Interlink Between Physiological and Biomechanical Changes in the Swim-to-Cycle Transition in Triathlon Events: A Narrative Review

Abstract

Triathlon is a multisport composed of swim, cycle, and run segments and two transition periods. The swim-to-cycle transition is considered a critical period for the change in body position and the modifications in physiological (heart rate, VO2, lactate) and biomechanical parameters (cycling power and cadence, swimming stroke rate). Therefore, the aim of this review was to summarize the current evidence regarding the physiological and biomechanical changes and their interlink during the swim-to-cycle transition hinting at practical recommendations for coaches and athletes. The influence of the swim segment on cycle one is more evident for short-distance events. Greater modifications occur in athletes of lower level. The modulation of intensity during the swim segment affects the changes in the physiological parameters (heart rate, blood lactate, core temperature), with a concomitant influence on cycling gross efficiency. However, gross efficiency could be preserved by wearing a wetsuit or by swimming in a drafting position. A higher swim leg frequency during the last meters of the segment induces a higher cadence during the cycle segment. Training should be directed to the maintenance of a swimming intensity around 80–90% of a previous maximal swim test and with the use of a positive pacing strategy. When athletes are intended to train consecutively only swim and cycle segments, for an optimal muscle activation during cycling, triathletes could adopt a lower cadence (about 60–70% of their typical cadence), although an optimal pedaling cadence depends on the level and type of athlete. Future research should be focused on the combined measurements of physiological and biomechanical parameters using an intervention study design to evaluate training adaptations on swim kick rate and their effects on cycling performance. Coaches and athletes could benefit from the understanding of the physiological and biomechanical changes occurring during the swim-to-cycle transition to optimize the overall triathlon performance.

A Higher Kick Frequency Swimming Training Program Optimizes Swim-to-Cycle Transition in Triathlon

“…Furthermore, the improvement in the minimum cadence was accompanied by a significant decrease between Pretraining and Posttraining for the average HR, V̇O 2 , and energy expenditure and that the significant difference found between K6 and CG in the minimum cadence was accompanied by the nominal differences in the average V̇O 2 and energy expenditure parameters. Therefore, the multidisciplinary nature of the triathlon performance requires a continuous adaptation in cycling cadence based on the various phases of the competition, the position acquired in the previous swim segment (1), and in view of the final run segment (40).…”

“…However, it is a common strategy among triathletes to use 2 swim kicks each stroke cycle, with the intention to save energy for the subsequent cycle segment, although a few of them adopt a 6-kick strategy. Therefore, it is hypothesized that an insufficient use of the legs during the swim segment could be detrimental for the following cycle segment (1,17). This hypothesis is based on the assumption that a previous high-intensity exercise (i.e., swim kicks) before a subsequent action (i.e., cycling) might elicit changes on physiological parameters, such as the improvement in muscle perfusion, the increase in residual acidemia, a better V Ȯ2 kinetics, and muscle fibers recruitment (6,17), and on biomechanical parameters, such as an increase in the cycling peak power and in the total work expressed during the first minutes of the cycling performance (8).…”

“…The multidisciplinary nature of the triathlon performance induces a unique profile with biomechanical and physiological changes occurring during the swim-to-cycle (T1) (1) and cycle-to-run (T2) (26) transition, with the influence of a previous segment on the subsequent segment based on the applied pacing strategy. Considering the swim-to-cycle transition for the short-distance triathlon, it has been demonstrated that greater cycling power is required during the first meters of the second segment for slower swimmers with the attempt to bridge the gap to the front group (31).…”