Having stronger calf muscles is a great way to help reduce the chances of injury. The lower leg and feet take something of a pasting when you run. The peak load that occur when you are running start at around 3 times your body weight. In the lower leg the peak loads on soleus are 7 times body weight at normal running speeds. Wse types of loads it is easy to see the benefits of stronger calf muscles. The 2.5 figure is at slower running speeds and not sprinting. When sprinting the overall peak load is 7 or 8 times your body weight. From this it is easy to see how any interval session is going to be even more stressful.
Tight, aching calves are a common complaint amongst runners and for all they stretch them regularly they don’t get any better. So why is this?
Lower leg anatomy
If we look at the anatomy of the lower leg. The gastrocnemius crosses the knee and attaches above the condyles of the femur. The soleus starts from the upper posterior tibia and head of the fibula and attaches to the heel. Both are involved in plantar flexing the foot with the gastroc also helping flexing the knee. When we run, or walk, the gastroc doesn’t spend a lot of time being stretched. The knee is bent for large periods of the movement meaning there is always a bit of slack. Soleus, on the other hand, is regularly being stretched.
Assessing range of movement
The best way to see if you actually have tight calves, in that the range of movement is reduced in plantar flexion, is to do the knee to wall test. This simple test will show you if there is an issue here and should, ideally, be around 10 cm. That is the distance that your toes are from the wall when the knee touches it is about 10 cm.
Mark 10 cm away from the wall. In a half kneeling position have your big toe touching the mark. from here now push the knee push the knee towards the wall. You need to make sure that it travels through the middle of the foot. If you can’t reach the wall without your heel coming off the floor don’t worry this is just to give you a base line to work from, the range of what is normal is quite large though if things do feel tight then some remedial action is advisable.
If it is around this 10 cm mark then things are ok. At this point there is no need for more ROM but the soleus may still feel tight.
Why is it tight?
I noted at the start that the soleus has to absorb peak forces in excess of 7 times your body weight. If soleus isn’t strong enough for the task then it will be constantly fatigued. It is this fatigue that causes the protective tone You feel as stiffness. The reason for it is to prevent any excessive movement and reduce the demands being placed on it. So rather than needing to stretch it you need to strengthen it. It is reducing the fatigue and the protective tone that results from it that needs to be addressed. This is for the very same reason that achilles tendon rehab focuses on strengthening of the soleus. The stronger it gets the better able it is to handle the tensile load that is placed on it as you run.
What is tensile strength? It is the ability of the muscle to lengthen under load. When the foot hits the ground you are trying to maintain the same knee angle as you move through the gait cycle. This requires the tibia to move over the foot. The gastroc is helping control the knee angle so the soleus is controlling the movement of the tibia. To do this soleus working eccentricly as it lengthens. It is the loss of this ability that is what you re feeling when you experience the tightness in your calf muscles.
So what can you do?
We really need to be working soleus with the knee bent to around 80º to 90º. It takes quite a bit of weight, 50% of body weight for 10 reps if you are doing it on one leg. If you are doing both 150% and upwards for sets of 10. This can be quite hard to do at home due to a lack of available equipment. You are likely to need to go to a gym in order to really be able to work it hard enough. It is worth paying attention to lowering phase of the movement. The lowering phase is replicating the type of loading that occurs when running. Slowing this part down a little and making sure you work through as full a range as you can.
One other upside of getting the soleus stronger is that there will be a protective element against achilles tendenopathy. Achilles tendenopathy is an over use issue which has it’s beginnings in similar situations to tight calves.