Injured your calf? Calf tightness? Think a few simple bodyweight calf raises will get you sorted? Think again!
Firstly let's look at the contribution of the calves when running, & in short, they do a LOT of work. The larger of the calf muscles, the soleus, is highly important for running taking 6.5-8 times bodyweight of force, whilst the other calf muscle, the gastrocs, takes 2-3 times body weight (Dorn 2012). The Achilles tendon also needs to absorb a high amount of force when running, equalling 4.15-8.0 body weights of force (Gheidi 2018, Sinclair 2015, Willy 2016).
So how do we replicate this high amount of force going through the calf & Achilles without running (up to 8 x bodyweight)? Does this mean we need to put 7 times our body weight on our back & do a calf raise? Fortunately not. Now it’s outside the scope of this blog to discuss further, but due to the moment arms of the foot & Achilles, an unweighted single-leg heel raise equates to 3.98 body weights of force through the calf & Achilles. (Gheidi 2018)
Therefore to achieve 6.5-8 times body weight through the calf & Achilles, you need to perform a single leg calf raise with an ADDITIONAL 60% - 100% bodyweight.
Now a weighted calf raise might be able to equal the force required to that of running, but what about the loading rate? Unfortunately, it doesn’t get near that. A single-leg calf raise only reaches 25% of the loading rate of running (see the graph below).
So what does this mean? Well, it means if we want to strengthen the calf & Achilles to try & match the demands of running, you can NOT just simply do weighted calf raises. You need to supplement your rehab with plyometric exercises (ie. jumping, hopping, skipping, pulsing, etc) &/or dynamic sled pushes.
Lastly, no exercise in isolation loads the calf & Achilles like running does, so ultimately you need to safely & gradually get back to running!
If you are suffering from recurrent calf strains, don't hesitate to contact us for assistance!
References
Dorn, T. W., et al. (2012). "Muscular strategy shift in human running: dependence of running speed on hip and ankle muscle performance." J Exp Biol 215(Pt 11): 1944-1956.
Gheidi, N., et al. (2018). "Achilles tendon loading during weight-bearing exercises." Phys Ther Sport 32: 260-268.
Sinclair, J., et al. (2015). "Influence of running shoes and cross-trainers on Achilles tendon forces during running compared with military boots." J R Army Med Corps 161(2): 140-143.
Willy, R. W., et al. (2016). "Patellofemoral Joint and Achilles Tendon Loads During Overground and Treadmill Running." Journal of Orthopaedic & Sports Physical Therapy 0(0): 1-31.