A Brief Review on Concurrent Training: From Laboratory to the Field

Abstract

The majority of sports rely on concurrent training (CT; e.g., the simultaneous training of strength and endurance). However, a phenomenon called “Concurrent training effect” (CTE), which is a compromise in adaptation resulting from concurrent training, appears to be mostly affected by the interference of the molecular pathways of the underlying adaptations from each type of training segments. Until now, it seems that the volume, intensity, type, frequency of endurance training, as well as the training history and background strongly affect the CTE. High volume, moderate, continuous and frequent endurance training, are thought to negatively affect the resistance training-induced adaptations, probably by inhibition of the Protein kinase B—mammalian target of rapamycin pathway activation, of the adenosine monophosphate-activated protein kinase (AMPK). In contrast, it seems that short bouts of high-intensity interval training (HIIT) or sprint interval training (SIT) minimize the negative effects of concurrent training. This is particularly the case when HIIT and SIT incorporated in cycling have even lower or even no negative effects, while they provide at least the same metabolic adaptations, probably through the peroxisome proliferator-activated receptor-γ coactivator (PGC-1a) pathway. However, significant questions about the molecular events underlying the CTE remain unanswered.

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“…Moreover, these authors found that when lower aerobic intensities were implemented during CT, smaller performance decrements were shown after detraining period. Conversely, recent reviews [27,34] on CT suggested that high intensity interval training can be prescribed alongside resistance training without negatively impacting changes in muscle mass. Despite it seemed contradictory recommendations, all seemed to agree that an adequate rest between aerobic and resistance training sessions should be provided for these gains to occur.…”

“…Thus, the degree of the interference effect can vary depending on depending on how the training variables are configured [21,23]. Several studies have indicated that an interference effect exists between aerobic training and resistance training when the weekly training volume is high [21,[24][25][26][27][28]. It seems quite clear that high volumes of aerobic training, either due to an increase in the frequency and/or duration of aerobic exercises, results in the inhibition of strength gains, in contrast to low volumes of aerobic training [27,28].…”

“…Several studies have indicated that an interference effect exists between aerobic training and resistance training when the weekly training volume is high [21,[24][25][26][27][28]. It seems quite clear that high volumes of aerobic training, either due to an increase in the frequency and/or duration of aerobic exercises, results in the inhibition of strength gains, in contrast to low volumes of aerobic training [27,28]. According to these studies [27,28], it seems that an increase in the volume of aerobic training induces a higher degree of fatigue, which compromises the quality of strength training and, consequently, the possible chronic adaptations.…”

“…It seems quite clear that high volumes of aerobic training, either due to an increase in the frequency and/or duration of aerobic exercises, results in the inhibition of strength gains, in contrast to low volumes of aerobic training [27,28]. According to these studies [27,28], it seems that an increase in the volume of aerobic training induces a higher degree of fatigue, which compromises the quality of strength training and, consequently, the possible chronic adaptations. Nevertheless, it is still not clear what happens on both cardiorespiratory and neuromuscular performance when the intensities of the aerobic or/and strength training performances are manipulated.…”

“…In recent years, several reviews have been published analyzing CT [21,27,28,34], but, to the best of authors' knowledge, no systematic review has comprehensively examined the literature regarding the effects different resistance and/or aerobic intensities in CT and the effects of the subsequent detraining period on performance. Analyzing studies that have evaluated CT intensities would provide coaches and sports scientists with valuable knowledge and strategies to effectively combine aerobic exercise with bouts of resistance training when seeking improved performance across training and competition.…”