Swimming and bone density: why walking and strength training matter

Swimming develops muscles, cardiovascular fitness and mobility while placing little stress on the joints, yet this same quality limits the direct stimulus it provides to bones. To maintain bone density, weight-bearing activities such as brisk walking, stair climbing and strength training are generally more beneficial, as they place mechanical loads on the skeleton that encourage it to adapt.

Why does walking stimulate bones differently from swimming?

In water, buoyancy takes away some of the body weight the skeleton would otherwise need to support. When walking, however, every step sends force through the feet, legs and hips. Bone tissue detects these loads as part of the ongoing remodelling process, through which older structures are broken down and new tissue is created.

This does not mean that running or high-impact exercise is essential. For many people, walking at a moderate or brisk pace already provides a mechanical stimulus that is not produced in the same way by activities where the water supports the body.

• Walking requires the body to bear its own weight;
• Climbing stairs increases the load on the legs and hips;
• Dancing also combines impact with weight-bearing movement;
• Running and small jumps provide greater stimulation when suitable;
• Intensity should match each person's physical ability.

Can strength training be even more important than walking?

Resistance training complements impact-based activity because strong muscles pull on bones during squats, rows and exercises using free weights, machines or resistance bands. For this reason, programmes designed to support bone health commonly combine standing exercises with progressive strengthening rather than relying on a single form of activity.

Why does concern increase after the age of 50?

Bone mass changes throughout life, and bone loss may speed up with ageing. In women, falling oestrogen levels during and after menopause particularly increase the rate of bone resorption, which is why osteopenia and osteoporosis become more common concerns at this stage.

Exercise is not the only part of prevention, but it provides a type of stimulus that diet alone cannot replicate. A weekly routine may include a range of movements:

• Brisk walking on safe ground;
• Stair climbing according to fitness level;
• Adapted squats;
• Exercises with weights or resistance bands;
• Balance activities to help prevent falls.

Should people who want to protect their bones stop swimming?

No. Swimming remains an excellent activity for cardiorespiratory endurance, muscular strength and maintaining an active routine. It is also particularly useful for people who do not tolerate impact exercise well. The key point is that it may need to be supplemented with gravity-based exercise when preserving bone mineral density is also a goal.

• Continue swimming as aerobic exercise if you enjoy it;
• Add muscle-strengthening sessions on other days of the week;
• Include standing activities whenever they are safe;
• Train balance and coordination as well;
• Increase load and impact gradually.

The best programme for bones combines load, strength and consistency

There is no single exercise against osteoporosis that meets everyone's needs. Walking provides weight-bearing stimulus, while weight training adds progressive resistance and can challenge different areas of the skeleton. For people who already have osteoporosis, a history of fractures or significant spinal changes, higher-impact exercise and certain movements need to be adapted to reduce risk.

The main difference from exercising in a pool is the type of stimulus the body receives. Water reduces the load placed on the skeleton, whereas walking, climbing steps and working against resistance require bones and muscles to deal directly with external forces. Therefore, people who enjoy swimming do not need to replace the pool with the pavement, but they can create a more complete routine by combining swimming with weight-bearing, strength and balance exercises.