Last week I talked about the relationship of achilles flexibility and achilles strength. Basically, if you are too tight or muscle bound, the charge within the muscle between the actin and myosin filaments is too sluggish and you lose strength. If the muscle is too loose, there is less of the actin and myosin filaments in contact with each other, and we lose strength. So being too tight or too loose can be major reasons that you are weak, but there are also solutions. Everyone with a loose ligament issue, which dramatically also affects their tendons, knows that they can not stretch normally, and that strength is their answer. I do agree that achilles flexibility has a range in terms of degrees that is normal for any individual, and that degree may not be exactly our normal valves, but pushing my patients towards normal valves is a big help.
After measuring achilles flexibility ranges for gastrocnemius and soleus, we should turn to the classic benchmarks for pure strength. These tests that patients do in front of me are straight knee (gastrocnemius) and bent knee (soleus) heel raises. Heel raises are also called Calf Raises, and I know that can get confusing. Ideal gastrocnemius tone is 25 Single Straight Knee Heel Raises. Ideal Soleus tone is 12-13 Single bent knee heel raises. The presence of pain while doing may proclude the patient from being tested at that time. You may start with double or 2 sided heel raises which only puts 50% of the load on either achilles complex. This is different then strengthening, as you are just tying to see what their benchmark is now, to compare some other time in the rehabilitative process. I am happy when my patients can do 25 and 13 on both sides as I know they have adequate strength. Since this is not a balance test, please have them hold on to something. You want this to be a gauge of pure strength.
Single Leg Straight Knee (Gastrocnemius) Heel Raise
Single Leg Bent Knee (Soleus) Heel Raise
A comment is needed on Soleus strength testing or strengthening in general. Some of your patients will not know how to do it well which will influence your early results. As the heel lifts off the ground, the pelvis has to stay down like you are sitting almost. You should not see the same up and down of the pelvis as when you are contracting your gastrocnemius. You may have to send them off to practice, and make the observation on a subsequent visit.
