For the past 25 years, the average Ironman performance has risen progressively, resulting in an average 7.5% – 8% time improvement for all age groups over 45 years old. In a recent study of more than 900,000 marathon participants, one fourth of the runners in their mid to late 60’s outperformed half the runners aged 20 to 54.
– Source: Journal of the American Academy of Orthopaedic Surgeons, September 2014