Electromyography Assessment of Muscle Recruitment Strategies During High-Intensity Exercise

Billaut, François

doi:10.5772/24358

Cited by 5 publications

(4 citation statements)

References 92 publications

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“…This includes, the differential activation of muscles to limit force production to maintain fuel resources and limit tissue damage (St. Clair Gibson et al, 2001). For example, maximal voluntary knee extensions and leg cycling sprints result in a considerable amount of NM fatigue related to alterations in quadriceps activation, limiting performance (Billaut, 2011). When evaluating EMG, a decrease in MDF suggests a decrease in motor unit (MU) firing rate, muscle fiber recruitment and/or a decrease in conduction velocity (Billaut, 2011) and can be used as an index of fatigue (De Luca, 1997;Nagata et al, 1990).…”

Section: Discussionmentioning

confidence: 99%

“…For example, maximal voluntary knee extensions and leg cycling sprints result in a considerable amount of NM fatigue related to alterations in quadriceps activation, limiting performance (Billaut, 2011). When evaluating EMG, a decrease in MDF suggests a decrease in motor unit (MU) firing rate, muscle fiber recruitment and/or a decrease in conduction velocity (Billaut, 2011) and can be used as an index of fatigue (De Luca, 1997;Nagata et al, 1990). In addition, EMG RMS amplitude has been positively correlated with muscle force as greater MU recruitment and higher firing rate contributes to an increase in the cumulative EMG.…”

Section: Discussionmentioning

confidence: 99%

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Carbohydrate Mouth Rinse Counters Fatigue Related Strength Reduction

Jensen

Stellingwerff²,

Klimstra³

2015

International Journal of Sport Nutrition and Exercise Metabolism

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The purpose was to determine the effect of carbohydrate (CHO) mouth rinse on maximal voluntary contraction (MVC) and neuromuscular output in a fatigued state. It was hypothesized that CHO mouth rinse would potentiate torque output in a fatigued state. In a double-blind, cross-over design, 12 competitive male athletes (9 rowers, 1 cyclist, 1 runner and 1 volleyball player) initially performed 3 × 5 s MVC isometric knee extensions followed by a 50% MVC contraction until volitional exhaustion, with quadriceps muscle activity measured via electromyography (EMG). Immediately after, either an 8% CHO maltodextrin (WASH), or noncaloric artificial sweetener (PLA) was mouth rinsed for 10sec, before 3 × 5 s final MVCs. Fatigue caused a significant decline in post fatigue MVC trial 1 for 3 s average torque (p = .03) and peak torque (p = .02) for PLA. This fatigue related decline in torque was not noticed for WASH, with a 2.5% and 3.5% less attenuation in peak and average torque, respectively in post fatigue MVC1 compared with PLA. The effect size for MVC trial 1 between WASH/PLA was seen to be small positive (ES = 0.22; 55% likelihood of positive). Overall for EMG RMS, there were no significant differences between PLA and WASH among all muscles. EMG median frequency showed comparable results between conditions with significant reductions due to fatigue. Taken together, this evidence suggests that the attenuation of torque post fatigue was less for CHO mouth rinse than a placebo. Even though the gains were marginal, these discoveries may play an important role in sport performance, as small performance effects can have significant outcomes in real-world competitions.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Carbohydrate Mouth Rinse Counters Fatigue Related Strength Reduction

Jensen

Stellingwerff²,

Klimstra³

2015

International Journal of Sport Nutrition and Exercise Metabolism

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“…Surface EMG is a common methodology used to examine neuromuscular recruitment patterns during exercise and may be interpreted as a surrogate measure of descending motor command (Billaut, 2011 ). Notably, a direct correlation exists between declining EMG amplitudes and work output during repeated 5 s cycle sprints with minimal recovery (<30 s) (Billaut and Smith, 2010 ).…”

Section: Recovery Of Cns Function After Intermittent-sprint Exercisementioning

confidence: 99%

“…Contrastingly, the regulation of performance during exercise has been increasingly interpreted as an integrative, multifaceted phenomenon (Knicker et al, 2011 ; Noakes, 2012 ) with the brain highlighted as central to this process (Gandevia, 2001 ). While some debate exists as to whether the regulation of exercise performance are conscious (Marcora, 2008 ) or anticipatory events (Marino, 2004 )—derived from afferent or efferent origins (St Clair Gibson and Noakes, 2004 ); all highlight changing CNS drive and motor unit recruitment to be associated with fatigue and the reduction of intermittent-sprint exercise performance (Billaut, 2011 ; Girard et al, 2011 ). Conceptually, if the brain is held as central to the process of performance declines (i.e., fatigue), it stands to reason that it would also have some role in post-exercise recovery (De Pauw et al, 2013 ).…”

Section: Introductionmentioning

confidence: 99%

Is recovery driven by central or peripheral factors? A role for the brain in recovery following intermittent-sprint exercise

Minett

Duffield

2014

Front. Physiol.

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Prolonged intermittent-sprint exercise (i.e., team sports) induce disturbances in skeletal muscle structure and function that are associated with reduced contractile function, a cascade of inflammatory responses, perceptual soreness, and a delayed return to optimal physical performance. In this context, recovery from exercise-induced fatigue is traditionally treated from a peripheral viewpoint, with the regeneration of muscle physiology and other peripheral factors the target of recovery strategies. The direction of this research narrative on post-exercise recovery differs to the increasing emphasis on the complex interaction between both central and peripheral factors regulating exercise intensity during exercise performance. Given the role of the central nervous system (CNS) in motor-unit recruitment during exercise, it too may have an integral role in post-exercise recovery. Indeed, this hypothesis is indirectly supported by an apparent disconnect in time-course changes in physiological and biochemical markers resultant from exercise and the ensuing recovery of exercise performance. Equally, improvements in perceptual recovery, even withstanding the physiological state of recovery, may interact with both feed-forward/feed-back mechanisms to influence subsequent efforts. Considering the research interest afforded to recovery methodologies designed to hasten the return of homeostasis within the muscle, the limited focus on contributors to post-exercise recovery from CNS origins is somewhat surprising. Based on this context, the current review aims to outline the potential contributions of the brain to performance recovery after strenuous exercise.

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