Watch enough fitness gear infomercials and it’s easy to assume that working out is the domain of the young. But a new meta-analysis published in the February 2011 issue of Medicine & Science in Sports & Exercise reveals huge benefits to continuing to train as you age. Researchers looked at 49 studies and found that resistance exercise, especially higher-volume programs, significantly increases lean body mass in aging adults. They also found that these programs may be even more effective for individuals who have lifted weights earlier in life. Meanwhile, a study in the February 2011 issue of the Journal of Strength and Conditioning Research found that when older men undertake a whole-body, heavy-resistance training program, they can increase muscle mass and strength to levels similar to those of younger men. Combine the two findings, and you really have no reason not to hit the gym at 40, 50, 60, 70 and beyond. Rest in peace, Jack LaLanne.