Mixed
High-intensity resistance training (above 60% 1RM) reverses muscle atrophy and functional decline in frail, institutionalized elderly individuals (ages 87-96).
If you are an elderly individual, especially if you live in a care facility or feel frail, high-intensity resistance training (lifting weights at 60-100% of your maximum capacity) can significantly increase your muscle strength and size, even in your 90s. This leads to better functional status and independence. You do not need to be young or fit to start; the key is the intensity of the stimulus, not your current fitness level.
In a population of 100 nursing home residents, a randomly assigned high-intensity strength training program resulted in significant gains in strength and functional status... The fact that significant muscle hypertrophy was seen in this population indicates that age does not decrease the capacity to adapt to a progressive resistance training program.
Why this rating
Based on a randomized controlled trial (n=100) with significant results, though the paper is a review summarizing multiple studies.
Source
Effects of Exercise on Body Composition and Functional Capacity of the Elderly
Rand S. Schwartz et al. · The Journals of Gerontology Series A · 1995
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