Effects of endurance cycling training on neuromuscular fatigue in healthy active men. Part II: Corticospinal excitability and voluntary activation.
This study investigated the effects of 9-week endurance cycling training on central fatigability and corticomotor excitability of the locomotor muscles. Fourteen healthy participants undertook three incremental fatiguing cycling tests to volitional exhaustion (EXH): (i) before training (PRE), (ii) after training at the same absolute power output as PRE (POSTABS) and (iii) after training at the same percentage of V̇O2max as PRE (POSTREL). At baseline (i.e. before cycling), every 5 min during cycling and immediately at EXH, a neuromuscular evaluation including a series of 5-s knee extensions at 100, 75 and 50% of maximal voluntary knee extension (MVC) was performed. During each contraction, transcranial magnetic and peripheral nerve stimuli were elicited to obtain motor evoked potential (MEP), silent period (SP) and compound muscle action potential (Mmax) and to calculate voluntary activation (VA). The MEP·Mmax-1 ratio recorded from vastus lateralis at 100 and 50% MVC did not show any difference between conditions. At 75% MVC, MEP exhibited significantly lower values in POSTABS and POSTREL compared to PRE at baseline (P = 0.022 and P = 0.011, respectively) as well as at 25% of time to EXH of PRE (P = 0.022) for POSTREL. No adaptations, either at baseline or during cycling, were observed for VA and SPs. In conclusion, endurance training may result in some adaptations in the corticomotor responses when measured at rest or with low level of fatigue, yet these adaptations do not translate into attenuation of central fatigue at a similar cycling workload or at exhaustion.
['Aboodarda|S J|SJ|', 'Mira|J|J|', 'Floreani|M|M|', 'Jaswal|R|R|', 'Moon|S J|SJ|', 'Amery|K|K|', 'Rupp|T|T|', 'Millet|G Y|GY|http://orcid.org/0000-0002-6395-0762']
D000328:Adult D001642:Bicycling D004558:Electric Stimulation D004576:Electromyography D000076663:Endurance Training D005267:Femoral Nerve D006801:Humans D008297:Male D009044:Motor Cortex D009119:Muscle Contraction D018763:Muscle Fatigue D010101:Oxygen Consumption D011712:Pyramidal Tracts D052097:Quadriceps Muscle D050781:Transcranial Magnetic Stimulation D055815:Young Adult
Locomotor muscles Brain Central adaptation Electromyography Transcranial magnetic stimulation