Early resistance training-induced increases in muscle cross-sectional area are concomitant with edema-induced muscle swelling

Autor(es)

Damas, Felipe ^[1] ; Phillips, Stuart M. ^[2] ; Lixandrao, Manoel E. ^[1] ; Vechin, Felipe C. ^[1] ; Libardi, Cleiton A. ^[3] ; Roschel, Hamilton ^[1] ; Tricoli, Valmor ^[1] ; Ugrinowitsch, Carlos ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Phys Educ & Sport, BR-05508030 Sao Paulo, SP - Brazil

^[2] McMaster Univ, Dept Kinesiol, Hamilton, ON L8S 4K1 - Canada

^[3] Univ Fed Sao Carlos, Lab Neuromuscular Adaptat Resistance Training, BR-13565905 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY; v. 116, n. 1, p. 49-56, JAN 2016.
• Citações Web of Science: 49

Resumo

It has been proposed that skeletal muscle shows signs of resistance training (RT)-induced muscle hypertrophy much earlier (i.e., similar to 3-4 weeks of RT) than previously thought. We determined if early increases in whole muscle cross-sectional area (CSA) during a period of RT were concomitant with edematous muscle swelling and thus not completely attributable to hypertrophy. We analyzed vastus lateralis muscle ultrasound CSA images and their respective echo intensities (CSA-USecho) at the beginning (T1), in the 3rd week of RT (T2) and at the end (T3) of a 10-week RT period in ten untrained young men. Functional parameters {[}training volume (TV = load x reps x sets) and maximal voluntary contraction (MVC)] and muscle damage markers (myoglobin and interleukin-6) were also assessed. Muscle CSA increased significantly at T2 (similar to 2.7 %) and T3 (similar to 10.4 %) versus T1. Similarly, CSA-USecho increasedat T2 (similar to 17.2 %) and T3 (similar to 13.7 %). However, when CSA-USecho was normalized to the increase in muscle CSA, only T2 showed a significantly higher USecho versus T1. Additionally, TV increased at T2 and T3 versus T1, but MVC increased only at T3. Myoglobin and Interleukin-6 were elevated at T2 versus T1, and myoglobin was also higher at T2 versus T3. We propose that early RT-induced increases in muscle CSA in untrained young individuals are not purely hypertrophy, since there is concomitant edema-induced muscle swelling, probably due to muscle damage, which may account for a large proportion of the increase. Therefore, muscle CSA increases (particularly early in an RT program) should not be labeled as hypertrophy without some concomitant measure of muscle edema/damage. (AU)

• Processo FAPESP: 14/19594-0 - O papel do dano muscular na modulação da síntese protéica muscular
• Beneficiário: Felipe Romano Damas Nogueira
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado
• Processo FAPESP: 12/24499-1 - O papel da magnitude de dano muscular nas respostas hipertróficas
• Beneficiário: Felipe Romano Damas Nogueira
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 13/21218-4 - O papel da magnitude de dano muscular nas respostas hipertróficas
• Beneficiário: Cleiton Augusto Libardi
• Modalidade de apoio: Auxílio à Pesquisa - Regular