1920 in Canadian football 1920 in Canadian football CIRFU and IRFU adopted a four-yard Interference rule while the CRU opted for three yards of Interference. ARFU played games with 12 players per side and introduced the snap-back. The reduction in the number of players was done for monetary reasons as train rates were high after World War I. The CRU would make the same changes in 1921. The MRFU champion Winnipeg Victorias were unable to field a full team for the WCRFU finals and withdrew from competition. The MRFU wanted to substitute the second place University of Manitoba Varsity team but the SRFU refused
Comparison of Canadian football and rugby union running backs, receivers, and quarterbacks have roles similar to backs in rugby. Because of the playing time, number of pauses, number of players and the nature of the game in general, rugby players will typically need higher physical endurance than Canadian football players while more short-term bursts of physical strength, power, and speed are required in Canadian football (amongst equivalent positions and weights). Collisions between players in rugby union tend to last significantly longer than Canadian football, in which collisions are more often "hits" in which the momentum of the player is enough to bring the other player to ground