The Single-Leg Swap Is the Most Important Exercise You're Not Doing

This article is exclusive to AHP.  It represents the uncut, updated, and fully extended version of an abbreviated article originally featured on stack.com

Improving foot, ankle and hip function is something I work on quite extensively with my athletes and clients. One exercise I use on a consistent basis to do this is the Single-Leg Kettlebell Swap.

A common phenomenon I've noticed over the years is that areas of dysfunction, particularly in the lower body, are all related, as each affects the others. For example, if the feet and ankles are not functioning as they should, this impacts activation patterns throughout the muscles surrounding the hips and knees. The opposite is also true. If the hips aren't activating properly, this promotes dysfunction in the muscles around the knees, feet and ankles.

The upside to this neuromuscular chain reaction is that improvement in one area tends to have a positive impact on all others. For example, train the feet and ankles to fire properly, and the majority of issues in the knees, hips, low back and core tend to improve greatly if not completely resolve themselves. Similarly, as you improve hip function, you should notice an almost immediate impact on function throughout the rest of your extremities.

This is where the Single-Leg Kettlebell Swap comes in. I've found it to be highly effective at improving lower-body function, alignment and muscle activation from the feet to the hips. In fact, this was something I developed out of pure necessity after witnessing a large number of athletes who displayed various types of foot and ankle deficiencies that were wreaking havoc on the rest of their bodies, particularly in the knees, hips and low back.

Before we dive into multiple variations of the exercise, let's discuss some key components of the Single-Leg Swap, as well as what makes it so effective.


The Drill

While holding a kettlebell in one hand, balance on one leg, swap the kettlebell to the opposite arm, and keep your body fully aligned from head to toe. Hold each position 3-5 seconds (or as long as it takes to fully stabilize each side) before swapping the weight again. Perform 8-12 swaps (4-6 swaps per arm on each leg) before switching to the other leg.

In addition when holding the single leg position it's critical that both legs be roughly in-line with each other with little if any visible space between the legs from left to right.  In other words if you were looking front on from someone performing this there should be no visible space between the left and right foot regardless of which leg is elevated.  Think in-line position not staggered (feet spread apart) position.  Anything other than an in-line position during any single leg stand variation (lunges included) is simply reinforcing dysfunctional mechanics and faulty alignment. 

Benefits

1. Works for All Types of Foot, Ankle and Hip Deficiencies

One of the great features of the Single-Leg Swap is that it's effective for improving nearly all forms of foot, ankle and hip deficiencies. When you hold in an ipsilateral fashion (same arm, same leg), your ankles have to provide anti-supination support as you resist various forces wanting to drive your hip and knee out laterally. When you hold the weight in a contralateral fashion (opposite arm and leg), it turns the movement into an anti-pronation exercise where you have to avoid valgus collapse around the ankles, knees and hips. Whether you're prone to supination or pronation of the ankles and feet—or display any form of valgus or various knee and hip collapse—there are few lower-body deficiencies this exercise doesn't address.

2. Improves Alignment from Head to Toe

Most athletes have very poor body alignment, often displaying at least several areas that need to be addressed. The Swap forces the feet, knees, hips, shoulders and head to be properly aligned, not only to the surroundings but relative to each other. Anything but proper alignment from head to toe results in an immediate loss of balance.

3. Enhances Full Body Stability

The single leg swap is one of the single greatest drills for enhancing rigidity, stability, tightness and motor control throughout the entire body. Besides improving force production and power output, it teaches athletes how to absorb force, thereby enhancing performance and decreasing risk of injury

4. Eliminates Energy Leaks

Most athletes have numerous areas of energy leaks throughout their bodies, with the feet, ankles, hips and core being most common. With the Single-Leg KB Swap, any energy leak is quickly exposed, as there is an almost immediate loss of balance. Learn to stabilize and maintain optimal alignment while swapping from side to side, and watch energy leaks gradually disappear.

5. Promotes Anti-Rotation, Anti-Lateral Flexion and Core Stabilization

Besides being an incredible exercise to strengthen the feet, ankles and hips, the Single-Leg KB Swap is a surprisingly effective movement for improving core stabilization. In fact, the movement feels very similar to a Suitcase Carry, which is one of the most effective drills for targeting the core. Each time you swap the load, you resist rotation of the spine, making the movement a highly effective rotary stability, anti-lateral flexion and anti-rotation exercise.

6. Improves Posture and Spinal Alignment

The first time you introduce a Single-Leg KB Swap into your own training routine and those of your athletes, you'll notice an immediate improvement in posture and spinal alignment. The movement requires proper positioning of the spine, since faulty postural mechanics make it almost impossible to stabilize.

7. Teaches Mental Concentration

Perhaps the most difficult aspect of the Single-Leg KB Swap is the degree of mental focus and concentration required to successfully perform it. If you're not mentally engaged, you'll be unable to balance and stabilize your body while swapping the load. In essence, anything short of Jedi-like focus will result in a failed attempt.

8. Easy to Coach

The Single Leg Swap is one of the simplest exercises to coach, making it highly conducive for large groups of athletes as well as one-on-one training. The drill itself provides most of the necessary feedback to the athlete. If the movement becomes sloppy, there will be a loss of balance.

9. Enhanced Body Awareness and Proprioception

Teaching athletes to be aware of their bodies and tune in to their muscles' proprioceptive feedback can be highly challenging. The Single-Leg KB Swap is an incredible drill for teaching body awareness, because the athlete is forced to attend to all facets of body positioning in order to successfully complete the movement.

10. Highly Versatile

The Single-Leg KB Swap is a highly versatile movement that lends itself to numerous modifications and variations, and can be customized for each scenario or training goal. Below are of few of my favorite variations of the Swap.


Variations

Single-Leg Kettlebell Swap

This is the most fundamental variation. Although it can be performed with iron grip-style weight plates or even dumbbells, kettlebells tend to feel the most natural.

Rapid Single-Leg Swap

This is a simple but advanced variation. The key is performing the handoff rapidly, which forces the muscles to turn on and stabilize quickly. This improves rate of stabilization development (RSD) as well as reactive stabilization, both of which are critical biomotor capabilities that every athlete should possess.

Toe-Touch Stride Hold Kettlebell Swap

For some athletes—particularly those with weak ankles and more severe levels of dysfunction—the standard Single-Leg Swap can often be too difficult. The toe-touch stride hold variation is an excellent regression that nearly all athletes at every level can perform. It's also an excellent movement for teaching individuals to keep their feet and hips aligned with each other (a critical component of proper walking, running, sprinting, and overall gait mechanics). Here are a few of my football players demonstrating the movement.

Eccentric Isometric Lunge with Kettlebell Swap

Lunges are one of the most beneficial exercises for improving lower-body function, not only through the larger muscles around the hips and knees but also in the smaller muscles around the feet, ankles and toes. Add a significant destabilizing element such as single leg swaps, and you will greatly increase the demands on the involved musculature. With a kettlebell in one hand, slowly lower yourself into a Lunge and pause, while smoothly swapping the kettlebell back and forth (under your legs) from hand to hand. As a bonus, you'll be performing an eccentric isometric (pause in the eccentric or stretched position) while holding the bottom of a Lunge. Eccentric isometrics are among the most beneficial types of muscle contractions for improving mobility, stability, strength, size and overall muscle function.

Single Leg Swap with Hanging Band Technique (HBT)

By adding the hanging band technique (HBT) single leg swaps, this increases the number of oscillations and ultimately the level of instability.  This forces the individual to aggressively activate their feet, ankles, and core as well as maintain proper spinal alignment.  Anything but intense full body activation will result in failed attempts and the inability to maintain balance. Here's collegiate superstar and NFL athlete Blake Sims performing it to prepare for the demands of NFL season. 

Single-Leg RDL Swap

The Single-Leg Romanian Deadlift Swap is an incredible drill for improving mobility and stability of the hip hinge position. Simply perform a Single-Leg RDL and swaps while holding the eccentric isometric position. Just be prepared to deal with a serious burn in your glutes and hamstrings, as well as your feet and ankles.

Landmine Swap

The landmine or T-bar apparatus lends itself very well to a unique version of the single leg swap.  This variation is particular difficult as the land-mine station produces greater rotational forces making even more difficult on the lifter as they must resist these forces particularly throughout the feet, ankles, hips, and core.  If you suffer from pronation, supination, flat feet, fallen arches, poor toe splay, and general weakness in the feet and ankles this one is a must.  Here’s one of my NFL athletes Jake Banta performing it.

Bumper Plate Swap

The Bumper Plate Swap is one of my favorite variations. It simultaneously addresses strength deficits in the grip and hands as well as the feet and ankles. In addition, it has an immediate impact on improving balance and stability, as the heightened activation of the hands and fingers produces concurrent activation potentiation (CAP). The CAP phenomenon describes a scenario where activation of the smallest muscles in the extremities increases neural drive throughout the entire body, including activation of the core, spinal stabilizers, shoulders, hips and other muscles. As a result, there's improved balance and motor control due to increased activation of stabilizers, as well as immediate reduction in energy leaks.

Overhead Dumbbell Swap

The overhead variation of the swap (dumbbell’s feel most natural) further increases the difficulty as it raises the center of mass causing greater rotational torque and destabilizing forces on the body.  In addition this specific variation reinforces the idea of integrating stabilization in the feet, ankles, core, and shoulders (head to toe integration) and coordinating these components together to stabilize the body as a whole unit.  This is an important capability that all individual from athletes to fitness enthusiasts should master.  Here are a few of my collegiate and NFL athletes Tyler Claytor and Jake Banta demonstrating it. 

Overhead Medicine Ball Swap

Using a medicine ball (which produces a similar effects as holding a bottoms up kettlebell position but the ball is more conducive for swaps) is a great way to incorporate simultaneous shoulder stability, postural alignment, motor control, mental focus, and overhead mobility while learning to maintain balance throughout the body. 

Here’s one of the collegiate quarterbacks I work with Drew Dinsmore improving his lower body stability, core activation and shoulder function all at once. And yes this an another drill that’s much trickier than it looks. It’s also an excellent warm-up exercise to get the entire body functioning as a whole unit and sending blood flow to all major muscles of the body.


Overhead Landmine Swaps

Here's another highly effective overhead swap variation developed by expert trainer and strength coach Meghan Callaway.  Incorporating the landmine variation into the overhead position is very challenging as you'll not only have the higher center of mass creating more torque on your body but you'll have to deal with the added rotational element of the landmine station.  It's also excellent for teaching the lifter to pack and centrate the shoulder joint.


Eyes Closed Variations

Performing any swap with the eyes closed is incredibly challenging as it requires the utmost in motor control, proprioception, kinesthetic awareness, balance, stability, and postural control.  Even the slightest lapse in concentration and you'll lose your balance.  These are some of the most mentally and physically challenging exercises you’ll ever perform as the level of focus needed to maintain balance and motor control is off the charts.  Fortunately my client Matt Jordan who is performing these in the video is training to be a Jedi knight for the upcoming Star Wars films, so as Yoda would say "swap, he must”. 


Eccentric Isometric Bulgarian Squat and Swap

The Bulgarian Swap is perhaps the most painful yet also one of the most beneficial variations of the Swap. Simply perform an eccentric isometric Bulgarian Squat and hold this position while passing the weight between your legs. This is also one of the single most effective drills for simultaneously improving mobility and stability in the lower extremities. You're essentially forced to stabilize your lower body and core while the surrounding musculature is contracting in a stretched and loaded position. The significant burn this one creates is only surpassed by the tremendous impact it has on athletic performance and muscle function.

As an added bonus this Bulgarian squat variation is incredibly beneficial for inducing functional strength and hypertrophy throughout the entire lower body including the quads, glutes, hamstrings, and hip flexors.  This is due to several factors including significant time under tension, mechanical tension, muscle damage, and metabolic stress, all of which are key triggers for inducing muscular hypertrophy.