The Trailhead
Hi, I'm Kevin
I am a biomechanics researcher. Most of my work is related to running, gait, and foot and ankle biomechanics, and a lot of it comes down to getting a number out of noisy sensor data that is actually worth reporting.
About the cartographer
I am the Biomechanics Research Manager at Superfeet. Before that I spent several years at Drexel University studying gait biomechanics, first as a doctoral student and then as a postdoctoral researcher and research scientist. Along the way I have written a lot of code to pull usable measurements out of wearable sensor data, and worked as a data scientist and biostatistician.
I also build things, apparently more than I have time for. A route intelligence app, a fitness RPG, a handful of interactive explainers, a few small games. This site is where most of it lives. Every stop is either a place I have been or something I made.
A fork in the trail
Pick a trail
Everything here runs along three trails. Take whichever turn you like, and use the map button up top to jump back to this fork any time.
Trail · Places
Where we move
Maps, public land, and the trails between them. A few of these are places I have studied. Most are places I have just spent a lot of time.
Places I Have Been
There and back again
I grew up a Pacific-Northwest kid, looped through Oregon and Washington, took one big leap across the country to Philadelphia, and came home again, learning something new each step along the way. Tap a pin or a number to walk the route.
The Field · Interactive
Connections
Small infrastructure with outsized impact, and the case for the missing link.
Connections
InteractiveThe three maps below each show a real transportation barrier. Explore each one and draw the fix you would build, then see what was actually built, how it changed the network, and why it mattered, from a trail connector outside Philadelphia to an underpass beneath I-90 in my Washington hometown.
It is a small argument with a big claim: A few hundred feet of the right infrastructure can hand you a whole landscape.
The Commons · A Field Note
Common Ground
Third places, public land, and the strange luck that some ground belongs to all of us.
Common Ground
InteractiveThis is a field note that grew out of nine years on one public trail. Ride the real Schuylkill River Trail, watch the lopsided map of American public land tip from West to East, then flip between countries to see where an ordinary person is actually allowed to walk.
The claim underneath it is a large one. The ground you can stand on freely is neither an accident nor a guarantee, and it is worth defending.
The Workshop · Apps
RouteReveal
A tool for exploring the relationship between person and place during movement.
RouteReveal
Live appMost running apps are good at telling you how far and how fast you went. I am more interested in what the accumulated data says about the places you know. RouteReveal treats every revisit to the same ground as its own small experiment, which surfaces patterns that are easy to miss when you only look at one activity at a time: Place-by-place personal records, pace adjusted for conditions, and maps of where you are actually getting faster.
It is not meant to be another tool for comparing yourself to other people. The goal is a better understanding of your own experience across time and place. It is also where three of my interests overlap: Running, signal processing, and maps.
Trail · Biomechanics
How the body moves
Running mechanics, gait, and training. What the evidence actually supports, what it does not, and what is worth changing.
For Coaches
The Coach's Trailhead
Evidence-based answers to the questions running coaches actually ask, each one an honest verdict, how sure we are, the research worth reading, and what to do Tuesday. Pick a trailhead.
Watch & wearable metrics
How much should I trust my runner's watch metrics?
Read the verdict →Footstrike: Fix it?
My runner is a heel striker. Do I need to fix it?
Read the verdict →Cadence: Worth changing?
Should I get my runner to a higher cadence?
Read the verdict →Managing training load
My runner keeps getting hurt. What does the evidence say?
Read the verdict →From the Bench · Explainer
Anatomy of a Stride
One running stride, pulled apart. Scrub the gait cycle and watch the limb, the ground reaction force, and the joint angles move together.
Anatomy of a Stride
InteractiveThis explainer takes apart a single running gait cycle. Drag through stance and swing, and watch how the leg, the ground-reaction force, and the hip, knee, and ankle angles line up at every instant of the step.
From the Bench · Timeline
The Long Run
A century and a half of learning to see, measure, and reshape the running body. Five threads of running science run side by side, from Muybridge's frozen stride to the carbon-plated super-shoe.
The Long Run
InteractiveScroll through the history of running science while a sticky illustration redraws itself for each milestone. Filter the five threads to follow just one line of discovery, and watch a running myth meet the data along the way.
The Workshop · Apps
Adventurer's Mile
Train like a party. Finish like a hero.
Adventurer's Mile
Live appAdventurer's Mile is a fitness platform that turns a few months of group training into a season-long RPG. Workouts earn XP, monthly quests award bonuses, and an ability shop lets players spend their gains on advantages in a final in-person showdown, keeping the whole party motivated right up to the last mile.
I built it as a personal project to keep myself and my group of D&D- and LOTR-obsessed friends active.
The Movement Lab · Playable
Play the movement
Bench games for the body in motion. Author a movement from the joint up, or feel the physics of what you land on. Each finishes in a coffee break.
Move In
Draw the ankle angle and the body obeys. Author a movement from the joint up, then thread the rings. Inverse dynamics, in your hand.
Play now →Drop In
Tune the material, not the shot. The physics of impact, restitution, and what a surface gives back. The stuff that happens underfoot.
Play now →More in the arcade
Signal-processing puzzles, a folding game, and the rest of the playable experiments are down at the Arcade.
See all games →Trail · Signals
Noise into trust
Wearable sensors produce noisy data. Most of the work is deciding what to filter out, and how much to trust what is left.
From the Bench · Explainer
Anatomy of a Signal
The whole craft on one screen. Take a noisy impact from a single accelerometer, choose how to sample and filter it, and watch an honest measurement appear, or slip away.
Anatomy of a Signal
InteractiveA running stride spikes the shin with a sharp burst of acceleration. Drag three sliders, noise, sampling rate, and filter, and feel the trade-off every wearable study lives with: Sample too slowly and the peak slips between samples; filter too little and noise invents one; filter too much and you smear it flat.
Signals · From the research
One sensor, honest answers
The clearest version of the whole idea is finding every footstrike in a run from a single shoe-mounted accelerometer, no force plate, no lab.
Foot contact from one accelerometer
Peer-reviewedA lot of biomechanics needs a force plate bolted to a lab floor. This work pulls the same event, the instant the foot meets the ground, out of a single triaxial accelerometer you can wear out the door. A cheap sensor, careful signal processing, and a measurement you can trust in the field; that is the through-line of most of my work.
The Workbench · Tools
Things I have built
The tools behind the research. Small, sharp, and built to make the next study easier. A few favorites.
Running Surface ID
A Python tool that fuses GPS tracks with map APIs to classify the ground underfoot, the experiment that grew into RouteReveal.
Python · GPS · APIs →Live Mocap Feedback
Real-time marker-quality feedback in the motion-capture lab (Vicon Nexus + MATLAB + Visual3D), fewer ruined trials, faster training.
Vicon · MATLAB · Visual3DData-Pipeline Automation
Scalable pipelines for messy, multimodal data (biomechanics, physiology, user feedback) that cut processing time by ~75%.
Python · automationThe Signal Lab · Playable
Play the signal
Two small bench games about the same craft, pulling a clean answer out of a noisy world. Each one teaches a real idea and finishes in a coffee break.
Zero In
Match the signal. Twist knobs, sliders, and switches to rebuild a hidden processing chain until your trace locks onto the target.
Play now →1D Chess
Collapse the board to a line. Rotate the axis until a weighted cloud of pieces spreads out the most, then see what the squeeze throws away. (That is principal component analysis.)
Play now →More in the arcade
The rest of the playable experiments live down at the Arcade: Physics, biomechanics, and a folding puzzle.
See all games →The Summit
Where the trails meet
Biomechanics and signals share one field. Here is the peer-reviewed work, and a résumé if you would rather skim than scroll.
The Summit · Research
Research & Résumé
Peer-reviewed work in running biomechanics and wearable-sensor signal processing, most of it about measuring impact honestly and detecting what the body is doing from a single accelerometer.
- Increasing ground contact time reduces Achilles tendon forces during rearfoot strike running outdoors
- Whipping or tearing? Mechanisms for the development of Achilles tendinopathy in runners
- Minimum sampling frequency for valid and reliable tibial acceleration measurements during running in the field
- Foot contact identification using a single triaxial accelerometer during running
- Tibial acceleration reliability and minimal detectable difference during overground and treadmill running
- Tibial acceleration during running is higher in field testing than indoor testing
- Relationship between iliotibial band syndrome and hip neuromechanics in women runners
The Arcade · Games
Little games, real ideas
Playable experiments, small enough to finish in a coffee break, nerdy enough to teach you something.
Zero In
Match the signal. Rebuild a hidden processing chain until your output trace locks onto the target. Signals.
Play now →1D Chess
Collapse a weighted cloud of chess pieces onto a single line. It is principal component analysis, by hand. Signals.
Play now →Move In
Draw the ankle angle and the body obeys. Author a movement from the joint up and thread the rings. Biomechanics.
Play now →Drop In
Tune the material, not the shot. Dial in restitution and friction until the physics drops the ball where you need it. Physics.
Play now →Fold In
Fold a ring of glyphs back onto its target with slides, folds, and presses, a bit of group theory hiding in your hands. Math.
Play now →Base Camp
Field guides
Curated trail maps to the things I am interested in. Annotated, opinionated, and rated by how much footing you will need. Green circle, blue square, black diamond.
Biomechanics
The books, sites, and tools I would hand a new biomechanist.
8 entries →Signal Processing
Filters, transforms, and sampling. The stuff that finally made it click for me.
7 entries →Foundations
The papers that built the field, the ones I keep coming back to.
27 entries →Learning
Interesting corners of math, data, and the web worth wandering into.
11 entries →Kevin's Picks
Books and the odd thing I just like, no syllabus, no agenda.
10 entries →Favorite Places
Trails, ridges, gardens, and far-flung corners that stuck with me.
21 places →