Potentiation of the first and second phases of the M wave after maximal voluntary contractions in the biceps brachii muscle
- 12 Downloads
The study was undertaken to examine separately the potentiation of the first and second phases of the M wave in biceps brachii after conditioning maximal voluntary contractions (MVCs) of different durations. M waves were evoked in the biceps brachii muscle before and after isometric MVCs of 1, 3, 6, 10, 30, and 60 s. The amplitude, duration, and area of the first and second phases of monopolar M waves were measured during the 10-min period following each contraction. Our results indicated that the amplitude and area of the M-wave first phase increased after MVCs of long (≥ 30 s) duration (P < 0.05), while it decreased after MVCs of short (≤ 10 s) duration (P < 0.05). The enlargement after the long MVCs persisted for 5 min, whereas the depression after the short contractions lasted only for 15 s. The amplitude of the second phase increased immediately (1 s) after all MVCs tested (P < 0.05), regardless of their duration, and then returned rapidly (10 s) to control levels. Unexpectedly, the amplitude of the second phase decreased below control values between 15 s and 1 min after the MVCs lasting ≥ 6 s (P < 0.05). Our results reinforce the idea that the presence of fatigue is a necessary condition to induce an enlargement of the M-wave first phase and that this enlargement would be greater (and occur sooner) in muscles with a predominance of type II fibers (quadriceps and biceps brachii) compared to type-I predominant muscles (tibialis anterior). The unique findings observed for the M-wave second phase indicate that changes in this phase are highly muscle dependent.
KeywordsM wave Brachial plexus stimulation Electromyography Biceps brachii Isometric contraction M-wave potentiation
Amplitude of the first phase of the M wave
Amplitude of the second phase of the M wave
Amplitude resulting from the sum of AmpliFIRST and AmpliSECOND
Area of the first phase of the M wave
Area of the second phase of the M wave
Area resulting from the sum of AreaFIRST and AreaSECOND
Duration of the first phase of the M wave
Duration of the second phase of the M wave
Time interval between the first and second peaks of the M wave
Maximal voluntary contraction
- M wave
Compound muscle action potential
Standard error of the mean
This work has been supported by the Spanish Ministerio de Economia y Competitividad (MINECO), under the TEC2014-58947-R project.
J.R-F, A. B, T. V, and N. P designed the experimental study; J.R-F, A. B, and T. V performed the experiments; J.R-F and A. B analyzed the data; J.R-F, A. B, T. V, and N. P interpreted the results of the experiments; J.R-F drafted the manuscript; J.R-F, A. B, T. V, and N. P edited and revised the manuscript; J.R-F, A. B, T. V, and N. P approved the final version of the manuscript.
Compliance with ethical standards
Approval for the project was obtained from the local Ethics Committee, and all procedures used in this study conformed to the Declaration of Helsinki.
Conflict of interest
The authors declare that they have no conflict of interest.
- 11.Gydikov A, Kosarov D (1972) Volume conduction of the potentials from separate motor units in human muscle. Electromyogr Clin Neurophysiol 12(2):127–147Google Scholar
- 26.Maganaris CN (2003) Tendon conditioning: artefact or property? Proc Biol Sci Suppl 1:S39–S42Google Scholar