New Delhi, March 14 -- Fatigue is natural. The body gets tired and sore after physical activity. There is mental fatigue as well, but in fitness, the term usually refers to a more intense feeling of tiredness. When experienced physically, fatigue can lead to throbbing and quivering muscles, inhibited movement, queasiness and even lightheadedness. None of this sounds fun, but what if there was a way to use this feeling in a measured way to get fitter and build endurance thereby pushing the body's fatigue threshold even further?

The first time I heard of "training in fatigue" was during an interview with Peter Hartley, former captain of Jamshedpur FC, for a Lounge story titled ISL: How Jamshedpur FC's Peter Hartley trains to win. In the in...