Many traditional strength training programs only incorporate double-leg exercises for the lower body such as the squat, leg extension, leg press, and leg curl. At T3, our athletes perform single-leg exercises more often than double-leg exercises for the reasons discussed below.
1. You Can't Fire A Cannon From A Canoe
Athletes need stability! How many sports are played with both feet in contact with the ground at the same time? Not many. Most skills during a sport are performed with one leg on the ground (i.e. running, kicking, bounding). Single-leg strength cannot be developed through double-leg exercises. If an athlete already has a weaker left side, bilateral exercises like a deadlift or squat will allow the left side to stay weaker while the right side compensates for it. This is called bilateral deficit.
Bilateral Deficit : strength of the right leg alone + strength of the left leg alone > strength of both legs together
Therefore, training the legs one at a time will result in more powerful double-leg and single-leg movements. It will also strengthen the core and torso as a whole, resulting in a more powerful boat from which to fire your cannon.
2. Injury Prevention
When it comes to safety while training, single-leg exercises cause less spinal compression so they put the back through less "wear-and-tear". In sports, athletes in movement will be on one leg at time. Improving stability in those movements will reduce an athlete's risk of injury. They will land and take off from more stable positions than an athlete who only trains from a two-legged stance.
Referring back to the bilateral deficit; if there is a weaker side, single-leg exercises will isolate and strengthen that side so that further imbalances do not form. This is important because imbalances and compensations lead to injury.
There are also long-term implications of disregarding training the legs individually. The gluteus medius is a stabilizer muscle of the hip that is often neglected. It's primary function is to stabilize the lower extremity in single-leg movements such as running, jumping, or squatting. Many athletes who suffer from knee problems such as patellar tendinitis have a gluteus medius that is too weak to perform its function. As a result, the support structures of the knee are forced to provide stability instead, causing pain in the IT Band or under the kneecap. (See figure to the right)
So What Are Good Single-Leg Exercises For Athletes?
It is important to note that athletes should begin performing single-leg exercises with no external load (body weight) until they are stable in the movement. Once they are stable, they can begin adding dumbbells, barbells, or weighted vests to perform the exercise.
1. Split Squat: This exercise is great for beginners. Many young athletes have poor running form, simply because they cannot stabilize their body on one leg. Putting them into a split stance allows them to begin strengthening those stabilizer muscles.
2. Bulgarian Split Squat: This is a slightly more advanced movement with the rear leg elevated. This exercise isolates the front leg more than a traditional split squat and requires greater recruitment of stabilizer muscles.
3. Single-Leg Romanian Deadlift: This movement recruits muscles of the posterior chain (hamstrings and glutes) as well as the hips to stabilize. It also requires use of the core to prevent twisting of the lower back and hips. It is important to keep the back straight and the hips square to the ground during this movement.