Long Slow Distance or Long Steady Distance (LSD) is running at moderate intensity just below your maximum aerobic heart rate. The LSD run is at a comfortable pace that, for most runners, is about 2 minutes slower per mile than their current 10k pace. You should be able to easily carry on a conversation without panting for breath or cramping.

Running LSD means that you’re running aerobically, that is, your body is getting sufficient oxygen. The objective of these runs is to build blood volume and to increase muscle strength, endurance, and aerobic fitness. As you run, you put your body under stress, and body cells are destroyed. During the 48 hours after your runs, your body reacts to the stress by rebuilding the body cells, and the end result is that you’re stronger than you were before.

By gradually extending LSD runs, you train muscle cells to expand their capacity to utilise oxygen efficiently, sustain energy production and, in general, increase their capacity to get you further down the road.  The continued increase of the distance of long runs extends the reach of blood artery capillaries to deliver oxygen and improves the return of waste products so that the muscles can work at top capacity.  LSD runs improve the muscles response to speed training and racing.

See more definitions in the Definitive Guide to Running Terms.

Popularity: 1% [?]