“What arm do I hold the weight with?”
“What leg goes forward?”
“Why the hell am I doing this?”
These are common things I hear all the time in my training sessions, especially with movements that require split stance or single leg stance and holding a weight with on arm.
It can seem confusing to put it all together, especially with novel movements where the exact goal may not seem apparent, and where the positioning can take advantage of fascial sling systems and neural drive not readily visible in most anatomy charts.
Ipsilateral means using the same side arm and leg. For instance, this would me like a boxer throwing a punch with their right hand and driving off their right foot. The benefit to a movement like this is the generation of joint compressive tension throughout the entire system where the impulse from the foot travels fairly efficiently through the entire body and extends through a solid lever system.
The development of power along this line typically hinges on the ability of the glutes to pull the hip into extension and external rotation. This external rotation of the hip, when the foot is planted, causes the upper body to rotate through and generate some snap.
Watch how Mike Tyson, one of the most feared hitters of all time generates stupid amounts of hip extension and rotation with his body uppercut combo:
The slow-motion capture around 2:15 shows it really well.
The lateral fascial line, shown by Thomas Myers in Anatomy Trains, encapsulates a lot of the anatomical linkages between the driving foot and the arm throwing the blows.
When under contraction, the system can produce a great level of rigidity through the entire line, which can make it sort of like a wound up spring. This elasticity and rigidity is not only used to produce power up through the hands, but produce power down through the foot, like in walking or running. The drive back and down from the leg is met with a drive up and forward from the same side arm. The extension and external rotation of the hip is met with an antagonistic movement from the opposing core, involving flexion, rotation and lateral flexion, which produces the upper-lower rotation seen in locomotion.
This is an incredibly intricate system that this describes in an incredibly simplified manner, and truly doesn’t do it justice, but for the sake of keeping this post under 5000 words, we’ll leave it at that.
A breakdown in the control of this system is commonly seen when people don’t have the reactive strength through the hips and core to be able to produce the efficient transfer of power through the leg to the reaching arm, and wind up showing something like a trendelenburg gait pattern where their hips flop around like a lava lamp set on high. This is a common issue in runners who get a lot of lateral hip pain, IT band issues, medial knee pain and shin splits, which is pretty much any runner who prides volume over technique. You could also see a coxalgic gait, where the person is leaning hard over the hip to try to reduce the stability requirement of the contralateral stabilizing system.
The continuity seems to break down somewhat when it goes from horizontal force production to vertical force production. This case seems to favour contralateral linkage, as seen in a typical lay up in basketball where the shooting arm extends off the contralateral leg.
So what does this mean when it comes to training? Essentially, any movement that involves pressing or some level of drive comes into ipsilateral continuation. An example of this would be a cable lunge & press.
A powerful force in this movement is the extension and rotation of the right hip, as mentioned above.
Can you stretch the line? Sure, and one of my favorite ways of doing this is to use a lunge with a back rotation of the upper body.
People with chronically “tight” hip flexors tend to absolutely hate this one, and can’t help but wonder why they can’t get their arm higher than parallel to the ground.
At a more neurodevelopmental level, rolling patterns take an ipsilateral pattern in a new direction. A lot of people with spinal issues tend to really struggle with rolling, specifically as it relates to the duality of stability and mobility through the system.
When people get stuck on these, they tend to hold their breath and try to flex harder to get through, not realizing this isn’t the answer. In many ways, it’s one of the harder movements you can get down without cheating, due to how much thoracic mobility and core control is needed. Once it gets easy, there’s no reason to continue using it, but it’s tricky for a lot of people for a long time. I haven’t journied far enough down this specific rabbit hole to offer too much in the way of knowing the why and how, but for more information on that reach out to someone who studies DNS work.
Where ipsilateral work could be considered the driving movement, contralateral work could be considered pull or reach dominant movements.
Much of the contralateral work relies on using an interconnected line of tissue known as the posterior functional line. This line connects the gluteus maximus of one hip to the opposite side latissimus dorsi muscle, which essentially crosses the low back in an X-shape, and provides a level of stabilization and also acceleration.
The main role of this system is to produce force to pull towards the body, such as in a single leg deadlift.
The glute and lat stretch simultaneously, which happens to get the low back stabilized through the thoracolumbar fascia. These are all fancy words, but they essentially mean this is easier to do with less to no pain compared to a bilateral deadlift or hip hinge movement, and is a cornerstone movement I use with a lot of low back pain clients due to the movement from the hip and pull through this chain.
A secondary use of this line is as an antagonist for the drive from the ipsilateral line. When running , the one foot drives into the ground while the other knee drives up and forward. This forward knee drive stretches and tenses the functional line, especially when coupled with the arm reach. This stretch provides a brake for the drive side, and allows for an elastic recoil effect to bring the next leg into position to drive into the ground for continued acceleration.
Combining the ipsilateral drive with the contralateral pull is one of the basic tennets of locomotion, much like a crawling pattern.
This brings us back to the original questions: “which arm/leg combo?” Essentially, the way I use it is if it’s a driving movement, ipsilateral produces the greatest power production and stability, meaning the right hand has the right leg back. Contralateral work provides the greatest reach potential for pulling, which means the right hand has the left leg forward or standing on. Funny enough, they both wind up being kind of the same position, which makes it that much easier. This isn’t the only way to do things, but it’s a way I’ve used successfully with a lot of clients and it seems to work well.