TY - JOUR

T1 - Strength training increases the size of the satellite cell pool in type I and II fibres of chronically painful trapezius muscle in females

AU - Mackey, Abigail

AU - Andersen, Lars L

AU - Frandsen, Ulrik

AU - Sjøgaard, Gisela

PY - 2011/11/15

Y1 - 2011/11/15

N2 - While strength training has been shown to be effective in mediating hypertrophy and reducing pain in trapezius myalgia, responses at the cellular level have not previously been studied. This study investigated the potential of strength training targeting the affected muscles (SST, n = 18) and general fitness training (GFT, n = 16) to augment the satellite cell (SC) and macrophage pools in the trapezius muscles of women diagnosed with trapezius myalgia. A group receiving general health information (REF, n = 8) served as a control. Muscle biopsies were collected from the trapezius muscles of the 42 women (age 44 ± 8 years; mean ± SD) before and after the 10 week intervention period and were analysed by immunohistochemistry for SCs, macrophages and myonuclei. The SC content of type I and II fibres was observed to increase significantly from baseline by 65% and 164%, respectively, with SST (P <0.0001), together with a significant correlation between the baseline number of SCs and the extent of hypertrophy (r = -0.669, P = 0.005). SST also resulted in a 74% enhancement of the trapezius macrophage content (P <0.01), accompanied by evidence for the presence of an increased number of actively dividing cells (Ki67(+)) post-SST (P <0.001). GFT resulted in a significant 23% increase in the SC content of type II fibres, when expressed relative to myonuclear number only (P <0.05). No changes in the number of myonuclei per fibre or myonuclear domain were detected in any group. These findings provide strong support at the cellular level for the potential of SST to induce a strong myogenic response in this population.

AB - While strength training has been shown to be effective in mediating hypertrophy and reducing pain in trapezius myalgia, responses at the cellular level have not previously been studied. This study investigated the potential of strength training targeting the affected muscles (SST, n = 18) and general fitness training (GFT, n = 16) to augment the satellite cell (SC) and macrophage pools in the trapezius muscles of women diagnosed with trapezius myalgia. A group receiving general health information (REF, n = 8) served as a control. Muscle biopsies were collected from the trapezius muscles of the 42 women (age 44 ± 8 years; mean ± SD) before and after the 10 week intervention period and were analysed by immunohistochemistry for SCs, macrophages and myonuclei. The SC content of type I and II fibres was observed to increase significantly from baseline by 65% and 164%, respectively, with SST (P <0.0001), together with a significant correlation between the baseline number of SCs and the extent of hypertrophy (r = -0.669, P = 0.005). SST also resulted in a 74% enhancement of the trapezius macrophage content (P <0.01), accompanied by evidence for the presence of an increased number of actively dividing cells (Ki67(+)) post-SST (P <0.001). GFT resulted in a significant 23% increase in the SC content of type II fibres, when expressed relative to myonuclear number only (P <0.05). No changes in the number of myonuclei per fibre or myonuclear domain were detected in any group. These findings provide strong support at the cellular level for the potential of SST to induce a strong myogenic response in this population.

KW - Adult

KW - Chronic Pain

KW - Female

KW - Humans

KW - Hypertrophy

KW - Ki-67 Antigen

KW - Laminin

KW - Macrophages

KW - Middle Aged

KW - Muscle Fibers, Fast-Twitch

KW - Muscle Fibers, Slow-Twitch

KW - Muscular Diseases

KW - Musculoskeletal Pain

KW - Myosin Type I

KW - Neck Muscles

KW - PAX7 Transcription Factor

KW - Resistance Training

KW - Satellite Cells, Skeletal Muscle

U2 - 10.1113/jphysiol.2011.217885

DO - 10.1113/jphysiol.2011.217885

M3 - Journal article

C2 - 21946848

VL - 589

SP - 5503

EP - 5515

JO - The Journal of Physiology

JF - The Journal of Physiology

SN - 0022-3751

IS - Pt 22

ER -