The Effect of Crank Arm Length on Cycling Economy and Performance in Triathlon

Given the nature of a triathlon race, the cycling distance is typically much longer than swimming and running across race distances from sprint to Ironman. Besides, triathletes should try to not only maintain a certain level of cycling power but also consider cycling economy to make a better performance in both the cycling portion and the overall race (Bonacci et al., 2013; Sleivert & Rowland, 1996; Swinnen et al., 2018). The cycling economy is an important indicator to predict cycling performance in terms of time to complete a certain distance. Both cycling economy and performance are determined by the interaction between mechanical output and physiological input (Barratt et al., 2016; Korff et al., 2007; Sunde et al., 2010). Theoretically, improving cycling economy elicits a better cycling time trial performance and/or less physiological demands (e.g., rate of oxygen consumption: V̇O2, heart rate) to complete at a given distance. The crank arm length (CAL) is one of the important factors among many variables that affect the economy and performance in cycling (McDaniel et al., 2002). Therefore, the appropriate selection of CAL may play a key role in improving the cycling portion of the race and entire triathlon performance. The purpose of this review is to identify the effects of acute changing CAL on physiological and biomechanical responses during cycling.