Abstract
Although cycling impairs the subsequent metabolic cost and performance of running in some triathletes, the consequences on mechanical efficiency (Eff) and kinetic and potential energy fluctuations of the body center of mass are still unknown. The aim of this study was to investigate the effects of previous cycling on the cost-of-transport, Eff, mechanical energy fluctuations (Wtot), spring stiffness (Kleg and Kvert) and spatiotemporal parameters. Fourteen middle-level triathletes (mean ± SD: maximal oxygen uptake, dot{{rm{V}}}O2max = 65.3 ± 2.7 ml.kg−1.min−1, age = 30 ± 5 years, practice time = 6.8 ± 3.0 years) performed four tests. Two maximal oxygen uptake tests on a cycle ergometer and treadmill, and two submaximal 20-minute running tests (14 km.h−1) with (prior-cycling) and without (control) a previous submaximal 30-minute cycling test. No differences were observed between the control and post-cycling groups in Eff or Wtot. The Eff remains unchanged between conditions. On the other hand, the Kvert (20.2 vs 24.4 kN.m−1) and Kleg (7.1 vs 8.2 kN.m−1, p < 0.05) were lower and the cost-of-transport was higher (p = 0.018, 3.71 vs 3.31 J.kg−1.m−1) when running was preceded by cycling. Significantly higher stride frequency (p < 0.05, 1.46 vs 1.43 Hz) and lower stride length (p < 0.05, 2.60 vs 2.65 m) were observed in the running after cycling condition in comparison with control condition. Mechanical adjustments were needed to maintain the Eff, even resulting in an impaired metabolic cost after cycling performed at moderate intensity. These findings are compatible with the concept that specific adjustments in spatiotemporal parameters preserve the Eff when running is preceded by cycling in middle-level triathletes, though the cost-of-transport increased.
Highlights
Running cost-of-transport (CoT) is defined as the energy amount to cover a given distance commonly expressed in J.kg−1.m−1
CoT was increased with previous cycling and was kept constant during the four stages of submaximal running tests
The hypothesis was refuted because the Eff remains unchanged after cycling in middle-level triathletes, there was increase in CoT, adding that this decreasing of metabolic economy was related to mechanical adjustments
Summary
Running cost-of-transport (CoT) is defined as the energy amount to cover a given distance commonly expressed in J.kg−1.m−1. The CoT decreased by 3.7% and increased by 2.3% in middle-level triathletes[9]. According to the spring-mass model system, the combination of passive (tendons and intramuscular connective tissues) and active (muscles) structures are responsible for elastic energy recovery during running[10]. It is difficult to specify the extent to which the elastic mechanism affects the CoT and Eff, higher Wtot and Eff are related to improvements in parameters of spring-mass model. In middle and elite triathletes, no significant changes in Kleg, Kvert stride length, and stride frequency were reported between the initial and final stages of an Olympic distance, in triathletes who adopted the same running speed during these two stages[17]. The testing of these hypotheses may contribute towards a better design of training for triathletes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
