Serum collagen-derived peptides are unaffected by physical training in older sedentary subjects.

Cardiac fibrosis occurs with normal aging and may have important pathological consequences. Accumulating evidence shows that biochemical assessment of fibrosis using collagen markers such as serum levels of the aminoterminal propeptide of types I and III collagen (PINP, PIIINP) and the carboxyterminal telopeptide of type I collagen (ICTP) represents a practical, validated and non-invasive method to assess myocardial collagen turnover. It is generally accepted that a sedentary lifestyle may be at least partly responsible for the age-related changes in the cardiovascular system. We aimed to investigate whether dynamic aerobic endurance training at lower or higher intensity (33% and 66% of heart rate reserve) may influence markers of collagen synthesis (PINP, PIIINP) and degradation (ICTP) in at least 55-year-old healthy sedentary men and women. A randomised crossover study comprising three 10-week periods was performed. In the first and third period, participants exercised at, respectively, lower or higher intensity in random order, with a sedentary period in between. Training programs were identical except for intensity and were performed three times 50 min/week. 39 (18 men) out of 48 randomised participants completed the study; age averaged 59 years. Serum concentrations of PINP, PIIINP and ICTP were determined at baseline and at the end of each 10-week period. Our results showed that 10 weeks of endurance training at lower or higher intensity did not significantly alter serum markers of collagen synthesis and degradation in healthy older men and women.