The concept of cross training is a relatively recent athletic application, in which a training regime includes the use of one distinct athletic discipline to build skills or fitness in another.
In the not-so-distant past, sporting success was equated to the devotion of an athlete to the discipline. For an individual pursuit such as running or cycling, devotion was translated into the athlete spending every training opportunity engaged in one aspect or another of the sport to simulate competition. In team sports, the athlete would play or practice at every available moment; where there were no formal practices or games, the striving basketball player, soccer player, or ice hockey player would find a pick up game in their sport to continue the quest for excellence.
Increased popular interest in multi-sport events such as the triathlon in the 1980s, and the appreciation by the wider sport community of the training demands that such sports required, spurred a broader interest in the use of cross training. It became a fashionable approach to physical improvements in a very wide range of sports.
While the triathletes may have popularized multi-sport training regimens, the benefit of placing disparate—and sometimes contrary—demands on the body had its origins well before the Hawaii Ironman event rose to prominence in the 1980s. European sports trainers had advocated variety and intensity in athletic training regimens since the 1940s, usually through the introduction of cycling or an aerobic sport like soccer into an anaerobic training discipline, both for the building of strength as well as an understanding that, for the mental health of a serious athlete, "a change is often as good as a rest."
In the fabled 1972 Summit Series, an eight-game battle between the Russian and Canadian ice hockey powers, the superior skating speed, overall fitness, adept footwork, and balance demonstrated by the Russian players was later attributed to their cross training that included cycling and intense soccer games.
The physical preparation required in American football, a sport highly disciplined in its tactics and regimented through rules that stress positional play, has developed into a cross training emphasis that varies position by position. Running backs and receivers, the fast and powerful players who account for most of the scoring in a football game, have been engaged in high-level interval running, plyometrics, and weightlifting programs for many years.
Long before the development of sport science as a freestanding branch of academic and physical study, running was a common training adjunct to a wide range of sports. The mechanisms by which running generally assisted athletes were improperly understood, but there was a general understanding among athletes and trainers that distance running added strength and stamina to a competitor. Boxers are a notable example of this long-held knowledge; the sport is anaerobic in nature, as the athlete is required to expend significant amounts of energy in short intervals. Running provides the boxer with the endurance that permits a speedier recovery to resting heart rate and respiration levels before the next round in a fight begins.
Today, the principles of effective cross training are well established. Cross training generally is accepted as building a better all-around athlete, while providing a measure of protection for injury through increased fitness, as well as reducing the mental fatigue associated with a lack of training variety. Cross training also permits an injured athlete to continue with workouts and thereby reduce the degree of fitness that might otherwise be lost to injury.
The specific areas of human performance that are addressed in a typical cross-training program include: cardiovascular fitness; power, through increased muscle strength; speed; agility/reflexes; the use of all three of the body's energy systems, the aerobic system (endurance), the anaerobic lactic (intense energy demands of up to 90 seconds in duration), and the anaerobic alactic (short, very intense energy requirements); musculoskeletal flexibility; and mental acuity.
In many sports, the effect of cross training is achieved through simple means. A marathoner will today often augment a training program that involves running in excess of 80-100 miles per week (130-160 km), with a focused stretching, yoga, and weight training series, to assist with general fitness and help the body recover more quickly from the primary activity. Weight training has become an equally common cross training component of virtually every sport, as the science supporting cross training is clear that overall muscle strength is important to general athletic success.
The triathlon and the decathlon are the sports that most keenly bring into focus the principles of cross training. The triathlon, usually made up of swimming, cycling, and running segments that may be variable in length, is popular because it is a competitive sport for hundreds of thousands of participants who enjoy the training variety of the three disciplines. It is impossible to succeed in a triathlon unless the athlete spends significant training time and effort in each aspect. For events such as the Hawaii Ironman, the individual segments are so demanding (the run portion, after the competitor has completed a lengthy swim, followed by a road cycling segment, is a full 26.2-mi [42.2 km] marathon) that the training, which is a cross training schedule, will be very time consuming.
The decathlon presents an even more difficult cross training proposition. The athlete must prepare for ten different sports, each of which will engage systems and techniques that are almost contrary to the others. The 100-m sprint, requiring the short-term power of anaerobic alactic energy system, is a virtual polar opposite to the combined speed and endurance of the 1,500-m race. The high jump, with its emphasis on the takeoff, finesse, and form, has vastly different physical demands than those inherent in the shot put or the javelin.