The purpose of our study is to establish the most effective running retraining technique to decrease ground contact time. This will be investigated by applying three running retraining conditions and assessing the change in ground contact time and other biomechanical variables between the runner's baseline running and each retraining technique.

The purpose of our study is to establish the most effective running retraining technique to decrease ground contact time utilizing three common running retraining methods in healthy runners.

The first aim will be to apply three running retraining conditions and assess the change in ground contact time and other spatiotemporal and biomechanical variables between the runner's baseline running and each retraining condition.

The three running conditions will be at the participant's self-selected speed corresponding to "a comfortable run for 30 minutes". The conditions will be, condition 1: a verbal cue to "pull your foot off the ground as quickly as you can," condition 2: a metronome set to 10% above their preferred cadence found during the baseline run, and condition 3: visual feedback to reduce their ground contact time through observing that number in real time provided by a commercial IMU. The participant will attempt to lower that to 5% below their baseline run ground contact time by being given that target number on a sheet of paper.

The second aim will be to examine the effect of the 3 running conditions on the runner's level of exertion and difficulty using the Omni Rate of Perceived Exertional Scale, the Rate of Perceived Difficulty, and ranking the techniques from 1 to 3 on which they felt was most natural.

We hypothesize that each method will reduce ground contact time, but condition 3 providing continuous visual feedback will result in the most consistent decrease to ground contact time across the runners and will be perceived as the easiest to perform.

Overall, this study will provide clinicians with a running retraining intervention that has been objectively shown to decrease ground contact time and provide researchers with a method to further investigate its effect on running injuries.

Inclusion Criteria:

• Military Service Member or USMA cadet between the ages of 17-60
• Run at least 2 miles three times per week for the past 3 months
• Able to run for at least 15 continuous minutes at a self-selected speed
• Fluent in the English language to read and provide informed consent and follow study instructions

Exclusion Criteria:

• Lower extremity or low back pain in the previous 3 months
• Lower extremity or low back surgery in the previous 6 months
• Self-reported pregnancy or given birth within the last 6 months
• Currently on a profile that restricts or limits running

We do not have a data sharing agreement or plan to share IDP as part of our IRB protocol.