Planks are one of the most effective exercises because they fire up so many muscles at once, especially the core and upper body. You can make them even harder – you know you want to! – by adding a pair of dumbbells. Grab a pair of three- to 10-pounders and throw these moves into your next routine. Since plank position can be tough on the wrists, alternate these plank variations with moves that give your hands a break, such as squats or lunges.
Related: 2-Week Plank Challenge
Source: Pop Sugar