Unequivocally, frontal plane deficiency is one of the most common deficiencies I see with my athletes. For those who are familiar with the broad parameters of military-style training this should come as anything but a surprise, as their training is almost exclusively sagittal plane dominant and wildly redundant. Moreover, the volume and intensities that these individuals are exposed to in training is tremendously high. This combination of unscrupulous training volume/intensities and restrictive movement variability can have deleterious effects on the body. A general adverse outcome I’ve noticed with this population, as a result from their training demands, is a vast margin between where they are strong and where they are weak. For instance, being very strong in hip flexion, but very weak in hip abduction. From what I’ve observed over the years, the wider the margin of difference between strengths and weaknesses- albeit a localized joint or global planes of movement- the greater potential for injury vulnerability. And if this margin is not addressed adequately, injury will be an inevitable outcome.
Along with the conventional anatomy in focus here we also have the fascial slings to consider. I’ve written extensively about the fascial system over the years, to include a couple of webinars, but as it applies here we are specifically interested in the lateral fascial line (or sling). One of the primary reasons I’ve been so influenced by the fascial system is its integrated function. Without getting deep into the technical side on this, I think logic should easily be applied here… our bodies are very literally interconnected from head to toe. And with this knowledge, we should appreciate the significance of symbiotic and integrated function. When something can't or isn't doing it's job, something else will create a solution; sometimes compensatory strategies are helpful, other times they're detrimental. But in either case, we have to recognize that human function demands global contribution and that there is no such thing as isolation. This also applies to systems, as no biological system functions in singularity at any time. The more I see and learn, I continue to find that abandoning the conventional muscle/cadaver anatomy has only helped my ability to provide effective training solutions with my athletes.
Defining the Lateral Line
The lateral line includes the fascia enveloping the lat, obliques, QL, and glute medius/minimus and the peroneal group of the lower leg. These muscles represent what we know as frontal plane movers, which are prime movers for actions such as ab/adduction, external/ internal rotation, and contribute to rotational and bending movements. This muscle group is also largely responsible for providing unilateral stability (i.e., stance leg during gait/sprint, plant leg on a throw). When an athletes training consists of almost exclusively sagittal-based actions, the lateral group is only required to play a support role at best. An underdeveloped lateral line can have a cascade adverse effect on the athlete. Chief among them includes incomplete kinetic transfer/sequencing, poor pelvic control, inefficient gait/sprint cycle, compromised lumbar stability, and compromised core strength.
The lateral line is going to be a main contributor or factor in a number of common sport actions- sprinting, cutting/change of direction (deceleration specifically), throwing/pitching, single-leg jumping to name a few. When we concentrate our training on conventional compound movements like bench press, back squats, and bilateral RDL’s we aren’t addressing the lateral line or frontal plane muscle group much at all. And, in my strong opinion, we aren’t adequately preparing the athlete for the natural demands of sport. It’s beyond the scope of this article to dig into the never ending “bilateral vs. unilateral” debate but put simply- sport isn’t played with feet side-by-side.
To emphasize the lateral line, we broadly want to think predominantly two things- single leg variations and rotational/anti-rotational movements. In the single-leg variations we are specifically challenging the distal portion of the lateral line (i.e., the peroneal group, distal hamstring and the glute group). The way I coach any single leg movement starts by cueing the foot and (indirectly) the lower leg. I’ll start by instructing the athlete to evenly distribute pressure across the foot by driving through big toe, pinky toe and heel evenly. Then, I want them to “lift their arches” off the ground. What this does is prompt them to supinate and invert the foot, which creates an internal rotation effect at the lower leg and external rotation at the femur (screw home mechanism). Collectively, this promotes optimal ground contact and lateral pelvic stability; we want to continue cueing this until it becomes natural behavior for the athlete.
Speaking to the rotational piece, the primary muscles of interest include the lats, obliques and QL. While the obliques are well known as the powerhouse muscle of rotation, the lats are often overlooked for their contribution. Recall that the lats, which are a huge muscle, span from the inner groove of the humerus all the way to the posterior aspect of the hip. Moreover, the lats have attachment to the spine at the thoracolumbar junction (T7-L3). Acting as a mover of the shoulder and stabilizer of the spine and hip, it should be clear to see the role the lats play in rotational movements.
While the obliques can act as prime movers for rotation and lateral bending, it’s often overlooked the role they play in trunk stability. I look at the oblique group as being the reinforcement for the anterior and posterior core (i.e., transverse abdominis, rectus abdominis, erectors). Having strong oblique muscles that can provide rapid stiffness and strong contractions provides a more stable foundation for the anterior/ posterior core muscles to fire. When we lack strength in the obliques, the other core muscles won’t be in a position to fire as forcefully as they should. Collectively between the two, an additional consequence to this is poor pelvic stability and control. A common issue I work with is unilateral oblique weakness creating a unilateral hip hike or shift. Sometimes this is consequential of a significant back injury, other times it’s just a result of having unilateral work demands and never training to accommodate it.
Some of the best ways you can stress the lateral line is through movements like marching & crawling patterns. The locomotive aspect naturally makes them good candidates for challenging the lateral sling. In addition, other foundational patterns like chop variations, bridge and plank variations, and virtually anything single leg each offer good lateral sling options as well. These aren’t only good entry-level options for training the lateral line, but also serve as great options to continue cycling throughout your warm-ups and movement prep. These can each be modified a thousand different ways, but honestly not too much nuance is needed to be effective.
Once the foundations have been established, you can progress the athlete into some more challenging variations. Adding new vectors and ranges of motion is a novel first progression using mostly the basic patterns mentioned above. From there, adding speed, combination movements, and change of direction drills can be included with an emphasis on lateral and non-linear movement. In addition to that, below is a chart of some of my more frequently programmed lateral sling variations:
As it applies to the individual athlete, it’s important to recognize that there isn’t one unified way to go about training the lateral sling. Again, no differently than if we were having the same discussion but saying muscles instead of fascia, specificity applies. The fascial system is particularly keen on movement (or vector) specificity, given the multitude of angles the fascial fibers are oriented and the way collagen fibers are laid down. We need to be cognizant of setting up and stressing our athletes in positions and vectors that complement their sport. We also must train this system under the same type of speed conditions they will see in sport. Needless to say, the way I would address lateral sling training for a football player is different than a baseball player. For throwing and club athletes, the primary role of the lateral sling is to generate, transmit, and decelerate force in rotational planes. Whereas for football players I’m more focused in rapid deceleration, pivoting and non-linear acceleration.
For my population, I’m usually challenging the lateral sling in an effort to address non-functional imbalance, which in a lot of cases is also contributing to low back pain. I almost inherently find weakness in the QL with my athletes, and the QL is a very significant (also overlooked) posterior core muscle. The QL (quadratus lumborum) sits deep beneath the erectors and has some unique attachments- four independent attachments to the lumbar spine, the superior posterior aspect of the hip, and the posterior aspect of the rib cage. It’s primarily responsible for assisting in terminal hip extension, stabilizing the lumbar spine, and depressing the rib cage ipsilaterally. The QL is a sneaky important muscle, and for whatever reason since I’ve started addressing this directly, my athletes back pain absolves quicker.
Bringing it All Together
The lateral sling is foundational not only to sport but to human movement in general. As it applies to strength training, we don’t need to blindly start throwing “fascia sling” exercises at athletes. However, we do need to recognize that this is a significant system, and there should be some consideration as to how you can modify movements to make them more laterally emphasized. Observe how this sling system is prevalent in the sports your athletes play and apply to the exercise selection and movements provided in training. Some final points to consider:
-It’s important to strengthen the involved muscle groups both independently and collectively to optimize the function of the sling subsystem.
-Single-leg movement and rotational movements are naturally great for the lateral sling
-Perform your dynamic movements and plyometric drills laterally (frontal plane)
-Anti-rotation should also be trained and considered in multiple vectors
-There is almost inherently unilateral dominance with the slings; discern whether or not the margin of difference promotes any adverse effect.