The squat is one of the most functional exercises you can perform, yet is also one of the best exercises for building leg strength and muscle mass, as well as core strength. Yet if you walk into many gym chains these days you’ll find trainers having their clients do squats on exercise balls and other instability devices because they tell them it’s better than doing them the regular way on the floor. FLEX has always believed this overuse of “functional” training devices to be a step in the wrong direction. And unless you’re training a circus performer, squats done with both feet flat on the floor is the best way to increase muscle size, strength, and functionality.
Researchers from Norway had subjects with about five years of weight-training experience perform squats either on the floor or on three different unstable surfaces: a power board, a BOSU ball, or a balance cone. They measured their force output (strength), as well as the muscle activity of the vastus lateralis, vastus medialis, rectus femoris (three of the major quadriceps muscles), biceps femoris (major hamstring muscle), rectus abdominis, external obliques, soleus (deep calf muscle), and erector spinae during each of the four different variations of the squat.
They reported in a 2013 issue of the Journal of Strength and Conditioning Research that the subjects had the highest strength when they squatted with their feet on the floor. The power board led to a 10% reduction in their strength, the BOSU ball reduced their strength by 20%, and the balance cone reduced strength by 25%. When they squatted with their feet on the floor they also had significantly higher muscle activity of the three major quadriceps muscles measured and the erector spinae, compared with the unstable-surface squatters.
Squatting with both feet on the floor rather than on unstable devices is definitely the best way to go for building bigger and stronger legs.
When it comes to squats, the only equipment you need is a power rack or squat rack, a good Olympic bar, and a lot of 45-pound plates. Let the “know-it-all” trainers use the unstable devices with their clients who somehow never seem to get bigger or stronger legs.