EMG Activity does not Change During a Time Trial in Competitive Cyclists

Abstract

The purpose of the present study was to measure the electromyographic (EMG) activity of four lower limb muscles and the propulsive torque during a cycling time-trial (TT). Nine competitive cyclists (V·O_2max: 73.8 ± 5.3 ml · min^-1 · kg^-1) performed two tests separated over a one-week period on a friction-load cycle ergometer equipped with a SRM crankset scientific system: 1) a continuous incremental test for the determination of the peak power output (PPO); and 2) a 30-min TT test at a self-selected work intensity. The EMG activity of the vastus medialis (VM), the rectus femoris (RF), the biceps femoris (BF), and the gastrocnemius medialis (GAS), and the propulsive torque were recorded every 5 min for 10 s. There was no time effect on the power output, the pedalling cadence, and the mean propulsive torque. The EMG activity of the VM and the RF muscles was unchanged during the TT (p > 0.05). The EMG activity of the two knee flexor muscles (BF and GAS) tended to increase with time but it was not significant (p > 0.05). The EMG/torque of the VM and the RF muscles tended to decrease with time but it was not significant (p > 0.05). The lack of increase in the EMG activity of the four investigated muscles seems to indicate that the subjects performed the TT test at a muscular work steady-state.

Key words

Cyclists - self-paced race - SRM - EMG - propulsive torque

References

• 1 Arendt-Nilsen L, Mills K R, Forster A. Changes in muscle fiber conduction velocity, mean power frequency, and mean EMG voltage during prolonged submaximal contractions.  Muscle Nerve. 1989;  12 493-497
• 2 Ericson M O, Bratt A, Nisell R, Arborelius U P, Ekholm J. Power output and work in different muscle groups during ergometer cycling.  Eur J Appl Physiol. 1986;  55 229-235
• 3 Gerdle B, Wretling M L, Henrikson-Larson K. Do the fibre-type proportion and the angular velocity influence the mean power frequency of the electromyogram?.  Acta Physiol Scand. 1988;  134 341-346
• 4 Hagg G M. Interpretation of EMG spectral alterations and alteration indexes at sustained contraction.  J Appl Physiol. 1992;  73 1211-1217
• 5 Hausswirth C, Bigard A X, Le Chevalier J M. The Cosmed K4 telemtry system as an accurate device for oxygen uptake measurements during exercise.  Int J Sports Med. 1997;  18 449-453
• 6 Hautier C A, Arsac L M, Deghdegh K, Souqet J, Belli A, Lacour J R. Influence of fatigue on EMG/force ratio and cocontraction in cycling.  Med Sci Sports Exerc. 2000;  32 839-843
• 7 Hickey M S, Costill D L, McConell G K, Widrick J J, Tanaka H. Day to day variation in time trial cycling performance.  Int J Sports Med. 1992;  13 467-470
• 8 Housh T J, Perry S R, Bull A J, Johnson G O, Ebersole K T, Housh D J, deVries H A. Mechanomyographic and electromyographic responses during submaximal cycle ergometry.  Eur J Appl Physiol. 2000;  83 381-387
• 9 Kautz S A, Feltner M E, Coyle E F, Baylor A M. The pedaling technique of elite endurance cyclists: changes with increasing workload at constant cadence.  Int J Sports Biomech. 1991;  7 29-35
• 10 Kay D, Marino F E, Cannon J, Clair Gibson St A, Lambert M I, Noakes T D. Evidence for neuromuscular fatigue during high-intensity cycling in warm, humid conditions.  Eur J Appl Physiol. 2001;  84 115-121
• 11 Lucia A, Hoyos J, Chicharro J L. The slow component of VO₂ in professional cyclists.  Br J Sports Med. 2000;  34 367-374
• 12 Lucia A, Sanchez O, Carjaval A, Chicharro J L. Analysis of the aerobic-anaerobic transition in elite cyclists during incremental exercise with the use of electromyography.  Br J Sports Med. 1999;  33 178-185
• 13 Madigan M L, Pidcoe P E. A muscle temperature compensation technique for EMG fatigue measures.  Med Sci Sports Exerc. 2002;  34 780-784
• 14 Martin J C, Milliken D L, Cobb J E, McFadden K L, Coggan A R. Validation of mathematical model for road cycling power.  J Appl Biomech. 1998;  14 276-291
• 15 Moritani T, Muro M, Nagata A. Intramuscular and surface electromyogram changes during muscle fatigue.  J Appl Physiol. 1986;  60 1179-1185
• 16 Perrey S, Grappe F, Girard A, Bringard A, Groslambert A, Rouillon J D. Physiological responses during a simulated 30 min time trial in triathletes.  Int J Sports Med. 2003;  24 138-143
• 17 Petrofsky J S. Frequency and amplitude of the EMG during exercise on the bicycle ergometer.  Eur J Appl Occup Physiol. 1979;  41 1-15
• 18 Ryan M M, Gregor R J. EMG profiles of lower extremity muscles during cycling at constant workload and cadence.  J Electromyogr Kinesiol. 1992;  2 69-80
• 19 Saunders M J, Evans E M, Aringrimsson S A, Allison J D, Warren G L, Cureton K J. Muscle activation and the slow component rise in oxygen uptake during cycling.  Med Sci Sports Exerc. 2000;  32 2040-2045
• 20 St Clair Gibson A, Schabort E J, Noakes T D. Reduced neuromuscular activity and force generation during prolonged cycling.  Am J Physiol. 2001;  281 187-196
• 21 Takaishi T, Yamamoto T, Ono T, Ito T, Moritani T. Neuromuscular, metabolic, and kinetic adaptations for skilled pedalling performance in cyclists.  Med Sci Sports Exerc. 1998;  30 442-449