What Should Exercise Look Like in Midlife?

I’m 40 and a busy mom of two young kids who is trying to be active. I have dreams of a personal trainer and specific strength training to build bone mass so I’m good later in life, but that’s just not happening right now. Any recommendations on bare minimums I should be doing now? I walk a few miles most days and do a yoga-influenced workout once a week — mostly core and legs, a bit of shoulder and arms. Is that enough? My PCP says yes, but I don’t want to regret not doing something now I should be doing.

—Busy bones

It can be difficult in the midst of a busy life to make exercise a priority. It sounds like you are off to a pretty good start. The National Institutes of Health recommends 150 minutes of weight-bearing aerobic exercise, such as brisk walking or jogging, each week to support bone health. They recommend an additional two sessions — they aren’t specific about the length of these sessions — of strength training, such as lifting weights or using resistance bands or body weight, with the intention of building muscle.

But what does the data say? In a meta-analysis of 74 prospective studies including 84 different exercise interventions, the authors found that both weight-bearing aerobic exercise such as brisk walking, and resistance training such as lifting weights, increased bone density in postmenopausal women.

The exercise interventions implemented in the studies included in the analysis were incredibly varied, from heel raises to tai chi to jumping, skipping, and brisk walking. I think what this tells us is that there are lots of different ways in which we can move our body to keep our bones strong. The key is to have muscles or gravity putting stress on our bones. This stress causes microscopic breaks in the bone, triggering the repair crew to spring into action. The repaired bone is stronger than the bone it replaced.

However, exercise is an area where I encourage my patients not to let the perfect be the enemy of the good. Most weeks, I aim to run three to five miles five days per week and do Reformer Pilates twice per week. But I have a busy life. I work full-time and have four big kids, a husband, and friends I want to spend time with. As a result, many weeks I don’t quite meet my exercise goals. Is it perfect? No. Is it better than doing nothing? Absolutely!

The upshot: The recommended exercise regimen for bone health is 150 minutes of weight-bearing aerobic exercise and two sessions of resistance training weekly. Both weight-bearing aerobic exercise and resistance training improve bone density.