Originally published on 14 December 2015

 

Think back to your physical education classes at school. We were always taught to line up and do our stretching; this is something that was engrained into our routine. However, is it still relevant for the recreational runner? Do we notice any differences and what are we trying to improve?

 

There are different types of stretches:

  • Static stretching which involves you standing on the spot stretching one muscle group i.e. a calf stretch (one leg in front of the other, feeling the stretch in the calf muscle).
  • Dynamic stretching that involves an active movement, for example slow jog five steps, bend down and pretend to scoop up some grass, which also stretches the calf muscle. 

How do we know what this stretch is doing and is it just adding unnecessary time into our schedule?

Believe it or not, there is a wide range of formal recommendations when it comes to stretching, and the research still cannot confirm what type of stretching is best and how long you must do it. The idea of stretching our muscles and tendons is to ultimately reduce injury risk and improve performance. Which sounds great, no one wants to get injured. So what do we know from the research?

 

Getting started, we need to understand a little bit of what stretching is trying to do.

So we firstly need to understand a little bit about muscles, tendons and loads. There are two ways your muscles and tendons generate force. Firstly, think of your lower limb as an elastic spring or coil, which can bounce higher for different activities i.e. higher for jumping than walking. This recoiling or bouncing is the bodies Stretch-Shortening Motion, the amount of stretch-shortening (elastic) force you require depends on the activity, i.e. sprinting has a higher force compared to slow jogging. The second force we need to understand is generated by your body’s ability to convert metabolic energy (i.e. energy you have stored from food) into a mechanical force (getting your muscles to work). This type of force is noticeable when we are ticking over nicely in a jog.

The goal of stretching is to improve the tendons’ ability to absorb energy thus converting it into force. It does this by reducing the stiffness in the tendon and associated muscle.

 

So what does this mean for a recreational runner?

A recreational runner is generally running at the same speed, so they generate most of their tendon/muscle force through the rapid conversion of metabolic energy into mechanical energy. However, if they are looking to improve in speed, then the tendon will require the ability to store more energy to help the Short-Stretch cycle.

 

What does the research say about stretching for running?

  • Stretching increases joint range of motion and reduces muscle stiffness, which can allow a freer movement pattern. However, optimal stretch duration and type of stretch is still to be determined.
  • Recreational runners who only jog do not need the tendons to function as good energy absorbing structures. So an unstretched (stiff) tendon is at low risk of injury and will be able to cope with the loads of jogging.
  • Long distance runners require less joint range of motion, in comparison to other sports such as ballet and as long as there is enough range of motion they will be able to perform adequately. So a simple warm up with or without stretching can help achieve sufficient joint range of motion.
  • Runners looking to improve their speed with stiff tendons may have an increased risk of muscle injury during explosive movements, as the majority of energy produced is done by the muscle not the tendon. So a runner with a stiff tendon would benefit from doing appropriate stretches.
  • Runners looking to improve their speed with elastic tendons have greater energy storage in their tendons, which can reduce their injury risk during explosive movements.
  • Static stretching and dynamic stretching does not impact running economy. Running economy is how much fuel your body takes for you to travel a certain distance, fuel is measured in the body as calories and oxygen.

 

Take home message

There are mixed messages when it comes to stretching with regards to how much, if at all and for how long. For someone who is a recreational runner that is happy at his or her current level, stretching may not show a huge difference for you. However, if you are a runner looking to improve your performance (i.e. longer distance, faster) then you will need your tendons to be working in an elastic range, which can reduce your injury risk. We can’t get an exact measurement of tendon stiffness in the clinic, however we can do functional tests that can provide gross indications if your tendons are stiff. For example, hopping on one foot and then the other. We would look to see if there was a difference in height of the hop, speed and control. Assessing basic joint range of motion is also useful and may indicate that stretching is required.

 

References

  1. Hayes, P.R; Walker, A. (2007). Pre-exercise stretching does not impact upon running economy. Journal of Strength and Conditioning. 21 (4), pp.1227-1232
  2. Mojock, C.D; Kim, J.S; Eccles, D.W; Panton, L.B. (2011). The Effects of Static Stretching on Running Economy and Endurance Performance in Female Distance Runners During Treadmill Running. Journal of Strength and Conditioning. 25 (8), pp. 2170-2176
  3. Damasceno, M.V; Duarte, M; Pasqua, L.A; MacIntosh, B.R; Bertuzzi, R. (2014). Static stretching alters neuromuscular function and pacing strategy, but not performance during a 3-km running time trial. PLos ONE. 9 (6), ee99238
  4. Nelson, A.G; Kokkenon, J; Eldredge, C; Cornwell, A; Glickman-Weiss, E. (2001). Chronic stretching and running economy. Scandinavian Journal of Medicine and Science in Sports. 11(5), pp.260-265
  5. Witverouw, E; Maheiu, N; Danneels, L; McNair, P. (2004) Stretching and Injury Pevention, An obscure relationship. Sports Medicine. 34(7), pp. 443-449
  6. McHugh, M.P; Cosgrave, C.H. (2010) To stretch or not to stretch: the role of stretching in injury prevention and performance. Scand J Med Sci Sports. 20 pp.169-181