Stand facing a Smith machine bar set at waist height with feet shoulder-width apart. Grasp the bar with an underhand grip and keep your elbows close to your sides. Curl the bar upward by bending at the elbows, squeezing your biceps at the top, then lower the bar back down with control while keeping your core engaged and upper arms stable.
Log your smith machine bicep curl sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.