Stroke Training and Awareness Resources (STARs)


What happens when we stretch a shortened muscle?

  • When a muscle becomes shorter it becomes stiffer, less easy to move.
  • Re-lengthening occurs by creep.
  • Creep allows soft tissues to tolerate applied loads by lengthening, but only occurs at end of range/when stretched out of position.
  • As a muscle lengthens it regains sarcomeres plus tension and therefore the ability to contract.

As overall volume of sarcomeres increases, there is a relative reduction in the amount of connective tissue present which makes the muscle less stiff and more elastic – so less resistant to passive stretch.

There are three types of skeletal muscle fibres.

  • Slow oxidative – these contract relatively slowly and use aerobic respiration (oxygen and glucose).
  • Fast oxidative – have faster contractions but because they may switch to anerobic respiration (gycolysis) they can fatigue more quickly than slow oxidative fibres.
  • Fast glyolytic fibres – faster contraction using primarily anerobic glycolysis. These fibres fatigue more quickly than the other fibres.

Changes in muscle fibre properties i.e atrophy, result in an increase in number of fast oxidative fibres and decrease in slow oxidative fibres – this can also be reversed.

Ability to generate tension is best at optimum length – so muscle is able to contract and function as needed.

Video transcript

Muscle position and stretch

M. So if we are thinking about your leg Allan and maintaining range of motion. Because muscles tend to tighten up in particular patterns, we want to try and oppose those patterns. One of the common things we see is that the leg falling in to this position and the foot point down the way. And so the hip gets out in to this position and we begin to lose range of motion moving in the opposite way. So what we will do is we’ll just raise the knee here OK. And we’ll start just by moving the hip across and we can feel there’s just in the hip here. The abductors and lateral rotators of the hip are a bit tight. So we can stretch those just by bringing the hip across into adduction and also putting a wee bit of medial rotation.

A. Right.

M. So you should feel that quite tight.

A. Yeah.

M. So that’s a nice position.

A. I feel it tight here.

M. So there is a band here called the ileo tibial band which connects your pelvis, effectively to your knee. And that can get quite tight as well. It is a good one to stretch. The other thing that’s particularly important I think is that clearly we can lose range of motion at the knee. The knee can become flexed if we have got increased activity in the hamstring groups. So we need to make sure we maintain that knee extension. But we have to be careful that we are don’t hyperextend the knee and over stretch the structures at the back because that can give you a bit of an unstable knee as well.
If we think about the ankle. The foot and ankle. We want to maintain movement to beyond ninety degrees in the ankle at dorsi flexion. So that means that’s the position where your foot comes up. OK. Now with the knee bent like this we can relatively easily make this movement which we call dorsi flexion, which is lifting the foot up at the ankle. Because we are stretching a single muscle group here – the soleus group. I am also making sure your toes are extending so your toe flexors which are also deep muscles here are getting a stretch as well. But we also need to make sure. It is very important for when you are walking that we maintain that position at the ankle while we extend the knee. Because that then stretches a second muscle group called the gastrocnemius and the reason that we have to do stretches in this position is because it actually connects above the knee. So you need to stretch both the ankle and the knee at the same time. And if we are really going to get a good stretch through the lower limb we also need to bring you up in to a little bit of flexion. So we need a little bit of a straight leg raise just tell me when it is enough. OK

A. Yeah that’s enough.

M. That’s enough. OK. Because this is a combined stretch of your hamstrings but also the nerve roots from your lumbar spine. The sciatic nerves are coming down the back so this is maintaining the ankle dorsi flexion the knee extension and the hip flexion gives you a really good stretch thought the whole leg.

Page last reviewed: 04 May 2020