Neuromuscular adaptations during concurrent strength and endurance training versus strength training

Abstract

The purpose of this study was to investigate effects of concurrent strength and endurance training (SE) (2 plus 2 days a week) versus strength training only (S) (2 days a week) in men [SE: n=11; 38 (5) years, S: n=16; 37 (5) years] over a training period of 21 weeks. The resistance training program addressed both maximal and explosive strength components. EMG, maximal isometric force, 1 RM strength, and rate of force development (RFD) of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) throughout the lengths of 4/15-12/15 (L(f)) of the femur, muscle fibre proportion and areas of types I, IIa, and IIb of the vastus lateralis (VL), and maximal oxygen uptake (VO(2max)) were evaluated. No changes occurred in strength during the 1-week control period, while after the 21-week training period increases of 21% (p<0.001) and 22% (p<0.001), and of 22% (p<0.001) and 21% (p<0.001) took place in the 1RM load and maximal isometric force in S and SE, respectively. Increases of 26% (p<0.05) and 29% (p<0.001) occurred in the maximum iEMG of the VL in S and SE, respectively. The CSA of the QF increased throughout the length of the QF (from 4/15 to 12/15 L(f)) both in S (p<0.05-0.001) and SE (p<0.01-0.001). The mean fibre areas of types I, IIa and IIb increased after the training both in S (p<0.05 and 0.01) and SE (p<0.05 and p<0.01). S showed an increase in RFD (p<0.01), while no change occurred in SE. The average iEMG of the VL during the first 500 ms of the rapid isometric action increased (p<0.05-0.001) only in S. VO(2max) increased by 18.5% (p<0.001) in SE. The present data do not support the concept of the universal nature of the interference effect in strength development and muscle hypertrophy when strength training is performed concurrently with endurance training, and the training volume is diluted by a longer period of time with a low frequency of training. However, the present results suggest that even the low-frequency concurrent strength and endurance training leads to interference in explosive strength development mediated in part by the limitations of rapid voluntary neural activation of the trained muscles.

Análise morfológica do músculo gastrocnêmio medial de ratos submetidos a um protocolo de treinamento concorrente

“…Embora atualmente observa-se disucssões controversas sobre o assunto, há achados que sugerem que a falha ou o sucesso depende da forma específica de sua aplicação (NADER, 2006). Dessa maneira, o termo "concorrência" é utilizado quando o TF e o TRA são utilizados de forma conjunta, causam adaptações contrárias ao organismo (HAKKINEN et al, 2003), podendo tais ocorrências serem justificadas pelo curto período de tempo na recuperação entre os estímulos, além de possivelmente ocasionar redução nas capacidades físicas (HICKSON, 1980).…”

“…O efeito de interferência pode existir quando o volume total e/ou a frequência é mais elevado, durante longos períodos de treinamentos (HAKKINEN et al, 2003). Porém, tal efeito não foi observado no presente estudo, havendo discreta ocorrência de hipertrofia muscular, indo contra o proposto por Hakkinen et al, (2003).…”

“…Porém, tal efeito não foi observado no presente estudo, havendo discreta ocorrência de hipertrofia muscular, indo contra o proposto por Hakkinen et al, (2003).…”

Efeitos Do Treinamento Combinado Sobre a Força, Resistência E Potência Aeróbica Em Idosas

“…Em relação ao treinamento combinado (TC), existe uma divergência nas pesquisas no que diz respeito ao "fenômeno da interferência". Alguns estudos relatam que o TC inibe o desenvolvimento de força [5][6][7] , assim como se observa uma magnitude mais baixa do desenvolvimento da resistência aeróbica quando comparado a um modo de treinamento realizado de forma isolado 8,9 . Em oposição, outros estudos demonstram que o TC não tem nenhum efeito inibitório no desenvolvimento de força e da resistência aeróbica 10,11 .…”

Functional and morphological effects of resistance exercise on disuse-induced skeletal muscle atrophy

“…The morphological and functional adaptations to resistance exercise (RE) have been well described, among them the positive responses of the neuromuscular system (neural adaptations) (1,2), muscle architecture (angle of pennation), biochemical composition (myosin heavy chain (MHC) isoform transition) (3,4), and the accumulation of myofibrillar proteins (5,6). These responses may occur according to the nature of the stimulus applied (i.e., the variables of the training program).…”