Post-run stretching is an essential part of running that many runners tend to neglect or rather, forget. ADMIT IT! YOU’RE ONE OF THEM. I was one of them too. Keyword: WAS! These days, I spend close to 20 minutes doing a full body stretch after my run!
When to Stretch?
Back in high school, we were always taught to do static stretching before any form of sport/activity. I always wondered why that whenever I stretched before my run, my muscles would feel extra stiff, almost immovable. I noticed that I felt better on days when I forget to stretch. Eventually, I stopped stretching altogether.
Only a few years later did I come across an article on how static stretching before a run/workout was not recommended. I was thrilled when I found out because I had experienced the negative effects it had on my own without being biased if I had known this fact beforehand.
Before your Run
Never stretch cold muscles. Do a short warm up to get the blood pumping throughout the body. The warm up should involve the large muscle groups. It can be anything from a short jog to a quick ride on the bicycle. The warm up should be about 5-10 minutes before performing any form of stretching. A good gauge would be when you start to break a sweat.
Dynamic stretching (not holding each pose for more than 2 seconds) is the preferred form of stretching before any activity. It serves to activate the muscles, warming it and firing it up in preparation for the real deal.

After your Run
Static stretching (where you hold a stretch pose for at least 30 seconds) signals the muscles to relax. This was the reason I felt like my muscles were immovable, because it was TOO RELAXED!
The Facts on Stretching
The 2 proprioceptors involved in stretching are the muscle spindle and the Golgi tendon organ.
The muscle spindle is sensitive to the change in muscle length and rate of change in muscle length; the Golgi tendon organ responds to the change in tension and the rate of change in tension in the muscle.
When you stretch (increase the length of the muscle), the muscle spindle would resist the change in muscle length by causing the stretched muscle to contract as a protective mechanism to prevent the muscle from stretching beyond its breaking point.
When the muscle contracts in response to a stretch, tension is produced which are detected by the Golgi tendon organ. When this tension reaches a certain threshold, it signals the muscle to relax. Again, this acts as a protective mechanism by causing the muscle to relax before the applied force causes an injury. This is why when you lift a heavy object beyond your capability, your muscles react by relaxing thereby causing you to drop the object.
Stretching uses this principle: triggering autogenic inhibition via the Golgi tendon organ.

How Long Should You Hold a Stretch?
At least 30-60 seconds. This allows time for the signalling from the Golgi tendon organ (causes the muscle to relax) to override the signals from the muscle spindle (causes the muscle to contract).
Why Stretch After a Run?
You may not realise it but your body works REALLY HARD when you run. You have no idea how many physiological changes are at play just by taking a few steps. With every stride, your legs flex and extend to propel you forward. This places a great deal of stress on your musculoskeletal system. Over time, tension and tightness in the muscles can build up, increasing the risk of injury and compromising your performance.

Runners are usually tight in certain muscles, mainly those of the lower body. Post-run stretching is a good way to regain muscle flexibility and range of motion (to be able to continue your active daily lifestyle and of course, more efficient running!)
Also, it prevents the pooling of blood in your lower limbs by improving venous return to the heart. This ultimately speeds up recovery by flushing out metabolic waste accumulated in your muscles during your run.
Plus, it feels REALLY GOOD. Need I say more? Get stretching!
Proper technique and form is KEY. Merely lifting your limbs to undesired levels of comfort, angles and height, pulling it here and there does not necessarily mean you’re stretching the intended muscle. Stretching takes focus and you have to KNOW what moves stretches WHICH muscle.
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