Non-invasive assessment of muscle fiber conduction velocity during an incremental maximal cycling test

Sbriccoli, Paola; Sacchetti, Massimo; Felici, Francesco; Gizzi, Leonardo; Lenti, Mauro; Scotto, Alessandro; Vito, Giuseppe De

doi:10.1016/j.jelekin.2009.03.008

« Previous Next »Journal of Electromyography and Kinesiology
Volume 19, Issue 6 , Pages e380-e386, December 2009

Non-invasive assessment of muscle fiber conduction velocity during an incremental maximal cycling test

Paola Sbriccoli
- Department of Human Movement and Sport Sciences, IUSM University of Rome “Foro Italico”, 00194 Rome, Italy
- IIM, Interuniversity Institute of Miology, Italy
- Corresponding author. Address: Department of Human Movement and Sport Sciences, IUSM University of Rome “Foro Italico”, 00194 Rome, Italy. Tel./fax: +39 06 36733 214.
Massimo Sacchetti
- Department of Human Movement and Sport Sciences, IUSM University of Rome “Foro Italico”, 00194 Rome, Italy
- IIM, Interuniversity Institute of Miology, Italy
Francesco Felici
- Department of Human Movement and Sport Sciences, IUSM University of Rome “Foro Italico”, 00194 Rome, Italy
- IIM, Interuniversity Institute of Miology, Italy
Leonardo Gizzi
- Department of Human Movement and Sport Sciences, IUSM University of Rome “Foro Italico”, 00194 Rome, Italy
Mauro Lenti
- Department of Human Movement and Sport Sciences, IUSM University of Rome “Foro Italico”, 00194 Rome, Italy
Alessandro Scotto
- Department of Human Movement and Sport Sciences, IUSM University of Rome “Foro Italico”, 00194 Rome, Italy
Giuseppe De Vito
- Department of Human Movement and Sport Sciences, IUSM University of Rome “Foro Italico”, 00194 Rome, Italy
- School of Physiotherapy and Performance Science, Institute of Sport and Health University College Dublin, Dublin, Ireland
- IIM, Interuniversity Institute of Miology, Italy

Received 20 November 2008; received in revised form 19 March 2009; accepted 19 March 2009. published online 24 April 2009.

Abstract

Muscle fiber conduction velocity (MFCV) gives critical information on neuromuscular control and can be considered a size principle parameter, being suggestive of motor unit recruitment strategies. MFCV has been recently measured during constant-load sub-maximal cycling exercise and was found to correlate positively with percentage of type I myosin heavy chain.

The aim of this study was to test the hypothesis that MFCV measured during an incremental cycling test using surface electromyography (sEMG), can be sensitive to the different metabolic requests elicited by the exercise. In particular, the relationship between ventilatory threshold (T-vent), V^′O_2max and MFCV was explored.

Eleven male physically active subjects (age 30±9years) undertook a 1-min incremental cycling test to exhaustion. T-vent and V^′O_2max were measured using an open circuit breath by breath gas analyzer. The sEMG was recorded from the vastus lateralis muscle with an adhesive 4-electrodes array, and the MFCV was computed on each sEMG burst over the last 30-s of each step.

The mean V^′O_2max obtained during the maximal test was 53.32±2.33mlkg⁻¹min⁻¹, and the T-vent was reached at 80.77±3.49% of V^′O_2max. In all subjects reliable measures of MFCV were obtained at every exercise intensity (cross correlation values >0.8). MFCV increased linearly with the mechanical load, reaching a maximum value of 4.28±0.67ms⁻¹ at an intensity corresponding to the T-vent. Thereafter, MFCV declined until maximal work intensities. This study demonstrates that MFCV can be used as non-invasive tool to infer MUs recruitment/derecruitment strategies even during dynamic exercise from low to maximal intensities.