So the basic measurement of overall volume is probably important for the calf. For athletes you would certainly want to monitor for really sudden increases in how much acceleration and deceleration they are exposed to as well. If you can somehow record that, and graduate it in a sensible fashion, that will probably go a long way to preventing running based injuries. A problem in field-based athletes can simply be that they aren’t exposed to activities like accelerating, decelerating, running at high velocities, and cutting enough; prior to being asked to do it in training and matches. Injuries can occur because of oversights in these areas, regardless of how strong or powerful someone is!
Sudden changes in footwear and sudden changes in running surface might play a role as well. We would all remember the person who hasn't run on sand and then they do a 6km speed session in the sand dunes and they come to see you, limping badly, and ask you how it has happened. Or the person who has worn shoes their entire life and suddenly completes every session in bare feet. I'd be monitoring these factors too.
Mick: So as you mentioned earlier, we’ve started only to understand how important the soleus muscle is. I’ve read that soleus can produce forces equivalent to 8x body weight versus gastrocnemius 3x body weight. Yet, I often see that people will only rehabilitate a gastrocnemius tear with straight knee heel raises. Do you think that there is a “victim verse culprit” scenario there, in that maybe the gastrocnemius tore (and continues to re-tear) because the soleus is neglected?
Brady: Irrespective of the muscle involved you still need to rehabilitate both muscles. This is essential for all calf rehab. Clearly there's a deficiency in the system that needs to be addressed. In saying that, we don't want to be only ‘local’ with our prescriptions either and focus just on the calf muscles in an isolated way. We should also train the propulsive attributes of the entire lower limb too. Coordinated well at the trunk, at the hip, at the knee.
But back to the calf: what I will say is that, if we’re going to train the soleus, we need to be really clear with what you are training the soleus for. It's all well and good doing our high load strength-endurance training, and trying to get our strength up to those really high numbers that you quoted, but ultimately, to attain these strength values the chances are you won’t be performing the reps at a very fast speed or at a very high velocity with rapid rate of force development, which at the end of the day is what we need out of the soleus and gastrocnemius during activities like high speed running. So we need to ensure our rehabilitation matches the end point of what will be asked of it when the person is cleared to return.
In summary, yes get soleus really strong and don't neglect it, it will certainly help us part of the way. Sure you can try to get those strength numbers up as close as is reasonable to mimic what we read about. But I wouldn't have those strength numbers as really rigid exit criteria either. And we need to invest time training the other attributes, such as rate of force development via plyometric training, and the special endurance profile, that will be called upon when they return to play.
Mick: It seems that plyometrics are a missing link in rehabilitation. But are there any valid/reliable or clinically useful tools you can use to decide on whether or not someone is ready to run or not following a calf strain?
Brady: I’m not aware of any single test that has been validated in the literature. But for one of my PhD studies I've done a similar thing to what you're doing now: chatting to clinicians and researchers from around the world to gather data on best practice for the assessment and management of calf strain injuries. Invariably we end up talking about mistakes and shortcomings, and things you'd do differently if you had your time again!
To assess readiness for running, the test should involve testing the tolerance of the calf to go through its stretch-shortening cycle in a repeated way that closely replicates what it will be exposed to when you do your first run. I am a fan of sub-maximal hop testing for assessing readiness to run. I'd be even happier with hop testing over a given duration. For example, 30 seconds of very light submaximal hopping, with good rhythm. I don't think it's good enough just to do a max effort hop, because you might have the ability to produce an “all-out effort”, but you don't have the repeat ability or the tolerance with fatigue.
Another message with running is: don't be afraid to run a calf a little bit later if your clinical markers tell you that they need a bit more time. So for arguments sake, if you had a low-grade hamstring strain running at very low speeds is usually ok within the first few days following injury. From the research we know at slow speeds the the work isn't going to be high for the hamstrings at these slow speeds, and its better to get some low level restorative loading early in rehabilitation. Whereas things are different for the calf, particularly soleus, and so if we are dealing with a significant injury we probably need to follow a different trajectory.
While we are on this path another big consideration is how you then progress through rehab to get to the decision to return to sport and unrestricted activity. For the more significant calf injuries I think it’s important that we spend more time setting benchmarks with our body weight calf capacity; working on our strength endurance; introducing low level plyometrics, first vertically, then horizontally. And before they get the all clear to run they should clear a test, such as the 30 second sub maximal hopping test we talked about earlier. And when I say that first intro run, it shouldn’t be a 2km jog around the park or anything involving a prolonged distances of continuous non-stop running. That is a recipe for recurrence. I'm sure we've all been guilty of giving something like that out at some stage. For that really early running you wouldn't want the duration to be too long. But these would just be some guidelines to work with for a starting point.
Mick: Yeah, nice one. Good advice mate. Lastly, can you give any advice to the reader, be it the clinician or the patient who've had recurring calf strains, to lower the chances of both primary and recurrent calf injury?
Brady: So to reduce the risk of primary injuries, it’s important to understand the demands of the sport and what's required of the calf muscle tendon unit. And then you almost work backwards from your end goal, about what you need from the calf to perform, and then you ensure that you cover all of the bases along the way. At the end of the day this is also a principle that can be applied to the entire body to ensure physical preparedness.
For the guys who have had recurrences, we’ve covered that in good detail. Don’t neglect developing the capacity and strength-power qualities of soleus and gastrocnemius. Invest time developing the specific plyometric profile. Follow a scientific approach to beginning and progressing running. But I also think there's merit, particularly for the guys with multiple recurrences, to go searching above and below the calf for the presence of any other contributing factors. They could be closer to the hip/pelvis or the knee, or they could be more distal (foot & ankle mechanics).
For the hip in particular, I'd be interested in their hip extension ROM & strength on their affected side, and their hip extension ROM & strength on their unaffected side as well. Whether that's having an impact on their stance time and the work demands on the calf, it is probably worth checking. For the foot and ankle we talked about limited dorsi-flexion earlier on, but I’d be also interested in first toe extension, if they've got a restriction there and how that's impacting their propulsion. Checking the plantar fascia. Their Achilles tendon.
So in summary, for the guys with lots of recurrences, put your detective hat on and go searching proximally & distally to the soleus and gastrocnemius and see what you find, and you'll probably be surprised when you look at the person holistically rather than just at the calf.
Before we go I’d also like to thank the AFL Physiotherapists Association (AFLPTA) for the assistance they have provided in completing projects relating to my PhD. Research of this kind would otherwise be impossible without their continued effort and support of the Soft Tissue injury Registry of the AFL. So thank you to the AFLPTA.
Mick: Perfect Brady. Thank you very much for your time and expertise today mate. As per usual, I take so much out of these Q&A chats, and today was no exception!