The influence of chronic training status on the mechanical behavior of the vastus lateralis during repetitive trapezoidal contractions |
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Authors: | Alex A. Olmos Trent J. Herda Stephanie A. Sontag Michael A. Trevino |
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Affiliation: | 1. Applied Neuromuscular Physiology Laboratory, Department of Kinesiology, Applied Health, and Recreation, Oklahoma State University, Stillwater, USA;2.Neuromechanics Laboratory, Department of Health, Sport, and Exercise Sciences, The University of Kansas, Lawrence, USA |
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Abstract: | Objectives:To examine maximal strength and fatigability of the knee extensors, and mechanomyographic amplitude (MMGRMS)–force relationships of the vastus lateralis (VL) during repetitive muscle actions for 5 aerobically-(AT), 5 resistance-trained-(RT), and 5 sedentary (SED) individuals.Methods:Participants performed maximal voluntary contractions before (MVCPRE) and after (MVCPOST) attempting 20 isometric trapezoidal muscle actions at 50% MVCPRE. MMG was recorded from the VL. b terms (slopes) were calculated from the natural log-transformed MMGRMS-force relationships for each participant (increasing and decreasing segments). MMGRMS was averaged during steady force.Results:RT had greater MVCPRE (P<0.001) and MVCPOST (P=0.001–0.004) than AT and SED. Only AT completed 20 muscle actions and exhibited no decrease in MVCPOST (P=0.149). The b terms were greater for RT than AT during the increasing segment of the first contraction (P=0.001) and decreasing segment of the last contraction (P=0.033). The b terms were also greater for RT (P=0.006) during the increasing than decreasing segment for the first contraction. MMGRMS during steady force was greater during the last contraction when collapsed across training status (P=0.021).Conclusion:Knee extensor MVC and fatigability, and motor unit control strategies for the VL during a series of repetitive contractions were influenced by chronic training status. |
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Keywords: | Isometric Trapezoidal Muscle Action Log-Transform Model Mechanomyography Motor Unit Control Strategies Vastus Lateralis |
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