Experienced gym trainer here. Setelah mencoba2, yang sampe skrg bikin :
Makin lama =
- plank
- lari pelan, tapi inclined.
- berenang
Makin kuat hentakan, alias bikin gacor =
- lower body, kaya hip abductor
- lunges
- kickback.
paling best -> megacore / lagree. ini bikin "genjotan" kaya ombak laut.