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Strength Training with One Leg or Two? Unilateral vs. Bilateral Training for Runners

Sprinter Waiting for Start of Race

When you walk, both feet are in contact with the ground, but while running, only one foot is making contact at any given time. Your muscles and joints are constantly reacting to various forces to keep you moving in a controlled manner across the finish line. In fact, every step you take in your running stride increases the impact force through each joint to about 5 to 12 times your body weight. Therefore, it is crucial that during training, runners develop efficient mechanics, controlled ranges of motion, and symmetrical strength and timing through each leg.

Training can be simply defined as taking your body and mind out of the comfort zone in order to adapt, react, and prepare for future events. As you train for your upcoming race, it is important to incorporate strength training and various forms of cross training in your routine to improve upon imbalances and to stretch your limits.

A common question that runners tend to ask is: “If running is a single-legged sport, should I only focus on single-legged exercises while training?”

From a rehabilitative and performance perspective, it’s important to develop bilateral stability, strength, and timing before focusing on only unilateral movements. With each phase of running, you want to make sure there is an adequate and even transfer of energy and weight throughout each joint in your body.

According to the kinetic chain principle, our body is made up of a series of links (body joints and muscles) in an interconnected chain (human body) working together to maximize efficiency during a movement. When one link is moving it has an effect on the movement of the other links in the chain. During running, each the foot makes contact, the ground has a reaction force on the foot which then translates to the ankle, knee, hip, back, shoulders, and neck. If the runner’s technique is compromised, it can have a chain reaction to other parts of the body leading to compensations and injuries.

Let’s say your goal was to do a single-legged squat for the first time. The process might look something like this:

  • You try to do one and find out it’s very difficult. In order to achieve your goal, you may start by focusing on having good form with a two-legged squat.
  • As your strength increases, you can introduce a single-leg squat pattern by elevating one foot on a yoga block or a half foam roller. This way, you can shift your weight onto one leg while squatting, but still have some support for the other leg.
  • To further increase motor control and timing, you can practice single leg squat sequencing by utilizing TRX assistive straps, cables, or simply holding on to a firm surface for assistance.
  • While continuing this program, you increase your load and continue to work in different planes to allow your body to adapt to forces from different directions. To accomplish this, you can do exercises such as stepping down, single-leg deadlifts, standing clam shells, monster walks, hip clocks, and multi-directional lunges.

At this point, you’ve built a stable symmetrical base. When you go back to your original goal and try to do a single-legged squat, your body is more inclined to adapt to this challenging task because it is more familiar with the previous activities.

And so, for our runners out there participating in strength-training programs, make sure to build a strong stable base bilaterally and don’t forget that running requires full-body strength and mobility, so upper-body strength exercises and foam rolling should be part of your program as well!

*Before attempting any new training program, or difficult movements make sure to be assessed by a Sports Physical Therapist or Performance Specialist to evaluate your technique, identify any risks for injury and education on correct exercise progressions.*

A version of this article appeared in New York Road Runners’ Ask the Experts series.

HSS physical therapist Anil Nandkumar

Anil Nandkumar, PT, DPT, CSCS is a physical therapist with HSS Rehabilitation. He received his doctorate of physical therapy from Northeastern University and is currently working with a variety of populations providing pre- and postoperative care. He enjoys working with athletes to aid in recovery and to return to a high level of sport, in a safe way. Anil is a member of the HSS recovery team for many races throughout the 5 boroughs, as well as presenting at the NYRR RunCenter, and featured on NYRR Facebook Live Chat in December 2018. His clinical interests include orthopedics and sports medicine, with a special interest in treating runners and tennis players.

The information provided in this blog by HSS and our affiliated physicians is for general informational and educational purposes, and should not be considered medical advice for any individual problem you may have. This information is not a substitute for the professional judgment of a qualified health care provider who is familiar with the unique facts about your condition and medical history. You should always consult your health care provider prior to starting any new treatment, or terminating or changing any ongoing treatment. Every post on this blog is the opinion of the author and may not reflect the official position of HSS. Please contact us if we can be helpful in answering any questions or to arrange for a visit or consult.