The sample size ranged from 30,801 (1999) to 33,326 (2001), and the response rate ranged from 69.6% (1999) to 74.3% (2002).7 Respondents were asked to report the frequency with which they engaged in strength training by answering the following question: ???How often do you do physical activities designed to strengthen your muscles, such as lifting weights or doing calisthenics???? The same questio