Older adults with muscle weakness had less steady force

In an observational study, 11 older adults with sarcopenia, 22 adults without it and 19 older athletes performed ankle contractions. Participants averaged 74.3 years of age; half were female. Researchers defined sarcopenia, a condition involving muscle weakness, by low grip strength and slow walking speed. Participants held contractions at 30% of their maximum turning force, either while subtracting numbers or without a mental task. Electrical recordings from muscles allowed researchers to assess the timing of signals activating muscle fibres.

The sarcopenia group produced less steady force than both comparison groups during both tasks. Their force variability rose about 35% when they also subtracted numbers. The intervals between signals activating muscle fibres became more variable in this group during the combined task. That timing measure stayed unchanged in controls and became less variable in athletes.