Holding a barbell with both hands, palms facing towards your body in front of your legs, plant both feet on the floor hip-width apart. Draw your shoulder blades down and back to push your chest out slightly. This is your starting position. Inhale. Bending from the hips only, allow the barbell to run along the length of your thighs. Once the bar reaches your knees (A), bend your knees and allow the bar to run halfway down your shins and exhale (B). You should feel tension in your hamstrings (back of your legs). Push through your heels and, using your glutes and hamstrings, extend your knees and hips to return to the starting position. Ensure the barbell stays in contact with your legs. Do as many reps as you can in 20 seconds.