Clincians, coaches and academic researchers around the globe trust RunScribe to deliver consistent and accurate metrics. We have partnered with leading researchers to validate the RunScribe footsteps model and ensure accrate metrics. We're committed to sharing our research and validation studies with our community at Running Unraveled.
A Better Yardstick
Traditionally, athletes have been limited to simple metrics - like speed, distance and cadence - to measure performance. RunScribe's advanced metrics provide deeper and more meaningful metrics to help sports professionals: Improve assessment, establish performance baselines, holistically track change to assess improvements and evaluate risk, and quantify progress with injury recovery and therapy.
- Contact Time
- Impact & Braking Gs
- Step Rate & Stride Length
- Flight Ratio
|Time Breakdown (Moving, Running, Stationary, Walking)|
|Shock (per footstrike)|
- Contact Time is the length of time (in ms) the foot is in contact with the ground during a running stride, from heel strike to toe off. This is an important component of the complex timing of events during a running stride. As speed increases, ground contact times tend to decrease. Sprinters will have Contact Times in the 115 ms to 150 ms range, and distance runners will be in the 170 ms to 275+ ms range.
- More-accomplished distance runners tend to have shorter Contact Times than novice runners at comparable speeds. There is some evidence that runners with shorter Contact Times are more economical than those with longer, but the subject pools for these studies are limited and short Contact Times may also be associated with higher impact characteristics at footstrike.
- There are three general categories when describing Footstrike Type: heel, midfoot, and forefoot striker. Heel striking has gotten a lot of bad press recently, largely because of the Christopher McDougall book Born to Run and a study (Daoud, et al, 2012) out of Harvard indicating that heel strikers are roughly twice as likely to have a stress related injury than forefoot strikers. However, other studies have shown no difference in injury rates between the two groups (Kleindienst, 2003 and Walther, 2005).
- Types of injuries tend to differ between the groups. Heel strikers tend to have more knee and hip injuries, and forefoot strikers tend to have more Achilles and calf strains and metatarsal injuries. Midfoot strikers will have characteristics in common with the both, often moving between the heel and forefoot strike patterns.
- Many things can influence Foot Strike Type—speed, footwear, and terrain being the most common.
Impact & Braking Gs
- When the foot impacts the ground it goes through a very rapid change in velocity—from around 1 m/s to zero in a matter of milliseconds. This creates a "shock" at footstrike that is transmitted through the body primarily via the skeletal system. This rapid change in velocity, or shock, is called an acceleration and is measured with a 3-axis accelerometer. It is not a force, but it correlates well with certain characteristics of impact forces at footstrike and is thought to be a better predictor of injury than impact force peaks.
- By collecting RunScribe data from thousands of runners and pooling the data, we hope to determine if: 1) high-impact or Braking Gs are good predictors of injury, 2) different shoes or cushioning characteristics reduce or increase Impact Gs, and 3) different running surfaces affect Impact Gs.
- The maximum angular rate at which the foot pronates between footstrike and the point of maximum pronation. Values range between 200 and more than 1000 deg/sec and are influenced by a number of factors including: running speed, terrain, Footstrike Type and footwear.
- Research is not conclusive, but it is likely that max Pronation Velocity is related to increased injury risk.
- Pronation is a complex tri-planar movement that centers around the Subtalar foot joint. It is estimated by measuring the rearfoot angle during ground contact while running and/or walking.
- RunScribe measures Pronation Excursion, which is the total range of angular movement (in degrees) as the foot rolls inward between footstrike and the point of maximum pronation.
- It is important because it has been labeled as a potential indicator for overuse injuries while running. However, it is a natural movement and is an effective means of shock absorption at footstrike.
- Even though the running shoe industry has put enormous emphasis on the need to “control” excessive pronation, the research has been inconclusive in regard to its contribution to injury. We believe that with crowdsourced RunScribe data, we can get a better sense of the relationship between pronation and running injuries.
Step Rate & Stride Length
- Step Rate (SR) refers to the number of strides a runner takes per minute, and Stride Length (SL) is the distance, in meters, between footstrikes of the same foot. Speed is a function of both SR and SL and is calculated by the equation: Speed = SR x SL.
- Previously, it was believed that runners increased their speed by increasing both SR and SL together UP to a point, beyond which only SR could be increased to gain additional speed.
- We now know that different runners employ different strategies to change their running speed, but the reason for the variation in strategies is not well understood. It is well documented that more experienced runners tend to have higher SRs than novice runners at comparable speeds.
- These metrics are important because runners with shorter SLs and higher SRs tend to have lower impact forces and Impact Gs at footstrike which, in turn, may help prevent injuries.
- Flight Ratio is the ratio of a runner’s “Flight” time in the air (non ground contact phase) and overall step time. Step time is defined as flight time plus ground contact time. It is expressed as a percent and recent research has indicated it as an indicator of running efficiency.