The Muscle You're Missing on Leg Day
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OK. So, I copped out with a gimmicky title, but hear me out. Allow me to introduce you to your peroneals, a group of three muscles spanning the lateral compartment of the lower leg. The peroneus longus, specifically, is an extremely important muscle that is predominantly involved in sprinting, cutting, and jumping/ballistic actions. The primary muscle actions of the peroneus are plantarflexion and eversion of the foot (2). Note: Video below via Muscle Premium App
But before I go any further, the caveat here is this- you are training this region with your athletes. Albeit indirectly, anytime we’re sprinting, working COD, jumping, or squat/split squatting, we’re stressing the lower leg muscles. We can even take it a step further in saying anytime you do something on one leg or that involves plantarflexion you’re kicking on the peroneal group. That said, the likelihood that most coaches are spending enough time training this area with emphasis, is probably a reach.
There are two critical roles that the peroneal group provides that are often less considered in training. The first is its role as a stabilizer of the fibula. The peroneus brevis and longus originate on the posterior aspect of the fibular head, which is a bone that has minimal support to begin with (2). When the peroneal tendon is disrupted, such as avulsed or torn, the stability of the lower leg becomes significantly compromised. Adding to that, the ability to dorsiflex and stabilize the foot will be substantially impacted as well. The primary mechanism of injury with the peroneus involves a dorsiflexion force on the ankle accompanied by a rapid and strong contraction of the tendons with eversion of the hindfoot (2).
Images showing common mechanism of injury for the peroneal group. Image 1 (frontal view) and image 2 (sagittal view) are demonstrating the combination of dorsiflexion force combined with eversion of the foot.
Another overlooked role here is that of the peroneal nerve, which is primarily responsible for supplying plantarflexion and dorsiflexion of the foot (2). Although less common, this nerve can be entrapped when excessive joint laxity is present (i.e. weak/loose myotendinous junction). The peroneal nerve can also be damaged in severe ACL injuries (even less common). The recent and great example of this being Jaylen Smith, middle linebacker for the Dallas Cowboys. He’s an even greater reference now given the remarkable comeback he’s exhibited following that harrowing injury.
Training the Lower Leg
When we’re looking at emphasizing the peroneals, we want to consider the multiple planes of motion this group is responsible for. The low hanging fruit here are the sagittal-based actions (i.e. dorsi/plantarflexion). Of course, there are no direct right or wrong ways to go about achieving this. No differently than anything else, I would just encourage you to observe the angles, speeds, and actions demanded in their sport, and compare them to the specific weaknesses/deficiencies they show you in the assessment.
Nevertheless, considering the rigid, fixed nature to military footwear/boots and variable/dynamic terrain they're exposed to, my population often lacks fundamental strength and movement of the ankle. As such, when introducing sagittal-based movements, I will often start with the following progression:
Next, we will add in eccentric loading or emphasis:
Then, more dynamic action:
I would recommend doing the majority of these without shoes, exceptions being obvious such as movements with high impact or dynamic action. The reason being, when we’re emphasizing the peroneal group, we need to consider the distal attachment underneath the big toe. When we have shoes, we impede this muscle action, resulting in an incomplete contraction overall as the movement of the big toe is inhibited.
Once we’ve established good sagittal plane strength and function, I’ll then look to add in more unilateral and frontal plane-oriented movements to emphasize the rotational and lateral functions of this muscle group. As mentioned just above about no shoes, I would recommend the same for the exercises moving in the frontal and transverse planes as well. Again, always use good judgement, and plyo/higher speed movements should only be done barefoot with athletes who have trained progressively to get there. No exceptions.
In addition to everting the foot, the longus also plays significant roles in foot function, including maintaining the structure/function of the transverse arch (3).
Intuitively, we should recognize that in order to effectively stress this region we need to emphasize frontal plane actions. The focus now becomes challenging the mediolateral aspects of the lower leg. A good thing to know here is that literally anything done on one leg will challenge this area, due to the demand for managing supination and pronation of the foot.
My early introduction:
What we can do to progress:
Then, we combine common cardinal planes (challenges the system concurrently):
Once the above criteria have been addressed and demonstrated proficiently with the athlete, we can then start to implement some more advanced variations. Generally speaking, the progressions are going to include changing the stance or position of the foot, increasing velocity, multiplanar loading (rotational patterns), and change of direction. Some of the more common items here include:
A couple of plyometrics I particularly like for stressing the peroneal group:
*A quick note on plyos- remember that the only true purpose of jumping on to the box is to minimize eccentric loading. Yes, there is certainly a coordination and motor sequencing component involved in jumping on the box, but let's be honest that's very rudimentary. Point being, jumping off the box, designed to provide and eccentric overload effect, is actually the more demanding/progressive variation.
As mentioned, the longus is the primary mover for eversion of the foot, by adding a frontal plane component to something like a SL RDL or adding a MB squeeze to a hex bar deadlift we can alter the kinematics and thus firing pattern and activation of the lower leg. When we have external rotation at the femur, we get internal rotation at the lower leg (2). This is known as the screw-home mechanism, a great reminder of how all movement is rotational. We can also play with the velocity of movements to challenge the lower leg. The landmine is a common tool for me to achieve this. For instance, a LM SL Sweep which obviously is developed from the RDL, or a dynamic pressing option.
Another fairly advanced application is using what’s known as a floating heel technique (shown in video above). The theory here is that by suspending the heel, were driving more demand on the muscles surrounding the big toe (i.e. peroneus longus) and the plantarflexors by resisting collapsing out of the neutral foot position (3). This is similar to doing dynamic movements barefoot, in that it should be appropriately progressed up to, and not used with athletes who have low training history.
Where Does it Fit?
I know the common question or response to things like this are “yea, that’s great, but where the hell am I supposed to fit this in?” Well, the first response I always have to this is let’s look at your warm-up/movement prep. The warm-up and movement prep period is a critical component to creating a successful training environment and outcome. It’s easy to overlook and undermine the warm-up, but when used efficiently it can be a critical factor in progressing your athletes.
The added benefit to this part of training is that it is often the most flexible, meaning we can make subtle adjustments here and there, or make global sweeping changes over time. I would encourage the lower leg be a primary candidate to include during this time period. Especially for football, volleyball, and basketball athletes.
The next two places to look are your intraset work and accessory work. Recall that sometimes even just adjusting the position we work from or the stance/position of the foot can be a contributing factor. So for instance modifying from a bilateral bent row to a SL bent row w/ toe in pattern. This doesn’t need to be forever, or for every exercise. Just a few tweaks is all it takes.
Lastly, I would encourage you to considering adding this to your “recovery” or reset days. Getting the athletes out of the shoes for training once in a while is another indirect way to achieve some extra love for the lower leg. Giving appropriate attention to training on multiple planes of the foot (i.e. emphasizing pressure on outside and inside borders of the foot), adding a floating heel, or ball of the foot pattern for dynamic movements are great items to use as well.
These can all be very beneficial towards making athletes more resilient to lower leg injuries, including chronic ankle sprains and high ankle sprains. Of course we can’t prevent injury from occurring, but we certainly can do our part to build our athletes durability and reduce the chances of sustaining soft tissue injuries. I would also argue that emphasizing the lower leg a bit more in training will carry over very well to sprinting and jumping mechanics as the athlete will likely be more proficient with force transfer. In either case, Incorporating these drills into your training will go a long way for your athletes.
1.) Muscle Premium (Argosy Publishing Inc.) Version 7.1.56
3.) Zeidan, H. Suzuki, Y. Kajiwara, Y. Nakai, K. Shimoura, S. Yoshimi, S. Tatsumi, M. Nishida, Y. Bito, T. Aoyama, T., 2019. Comparison of the changes in teh structure of the tranverse arch of the normal and hallux valgus feet under different loading positions. Appl Sys Innov, 2(3)