RELIEF - Resistance Training for Life (RELIEF)

Resistance Training for Life - the Efficacy of Increasing Resistance Training Volume for Improving Muscle Mass, Function, Biology and Health in Young and Elderly

Sarcopenia is an age-related gradual loss of muscle mass and strength and is associated with physical disability and mortality risk. Currently, the most promising remedy for preventing and treating sarcopenia is physical activity, particularly progressive resistance training. Yet, the amount of resistance exercise needed to achieve optimal benefits remains largely unknown. This lack of knowledge is underpinned by the notion that aging reduces the ability to adapt to (and benefit from) resistance training, and is further complicated by a relative large degrees of between-subject heterogeneity. The primary aim of the study is to compare the effects of 10 weeks of resistance training with low- and moderate volume (one vs. three sets per exercise) on muscle mass accretion in lower and upper body extremities in young (<30 years of age) and elderly individuals (>70 years of age). Specifically, the study addresses the hypothesis that elderly individuals will benefit more from higher exercise volume (moderate vs. low) compared to their young counterparts. In addition, the study aims to compare the efficacy of the two volume conditions for altering other characteristics such as muscle strength and biology, including assessment of associations between individual changes in muscle mass, strength and biology (e.g. the relationship between muscle mass accretion and muscle content of rRNA/rDNA), and also to investigate the general health effects of the intervention.

Study conditions (exercise volume) are randomized to either leg/arm for within-participant comparisons. The effect of age is assessed from two parallel age groups.

Study conditions (exercise volume) and age groups identifiers are omitted from outcome assessments whenever possible. Assessment of the primary (and selected secondary) outcome(s) will be performed in a blinded fashion by assessors/investigators.

Participants in two age groups will receive moderate (three sets of per exercise per session) and low-volume (one set of resistance per session) training allocated to either right or left upper- and lower extremities. A total of 24 sessions will be performed over 10-12 weeks.

Progressive resistance training, performed with a target number of repetitions of 10 per set. Sets are performed to exhaustion, and external load will be adjusted to meet the target number of repetitions.

Muscle strength of the legs measured as a weighted average of lower body isokinetic and isometric knee extensor maximal force

Muscle strength will be assessed as a weighted average of lower body isokinetic and isometric knee extensor maximal force

Muscle fiber characteristics such as muscle fiber proportions, cross-sectional area, myonuclei content and capillarization measured in biopsies from m. vastus lateralis

Systemic inflammation measured as blood markers such as C-reactive protein (CRP) in resting blood samples.

Concentrations of hormones such as testosterone, growth hormone, thyroid hormones, cortisol and insulin (c-peptide) in serum

Dietary composition assessed using a food-frequency questionnaire (nutritional composition, energy intake, habitual patterns of dietary intake)

Dietary composition assessed using a food-frequency questionnaire (nutritional composition, energy intake, habitual patterns of dietary intake)

Activities of daily living measured using a questionnaire (i.e. time spent in activity, intensities and type of activity)

Inclusion Criteria: Ages between 18 and 30 or > 70 Exclusion Criteria: Resistance training, > 1 session per week Endurance training, > 3 sessions per week Unstable cardiovascular disease Illness or serious injury contradicting resistance training Serious mental illness Allergy to local anaesthesia

The full data sets used to analyze study outcomes will be made available with the publication of the study. Data sets will be included or referred to in the publication and hosted online.