Sit upright on a cable machine with your back supported and an ankle strap attached to one leg. Start with your knee bent and foot close to the starting position. Slowly extend your leg forward by straightening your knee against the cable resistance until your leg is fully extended. Pause briefly at the top and squeeze your quadriceps. Then slowly return to the starting position in a controlled motion. Keep your torso still and avoid swinging or using momentum.
Log your cable seated leg extension sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.