Doug Salomon
It's from Men's Health magazine, bit don't let that dissuade you from trying it. There's nothing exclusively "manly" about it.
Berikut tantangan plank 30 hari yang cukup bagus yang saya lakukan baru-baru ini. https://www.menshealth.com/fitness/a35856218/30-day-plank-challenge/
Awalnya cukup mudah, tetapi berakhir cukup sulit.