Flight Time in Running: What It Is and How It Affects Speed

What Is Flight Time in Running?

Flight time is the split second in every running stride when both feet are off the ground at the same time — the airborne phase between one foot pushing off and the other foot landing. It's what separates running from walking: walking always has at least one foot touching the ground, while running has this brief moment of full-body flight. For most recreational runners at an easy pace, flight time lasts somewhere around 100 to 150 milliseconds per step, and it gets longer as you speed up.

Flight time and ground contact time are the two halves of every stride cycle. Together, they determine your cadence (steps per minute) and, indirectly, how much time you spend generating force against the ground versus gliding through the air.

How Is Flight Time Different From Ground Contact Time?

Ground contact time (GCT) is the mirror image of flight time: it's how long your foot stays in contact with the ground during each step, from initial contact to toe-off. For recreational runners at an easy-to-moderate pace, GCT typically falls somewhere in the 200-300 millisecond range per step. Faster runners and sprinters spend far less time on the ground — often under 150 milliseconds at top speed — because they're pushing off harder and more explosively.

Every stride, then, is really just an alternating sequence of ground contact and flight: foot down, force applied, foot up, brief flight, other foot down. A shorter GCT usually pairs with more flight time at any given cadence, since less total cycle time is spent on the ground.

How Does Flight Time Relate to Speed?

Flight time increases with running speed, but not because you're bouncing higher off the ground. As pace picks up, most runners generate more horizontal force with each push-off, which both shortens ground contact time and covers more distance while airborne. The result is a longer flight phase measured in time, even though the runner isn't necessarily rising further vertically — they're moving forward faster during that airborne window.

This relationship is well documented in running-biomechanics research: as speed increases from a jog to a sprint, contact time drops substantially while flight time grows as a share of the stride cycle, a pattern seen consistently across studies of running gait mechanics.

Where this gets misread is assuming that any spike in flight time equals better performance. Flight time earned from more forward drive is useful. Flight time earned from popping straight up in the air is not — which is exactly where vertical oscillation comes in.

What's the Tradeoff Between Flight Time and Vertical Oscillation?

Vertical oscillation is the up-and-down movement of your center of mass with each stride, typically reported by running watches and footpods in the range of about 6 to 10 centimeters for recreational runners. It's a separate measurement from flight time, but the two interact.

Two runners can post nearly identical flight times and look completely different in efficiency. One gets that flight time mostly from forward momentum — a low, efficient trajectory that covers ground with minimal wasted vertical motion. The other gets it from bouncing noticeably higher off the ground with each step, which lengthens flight time but converts more energy into fighting gravity than into forward speed.

Excess vertical oscillation wastes energy: work spent lifting your body up and down doesn't move you down the road any faster, and over a long run it adds up to meaningfully more effort for the same pace. This is one reason coaches and sports scientists caution against chasing a single number — like "increase flight time" — in isolation. A useful flight time is a byproduct of an efficient stride, not a target to manipulate directly.

How Can You Measure Flight Time From Slow-Motion Video?

Flight time typically lasts well under 300 milliseconds, which is faster than the human eye can reliably time and faster than standard video can resolve. At a normal 30 frames-per-second video, each frame represents about 33 milliseconds — too coarse to pinpoint the exact moment of toe-off and the next foot strike with much confidence.

Slow-motion capture at 120 or 240 frames per second, available on most modern smartphones, narrows each frame down to roughly 4 to 8 milliseconds. That's enough resolution to count frames from the moment one foot leaves the ground to the moment the other foot lands, then divide by the frame rate to estimate flight time in seconds. Filming from directly to the side, at hip height, with the runner passing perpendicular to the camera, gives the clearest read. Our guide on how to read a slow-motion running video walks through the frame-counting process in more detail.

Even with slow-motion capture, treat the resulting number as an estimate, not a lab measurement. Camera angle, frame-rate consistency, and lighting all introduce error into a phase that's already measured in fractions of a second. A tool like StrideIQ can give you a quick read on cadence — the one metric a single phone video measures with reasonable confidence — from a short recorded video, but flight time and ground contact time carry more uncertainty from any single-camera setup and shouldn't be treated as precise. For that kind of millisecond-level accuracy, force plates or motion-capture gait labs remain the standard.

If you want a broader look at your mechanics beyond flight time alone, the running form checklist covers other things worth watching for in a self-filmed video.

What's a Good Flight Time to Aim For?

There's no single "good" flight time — it scales with pace, leg length, and running economy, and it isn't something you should try to directly increase. What's more useful is understanding the general range you'd expect to see at different efforts, and noticing whether your flight time is coming from forward drive or vertical bounce.

Effort / Pace Typical Ground Contact Time Typical Flight Time
Easy jog ~250-300 ms ~100-150 ms
Moderate / tempo ~220-260 ms ~150-200 ms
Fast 5K-10K pace ~180-220 ms ~200-250 ms
Sprinting ~100-150 ms ~250-300+ ms

These are general ranges drawn from running-biomechanics research, not fixed targets. Two runners at the same pace can have different flight times and both be running efficiently. If you're trying to figure out how these numbers should shift across your training week, how fast your easy runs should be is a useful starting point, since flight time and contact time naturally change with effort level, not just fitness. For a deeper technical breakdown of the metric itself, see what flight time in running actually measures.

What Can Slow-Motion Video Analysis NOT Tell You?

A phone video, even in slow motion, has real limits. It can give you a reasonable estimate of cadence and a rough sense of flight time and ground contact time, but it can't match the millisecond precision of a force plate, an instrumented treadmill, or a multi-camera motion-capture gait lab. Small errors in frame counting or camera angle become proportionally large when the phase you're measuring lasts a fraction of a second.

It also can't tell you whether a given flight time or ground contact time is "wrong" for you individually. The research on manipulating these variables — including cadence and vertical oscillation — to reduce injury risk or boost performance is genuinely mixed; some studies show benefits for specific joint loading patterns, others show no consistent effect on injury rates across runners. There's no universal ideal number that applies to everyone.

Finally, video analysis of any kind isn't a substitute for a professional evaluation. If you're dealing with recurring pain, a change in your stride after injury, or a performance plateau you can't explain, a physical therapist, sports medicine physician, or an in-person running gait lab can assess load, strength, and mechanics in ways a single video cannot. Use flight time and contact time numbers as one data point among several, not a diagnosis.

Frequently Asked Questions

What is a normal flight time in running?

For most recreational runners at an easy pace, flight time is roughly 100-150 milliseconds per step, increasing toward 200-300+ milliseconds at faster paces and sprinting. The exact figure varies by leg length, pace, and stride mechanics, so there's no single "normal" number that applies to everyone.

Does a longer flight time mean you're running faster or more efficiently?

Not necessarily. Flight time naturally lengthens as pace increases, but it can come from either efficient forward propulsion or from excessive vertical bounce. A longer flight time paired with high vertical oscillation often signals wasted energy rather than better running.

Can you measure flight time with a phone?

Yes, approximately. Recording at 120 or 240 frames per second and counting frames from toe-off to the next foot strike gives a rough estimate, but phone video carries more measurement uncertainty than lab-based force plates or motion capture, especially for a phase this short.

Is a shorter ground contact time always better for performance?

Generally, ground contact time shortens as pace increases among efficient runners, but there's no universal "ideal" number to chase in isolation. Evidence on manipulating contact time directly to improve performance or reduce injury risk is mixed, and it's best considered alongside pace, cadence, and overall training load.

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