Older adults needed more to keep their new muscle: in a trial of 70 adults aged 20-35 or 60-75, 16 weeks of resistance training 3 days a week was followed by 32 weeks of randomly assigned detraining or training at one-third or one-ninth of that dose, and both reduced doses held the muscle hypertrophy in the young (one-third even added fibre size) but not in the older group; the strength gained was largely kept even by those who stopped, with only a slight drop at the last test

Bickel, Cross and Bamman asked how little resistance training is enough to keep what a training block built, and whether older adults need more than young ones. Seventy adults, in a group aged 20-35 and a group aged 60-75, trained 3 days a week for 16 weeks.

For the next 32 weeks they were randomly assigned to stop (detraining) or to keep training at one-third or one-ninth of the phase-1 dose. The first phase produced the expected gains in strength, muscle fibre size and muscle mass, and the usual shift of type IIx fibres toward type IIa.

In the young, both reduced doses held the gained muscle size, and the one-third dose added further fibre growth; in the older group, neither held it. Stopping reversed the fibre-type shift at both ages, and of the two maintenance doses, one-third kept the shift better.

Strength gained in phase 1 was mostly kept even by those who stopped, slipping slightly only by the final test. The authors conclude that older adults need a larger weekly loading dose than the young to keep fibre hypertrophy, while their gains in specific strength held up well and stayed at or above the level of untrained young adults.

n = 70 adults in two age groups, 20-35 y and 60-75 y; men and women by the PubMed indexing (the abstract does not give the sex split). Not in the abstract: the number in each age group and in each phase-2 arm, how many finished, health status, body size and prior training.