Welcome back to Week Three of my Bone Health Series.
This week, we’re looking at the different forces that act on our bones every day. Understanding these forces can help us make informed decisions about exercise, bone health, and building resilience as we age.
Our bones are incredibly adaptable tissues. They respond to the demands placed upon them, becoming stronger when appropriately challenged. However, not all forces affect bones in the same way.
The Five Forces That Act on Bones
1. Compression
Compression occurs when a bone is pushed from both ends.
This is one of the most common forces experienced during everyday activities such as walking, standing, and resistance training. Bones are generally very good at handling compressive forces, and these loads can help stimulate bone growth and maintenance.
2. Tension
Tension occurs when muscles pull on the bones they are attached to.
Every time you move, your muscles create a pulling force on your skeleton. This mechanical loading is one of the reasons strength training is so beneficial for bone health. Strong muscle contractions encourage bones to adapt and become stronger over time.
3. Torsion
Torsion refers to a twisting force where one or both ends of a bone rotate in opposite directions.
Activities involving rotation, changes of direction, or certain sports can expose bones to torsional forces. Bones can adapt to these loads when introduced progressively and with good movement control.
4. Bending
Bending is a combination of compression and tension occurring at the same time.
When a bone bends, one side experiences compression while the other experiences tension. Many daily activities and exercises create bending forces that help maintain bone strength.
5. Shear
Shear occurs when one end of a bone is pushed in one direction while the other end is pushed in the opposite direction.
Of all the forces acting on bone, shear generally creates the greatest strain within the bone structure itself. This is why, when designing exercise programmes for bone health, we often aim to minimise excessive shear forces while still providing enough stimulus for adaptation.
How Much Force Do Your Bones Experience?
To give you an idea of the loads your body manages every day, consider these fascinating statistics:
- During walking at approximately 4 km/h, the hip joint experiences forces equivalent to around 238% of body weight.
- During jumping, the lumbar spine can be exposed to forces of approximately 4.7 times body weight.
These numbers can sound alarming, but they highlight just how remarkable the human body is at managing force.
Is More Force Better?
The answer is: it depends.
Force itself is neither good nor bad. What matters is whether your body is prepared to handle it.
When beginning an exercise programme aimed at improving bone health, it’s important to start with:
- Smaller ranges of movement
- Lighter weights
- Lower-impact exercises
- Smaller jumps or hops where appropriate
As your strength, confidence, coordination, and technique improve, you can gradually increase the challenge.
Progressive loading gives your bones, muscles, and connective tissues time to adapt safely.
Exercise for Better Bone Health
One of the most effective ways to support bone health is through regular weight-bearing and resistance exercise.
The key is finding the right starting point for your current fitness level and gradually building from there. Consistency over time is far more important than doing too much too soon.
Remember, stronger bones are built through appropriate challenge and recovery, not by pushing through pain.
Important Note
If you have been diagnosed with osteoporosis, osteopenia, or experience pain during exercise, always seek advice from your GP, consultant, or a qualified healthcare professional before starting a new exercise programme.
Looking after your bone health is a lifelong investment, and understanding how your body responds to different forces is a great place to start.
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