People lose 30% of their muscle strength between the ages of 50 and 70 years. However, maintaining muscle strength in old age is enormously important in order to maintain mobility and to be able to lead an independent life and manage everyday tasks independently. In the current issue of Deutsches Ärzteblatt International, Frank Mayer and colleagues from the University of Potsdam conclude that progressive strength (resistance) training counteracts（抵消，中和） muscular atrophy（萎缩） in old age (Dtsch Arztebl Int 2011; 108(21): 359-64). The authors investigated the extent of the effects that can be achieved by strength (resistance) training in elderly persons and which intensities of exercise are useful and possible in persons older than 60 years. They found that regular strength (resistance) training increased muscle strength, reduced muscular atrophy, and that tendons（肌腱） and bones adapt too. These successes in turn had a preventive effect in terms of avoiding falls and injuries. Greater intensities of training yielded greater effects than moderate and low intensities. In order to increase muscle mass, an intensity of 60-85% of the one-repetition-maximum is required. In order to increase rapidly available muscle force, higher intensities (>85%) are required. The optimum（最适宜的） amount of exercise for healthy elderly persons is 3 to 4 training units per week.

In the coming decades, the importance of maintaining the ability to work and to make a living will increase, as will the need for independence in everyday life and leisure activities. The increase in the retirement age to 67 years from 2012 means that one in three adults of working age will be older than 50 by 2020, and by 2050, the proportion of people older than 60 in Germany's population will rise to an estimated 40%. Currently, the proportion of elderly persons who practice strength (resistance) training is about 10-15%.