Project description:The skeletal muscle system plays an important role in the independence of older adults. In this study we examine differences in the skeletal muscle transcriptome between healthy young and older subjects and (pre‐)frail older adults. Additionally, we examine the effect of resistance‐type exercise training on the muscle transcriptome in healthy older subjects and (pre‐)frail older adults. Baseline transcriptome profiles were measured in muscle biopsies collected from 53 young, 73 healthy older subjects, and 61 frail older subjects. Follow‐up samples from these frail older subjects (31 samples) and healthy older subjects (41 samples) were collected after 6 months of progressive resistance‐type exercise training. Frail older subjects trained twice per week and the healthy older subjects trained three times per week. At baseline genes related to mitochondrial function and energy metabolism were differentially expressed between older and young subjects, as well as between healthy and frail older subjects. Three hundred seven genes were differentially expressed after training in both groups. Training affected expression levels of genes related to extracellular matrix, glucose metabolism, and vascularization. Expression of genes that were modulated by exercise training was indicative of muscle strength at baseline. Genes that strongly correlated with strength belonged to the protocadherin gamma gene cluster (r = −0.73). Our data suggest significant remaining plasticity of ageing skeletal muscle to adapt to resistance‐type exercise training. Some age‐related changes in skeletal muscle gene expression appear to be partially reversed by prolonged resistance‐type exercise training. The protocadherin gamma gene cluster may be related to muscle denervation and re‐innervation in ageing muscle.
Project description:Background: Exercising is know to have an effect on exercising skeletal muscle, but unkown is the effect on non-exercising skeletal muscle. Gene expression changes in the non-exercising skeletal muscle would point to a signalling role of skeletal muscle 9 healthy middle-aged men performed 1 hour of one-legged exercise, before and afterwards muscle biopsies were taken from both legs. Skeletal muscle biopsies were analyzed by microarray.
Project description:Human aging is associated with skeletal muscle atrophy and functional impairment (sarcopenia). Multiple lines of evidence suggest that mitochondrial dysfunction is a major contributor to sarcopenia. We evaluated whether healthy aging was associated with a transcriptional profile reflecting mitochondrial impairment and whether resistance exercise could reverse this signature to that approximating a younger physiological age. Skeletal muscle biopsies from healthy older (N = 25) and younger (N = 26) adult men and women were compared using gene expression profiling, and a subset of these were related to measurements of muscle strength. 14 of the older adults had muscle samples taken before and after a six-month resistance exercise-training program. Before exercise training, older adults were 59% weaker than younger, but after six months of training in older adults, strength improved significantly (P<0.001) such that they were only 38% lower than young adults. As a consequence of age, we found 596 genes differentially expressed using a false discovery rate cut-off of 5%. Prior to the exercise training, the transcriptome profile showed a dramatic enrichment of genes associated with mitochondrial function with age. However, following exercise training the transcriptional signature of aging was markedly reversed back to that of younger levels for most genes that were affected by both age and exercise. We conclude that healthy older adults show evidence of mitochondrial impairment and muscle weakness, but that this can be partially reversed at the phenotypic level, and substantially reversed at the transcriptome level, following six months of resistance exercise training. Keywords: resistance exercise, muscle, aging