It is well established that success in triathlon, like many endurance sports, is primarily dependent on limitations of the cardiovascular system (9). These fitness measures can be tracked in the laboratory using tests such as maximal aerobic power (V̇o2max) and the anaerobic threshold, with the primary goal of the conditioning program being to increase these physiological attributes. Although general improvements in both aerobic and anaerobic fitness can be accomplished through nonspecific aerobic training, in accord with the principle of specificity, the 3 subdisciplines of triathlon require sport-specific training for optimal physiological adaptation and performance. Genetic limitations exist in both an athlete's untrained baseline and his or her potential to adapt to training (2). Given these possible training constraints on fitness adaptations, methods to increase an athlete's efficiency are of heightened importance, especially for truly elite triathletes who may approach their limits of aerobic and anaerobic fitness. However, efficiency is important for triathletes of all levels because energy saved in one leg of the race can potentially contribute to a better performance on the next.
As with swimming and running, cycling performance is highly dependent on biomechanical efficiency, and research shows that triathlon performance is strongly associated with measures of efficiency in all 3 disciplines (7). Lucia et al. (6) have demonstrated an inverse relationship between V̇o2max and biomechanical cycling efficiency in elite cyclists, suggesting that those who have lower aerobic fitness remain competitive through better cycling technique even at the highest ranks. The cycling leg of a triathlon is unique in that athletes begin the stage in varying states of fatigue from the preceding swim. Athletes must race the cycling leg with the goal of finishing with as little accumulated fatigue as possible while maintaining a competitive race position to start the run. Using matched cycling speeds on multiple trials of a sprint distance triathlon, Hausswirth et al. (5) have demonstrated that a greater efficiency on the bike leads to a significantly better run in elite level men's triathlon.
TRAINING CYCLING EFFICIENCY
The most common drills used with competitive cyclists to improve biomechanical efficiency involve 1) independent leg training drills, 2) increased cadence drills, and 3) leg strength and power drills. Independent leg training is generally performed sitting upright on a stationary trainer and involves supporting one leg off of the bike while focusing on a smooth crank cycle with the other leg (Figure 1). By eliminating double leg pedaling, the athlete must focus on all phases of the crank rotation, rather than just the down phase. Cadence drills are performed with light to moderate resistance and focus on increasing crank rotation speed without altering the form. Typically, a cadence of >100-110 rotations per minute is used as a starting point. Athletes should focus on a smooth and efficient rotation of the crank, while minimizing any inefficient movement, particularly of the upper body. Thus, if the athlete's upper body begins to deviate from the center position, or their buttocks begin to bounce on the saddle, the cadence should be adjusted down to facilitate practice with proper form. The goal of each of these drills is to improve efficiency and power output by eliminating movement that is nonpropulsive and decreasing the pattern of intermittent high-force loading using the knee extensors and plantar flexors. This is accomplished by retraining muscular engagement patterns and increasing the contribution from muscle groups, such as the knee flexors, hip flexors, and hip extensors to accomplish a smooth circular power output throughout the pedal stroke. Learning to adopt a high pedaling cadence (i.e., 20% faster than freely chosen cadence) in the last portion of the cycling leg has been shown to improve run times in elite male triathletes (4).
Strength and power training, employing either traditional resistance exercises or cycle-specific drills, such as slow cadence uphill cycling using the large chain ring, are used to improve maximal strength. By improving maximal strength, this effectively reduces the percentage of maximal contraction required per pedal stroke during normal pedaling and makes the athlete more efficient for a given speed. High-intensity strength and power training, even during the race season, has been shown to improve submaximal efficiency and the anaerobic threshold (8). For optimal performance, triathletes must adhere to the training principle of specificity by ensuring that drills do not mimic an upright riding position, with open hip and knee angles, but rather a tight time trialing race position (Figure 2).
THE IMPORTANCE OF AERODYNAMIC EFFICIENCY
Today, most triathletes are aware of the benefits of decreasing external drag inefficiencies, and the use of specialized helmets, wheels, bikes, and aerodynamic riding form are now common. There is evidence that riding in an aerodynamic position with the upper body supported by the forearms and parallel to the top tube can reduce drag by 30-35% compared with sitting upright, and this effect is magnified at higher speeds (5). However, it is less well known that in the absence of wind resistance, riding in the time trial position increases the metabolic cost and decreases the biomechanical efficiency of both trained and untrained cyclists (1,10). Despite this decreased pedaling efficiency, the cost savings from the aerodynamic effect of riding in the “aero” position (100 W) far outweighs the costs of a decreased efficiency (−10 W) and increased metabolic cost (1.5 mL·kg·min−1 and 5 beats per minute); thus, triathletes should not abandon this race technique (3), but rather, athletes should train to adapt to the specific demands. If an athlete can complete the cycle leg of a race with less energy expenditure and/or accumulated fatigue as a result of a greater efficiency, he or she will be at an advantage for the proceeding run.
IMPLICATIONS FOR TRAINING
An increased riding efficiency allows athletes to either increase their velocity for given power output or decrease their power output for given velocity as the race strategy may dictate. Given the importance of the “aero” position for reducing drag combined with the associated decreased biomechanical efficiency, triathletes need to perform both regular training rides and efficiency drills using form which closely replicates the aerodynamic racing position to target these posture-specific improvements. Based on experience in working with coaches and athletes preparing for triathlon competition, it is the opinion of the authors that there exists an incorrect common practice of upright seated drills for cadence, independent leg training, and power drills (particularly at the subelite level), which should be replaced with variations that more closely mimic race conditions wherein the upper body is at an angle close to the horizontal and the hip angle is more severe (Figure 2). Because triathlon-specific bikes tend to have a steeper seat tube angle that orients the seat more vertically over the bottom bracket (pedal crank axis) compared with traditional bikes, knee flexion may be similarly affected. This position can be accomplished using an “aerobar” equipped race cycle on a stationary trainer, adding forearm pads—or a rolled towel—to the bars of a regular cycle ergometer or by creating similar external arm supports that position the upper body more proximal to the top tube. If the bike used for training will not be used to race, the seat may need to be adjusted forward to allow for proper rider positioning over the crank, which will affect the degree of knee flexion.
Off-bike dry land resistance exercises to increase strength and power should focus on starting positions with closed hip and knee angles similar to those used in an aerodynamic cycling form. This could include deep squats (hip and knee extensors) against a resistance or squat jumps, wherein the buttocks are dropped low behind the heels in the down phase of the movement (Figure 3). Other beneficial exercises to promote power throughout the pedal stroke are hamstring curls, good mornings, and straight leg deadlifts to target the hip extensors and knee flexors. Good mornings and deadlifts have the added benefit of increasing lower back core strength and should be combined with other core-training exercises to improve trunk stability, which is important to help control the bicycle and ward off back fatigue or cramping while racing in the aero position. Training in positions that represent the joint angles imposed during aerodynamic riding are essential to prepare the athlete for race conditions and limit the cycle-induced fatigue before the run. Incorporating riding drills where the trunk is internally stabilized in the horizontal aerodynamic position is also important to specifically train the core muscles that can influence riding stability, bike handling, and power output by the legs.
In summary, the demands and tactics of the cycling leg of triathlon differ from those of cycle racing and the athlete/coach team needs to prepare accordingly. Training and racing strategies will differ somewhat depending on race distance; however, the use of pedaling efficiency drills, altered cadences and body positions, and strength training should be incorporated. The principle of specificity should be adhered to throughout the training, and athletes should be encouraged to train using joint angles, which closely approximate those of the time trialing aerodynamic position used for racing.
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