WHETHER SEARCHING for the perfect workout or just the next fitness gimmick, coaches and trainers have a knack for creating wonderfully complicated routines. I once heard of a cycling coach who had his charges alternate between breathing and holding their breath every 10 to 15 pedal strokes during intervals that lasted several minutes. Between watching heart-rate monitors, counting their strokes, and monitoring their breathing, it's a miracle no one was hit by a bus.

Fitness doesn't have to be complicated to be effective. One simple approach is the negative-split workout, which entails starting at a moderate level and increasing it in the second half. This is great for:

Early-morning training: It's tough to go hard right after you wake up.

Chronic stiffness: Starting out slowly helps you loosen up, which means your hard efforts will be more effective.

The weight-conscious: Your body burns fat more efficiently once it's warmed up. If you go all out from the start, you'll be burning more carbohydrates than fat.

Here's an example of a 30-minute negative-split run: 1. Start with a five-minute warm-up of brisk walking and light jogging. 2. Run at a moderate pace for ten minutes. 3. Over the next ten minutes, subtly increase your pace at the end of each minute. If you start at a nine-minute-mile pace, you should finish at an eight-and-a-half-minute pace or faster. 4. Cool down for five minutes.