Some minor speed improvements occur but only when training is initiated from an untrained or marginally trained state. Thus, continuous training of this type is limiting with regard to its potential to make athletes complete events faster. For speed to improve, higher forces have to be developed in the muscles. This is best done through interval training where volumes of higher forces can be tolerated because of the intermittent rests that are involved. The increased forces recruit slow and fast-twitch fibers and with moderate training intensities adapt both fiber types aerobically.
Higher intensities increase the threat of lactic acid accumulation.
There is no option for improving speed and endurance in training other than to design training items that stimulate both types of muscle fiber bundles. Return to Table of Contents for this issue .