Both Young and Old Lose Muscle Strength After Short Term Inactivity Interview with:
Andreas Vigelsø PhD, research assistant
University of Copenhagen
Faculty of Health Sciences
Center for Healthy Aging
Dept. of Biomedical Sciences
Copenhagen Denmark

Medical Research: What is the background for this study?

Response: According to the UN, the number of individuals more than 60 years old is expected to more than double, from 841 million worldwide today to more than 2 billion in 2050. Furthermore, the aging process is associated with a reduction in muscle mass, strength and fitness level. Collectively, this may contribute to frailty and may limit independent living. In addition, disease or injuries that can cause short-term immobilization are a further threat to independent living for older individuals. Despite its clinical importance for an increasing population of older individuals, few studies have examined older individuals after immobilization. Thus, our aim was to determine the effect of aerobic retraining as rehabilitation after short-term leg immobilization on leg strength, leg work capacity, and leg muscle mass in young and older men.

Medical Research: What are the main findings?

Response: Interestingly, our study reveals that inactivity affects the muscular strength in young and older men equally. Having had one leg immobilized for two weeks, young people lose up to a third of their muscular strength, while older people lose approx. one fourth. A young man who is immobilized for two weeks loses muscular strength in his leg equivalent to ageing by 40 or 50 years. Moreover, short-term leg immobilization had marked effects on leg strength, and work capacity and 6 weeks’ retraining was sufficient to increase, but not completely rehabilitate, muscle strength, and to rehabilitate aerobic work capacity and leg muscle mass.

Medical Research: What should clinicians and patients take away from your report?

Response: Therefore, aerobic training alone should not be used as rehabilitation training after short-term immobilization. But, aerobic retraining may be considered as a partial alternative in combination with strength training without impeding the rehabilitation process. Moreover, aerobic retraining could be considered due to the beneficial effect of counteracting the increased risk of lifestyle-related diseases in the older population and may be advantageous for therapists, as not all individuals will enjoy or adhere to a single protocol.

For the patient our results pinpoints the importance for rehabilitation training after even short-term inactivity to maintain independent living throughout life.

Medical Research: What recommendations do you have for future research as a result of this study?

Response: This study included subjects who were average for their age group. However, the clinical relevance may be more pronounced in the proportion of the older population that is less physically active. Hence, our approach is applicable to a large proportion of the population, but possibly not to the weakest. Therefore, future research should search to optimize rehabilitation training that rehabilitates and improves strength, muscle mass and fitness level in the weaker part of the older population.


Six weeks’ aerobic retraining after two weeks’ immobilization restores leg lean mass and aerobic capacity but does not fully rehabilitate leg strenght in young and older men.

Vigelsø A1, Gram M, Wiuff C, Andersen JL, Helge JW, Dela F.
J Rehabil Med. 2015 Apr 21. doi: 10.2340/16501977-1961. [Epub ahead of print]


Andreas Vigelsø PhD, research assistant, & University of Copenhagen (2015). Both Young and Old Lose Muscle Strength After Short Term Inactivity 

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