SINGLE LEG BALANCE

Why Single-Leg Strength Is Non-Negotiable for Runners

If you’re a runner, here’s a simple but powerful truth: running is a series of single-leg hops.

At any given moment, only one foot is on the ground, absorbing forces of 2–3 times your body weight, stabilizing your pelvis, knee, and ankle and propelling you forward. Yet many runners train almost exclusively with double-leg exercises and bilateral strength machines.

And the consequences of this imbalance can show up as a variety of recurring injuries that stem from insufficient single-leg strength and control. 

When one leg lacks strength or stability, your body compensates. These compensations often show up at the hip, knee, or ankle, and over time these small inefficiencies can accumulate into injury. Single leg strength is also key for running efficiency. Strong lower body muscles - especially the glutes, quads, calves, and foot stabilizers - allow you to spend less time on the ground, maintain better posture late into your runs, and waste less energy controlling unwanted motion. Efficiency isn’t just about speed; it’s about how well you hold form when fatigue sets in. Symmetry is also important, as many of us have a “stronger” side. Using single leg training to help identify some of these gaps can help reduce injury risk and improve performance.

Try these single leg assessments barefoot or in running shoes and see how you do.

1. Single-Leg Balance Test (Foot & Hip Stability)

How to Perform

• Stand on one leg

• Hands on hips

• Eyes open

• Hold for up to 30 seconds

What to Look For

• Excessive wobbling

• Gripping toes

• Pelvis shifting side to side

• Needing the other foot down

Benchmarks

• ✅ 30 seconds steady = good baseline

• ⚠️ <15 seconds or significant wobble = needs work

Why it matters: Balance is the foundation of every stride. The harder it is to stand, the more work your leg is doing every time it hits the ground when you’re running.

2. Single-Leg Sit-to-Stand Test (Hip & Quad Strength)

How to Perform

• Sit on a standard chair

• One foot on the ground, other leg extended

• Stand up and sit down 10 times without using momentum

What to Look For

• Knee collapsing inward

• Trunk leaning excessively

• Difficulty controlling the descent (falling onto the seat)

• One side clearly harder than the other

Benchmarks

• ✅ 10 controlled reps per side

• ⚠️ Loss of control or asymmetry

Why it matters: This mimics the strength demands of mid-stance during running.

3. Single-Leg Heel Raise Test (Calf & Achilles Capacity)

How to Perform

• Stand on one leg

• Rise up onto your toes, slow and controlled

• Use a wall or finger support for balance only

• Perform to fatigue

Benchmarks

• ✅ 20–25 quality to full height reps per side

• ⚠️ <15 reps or noticeable side difference

What to Look For

• Incomplete heel rise

• Speeding through reps

• Shifting hips and weight forward to assist lifting the heel up

• Early fatigue on one side

Why it matters: The calf is the final force generator in each stride.

4. Single-Leg Squat Test (Whole-Chain Control)

How to Perform

• Stand on one leg

• Perform 5–10 slow squats

• Watch yourself in a mirror or record a video

What to Look For

• Knee drifting inward

• Pelvis dropping

• Trunk rotating or tipping

• Uneven depth between sides

• Loss of balance

Benchmarks

• ✅ Smooth, aligned squats 5+

• ⚠️ Loss of alignment or poor control

Why it matters: This test reveals how well your hip, knee, and foot work together.

5. Step-Down Test (Eccentric Control)

How to Perform

• Stand on a step or stair

• Slowly lower the opposite heel to tap the floor while keeping body upright

• Return to standing

• Perform 5 reps per side

What to Look For

• Knee wobble

• Hard “thud” on the floor

• Poor control on descent

Benchmarks

• ✅ Smooth, aligned step downs 5+

• ⚠️ Loss of alignment or poor control

Why it matters: Downhill running and fatigue demand eccentric control of the entire leg while the trunk remains upright.

What If You “Fail” a Test?

First—don’t panic. These assessments aren’t pass/fail; they’re information.

If you notice:

• Big left-right differences

• Poor dynamic control on one leg

• Early fatigue (form diminishes with more reps)

That’s your cue to prioritize:

• Single-leg strengthening

• Dynamic stability work

• Gradual progression before increasing mileage or speed

A physical therapist can help tailor exercises to your needs, but awareness alone is a powerful first step.

Runners often chase mileage, pace, and shoes—but strength is what allows your body to tolerate training. If you want to run longer without pain, reduce injury risk, improve running efficiency and stay consistent year and year, then single-leg strength isn’t optional—it’s essential.

Start by testing. Address what you find. Your future miles will thank you.