In working with the body for over a decade now, massive respect and acknowledgement has amassed for the foot & the critical role it plays in virtually all weight bearing movement. I have seen this foot exercise explained & demonstrated numerous times (best by podiatrist Emily Splichal) & have been implementing both personally & clinically for a few years now with great results.
This demo video going well beyond the short foot activation procedure & into how it is the catalyst to spark needed strength, stability, balance & power from the foot, to the ankle, to the knee, to the hip & pelvis; stabilizing the spine from the base at the sacrum upward through the lumbar, thoracic and even cervical regions. Due to fascial connections in the body, turning the foot on in this manner is arguably the first step to truly engaging and activating the core via concurrent triggering of the pelvic floor and diaphragm.
Proper short foot activation and subsequent biomechanics are an essential component when truly looking to address virtually all injuries from the lower extremity up.