https://www.healthline.com/health/fitness/functional-fitness-adults?slot_pos=article_2&utm_source=Sailthru%20Email&utm_medium=Email&utm_campaign=generalhealth&utm_content=2021-05-20&apid=36929682&rvid=cded95459555b445d044db2977410c97aa2ce21d0688c96624f02c326c3915c1#side-plank
