The foot is built to move
Pronation is a coordinated, three-dimensional motion that includes rearfoot eversion, forefoot abduction, and dorsiflexion. It helps the foot adapt to the ground and manage the transition from landing toward propulsion.1
In other words, the inward roll runners see from behind is only one visible piece of a larger load-management strategy happening inside the shoe.
A rear-view angle misses half the story
Video can show visible shoe or heel movement, but shoe motion is not identical to calcaneal motion; shoe-mounted markers underestimated calcaneal range of motion in the cited running study.2
STRIV combines shoe-frame roll with the path of pressure beneath the foot. That makes it possible to see how the roll pattern changes while pressure moves forward—or whether the movement and pressure-path trends begin telling different stories.
Pressure shows what the angle leaves out
Two feet can show a similar roll angle while moving pressure through different regions. One may progress directly from heel to toe; the other may spend more of stance toward the medial or lateral edge. The amount of roll is similar, but the load path is not.
That is why pronation becomes more useful when it is read beside CoP progression, contact timing, pace, and left–right differences—not reduced to one angle in isolation.
- Follow roll and pressure through the same phase of stance.
- Compare both feet under the same pace and terrain.
- Look for a change in strategy, not a universal perfect angle.
What STRIV follows through early stance
STRIV follows pronation-related roll through early stance and pairs it with the underfoot CoP path for the same foot.
Across hundreds of steps, the runner can see the repeatable pattern: how each side accepts load, how stable that strategy remains, and whether pace, terrain, footwear, or later-run mechanics begin to reshape it.
The roll value reflects sensor movement inside the shoe, which makes it most useful as a consistent personal comparison rather than a one-size-fits-all anatomical score.
Your own pattern is the benchmark
Research does not support one universal pronation cutoff that separates good running from bad. Static foot posture and dynamic movement are different, and runners bring different anatomy, shoes, speed, and training histories to every step.3,4
That makes the personal trend the stronger story. If the two feet normally move one way and one side begins to change under the same task, STRIV can make that shift visible—so the next decision is grounded in the runner's own mechanics.