Long Slow Distance

Long slow distance (LSD) is a form of aerobic endurance training in running and cycling. Physiological adaptations to LSD training include improved cardiovascular function, improved thermoregulatory function, improved mitochondrial energy production, increased oxidative capacity of skeletal muscle, and increased utilization of fat for fuel. Ernst van Aaken, a German physician and coach, is generally recognized as the founder of the long slow distance method of endurance training.

Long slow distance training is a form of continuous training performed at a constant pace of low to moderate intensity over an extended distance or duration. The moderate training intensity of LSD is effective in improving endurance and maximum oxygen uptake in individuals who are undertrained or moderately trained. Long slow distance training is thought not to be effective when used in isolation by well-trained athletes, who in order to achieve further improvements in metabolic conditioning require higher training intensities that are not sustainable at the work durations associated with LSD.