Do skeletal muscle composition and gene expression as well as acute exercise-induced serum adaptations in older adults depend on fitness status?

Daniel A Bizjak,Dhayana Dallmeier,Jürgen M Steinacker,Martina Zügel,Uwe Schumann,Mark A Tully,Michael Denkinger

doi:10.1186/s12877-021-02666-0

Abstract

BackgroundInactive physical behavior among the elderly is one risk factor for cardiovascular disease, immobility and increased all-cause mortality. We aimed to answer the question whether or not circulating and skeletal muscle biomarkers are differentially expressed depending on fitness status in a group of elderly individuals.MethodsTwenty-eight elderly individuals (73.36 ± 5.46 years) participated in this exploratory study after participating as part of the multinational SITLESS-clinical trial (implementation of self-management and exercise programs over 16 weeks). A cardiopulmonary exercise test (CPX) and resting skeletal muscle biopsy were performed to determine individual physiological performance capacity. Participants were categorized into a high physical fitness group (HPF) and a low physical fitness group (LPF) depending on peak oxygen uptake (VO2peak). Serum blood samples were taken before (pre) and after (post) CPX and were examined regarding serum BDNF, HSP70, Kynurenine, Irisin and Il-6 concentrations. Skeletal muscle tissue was analyzed by silver staining to determine the myosin heavy chain (MyHC) composition and selected genes by qRT-PCR.ResultsHPF showed lower body weight and body fat, while skeletal muscle mass and oxygen uptake at the first ventilatory threshold (VO2T1) did not differ between groups. There were positive associations between VO2peak and VO2VT1 in HPF and LPF. MyHC isoform quantification revealed no differences between groups. qRT-PCR showed higher expression of BDNF and BRCA1 in LPF skeletal muscle while there were no differences in other examined genes regarding energy metabolism. Basal serum concentrations of Irisin were higher in HPF compared to LPF with a trend towards higher values in BDNF and HSP70 in HPF. Increases in Il-6 in both groups were observed post.ConclusionsAlthough no association between muscle composition/VO2peak with fitness status in older people was detected, higher basal Irisin serum levels in HPF revealed slightly beneficial molecular serum and muscle adaptations.Trial registrationClinicalTrials.gov, NCT02629666. Registered 19 November 2015.

Highlights

Inactive physical behavior among the elderly is one risk factor for cardiovascular disease, immobility and increased all-cause mortality
Sarcopenia is defined as the gradual loss of skeletal muscle mass, quality and strength during ageing and/or immobility [1]
Physical performance measures and anthropometry The study population consisted of 28 participants (14 high physical fitness group (HPF), 14 low physical fitness group (LPF))

Summary

Introduction

Inactive physical behavior among the elderly is one risk factor for cardiovascular disease, immobility and increased all-cause mortality. Sarcopenia is defined as the gradual loss of skeletal muscle mass, quality and strength during ageing and/or immobility [1]. Harvey et al (2013) examined physical activity of older people in seven countries and found that approximately 67% of the age group > 60 years showed sedentary behavior of 8.5 h per day [4]. Sarcopenia and increasing immobility is associated with a functional decline such as impaired gait speed, increased fall and hospitalization risk as well as a higher mortality rate [2, 6, 7]. Sarcopenic obesity, the combination of obesity and low muscle mass, is a serious health problem as it enhances the pro-inflammatory and adipokine response, promotes insulin resistance and is associated with increased strength loss and mortality [10]

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