of force.
It's therefore important to ensure that each body part can first be placed comfortably into the appropriate position, and then that the muscles can contract well whilst in this position.
A good example is how the foot should be well dorsi-flexed (toes pulled towards the shin) prior to the foot landing. It's been shown that pre-stretching the achilles tendon and calf muscles in this way reduces ground contact time and improves the return of stored elastic energy. If an athlete is unable to effectively dorsi-flex they are decreasing their ability to generate as much force with each step and will therefore not run as efficiently, and will also reduce their maximum speed.
Post-activity stretching - both immediately following exercise and in the hours and days following exercise - improves blood flow to sore and fatigued muscles. Increased blood flow means more oxygen and nutrients are delivered to the muscles and recovery is enhanced.
Beware that stretching for recovery purposes should be very gentle, otherwise you run the risk of causing further muscle damage and impeding recovery.
Types of Stretches
There are two broad classes of stretches, static and dynamic.
A static stretch is simply one in which no movement occurs once you're in the stretch position (beyond perhaps a small increase in the stretch). Once you've moved into the correct position for the stretch, you stay there until the stretch is finished.
A sub-type of static stretching is PNF (Proprioceptive Neuromuscular Facilitation) stretching. In PNF stretching muscles are alternately stretched and contracted, which can improve flexibility more than standard static stretching, as well as strengthening the muscles.
Some PNF stretches can be done against either a partner or a static object (e.g. a park bench). The basic idea is to move into a stretch and hold it for a period of time (15-30 seconds is a good guide. You then apply a force against your partner or object, contracting the muscle, for a short period (about 5-10 seconds is a good guide; then stop applying the force and stretch again for another period of time (15-30 seconds).
Assisted - or passive - stretching is a type of static stretch in which a partner or a static object is used to stretch beyond what would usually be possible.
Assisted stretching can be dangerous if not done correctly and carefully. The usual rules of easing gently into a stretch and not stretching beyond what is comfortable should be applied.
A safe and increasingly-popular way of stretching with assistance is via the use of resistance bands.
Dynamic stretches are ones that involve some sort of movement.
Dynamic stretches should be performed with a deliberate, controlled motion. Start with a range of motion that is comfortable and gradually increase that range taking care not to place too much stress on the muscles being stretched.
An obsolete method of stretching called "ballistic" stretching would have athletes use rapid movements to stretch muscles beyond their comfortable range. It's no longer considered a very useful means of achieving improved flexibility, mainly because of the risk of injury, but also because it can result in the opposite of its intended effect and actually cause muscles to tighten up.
Although strictly-speaking not a type of stretching, foam rolling regularly can help reduce tightness and improve flexibility.
When to Stretch
Most physiotherapists, coaches, and experienced athletes will tell you it's best to perform dynamic stretches before a session and static stretches after a session. When stretching is performed separately from a running session, static stretching is the more useful for longer-term gains in flexibility.
It's very important that muscles are warm before stretching. This applies to both dynamic and static stretching. Warmer muscles are looser and more pliable and as well as reducing the risk of injury, ensuring that muscles are warm will mean that they respond much better to any stretching.
Before performing any stretching, at minimum a five-minute jog or light exercises should be performed, and ideally 10-15 minutes in colder weather.
The main goal of your pre-run stretch is injury prevention. While dynamic stretching is generally preferred in a warm up, you can perform some static stretching if you feel that it's needed.
There is some evidence that suggests that pre-exercise static stretching can impede performance somewhat by slowing muscle contraction speed. This could affect those activities that require power (sprinters and middle distance runners take note), so if you do perform static stretching in your warm up routine, it's best to do it early on (but still after 5-10 minute of light exercise to get the muscles warm) before any running-specific drills or dynamic stretching.
After a run the effects of multiple impacts can result in things being a bit compressed and various muscle contractions are also engaged. At this time some gentle static stretching is ideal for returning muscles to their pre-run state. Note that this is the primary goal of post-run stretching, rather than trying to improve overall flexibility.
The goal of stand-alone sessions is to improve long-term flexibility. You can perform both dynamic and static stretches during these sessions, but static stretches tend to be more effective.
Remember to warm the muscles up first. This should be done with 5-15 minutes of light activity. Jogging is ideal.
During stand-alone sessions, stretches can be held for much longer than during pre- or post-run stretching and can be repeated several times.
When Not to Stretch
One of the biggest mistakes that runners and other athletes make is overstretching injuries. Immediately after an injury internal bleeding may be taking place and stretching at this point can make things much worse. Application of an ice pack and rest should be your primary goal. And in the case of a bad injury seek medical attention.
With an ongoing injury some gentle stretching may be beneficial, and if a physiotherapist or expert has prescribed a stretch or set of stretches then that guidance should supercede what you read here. Do be wary of overstretching an injury since this may impede recovery.
How to Stretch
Warm muscles are more pliable, and making sure you're warmed up before doing any stretching is quite important.
Post-exercise this isn't a problem since the activity will have taken care of it. Before exercise 5-10 minutes of gentle exercise should suffice.
Making sure the muscles are warm before stretching will not only reduce the chance of injury, but also ensure that you get maximum benefit from any stretching.
Muscles respond much better to being stretched slowly and gently than they do to quick, sudden movements. The latter also considerably increases your chance to pulls and strains.
Ease into a stretch until slight tension is felt and don't push beyond this point.
Avoid holding your breath while stretching and try and relax. Unnecessary tension will make stretching more difficult and less effective.
You should be careful of holding stretches for too long after a session, particularly after a hard session, since your muscles have already been overloaded and excessive stretching can cause further breakdown and impede recovery.
It does take about ten seconds for a muscle to relax before the stretch starts to have any effect, so holding a stretch for about 15-20 seconds is probably ideal. You'll get the benefit of the stretch without overdoing it.
More important for post-run stretching than length of time is to ensure that the stretch is very gentle.
If your goal is improved flexibility then holding stretches for much longer after easier runs or during separate stretching sessions is fine. Unless you are naturally flexible a fair amount of time may have to be dedicated in order to see significant improvements. Diminishing returns are seen about 45-60 seconds after holding a stretch
Stretching each muscle group 2-3 times is more effective than just stretching an area once. The point at which tension is felt will increase with each subsequent stretch.
Consider that every muscle has an opposing muscle (for example, the quadriceps oppose the hamstrings) and you should stretch both when performing a routine.
Areas to stretch
When starting out it's more useful to focus on larger muscle groups than targetting individual muscles. Once general flexibility improves, the focus can shift to more specific areas. Of course, if there are areas of particular tightness then there is no harm in attacking these immediately. Runners should pay particular attention to the following areas:
- ITB (Illiotibial Band)
- Hip Flexors
- Lower Back
See our in-depth account of The Anatomy of Stretching by Brad Walker.
Runner's World has an eight-stretch routine that is perfect for post-run.