Single muscle fiber adaptations to resistance training in old (>80 yr) men: evidence for limited skeletal muscle plasticity

Abstract

The purpose of this study was to investigate whole muscle and single muscle fiber adaptations in very old men in response to progressive resistance training (PRT). Six healthy independently living old men (82 +/- 1 yr; range 80-86 yr, 74 +/- 4 kg) resistance-trained the knee extensors (3 sets, 10 repetitions) at approximately 70% one repetition maximum 3 days/wk for 12 wk. Whole thigh muscle cross-sectional area (CSA) was assessed before and after PRT using computed tomography (CT). Muscle biopsies were obtained from the vastus lateralis before and after the PRT program. Isolated myosin heavy chain (MHC) I and IIa single muscle fibers (n = 267; 142 pre; 125 post) were studied for diameter, peak tension, shortening velocity, and power. An additional set of isolated single muscle fibers (n = 2,215; 1,202 pre; 1,013 post) was used to identify MHC distribution. One repetition maximum knee extensor strength increased (P < 0.05) 23 +/- 4 kg (56 +/- 4 to 79 +/- 7 kg; 41%). Muscle CSA increased (P < 0.05) 3 +/- 1 cm2 (120 +/- 7 to 123 +/- 7 cm2; 2.5%). Single muscle fiber contractile function and MHC distribution were unaltered with PRT. These data indicate limited muscle plasticity at the single-muscle fiber level with a resistance-training program among the very old. The minor increases in whole muscle CSA coupled with the static nature of the myocellular profile indicate that the strength gains were primarily neurological. These data contrast typical muscle responses to resistance training in young ( approximately 20 yr) and old ( approximately 70 yr) humans and indicate that the physiological regulation of muscle remodeling is adversely modified in the oldest old.

The effects of whole-body vibration training and vitamin D supplementation on muscle strength, muscle mass, and bone density in institutionalized elderly women: A 6-month randomized, controlled trial

“…Finally, muscle plasticity in old age may be limited. (44) This study has several limitations that need consideration. Given the strict inclusion and exclusion criteria for participation in WBV training, the subject sample may not be representative of the overall institutionalized elderly population.…”

Plantaris muscle weakness in old mice: relative contributions of changes in specific force, muscle mass, myofiber cross-sectional area, and number

“…This could be achieved by resistance training that has been shown to increase specific force (Erskine et al 2011). The impact of training may decrease with increasing age (Degens 2012;Slivka et al 2008) and it thus appears essential to start interventions before sarcopenia takes its toll.…”

Adaptações neuromusculares ao treinamento de força e concorrente em homens idosos.

“…O treinamento de força (TF) é uma intervenção efetiva para o aumento na força [1][2][3]6 , potência 6,13,21 , ativação 7,8,10,13,15 e massa muscular 2,6,8,11,16 . Adaptações na função neuromuscular decorrente do treinamento de força nessa população aparenta ser semelhante do que em indivíduos jovens 16 , e essas adaptações resultam em melhora significativa na capacidade funcional dessa população 22 .…”

“…Indivíduos idosos submetidos ao treinamento de força (TF) apresentam aumento significativo na força muscular [1][2][3][4] , potência muscular 5,6 , ativação muscular [7][8][9][10][11] e massa muscular 12,13 . A melhora na força muscular decorrente do treinamento de força nessa população aparenta ser semelhante [14][15][16] do que à observada em indivíduos jovens, o que lhe confere grande treinabilidade, apesar do prejuízo na função neuromuscular decorrente do envelhecimento 9 .…”