Neuromuscular Fatigue After Repeated Jumping With Concomitant Electrical Stimulation

How to Work with Electromyography Decomposition in Practical Classes of Exercise Physiology and Biomechanics

Concepts about motor unit recruitment are important learning contents in exercise physiology and biomechanics classes that are usually taught theoretically. In the last few years, great advances have occurred in the decomposition of surface electromyography, allowing the learning of theoretical contents in an experimental way. In this tutorial paper, we have described the decomposition of surface electromyography methodological aspects and examples to teach motor unit recruitment concepts in exercise physiology and biomechanics practical lessons. This work has the aim to facilitate physiology and biomechanics academics to introduce this technique in practical classes.

Carbohydrate Mouth Rinse Fails to Improve Four-Kilometer Cycling Time Trial Performance

We investigated if a carbohydrate (CHO) mouth rinse may attenuate global fatigue and improve 4-km cycling time trial (TT_4km) performance. After a preliminary session, cyclists (n = 9) performed a TT_4km after a CHO or placebo (PLA) mouth rinse. Mean power output, time, and ratings of perceived exertion (RPE) were recorded throughout the TT_4km. Twitch interpolation responses (%VA; voluntary activation and ∆Tw; delta peak twitch torque) were compared pre and post TT_4km with traditional statistics and effect size (ES) analysis. Time-to-complete the 4 km and mean power output were comparable between CHO (386.4 ± 28.0 s) and PLA (385.4 ± 22.4 s). A lower central (p = 0.054) and peripheral (p = 0.02) fatigue in CHO than in PLA were suggested by an extremely-large ES in %VA (manipulation main effect: p = 0.052, d = 1.18; manipulation-by-time interaction effect: p = 0.08, d = 1.00) and an extremely, very-large ES in ∆Tw (manipulation main effect: p = 0.07, d = 0.97; time-by-manipulation interaction effect: p = 0.09, d = 0.89). The RPE increased slower in CHO than in PLA (p = 0.051; d = 0.7). The apparent reduction in global fatigue (central and peripheral) and RPE_SLOPE with only one CHO mouth rinse were not translated into improved TT_4km performance. Further tests may be required to verify if these likely differences in global fatigue might represent an edge in the short-lasting cycling time trial performance.