Concurrent exercise training: do opposites distract?

Abstract

Specificity is a core principle of exercise training to promote the desired adaptations for maximising athletic performance. The principle of specificity of adaptation is underpinned by the volume, intensity, frequency and mode of contractile activity and is most evident when contrasting the divergent phenotypes that result after undertaking either prolonged endurance or resistance training. The molecular profiles that generate the adaptive response to different exercise modes have undergone intense scientific scrutiny. Given divergent exercise induces similar signalling and gene expression profiles in skeletal muscle of untrained or recreationally active individuals, what is currently unclear is how the specificity of the molecular response is modified by prior training history. The time-course of adaptation and when 'phenotype specificity' takes place has important implications for exercise prescription. This context is essential when attempting to concomitantly develop resistance to fatigue (through endurance-based exercise) and increased muscle mass (through resistance-based exercise), typically termed 'concurrent training.' Chronic training studies provide robust evidence that endurance exercise can attenuate muscle hypertrophy and strength but the mechanistic underpinning of this 'interference' effect with concurrent training is unknown. Moreover, despite the potential for several key regulators of muscle metabolism to explain an incompatibility in adaptation between endurance and resistance exercise, it now seems likely that multiple integrated, rather than isolated, effectors or processes generate the interference effect. Here we review studies of the molecular responses in skeletal muscle and evidence for the interference effect with concurrent training within the context of the specificity of training adaptation.

Building strength, endurance, and mobility using an astaxanthin formulation with functional training in elderly

“…Resistance training (RT) has been most effective at treating muscle wasting,1 while endurance training has the greatest benefits to exercise intolerance 2, 3. However, combining training modes to treat both declines simultaneously typically yields a lower response than either mode applied separately 4, 5…”

Critical determinants of combined sprint and endurance performance: an integrative analysis from muscle fiber to the human body

“…So far, most research has addressed determinants of physical performance at the organ or whole-body level (e.g., in cycling, [1][2][3][4][5][6][7][8][9][10][11]. Another factor that adds to the complexity of optimizing physical performance is that adaptations for endurance or peak power are mutually exclusive, particularly in skeletal muscle (24)(25)(26).…”

Prolonged force depression after mechanically demanding contractions is largely independent of Ca 2+ and reactive oxygen species

“…Accordingly, muscle weakness and premature fatigue development are major health problems associated with numerous diseases, as well as normal aging (1). Skeletal muscle fibers are highly adaptive cells, and, when challenged with an unaccustomed load on energy metabolism or mechanical stress, they generally respond with increases in endurance capacity and strength, respectively (2)(3)(4). On the other hand, extensive challenges can depress contractile function (5,6).…”