From the paper itself:
"For runners, sprint/power athletes were defined as those who competed in 100–400 m races and high jump, while distance athletes competed in races ≥800 m. Short distance swimmers comprised those competing in 50–200 m races while middle-distance/distance athletes competed in 400–1500 m races. Eleven swimmers swam freestyle, 3 swam breaststroke and 2 swam backstroke."
The phrase "there were interesting if small differences" makes me suspect nothing statistically significant was found. Digging into the paper, I found the sentence I was expecting:
"Further research is required to delineate whether these observations are a product of a superior exercise stimulus, or a necessary adaptation to promote filling during upright exercise."
Any small sample of undergraduates always gives the same scientific result: more grant money required.