The Association Between Physical Activity in Leisure Time and Leukocyte Telomere Length

Lynn F. Cherkas, PhD; Janice L. Hunkin, BSc; Bernet S. Kato, PhD; J. Brent Richards, MD;
Jeffrey P. Gardner, PhD; Gabriela L. Surdulescu, MSc; Masayuki Kimura, MD, PhD;
Xiaobin Lu, MD; Tim D. Spector, MD, FRCP; Abraham Aviv, MD

This is a totally fascinating study that looked at the association between physical activity during leisure time and relative age in biologic twins. The study concluded that inactive subjects may be biologically older by 10 years compared with more active subjects of the same chronologic age. This was a huge study involving over 2400 biological twins. All of the subjects completed a questionnaire which detailed their self-reported physical activity level during their leisure time and at work for the past 12 months. They were broken down into four categories from inactive to heavy activity. The relative age was determined by measuring the length of a segment of their DNA called the telomere. The telomere is a inactive segment of DNA that acts like a bookend dividing the signaling part of the DNA. As the person ages the length of the telomere gets less and less over time. Since both the twins were born at exactly the same time, comparing the lengths of their telomeres allowed an estimate of their relative difference in age. The results of the study showed that comparing the most inactive to the most active twin revealed an age difference averaging 10 years. Essentially exercise or activity had made one of the twins biologically 10 years younger than the other.