Which is best exercise for activating intrinsic muscles of foot?

Your goal is to strengthen the intrinsics muscles of foot. The question is which exercise is best?

This study closely observed all muscle activation of the abductor hallucis, flexor digitorum brevis, abductor digiti minimi, quadratus plantae, flexor digiti minimi, adductor hallucis oblique, flexor hallucis brevis, and interossei and lumbricals with the short foot, toe spreading, big toe extension and lesser toes extension exercises with T2 weighted MRI.

They have found in study that

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all muscles showed increased muscle activation after all exercises. The mean percentage increase in activation ranged from 16.7% to 34.9% for the short-foot exercise, 17.3% to 35.2% for toes spread out, 13.1% to 18.1% for first-toe extension, and 8.9% to 22.5% for second- to fifth-toes extension.

All the intrinsic muscles assessed in this study showed increased activation with all exercises. The short- foot exercise, toes-spread-out exercise, first-toe–extension exercise, and second- to fifth-toe–extension exercise each activate the intrinsic plantar foot muscles.

image courtesy : runstatic.com

Full.text https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5094843/