There is simply no other exercise, and certainly no machine, that produces the level of central nervous system activity, improved balance and coordination, skeletal loading and bone density enhancement, muscular stimulation and growth, connective tissue stress and strength, psychological demand and toughness, and overall systemic conditioning than the correctly performed full squat... There is no such thing as “firming and toning.” There is only stronger and weaker... Strong people are harder to kill than weak people, and more useful in general.