Cycling Impairs Neuromuscular Coordination During Running In Triathletes, Which Reduces Performance And Is Likely Injury-related

Abstract

Triathletes report incoordination when running after cycling. PURPOSE: To investigate a) the influence of the bike-run transition on neuromuscular coordination of running (i.e. does cycling have a direct effect on running?), b) the effect of altered neuromuscular coordination on run economy (RE - steady-state V02), c) the association between a history of exercise-related leg pain (ERLP) and neuromuscular coordination, and d) the role of fatigue in coordination changes. METHOD: 27 highly trained triathletes participated. 3-D pelvic and lower limb kinematics and leg muscle recruitment were compared between a control-run (no prior exercise) and a 30 min transition-run (preceded by only 20 min of cycling; i.e. run vs. cycle-run). RESULTS: Kinematics were not different between control and transition-runs. Muscle recruitment was different in 5 of 17 triathletes without injury history; altered muscle recruitment during the transition-run was more similar to recruitment used during cycling. Altered muscle recruitment was associated with a 3.7 (CI 0.9%) increase in VO2. Muscle recruitment was altered in 7 of 10 triathletes with a history of ERLP. Altered muscle recruitment was not associated with indicators of fatigue from myoelectric and force data.FigureCONCLUSION: Short periods of cycling have no direct effect on running kinematics or muscle activity in most highly trained triathletes. However, running muscle activity is influenced by cycling in a proportion of highly trained triathletes. This influence is not related to altered kinematics or fatigue, but instead appears to be a direct effect of cycling on motor commands for running. This altered muscle recruitment is associated with reduced RE and 2.4 times greater likelihood of a history of ERLP.