Cross-training is athletic training in sports other than the athlete's usual sport. The goal is improving overall performance. It takes advantage of the particular effectiveness of one training method to negate the shortcomings of another.
In general sports
Cross-training in sports and fitness involves combining exercises to work various parts of the body. Often one particular activity works certain muscle groups, but not others; cross-training aims to eliminate this imbalance.
In mixed martial arts
In mixed martial arts and self-defense, cross-training refers to training in multiple martial arts or fighting systems to become proficient in all the phases of unarmed combat. This training is meant[by whom?] to overcome the shortcomings of one style by practicing another style which is strong in the appropriate area. A typical combination involves a striking-based art such as Muay Thai, combined with a grappling-based art such as wrestling and Brazilian Jiu-Jitsu. Many hybrid martial arts can be considered[by whom?] derivatives of such cross-training - most notably Dan Inosanto's Jeet Kune Do concepts, a hybrid of Filipino martial arts, wing chun and savate, Apolaki Krav Maga & Dirty Boxing, a hybrid martial-art blending Krav Maga, Filipino martial arts, silat and Brazilian jiu-jitsu and kajukenbo, an American hybrid art consisting of karate, tang soo do, jujutsu, kenpo, and boxing.
Modern mixed martial-arts training generally involves cross-training in the different aspects and ranges of fighting.
In water sports, cross-training often involves doing exercises and training on land. This is often referred to by swimmers as "dryland". For swimming, cross-training frequently includes running, stretching, and other resistance and agility training. Diving dryland exercises include various unique exercises such as on-land landing biomechanics training. 
- Chess boxing
- List of multi-sport athletes
- Multisport race