April: Play

   We are first seduced into running as children, usually by the exuberance of speed. Then we get all rational and buttoned down about it. Too often speed becomes a mechanized subsidiary of our running programs - interval training for racers, and infrequent drills and hill charges for the rest of us. The joy of speed is driven from our workouts.

   Pleasure aside, the payoff is sweet. We get progressively stronger with smaller amounts of effort. Sprinters have no alternative. Interval training - repetitive, calculated bursts of speed followed by ever-shorter recovery periods - is the single most powerful tool discovered in the past 70 years for improving performance. Middle distance runners benefit as well, since intervals improve stamina in the late stages of a race. And now even marathoners are discovering the sublime magic of intervals, Training hours can be slashed with no hit to performance. Intervals allow more time for rest between workouts, which is when muscle is built. They reduce the risk of injury. Two of the leading marathon programs in the country now try to eek out more speed and endurance with less training time. Intervals are key.

   Noncompetitive runners, on the other hand, tend to eschew any form of speed work, except as diversion-to strengthen neglected muscles and to bring variation to the workout. Yet a tide of evidence shows that interval training benefits those trying to lose weight, pre-diabetics, beginners, runners over 65, those returning from knee and foot injuries, cross-trainers, those with irregular workout schedules, and trail runners. Intervals help you lose weight with less work. They dramatically improve the efficiency with which your body uses oxygen. They increase stamina and speed. And these benefits accrue quickly - often within a matter of weeks. Suddenly, runners can't run away from speed. No matter what your goals are, intervals will help you achieve them.

   Of course, cod-liver oil and colonoscopies are good for you, too, though pleasure doesn't exactly capture their essence. So approach intervals as play. On your next run, simply put on a sprint. Enjoy it. When you begin to feel winded, slow to almost a jog. Once you recover, put on another sprint. This is your essential interval. How fast you go is less important than how long you sustain the quick pace. When the challenge and exuberance begin to please you, you'll want to use a stopwatch and, if you have one, a heart-rate monitor. There are all manner of interval workouts on the Internet; coaches and trainers perfect and post their techniques as if they were alchemy.

   Play should continue to guide you, even if you're a competitive runner. There are very few other rules that matter. Don't do intervals on successive workouts. Give yourself a longer cool-down session before you stop. lf you've had a serious leg injury, if you have a heart condition, or if you're over 50 years old, talk to your doctor first. Otherwise, return to speed work with a child's point of view.