Training of intramuscular connective tissue in elderly

Background The aging process is accompanied by losses in skeletal muscle mass and function, where strength losses are typically larger than those in muscle mass. Changes in the structure and composition of intramuscular connective tissue (IMCT), which is responsible for force transmission within muscles, may represent an important but overlooked factor accounting for this loss of muscle quality. Current exercise-based treatment approaches may not incorporate adequate stimuli to induce IMCT renewal. Aims and hypotheses The aim of this project is to test the potential of various forms of physical exercises in stimulating the renewal of IMCT in lower limb muscles of senior people. A novel resistance training regimen will be developed by incorporating exercises specifically stimulating the IMCT into a training program as conventionally prescribed for the treatment of age-associated muscle weakness. We hypothesize that the regular execution of jumps in combination with weight training will lead to superior strength gains as conventional weight training alone. Originality Studying exercise modalities to target the IMCT, our project will be the first to test the effectiveness of different training stimuli in inducing regeneration of non-functionally active muscle tissue. Thus, it adopts a new approach to the treatment of age-associated muscle function deficits. Study design and methods This project will be carried out in 2 phases. In Phase 1, we will compare 4 different exercises targeting thigh and calf muscles (A: Conventional weight training, B: Weight training assisted by foam rolling, C: Weight training using only lengthening muscle contractions, D: Jumps) to identify the single one demonstrating the greatest potential to induce IMCT rejuvenation. This will be accomplished through the analysis of the activity of genes associated with IMCT cell turnover in tissue samples extracted from the thigh after an acute training session consisting of the above-mentioned exercises. Phase 1 will be completed in a sample of 24 men aged 65-70 years. For Phase 2, we will then proceed to design an innovative training program by incorporating the exercise specifically stimulating the IMCT (identified in Phase 1) into a standard training program as typically prescribed for elderly cohorts. 28 subjects (equal number of men and women, aged 65-70 years) each will be assigned to groups training according to this novel, IMCT-specific program, conventional training recommendations, or a non-training control group. Following 4 months of training, the effectiveness of the different interventions will be compared based on histological (gene and protein analyses), imaging-based (muscle volumes, structure and density) and functional tests (e.g., strength measurements, walking speed, hand grip strength).