ECSS Paris 2023: OP-MH10
INTRODUCTION: Muscle power is essential for preserving functional capacity in older adults. It can be enhanced through power-focused resistance training, but optimal training loads remain unclear. Because force and velocity capacities differ between individuals, and power training adaptations are load- and velocity-specific, this study examined whether individualizing loads based on an older individual’s force-velocity profile improves power training outcomes compared with non-individualized training. METHODS: Force–velocity profiles were assessed in older adults (n = 80; ≥65 years) using a pneumatic leg press (Keiser A400). Each participant’s maximal force and maximal movement velocity were compared with the mean values of a younger reference group (n = 60; 20–35 years). Differences from the young reference values were converted to Z-scores. Older participants were classified as having a force–velocity imbalance when the absolute difference between their force and velocity Z-scores was ≥1. The type of deficit (force or velocity) was determined by the lower Z-score. Participants with a Z-score difference <1 were classified as neutral and excluded from the intervention. Fifty-nine participants exhibited velocity deficits, whereas only five showed force deficits. Due to the small number of participants with force deficits, statistical analyses were limited to those with velocity deficits, who completed a 12-week intervention and were assigned to either an individualized (IND) or non-individualized (NON-IND) program. Training was performed twice weekly: IND completed leg press progressive resistance training with low loads (40% one-repetition maximum [1-RM]) to target velocity deficits, while NON-IND trained with high loads (80% 1-RM). Force-velocity characteristics, muscle power and functional performance were assessed at baseline, 6 weeks and 12 weeks. RESULTS: IND demonstrated greater increases in maximal velocity compared with NON-IND (p = 0.003, d = 0.53 vs. p = 1.000, d = 0.01). In contrast, NON-IND showed greater increases in maximal force than IND (p < 0.001, d = 0.36 vs. p = 0.497, d = 0.17). Significant main effects of time were observed for maximal power (p < 0.001,) and all functional performance outcomes (p < 0.001 - 0.004), except stair climbing power (p = 0.135). No significant time × group interactions were detected for maximal power or functional performance outcomes (p > 0.05). CONCLUSION: Individualized power-focused resistance training led to force- and velocity-specific changes but did not produce greater improvements in muscle power or functional performance than non-individualized training. Tailoring loads based on F-v profiles may induce distinct adaptations but is not required to optimize power training outcomes in older adults.
Read CV Jolien DeboutteECSS Paris 2023: OP-MH10
INTRODUCTION: Muscle fasciculations are involuntary contractions that occur in healthy individuals but clinically, their manifestation is deemed a sign of denervation. Evidence exists [1] to suggest that the number of fasciculations someone experiences might increase with age, but the time-course of these changes compared to other common measures of age-related decline (e.g. muscle mass, muscle quality) is currently unknown. The aim of this study was therefore to compare muscle fasciculations and existing markers of age-related decline across a spectrum of different age ranges. METHODS: Participants in young (Y: 20-30 years), middle-aged (M: 45-55 years) and older (O: 70-80 years) age ranges completed a single testing session. Following a dual energy x-ray absorptiometry (DXA) scan to assess body composition, participants completed a resting muscle fasciculation assessment of the gastrocnemius medialis using dynamic ultrasound (60 Hz) and high-density surface electromyography (1000 Hz). Isometric plantar flexion strength was assessed using an isokinetic dynamometer (200 Hz), and a stair ascent-descent and gait speed reserve (GSR) test were used to assess functional performance. Fasciculations were analysed using a validated automated identification algorithm [2] in MATLAB. Differences groups were determined using Cohens d effect sizes and were categorised as small (>0.2), medium (>0.50) large (>0.8) or very large (>1.2). RESULTS: Moderate-large differences in muscle fasciculations were observed between groups (Y vs M: d=0.22, Y vs O: d=0.89, M vs O: d=0.71) with O observing 40% and 31% more than Y and M, respectively, and M experiencing 7% more than Y. These differences were also underpinned by moderate-to-large differences in appendicular lean mass (Y vs M: d=0.83, Y vs O: d=1.39, M v O: d=0.91) and muscle quality index (Y v M: d=0.51, Y vs O: d=0.92: M v O: d=0.46). Differences in strength and functional performance were more pronounced, with moderate-to-very large differences being shown in plantar flexor strength (Y v M: 1.01, Y v O: 1.67, M v O: 0.82), stair ascent-descent (Y v M: d=0.56, Y v O: d=2.99, M v O: d=2.72) and GSR (Y v M: d=0.56, Y v O: d=1.31, M v O: d=0.86). CONCLUSION: The lower levels of strength and functional performance in older and middle-aged adults occurred alongside reductions in muscle mass and muscle quality, as well as increases in muscle fasciculations. Since automated, reliable and non-invasive methods now exist to characterise involuntary muscle activity, greater utilisation of these methods in health screening may provide deeper insights into the neurophysiology of musculoskeletal decline and enable earlier intervention. References: [1] Fremont J et al. (2010) Amyotrophic Lateral Sclerosis; 11: 181-186 [2] Bibbings, K et al. (2019) Ultrasound in Med & Biol; 45:1164-1175
Read CV Gareth NicholsonECSS Paris 2023: OP-MH10
INTRODUCTION: Skeletal muscle ageing is driven by neural, muscular, and connective tissue alterations that impair muscle mass, strength, and quality, with sex being a major determinant of these trajectories (1–3). However, an integrated functional, physiological, and molecular characterization of these differences is still missing. This study seeks to advance knowledge through a sex-biased, multidimensional approach aimed at elucidating the differential contributions of neural and muscular components to ageing in males and females. METHODS: A total of 239 healthy participants (20–91 yrs., 55% F) was recruited. Fat mass (FM) was assessed by dual-energy X-ray absorptiometry. Vastus lateralis (VL) cross-sectional area (CSA) and muscle quality (echo intensity, EI) were evaluated by ultrasound imaging. Quadriceps maximal voluntary contraction (MVC) was measured by isometric dynamometry. Intramuscular electromyography was recorded on VL during isometric contractions at 25% MVC to evaluate motor unit (MU) properties. VL biopsies were collected to analyse fiber type and CSA, Neural Cell Adhesion Molecule (NCAM) expression (denervation marker), and collagen content. Single-nuclei RNA sequencing was performed on a subgroup with balanced male (M) and female (F) representation within the ageing spectrum, to assess sex-specific gene expression changes. Linear regression and linear mixed-effects models were conducted with age treated as a continuous variable. RESULTS: MVC declined similarly across the lifespan in both M and F, with M being consistently stronger. VL CSA decreased in both sexes, though decline was greater in M. Leg FM increased with age in F but not in M, while EI increased in M but remained stable in F, despite F exhibited higher values from young adulthood. MU firing rate declined equally in both sexes. In contrast, M exhibited larger MU potential (MUP) area and transmission variability (Jiggle) than F across the lifespan, while MUP complexity increased with age in both sexes. Type IIa muscle fibers were consistently smaller in F, whereas type I fiber CSA differed only at very old ages. NCAM expression increased with age in M but not F, while collagen content was higher in F across the lifespan. Cell type-specific gene expression analyses uncovered sex-specific transcriptional divergence in ageing, with only 2–5% of differentially expressed genes (DEGs) shared between M and F. CONCLUSION: Strength declines in both sexes, but muscle size shows a more pronounced age-related deterioration in M, whereas F exhibit greater fat accumulation and fibrosis. Despite sex disparities, age-related MU remodeling occurs at similar extent in M and F. Muscle fibers phenotype and gene expression profiles further confirm divergent molecular ageing trajectories between sexes. These findings emphasize the importance of considering sex in ageing studies. References: 1. Nuzzo, 2023 (J Str Cond Res); 2. Della Peruta, 2023 (IJMS); 3. Guo, 2025 (J Physiol) . Funding: PNRR Mission 4 Component 2
Read CV Ornella CaputoECSS Paris 2023: OP-MH10