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Inactivity leaves greater negative impact on older people

Older people experienced a greater and more severe decrease in muscle power of their lower limbs vs. younger people when they were inactive for identical periods of time, according to findings recently published in The Journal of Physiology.

“Bedrest experiments on senior healthy subjects are not so common and so easy to carry out,” Carlo Reggiani, MD, department of biomedical sciences, University of Padova in Italy, told Healio Family Medicine. “The issue of inactivity in elderly people is extremely important [to look into].”

Researchers looked at the changes in maximal explosive power of lower limbs caused by a 14-day bedrest and a subsequent 14-day retraining in 23 participants. Sixteen of the participants were aged 55 to 65 years, the remaining participants were aged between 18 to 30 years. Participants who had a short physical performance battery score of 9 or less; CV, neuromuscular and chronic skeletal conditions; a history of deep vein thrombosis; ferromagnetic implants; regularly consumed alcohol or were smokers were not included.

Reggiani and colleagues reported that significant changes were observed in the older group.

Specifically, maximal explosive power was approximately a third lower in older participants vs. the younger ones, and stayed significantly lower (–19%) when normalized by muscle volume. Further, bedrest significantly impacted maximum explosive power in the older participants (–15%), but did not affect younger participants. Though retraining was more likely to increase maximum explosive power, older patients were unlikely to return to pre-bedrest levels, researchers wrote.

The impact of bedrest on leg strength was independent of any pre-existing health conditions, showing that even previously healthy older individuals were significantly impacted, Regianni said in the interview.

“The most interesting and surprising result is the impairment of the neural control on muscle function. One could say that, in the elderly but not in the young, after two weeks of inactivity the nervous system has partially ‘forgotten’ how to use or control the muscles,” he said.

Noting that loss of muscle power can make moving challenging, thus potentially leading to more inactivity, he suggested that primary care physicians should stress to their patients the importance of daily activity, when feasible, even when the patient is hospitalized. He suggested PCPs consider the recommendations of the American College of Sport Medicine for Resistance Training Exercise, which encourage performing one set of eight to 12 repetitions to the point of volitional fatigue, performing at least eight to 10 exercises that train the major muscle groups; and conducting said exercises at least twice a week.

“Moreover, the rehabilitation protocols must be specifically designed for elderly people, taking into account the slow and difficult recovery,” Regianni added.

He also said that he intends to focus on the involvement of the nervous system in the response to inactivity in a future study. – by Janel Miller

Disclosure: Healio Family Medicine was unable to determine the authors’ relevant disclosures prior to publication.