1. Abebe Bikila, an unknown Ethiopian athlete won the Olympic road marathon barefoot in 1960. 
2. Matey Kaziyski registered an 82mph spike (a particular volleyball strike) at London 2012.
3. Of the 28 possible Olympic gold medals in basketball (across the years and sexes), USA have won 21. 
4. John Boland won the Olympic men’s singles tennis in 1896 wearing leather soled shoes with heels.
5. Gymnasts at the ancient Olympics used to perform nude – the word gymnos is Greek for naked. 
6. Archery arrows travel up to 140mph.
7. 25.4 tonnes of floating rubbish had to be removed from Guanabara Bay during rhe Olympic trials last year – not such a fun fact!
8. Horse rider Otomar Bures took over 2 1/2 hours to complete a 5 mile cross country course with a time limit of 17 minutes 46 seconds in 1936, he incurred 18000 penalty points.
9. In 1908 Cornwall won silver in rugby sevens (as the best English and Welsh players were unavailable, Cornwall’s team were fielded as they’d won the county championships).
10. Divers hit the water up to 35mph, to mitigate the stress on the body machines are used to produce tiny ripples of air bubbles to soften the water and lower water tension. 
11. Long distance runners have the greatest aerobic capacity of all athletes, followed by synchronised swimmers. 
12. Johnny Weissmuller aka “Tarzan” won 5 Olympic gold medals in swimming and water polo in 1924 and 1928 before finding fame on the big screen.
13. If Michael Phelps was a country, he would be 39th on the “all time medals” list! (As of 10/08/16 with 21 golds, 2 silvers, 2 bronze.) 
14. Great Britain’s first (ever) Olympic gold medal was in weight lifting, Launceston Elliot won the one-armed lift in 1896.
15. Male wrestlers have a rule about beards! They must either be close shaven or have a beard of several months growth.

All facts from bbc.co.uk/sport