Stable vs. Unstable Lifting: Which is Best for the Runner?
Stable strength exercises and unstable ones both have powerful benefits for running. Here's why and how to include both in your strength workouts.
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Strength training is a powerful performance-enhancing activity. Strong runners are faster, more efficient, and injury resistant.
When designing a strength plan for running you need to consider many variables. Stability is one of those variables. Stable strength training exercises such as two-legged (bilateral) squats, deadlifts, and overhead presses are distinctly different from unstable versions such as single-leg (unilateral) versions of these exercises.
Each version conveys unique benefits and limitations. The best strategy to enhance your running includes both stable and unstable weight training exercises.
The Benefits of Stable and Unstable Lifting
Stable lifting has two advantages that improve your running. First, a stable exercise allows you to generate more force and lift more weight—and one of the main reasons to lift weights is to train the muscles to impart more force into the ground. Tendons also respond favorably to heavy loads, becoming stronger, more injury resistant, stiffer and thus more springlike. Strong muscles along with strong, stiff tendons increase your running economy. Better running economy allows you to conserve energy while running.
Second, a stable exercise allows you to move through a full range of motion (ROM.) Several studies show that full-ROM training is superior to partial-ROM for building strength. Further, strength is position-dependent, meaning you gain strength only through the range in which the limbs and muscles move, not beyond that range. You don’t need to lift through a full ROM every time you lift, but some of your training should definitely involve full ROM.
While unstable lifting doesn’t allow for as much weight or range of motion, it too has an advantage—it enhances motor control. Motor control is defined as “the process of initiating, directing, and grading purposeful voluntary movement.” Think of motor control as movement skill.
Running is a series of alternating single-leg hops that require both stability and power. Your nervous system must reflexively coordinate the stabilizer muscles (gluteus minimus, gluteus medius, adductors, and muscles in the lower legs and feet) with the prime movers (quads, hamstrings, gluteus maximus, gastrocnemius) to drive you forward without injury. If you can’t stabilize your joints and limbs while running then you’ll waste energy and increase your chance of injury.
The Spectrum of Stability
You can take many tiny steps to increase or decrease stability of a lift. Here’s a spectrum of sample exercises, from most to least stable:
- Machine exercises such as the leg press, leg extension, and Smith machine
- Bilateral (both feet on the ground) barbell exercises such as squats, deadlifts, rows, and presses.
- Bilateral dumbbell versions of the above
- Unilateral (one foot on the ground) barbell exercises
- Unilateral dumbbell exercises
- Asymmetrically loaded bilateral exercises using barbells, dumbbells, and/or bands and tubing
- Asymmetrically loaded unilateral exercises
At the extreme is lifting on an unstable-surface training aka UST (lifting weights while standing on inflated rubber disks, balls, or foam mats). Research on UST is limited, what data there is indicates that it may be useful in the rehab setting but has limited use for healthy athletes. You can get all the instability you need from single-leg and asymmetrically loaded exercises.
Loads
The best way to get strong is to lift heavy: 3-6 reps for 2-5 sets is ideal. When lifting, you should work to a high level of exertion. The final reps of all sets should be just shy of failure. Use excellent form when lifting. Don’t sacrifice good technique for more reps or weight.
If you’ve never performed barbell lifts such as squats, deadlifts, presses, and Romanian deadlifts then you should consult with a personal trainer or strength coach.
Exercises
Here are several examples of stable exercises and their less-stable counterparts. Many exercises can be made more or less stable in numerous ways, these are only examples.
Squats
Stable: Bilateral back squat
Unstable: Unilateral back squat
More Unstable: Unilateral dumbbell asymmetric squat
Romanian Deadlift (RDL)
Stable: Bilateral barbell
Unstable: Unilateral barbell
More Unstable: Unilateral asymmetric
Overhead press
Stable: Bilateral dumbbell
Unstable: Unilateral dumbbell
More Unstable: Unilateral asymmetric
Sample workout
Here’s one way to structure a workout using both stable and unstable weight exercises:
Jump rope for several minutes.
Go through your favorite mobility routine to prepare for lifting.
Bilateral back squat: 5 reps x 3 sets
Unilateral dumbbell press: 5 reps x 3 sets
Unilateral asymmetric RDL: 10 reps x 2 sets
In sum: Stable exercises build the greatest amount of strength. Unstable exercises build both strength and motor control. Your weight training plan should include both heavy, stabilized exercises along with unstable exercises.