AGILITY & SPEED WHITE PAPER PART 2: THE HOW
By 
Dan Feeney 
Kate harrison
Follow on 
@Dfeeney31 and @running_geek
We have been busy in the BOA Performance Fit Lab scientifically studying the impact of performance fit solutions. Our recently published paper, Alternative upper configurations during agility-based movements: part 1, biomechanical performance was the first scientifically peer-reviewed paper showing that fit configurations can improve performance. Our second paper - Alternative upper configurations during agility-based movements: part 2, biomechanical mechanism - clarifies how these performance improvements came about. Specifically, we quantify the biomechanical changes responsible for the improvements we observed in performance.
Using data from the 31 subjects in our first study, we analyzed how ankle, knee, and hip motion and forces changed during the skater jumps and countermovement jumps. We measured the three key variables: 1) joint range of motion, 2) joint moments, and 3) joint powers, one hundred times per second. Briefly, the joint range of motion tells us how much the angle between two body segments changes during movement; for example, the ankle angle tells us the relative angle of the shank (lower leg) and foot. Joint moments approximate how much force the internal muscles are producing to cause a given movement. Lastly, joint powers estimate the net rate of energy generation and production at each joint (for a more thorough overview of these measurements, check out this article).
We calculate these variables by using reflective markers on key landmarks in the body and measuring forces with a force plate embedded in the ground. These allow us to create a geometric model (shown below) to estimate each of these variables during movement.
From part 1 of our study, we saw athletes could change direction more quickly during vertical and lateral (side to side) jumping and cutting drills. Not only that, but they produced greater rates of force development, and less work in our tri-panel and y-wrap configurations.
When athletes perform these movements, they need to optimize velocity and force in the direction they intend to move. For example, in a countermovement jump, the athletes want to optimize their vertical movements while minimizing any movement from side-to-side or in a rotation. In biomechanical lingo, this means athletes are moving more in their sagittal plane, while limiting motion in the frontal and transverse planes. Motion in the side-to-side or rotational planes may be thought of as wasted energy for a countermovement jump. In some cases, excessive motion in the frontal and transverse planes are also associated with injury risk. Our tri-panel and y-wrap configurations reduced motion in those undesired planes and increased range of motion and moments in the desired planes for each motion.
The purpose of our first technical report was to quantify performance enhancements due to BOA Performance Fit Configurations while the second technical report details the biomechanical mechanisms responsible for the observed improvements. Concretely, we saw reductions in wasted movements and moments in the tri-panel and y-wrap configurations. We will use this information to help our customer product development team continue to develop world-class configurations to make the best gear even better.