The Harvard School of Public Health Boston study – spanning 12 years and some 10,500 male subjects – saw the longitudinal study collect data from men aged 40-75 years.
Strength training – as opposed to aerobic exercise – has been found to be more beneficial in preventing an increase in waist circumference (WC) a recent study has found.
http://fitness.org.au/articles/most-recent/strength-training-the-key-to-your-waistline/50/1151/184