It is important to maintain proper posture when practicing the double-bass technique as you build strength. Sitting straight on the stool or bench and leaning forward slightly at the waist allows you to use the muscles responsible for the drumming, i.e., the calves on the backs of the lower legs and tibialis on the lower fronts (the shins). Correct posture will allow you to use these muscles as intended and not rely on muscles on the upper legs or thighs, which may result in an uneven-sounding lick or tire you out too quickly. Correctly placing your feet on the pedals will help you hit the pedals as required: place the groove of the pedal between your toes and the remainder of your foot, thus helping you strike the pedal without exerting extra effort.
Playing basic rudiments normally used for the hands can work being applied to the feet as well. Playing these patterns helps with the foot dexterity needed to make the double bass sound even. Simple paradiddles can help increase foot speed in both the right and left foot. Other drummers recommend beginning double-bass fills with the left foot versus the right, since the left is already positioned on the high-hat, thus making the transition to play the fill easier. It also pays to begin the lick heel up versus starting with your toes.
A favorite among bodybuilders, calf raises strengthen the related muscles. Simply stand or sit and press the pads of your toes into the floor, thus raising your foot using your calf muscles. Conversely, keeping your feet flat on the floor while sitting and raising your foot upward works the tibialis. These exercises can be performed either with your body weight or by using weights over your shoulders while standing or on your knees while sitting.