It depends on the case; there is no single guideline.
Effect by goal · level of evidence
Metabolic and muscle adaptations by age
improvesModeratestudy (A)
12 weeks in young and older people: all improved insulin sensitivity and lean mass, but only HIIT (aerobic intervals) and combined training improved aerobic capacity and muscle mitochondria, reversing aging-related changes, especially in older people. Strength training builds the most mass.
Metabolic and muscular adaptations by age — improves (Moderate, study). 12 weeks in young and older adults: everyone improved insulin sensitivity and lean mass, but only HIIT (aerobic intervals) and the combined program improved aerobic capacity and muscle mitochondria, reversing changes of aging, especially in older adults. Strength training builds the most mass. 28273480
Information, not medical advice. Prescription drugs require a doctor.
Information, not medical advice. Scientific evidence reflects the quality of the studies.