PURPOSE: Recent studies suggested that women and men's ultra-swim performances may be similar for distances of ~35 km. The present study investigated both the gender difference and the age of peak ultra-swim performance between 1983 and 2013 at the 46-km 'Manhattan Island Marathon Swim' with water temperatures <20°C.
METHODS: Changes in race times and gender difference in 551 male and 237 female finishers were investigated using linear, non-linear, and hierarchical multi-level regression analyses.
RESULTS: The top ten race times ever were significantly (P<0.0001) lower for women (371±11 min) than for men (424±9 min). Race times of the annual fastest and annual three fastest women and men did not differ between genders and remained stable across years. The age of the annual three fastest swimmer increased from 28±4 years (1983) to 38±6 years (2013) (r2=0.06, P=0.03) in women and from 23±4 years (1984) to 42±8 years (2013) (r2=0.19, P<0.0001) in men.
CONCLUSIONS: The best women were ~12-14% faster than the best men in a 46-km open-water ultra-distance race with temperatures <20°C. The maturity of ultra-distance swimmers has changed during the last decades with the fastest swimmers becoming older across the years.