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Science of Stretching

Updated: Sep 10, 2020

How to massively improve your results the next time you stretch

This post provides some strategies that will maximize the effectiveness of the stretching you do. It is aimed at the layman stretch enthusiast who does “standard” or static stretching, where you elongate the muscle or muscle groups and hold for a few seconds. There are advanced techniques you can perform on your own that will take your flexibility routine even further, which we will cover in future articles, but these tips are designed to be implemented immediately, without having to learn anything. We offer tips on how to choose the specific stretches, but don’t recommend any specific stretch, as there are many great resources.

Fundamental Guidelines of Stretching

Rule 1: Stretch completely warm

Both your internal temperature and the temperature of your muscles should be warm. Take extra care if you feel stiff or the weather is cold. If it’s freezing outside and you just worked out, you may have a hot core but chilly external tissues--you’ll most likely be stretching some more superficial muscles, and they need to be warm, too.

The Science: Warm muscles are more relaxed, better able to lengthen, and less likely to be injured. The next time you start your routine feeling a little cold, compare how deeply you can do a stretch before and after your warmup you will notice a difference.

See tips for warming up in the recommended routine below.

Rule 2: Stay in your comfort zone when you deepen the stretch

Good news: this is one area of life where there is no gain WITH pain. When elongating muscles, be gentle and ease into it. If you overstretch you are actively damaging muscle tissue and reducing flexibility, even if you don’t push to the point of a noticeable strain, pull, or tear.

Don’t assume that if you got a certain stretch depth last time, that you can jump there immediately. Elongation takes time—thus the “ease into it” guideline.

The Science: Your body has protective neurological mechanisms to keep your muscles from being pulled or torn, and they react to excess tension. If it senses a muscle is being overstretched, that muscle will be told to contract in an effort to bring it back to normal length. This is an involuntary reflex just like the knee-tap test.

Rule 3: Breathe into the stretch, and don’t forget to breathe the rest of the time

It’s a surprisingly common tendency for people to hold their breath while stretching and even during workouts. Don’t do it! Monitor your breath during physical activity (and during the rest of the day as well, you don’t stop needing to breathe).

The Science: Breathing facilitates blood flow, helping move metabolic byproducts out of your muscles (and the rest of your body) and replenish oxygen. IF you feel lightheaded during physical activity or when standing up, watch your breath (and your water intake)

Rule 4: Stretching certain muscles will bring you significantly more benefits than others. Some shouldn’t be stretched at all

This final rule is the most difficult rule to follow because it requires body awareness most people don’t have, and a little bit of research. It’s especially contingent on your body’s kinetic patterns.

Ideal posture means that muscles on either side of each joint are balanced.

Imperfect posture starts when one side becomes short and tight, pulling the body part a little to its side. Conversely the opposite muscle is forced to lengthen proportionately:

Over time, both become stiff and inflexible. Even the chronically lengthened muscles can fail to completely lengthen to the normal range—think of them as frozen where they are.

Virtually everyone has this kind of postural distortion to some degree, in some part of the body. Many people have it all over the body. These distortions give rise to a whole host of problems, including pain, musculoskeletal damage, and weakness.

How does this affect your stretch routine? You don’t want to lengthen the muscle that is already too long. It’s a waste of time, it doesn’t feel great, and most critically, it’s exacerbating your dysfunctional patterns. If you just worked out that muscle, you can stretch it; otherwise focus on other muscles.

You will benefit most from targeting your inflexible areas, rather than adopting a cookie-cutter list of stretches. Unfortunately, identifying your specific short vs long muscles is a complex matter. For now, you can go a long way by focusing on these questions:

  • What muscles feel most improved by stretching? A good stretch is like a deep breath for that muscle. Afterward, your body more naturally falls into better posture.

  • Which specific movements and positions feel restricted? If you hold your head forward all the time, and the front of your neck feels tight when you put your head where it should be, it’s a sign the front of your neck needs lengthening.

  • If you notice a difference in flexibility between sides, focus on the shorter side to bring the two into balance

Look in the places most commonly short:

  • the calf (back of lower leg)

  • the front, back, and inner thigh (quads, hamstrings, and adductors)

  • hip flexors

  • the low back

  • chest and front of shoulder

Areas less likely to need lengthening include the front of the lower leg, abs, upper and mid back, and back of the shoulder. The neck is a special case. It’s typically restricted during side-to-side and rotational stretches, but doesn’t benefit from pulling your head directly forward towards your chest.

Remember to focus your regular stretching on the muscles that are short, and stretch long muscles only after they’ve been worked out.

The Routine: Warming up

As per the rule to always stretch warm.

1-2 minutes of joint mobilization

The Science: Gentle movement of the joints literally lubricates them: the body makes its own joint lubricant and movement helps spread it around. Called synovial fluid, i’s just as important for your body as it is for your car, if you want to move smoothly and reduce the wear-and-tear that excess friction force. Not only does synovial fluid lubricate and cushion most joints in your body, it contains compounds that promote cartilage regeneration and decrease inflammation.

Interesting fact: synovial fluid is a non-Newtonian liquid.

Instructions: Each joint only needs to be moved for 5-10 seconds. Move in a controlled manner, in a slow-to-medium speed.

  1. Wiggle and spread your toes

  2. Rotate each ankle

  3. Bend each knee

  4. Rotate the hips in a circle and gently move them side-to-side. Rotate them in a figure 8 for extra points

  5. Rotate your torso, and bend side-to-side. Make sure to focus on both the lower and mid back regions. (as with any advice on the internet, consult your medical professional, but back activities are especially important to get cleared for.)

  6. Rotate each shoulder, then lift your arms and do windmills

  7. Rotate your head and neck, bend side-to-side and forward-and-backward

  8. Bend each elbow

  9. Rotate each wrist

  10. Wiggle and spread your fingers

If you're only stretching one area and pressed for time, it’s not as important to do this for joints in other areas. Whole body is ideal, however, because some stretches engage parts of the body that are not being stretched--you want them to be limber too.

5-8 minute of cardio


Start the exertion level at mild and move up to moderate. (If you track your heart rate, this is a movement from 40% to 60% of maximum heart rate). Whether you use cardio equipment (treadmill, StairMaster, elliptical) or not (bouncing, jumping jacks, jump rope, and running in place), choose an exercise that moves a good portion of the body.

The Science: In addition to raising your temperature, cardio has the benefits mentioned above for breathing: increased blood flow (and therefore tissue oxygenation and metabolic byproduct removal).

[Your Stretches Here]

You’re now ready to elongate some muscle fibers. Be sure to follow the Rules of Stretching.

Planned upcoming posts for this series:

- The stretching routine template

- Identifying your specific areas to stretch

- Stretching and flexibility techniques from basic to advanced


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