Effects of resistance exercise volume on the variability of the hypertrophic response in eldery

Author(s)

Manoel Emílio Lixandrão

• Document type: Doctoral Thesis
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Escola de Educação Física e Esportes (EEFE/BT)
• Defense date: 2020-10-26

Examining board members

Hamilton Augusto Roschel da Silva; Cleiton Augusto Libardi; Renato Barroso da Silva; Carlos Ugrinowitsch

• Advisor: Hamilton Augusto Roschel da Silva

Abstract

Aging is associated with a progressive loss of skeletal muscle mass, which ultimately reduces the functional capacity. Accordingly, resistance training (RT) has been well established as an effective strategy to promote muscle mass accrual in elderly. However, there is substantial inter-individual variability in resistance exercise-mediated changes in muscle mass (i.e., RT-responsiveness), with some individuals showing insignificant increases in muscle mass (i.e., low-responders) while others demonstrating robust gains (i.e., high-responders). It has been suggested this may be a function of an insufficient and/or inadequate RT stimulus rather than a definite reduced capacity to increase muscle mass content. Therefore, the present study aimed to investigate if the RT-responsiveness is modulated by variations in RT volume. Furthermore, we also investigated the effects of different volumes of RT on molecular biomarkers related with RT-responsiveness, i.e., total protein expression of UBF, Frizzled-1, c-Myc, rpL3 and TRIM24, associated with ribosome biogenesis. The experimental design was composed by 10-week, with a RT program (2 sessions●week-1) in a unilateral knee extension machine. Each leg of a given subject was randomly allocated, balancing for dominance, in one of the two possible conditions: 1) one set of 8-15 maximum repetitions and; 2) four sets of 8-15 maximum repetitions. Before and after the training period, all subjects were submitted to a magnetic resonance imaging exam, one repetition maximum test, and muscle biopsies (vastus lateralis). The main results showed that manipulating RT volume increased the hypertrophic response while reducing the number of low-responders (~80%) after the intervention. Regarding the molecular markers associated with ribosome biogenesis, we showed an increased protein expression of rpL3 and Frizzled-1 and significance trend for UBF. We also observed an increased skeletal muscle total RNA concentration, favoring the higher volume RT protocol. Our results showed a high inter-individual variability in resistance exercise-mediated changes for muscle mass in eldery; however, this can be modulated by manipulating RT volume. Specially, we observed that manipulations in RT volume increase the hypertrophic response and reduce the number of low-responders (~80%). This response was partially accompanied by an augmented ribosome biogenesis as well as an increased skeletal muscle total RNA concentration. Thus, our results suggest that RT volume prescription for elderly individuals should be individualized in order to proper optimize the hypertrophic adaptations in this population (AU)

• FAPESP's process: 16/22635-6 - Effects of resistance exercise volume on the variability of the hypertrophic response in ELDELY
• Grantee: Manoel Emílio Lixandrão
• Support Opportunities: Scholarships in Brazil - Doctorate