Hitting the Bricks

During training, a triathlete frequently attempts to mimic race conditions in an attempt to minimize outside factors which can affect their performance. One weapon in the triathlete’s training arsenal is “brick” training. “Brick” workouts are defines as training one triathlon discipline followed immediately by another, most frequently, a bike workout followed by a run. This article will focus mostly on this type of combination.
Brick workouts attempt to accustom the athlete to the demands of changing from one type of exercise to another. According to Milet et al , when looking at the transition between cycling and running, several factors negatively influence running performance. “Laboratory data indicate that triathlon running is harder than control running at the same speed.” (1) While most triathletes would undoubtedly agree, the protean reasons why the run challenges the athlete are debatable. Researchers have suggested glycogen depletion, ventilatory muscle fatigue, dehydration, leg muscle fatigue, redistribution of blood to different muscle groups, as well as modifications in running economy. Some or all of these factors may play a role, however, the ultimate result can compromise maximum running performance.
Training strategies can mitigate many if not all of the debilitating factors leading to an unencumbered running effort. That said, studies show that the elite triathlete gains little from brick workouts, presumably due to overcoming the afore-mentioned limiting factors either from previous training or from the multiple race transitions. Junior triathletes, however, can greatly improve ranking times after the cycling transition by employing some training and strategies:
1) Decreased cycling energy expenditure at a given speed results in increased running performance. Thus, athletes should take advantage of drafting in draft-legal competitions.
2) Increasing aerodynamics can decrease energy expenditure on the bike, thus, finding the most aerodynamic position can result in better run performance.
3) Increasing base aerobic capacity allows greater demands in the transition to be tolerated.
4) Short, back to back, brick sessions, i.e. cycling 10 k followed by a 2 k run followed again by a 10 k bike and a 2 k run.
5) Since the cycling transition compromises running economy, performing technical workouts focusing on maintaining running form after a cycling effort.
6) Minimizing the time in the transition area. ( A subject for a later article )
In summary, one can superficially see triathlon as three individual sports each which can be mastered in isolation. In reality, the intertwining of the disciplines frequently fools the novice triathlete. The sport must be seen as a whole whose parts integrate in such a manner that the swim affects the subsequent cycling just as the cycling ultimately affects the run. Without such insight, the triathlete will never reach their maximum performance.

Millet G, Vleck V, Physiological and biomechanical adaptations to the cycle to run transition in Olympic triathlon: review and practical recommendations for training. British Journal of Sports Medicine 2000;34:384-390