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An Innovative Ergometer to Measure Neuromuscular Fatigue Immediately after Cycling

DOYLE-BAKER, DOUGLAS; TEMESI, JOHN; MEDYSKY, MARY E.; HOLASH, ROBERT J.; MILLET, GUILLAUME Y.

Medicine & Science in Sports & Exercise: February 2018 - Volume 50 - Issue 2 - p 375–387
doi: 10.1249/MSS.0000000000001427
SPECIAL COMMUNICATIONS: Methodological Advances

Purpose When assessing neuromuscular fatigue (NMF) from dynamic exercise using large muscle mass (e.g., cycling), most studies have delayed measurement for 1 to 3 min after task failure. This study aimed to determine the reliability of an innovative cycling ergometer permitting the start of fatigue measurement within 1 s after cycling.

Methods Twelve subjects participated in two experimental sessions. Knee-extensor NMF was assessed by electrical nerve and transcranial magnetic stimulation with both a traditional chair setup (PRE- and POST-Chair, 2 min postexercise) and the new cycling ergometer (PRE, every 3 min during incremental exercise and POST-Bike, at task failure).

Results The reduction in maximal voluntary contraction force POST-Bike (63% ± 12% PRE; P < 0.001) was not different between sessions and there was excellent reliability at PRE-Bike (intraclass correlation coefficient [ICC], 0.97; coefficients of variation [CV], 3.2%) and POST-Bike. Twitch (Tw) and high-frequency paired-pulse (Db100) forces decreased to 53% ± 14% and 62% ± 9% PRE, respectively (P < 0.001). Both were reliable at PRE-Bike (Tw: ICC, 0.97; CV, 5.2%; Db100: ICC, 0.90; CV, 7.3%) and POST-Bike (Tw: ICC, 0.88; CV, 11.9; Db100: ICC, 0.62; CV, 9.0%). Voluntary activation did not change during the cycling protocol (P > 0.05). Vastus lateralis and rectus femoris M-wave and motor-evoked potential areas showed fair to excellent reliability (ICC, 0.45–0.88). The reduction in maximal voluntary contraction and Db100 was greater on the cycling ergometer than the isometric chair.

Conclusions The innovative cycling ergometer is a reliable tool to assess NMF during and immediately postexercise. This will allow fatigue etiology during dynamic exercise with large muscle mass to be revisited in various populations and environmental conditions.

Supplemental digital content is available in the text.

Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, AB, CANADA

Address for correspondence: Guillaume Y. Millet, Ph.D., Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4; E-mail: gmillet@ucalgary.ca.

Submitted for publication April 2017.

Accepted for publication September 2017.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.acsm-msse.org).

© 2018 American College of Sports Medicine