The effects of beta-alanine supplementation and high-intensity interval training on neuromuscular fatigue and muscle function

Abstract

The purpose of this study was to determine the effects of beta-alanine supplementation and high-intensity interval training (HIIT) on electromyographic fatigue threshold (EMG(FT)) and efficiency of electrical activity (EEA). A total of 46 men completed four, 2-min work bouts on a cycle ergometer. Using bipolar surface electrodes, the EMG amplitude was averaged and plotted over the 2-min. The resulting slopes were used to calculate EMG(FT) and EEA. Following initial testing, all participants were randomly assigned to either placebo (PL; n = 18), beta-alanine (BA; n = 18) or control groups (CON; n = 10). Following randomization, participants engaged in 6 weeks of HIIT training. Significant improvements in EMG(FT) and EEA resulted for both training groups. In conclusion, HIIT appeared to be the primary stimulus effecting EMG(FT) or EEA, suggesting adaptations from HIIT may be more influential than increasing skeletal muscle carnosine levels on delaying fatigue in recreationally active men.

Can the electromyographic fatigue threshold be determined from superficial elbow flexor muscles during an isometric single-joint task?

“…This y-intercept, named the EMG fatigue threshold (EMG FT ), was deWned as the highest power output that can be maintained without an increase in EMG activity level over time (i.e., iEMG slope = 0). The EMG FT has been widely studied using pedaling tests (Matsumoto et al 1991;Moritani et al 1993;Pavlat et al 1993;Pringle and Jones 2002;Graef et al 2008;Smith et al 2009) and has been shown to be an interesting tool to assess the Wtness level/ muscle performance (deVries et al 1982;Matsumoto et al 1991;Moritani et al 1993;Graef et al 2008;Smith et al 2009). This method has the advantage that it does not require submaximal exercise bouts to be performed until exhaustion.…”

“…In most of these studies, EMG FT was determined from the Vastus lateralis muscle (deVries et al 1982;Matsumoto et al 1991;Moritani et al 1993;Graef et al 2008;Smith et al 2009) assuming that this muscle is representative of all the muscles implied in pedaling. However, pedaling is a bilateral multi-joint task requiring the usage of numerous muscles [for review, (Hug and Dorel 2009)] and thus, the EMG fatigue characteristics of other muscles could result in diVerent EMG FT values, as demonstrated by Housh et al (1995).…”

The electromyographic fatigue threshold is not a valid tool to assess muscle function

“…The EMG FT has been widely studied using pedaling tests (Moritani et al, 1993;Graef et al, 2008;Smith et al, 2009), and it has been shown to be a useful tool in assessing the fitness level/muscle performance (deVries et al, 1982;Moritani et al, 1993;Graef et al, 2008;Smith et al, 2009). More recently, EMG FT has been determined from isometric single joint-tasks (Hendrix et al, 2009c;Hug et al, 2009).…”

Nutrition and Training Adaptations in Aquatic Sports

“…Hoffman et al (2008) found that high-dose BA over 3 weeks resulted in higher training volume in the bench press exercise, and a trend for a greater training volume was seen for all resistance exercise sessions. Conversely, Smith et al (2009) found no influence of BA supplementation to further enhance high-intensity interval training in relatively untrained men. Elite and subelite swimmers were recently given BA over 10 weeks (Chung et al, 2012), and a greater improvement in training performance after 4 weeks of BA vs. placebo was observed (mean = -1.3%, 90% confidence limit = 1.0), but the effect was unclear after 10 weeks (mean = -0.2%, 90% CL = 1.5).…”