The sport → The person

1. boxing → boxer

2. swimming → swimmer

3. skiing → skier

4. ice-skating → ice-skater

5. gymnastics → gymnast

6. athletics → athlete

7. motor racing → racing driver

8. cycling → cyclist

9. horse racing → jockey

10. the pentathlon → pentathlete

11. sailing → yachtsman

12. rowing → rower

13. sky diving → sky diver

14. weightlifting → weightlifter

15. climbing → climber