Tibialis Raise

Stand with your heels a step or two away from a wall, leaning your back against it for support, feet flat on the floor. Lift your toes and the front of your feet up off the floor as high as you can while keeping your heels planted, then lower them back down. This works the muscle running down the front of your shin, the opposite motion to a calf raise, and it fatigues fast even with no added weight. Keep your knees soft rather than locked, and use the wall for balance rather than to push yourself up.