Table 1 Selection criteria according to PICOS criteria (population, intervention, comparator, outcome, study design
Category | Inclusion criteria | Exclusion criteria |
|---|---|---|
Population | Higher- or lower-functioning healthy older individuals age ≥ 65 years or individuals with neurological conditions (e.g., Parkinson’s disease, multiple sclerosis, stroke) We determined the age criterion by averaging the age of participants across the training and control groups in each study and compared it against the age limit of 65 years. For lower-functioning older individuals, we used walking speed (< 1.0 m/s), short physical battery performance score (≤ 8.0) and author-reported diagnosis of sarcopenia | Higher- or lower-functioning healthy older individuals age < 65 years or individuals with neurological conditions (e.g., Parkinson’s disease, multiple sclerosis, stroke) |
Intervention | Resistance training, aerobic training, multimodal training, and other single-mode exercise interventions (e.g., aquatic, dance exercise) with or without dietary supplements | Studies that were shorter than six weeks in duration or used fewer than nine exercise sessions |
Comparator | Active (i.e., contrast with different training programs) and passive, placebo control or wait-list control groups | No control group |
Outcome | MMQ outcomes included intermuscular and intramuscular adipose and fibrous tissue, i.e., the amount of non-contractile tissue expressed in absolute terms and relative to total muscle size determined by imaging (e.g., magnetic resonance imaging [MRI], peripheral quantitative computed tomography [pQCT], computed tomography [CT], or ultrasound imaging [US]). NMQ outcomes were the ratio of maximal isometric or dynamic voluntary force, torque, or the load lifted relative to muscle size, i.e., muscle thickness, muscle mass, muscle volume or muscle cross-sectional area determined by MRI, pQCT, CT, US and also by dual-energy X-ray absorptiometry (DXA). We included both upper and lower extremity muscles | Failed to report the pre-post means or change scores and their standard deviations numerically or graphically; studies for which authors did not reply to our inquiries sent by email; failed to use at least one marker of MMQ or NMQ |
Study design | Randomized controlled trials including upper extremity and dietary supplement data | Case report, used a cross-over design or a diet-only intervention |