With proper form, tuck-ins build muscle across your entire body, but mostly the core.
Slik gjør du det
Perform tuck-ins by lying faceup with your arms extended above your head.
Simultaneously lift your upper body and lower body, bringing your knees close to your chest.
Reach your hands past your knees and pause for a moment in that position.
Lower your upper and lower body to the starting position while keeping your core engaged and repeat.