LSD

A Long Slow Distance run is exactly what it sounds like: a long run, completed at a slow, easy pace. Long slow distance training helps runners create strong cardiovascular fitness that can improve speed workouts as well. LSD exercise improves the efficiency with which the body uses energy and thereby less oxygen at a given speed. In other words, you need less energy to complete your run, which boosts your endurance performance. While any type of long-distance training helps improve endurance, long slow distance running accomplishes this goal with the least amount of damage to your body. As your mileage gradually increases throughout your training, your body creates more slow-twitch muscle fibers, thus helping decrease fatigue and increase your ability to sustain activity.