Sports athletes tend to use HIIT workouts (High Intensity Interval Training) to enhance their performance, HIIT also helps them burn off fat without losing their muscle mass.
Do not expect a workout like this to be a walk in the park though, HIIT is very intense if done right and because of its intense nature it will have you burning fat through the day long after you finished the routine.
The How To
Athletes keep HIIT workouts brief but like I said VERY intense.
First you warm up for 10 minutes to avoid injury, than sprint at top speed for 15-30 seconds depending on your fitness level, you jog light for 60 seconds, after that repeat the sprint making it shorter if you are getting fatigued, do this for 20-30 minutes, after that do 10 minutes of static stretching and you are done.
Including HIIT in Your Routine
It would be dumb to think that athletes only do HIIT without anything else, this is only a small part of what they do to enhance their athletic performance.
Athletes also lift weights, depending on the sport weightlifting is either a supplementary workout to their training (boxers) or a vital part of it (powerlifters), the point is that they all hit the gym.
HIIT workouts should be done 2-3 times a week on a non weightlifting day, HIIT alone will not help you lose as much fat just as only lifting weights wont (lifting weights also burns fat).
For The Sportsmen Out There
HIIT is in reality a conditioning workout that athletes use to avoid running out of steam, a boxer who would want to last longer in the ring will get endurance benefits from a HIIT workout, so will a football player who will benefit by being able to run in the field more without getting tired and since HIIT helps you avoid losing muscle big football players will benefit more.
If you are either playing an occasional match with friends or are in an amateur sports league you will get 10 times more benefits from doing HIIT, you will burn fat like crazy and do better in the sport.
Think For Yourself
One last thing, you might not be able to do a 15 second sprint and 60 seconds of rest might not be enough, the important thing is that you make the workout challenging for you but not impossible, every athlete follows a different program specifically customized for his abilities, even in the same sport so customize the workout to leave you tired in the end but not impossible.
The same thing goes if you find the HIIT workouts too easy.