It's hard to imagine, but as late as the 1950s, athletes could get kicked off a team if they were caught lifting weights. Coaches had long believed that strength training would slow down a player. Muscle was perceived as a bulky burden; training emphasized speed and strategy, not "brute" strength. Fast forward to today: the highest-paid strength and conditioning coaches can now earn $700,000 a year. Strength Coaching in America delivers...