*4.1. RunningCoach App*

The purpose of the RunningCoach app is to serve as the remote monitoring node. As such, it collects data about each run, including energy expenditure, cadence, speed, heart rate, and distance covered. In addition, the app administers the surveys after each run. Figure 3 depicts various screens from the RunningCoach app. Concretely, Figure 3a depicts the home screen of the app, listing previous runs; Figure 3b,c depict two screens shown during the run, presenting the runner's cadence and speed, respectively.

Finally, the app delivers the real-time feedback to the runners regarding their cadence and/or speed levels (depending on the settings). If the cadence or speed are outside of a preset range around the target values of the day, according to the training regimen, the phone provides haptic feedback (vibration) and auditory cues (beeping) to the runner. The vibration and beeping patterns depend on whether the runner is higher than the target value or lower than it, allowing the runner to adjust accordingly. This preset range can be set by the subject in the app, with a default value of 10% (around the target cadence or speed).


**Figure 3.** (**a**) A screenshot of the home screen of RunningCoach, summarizing the past runs; (**b**) a screenshot from the app during a run showing the cadence significantly lower than its target value (outside the 10% range of the target cadence); and (**c**) a screenshot from the app during the run showing the speed within acceptable range of its target value (within 10% of the target speed) [11].
