Resistance training improves strength more than muscle size in older adults

You grip the heavy kitchen chair to stand up, and for a moment, your legs feel uncooperative. It's a common frustration. Many assume that if you simply lift more often or with more weight, your muscles will grow back to their former strength ¹. But as you start to train, you might find that the way your body responds to the effort is not what you expected. Does training volume actually predict how much muscle you can gain after fifty ¹?

Research shows that resistance training does produce gains in lean body mass for adults aged 50 and older ¹. On average, these individuals see a pooled lean body mass gain of about 1.1 kg ¹. This magnitude is modest compared to the gains typically seen in younger adults ¹.

While muscle size increases, there is a clear distinction between how strength and muscle size respond to training. In very elderly adults aged 75 and older, resistance training produces a statistically significant increase in whole-muscle hypertrophy ². However, the effect size for muscle size is notably smaller than the effect seen for strength increases ². This suggests that for the oldest populations, improvements in strength may be driven more by neural adaptations than by structural muscle growth ².

Training volume appears to play a role in these outcomes for the general aging population. Higher-volume resistance training interventions are associated with significantly greater increases in lean body mass ¹. However, the relationship between training volume and actual muscle morphology remains unestablished ¹. This means that while more volume might help you gain overall lean mass, it is not yet clear how it changes the physical structure of the muscle itself ¹.

The connection between strength and everyday movement is also not a direct one. A large review of 121 trials found that while resistance training had a large effect on muscle strength, the effect on functional ability was small ³. For example, people showed modest improvements in gait speed and more significant improvements in their ability to rise from a chair ³. This indicates that the functional benefits of training might not reach the same heights as the gains in pure strength ³.

There are several things we still do not know. Most studies measure total lean body mass rather than the actual cross-sectional area of individual muscles ⁴. Additionally, the way researchers define "volume" varies widely between studies, making it difficult to compare results directly ⁴. There is also a possibility that the lack of data on muscle fiber hypertrophy in the very elderly reflects a difficulty in measuring these changes rather than a total absence of adaptation ².

If you are planning to begin a new or intense resistance training program, it is a good idea to talk with your doctor first, especially if you have existing health conditions or take medication.