The bone remodelling cycle

The bone remodelling cycle is a dynamic process that occurs throughout life, ensuring our skeleton stays strong and healthy. Learn all about it below.
tennis player

Bones are continually being broken down and rebuilt, changing and adapting across our lifespan. This skeletal change is known as bone remodelling – a highly regulated process, essential for preserving bone integrity and maintaining the balance of minerals in the body.

Wolff’s Law, developed by 19th century German anatomist and surgeon Julius Wolff, describes the nature of bone remodelling regarding physical stresses: bones adapt to the loads or stress they are subjected to1. Bones will remodel over time to become stronger if they are subjected to increased loading, and weaker if there are no forces to resist.

Wolff’s Law explains how weight-bearing exercises can strengthen bones and why bones can weaken with physical inactivity. For instance, the bones in a tennis player’s dominant arm may be up to 20% denser than the bones in their non-dominant arm2. Read more about weight-bearing activity in our blog post Why is weight-bearing activity important?.

tennis player

Bones are continually being broken down and rebuilt, changing and adapting across our lifespan. This skeletal change is known as bone remodelling – a highly regulated process, essential for preserving bone integrity and maintaining the balance of minerals in the body.

Wolff’s Law, developed by 19th century German anatomist and surgeon Julius Wolff, describes the nature of bone remodelling regarding physical stresses: bones adapt to the loads or stress they are subjected to1. Bones will remodel over time to become stronger if they are subjected to increased loading, and weaker if there are no forces to resist.

Wolff’s Law explains how weight-bearing exercises can strengthen bones and why bones can weaken with physical inactivity. For instance, the bones in a tennis player’s dominant arm may be up to 20% denser than the bones in their non-dominant arm2. Read more about weight-bearing activity in our blog post Why is weight-bearing activity important?.

Osteoblasts and osteoclasts

Bone contains two main types of highly specialised cells – osteoclasts and osteoblasts. One for building bone and one for breaking it down. 

Bone breakdown

Osteoclasts are responsible for breaking down old or damaged bone tissue, a process known as bone resorption. They dissolve the mineral matrix of the bone, releasing calcium and other minerals into the bloodstream. 

This process is critical for repairing micro-damage, adapting bone structure to changing physical demands and maintaining the balance of calcium in the body3.

Bone building

New bone is formed by osteoblasts in a process called ossification. Here’s how they function within the remodelling cycle:

Osteoblasts are responsible for synthesising and secreting new bone matrix, which is primarily composed of collagen. This matrix serves as the framework for new bone. Osteoblasts then deposit calcium and phosphate into the matrix in a process called mineralisation to harden bone.

Some osteoblasts become trapped in the matrix and differentiate into osteocytes. Osteocytes are mature bone cells that maintain the bone matrix and communicate with other bone cells to regulate bone health. 

diagram of osteoblast and osteoclast

Osteoblasts and osteoclasts

Bone contains two main types of highly specialised cells – osteoclasts and osteoblasts. One for building bone and one for breaking it down. 

Bone breakdown

Osteoclasts are responsible for breaking down old or damaged bone tissue, a process known as bone resorption. They dissolve the mineral matrix of the bone, releasing calcium and other minerals into the bloodstream. 

This process is critical for repairing micro-damage, adapting bone structure to changing physical demands and maintaining the balance of calcium in the body3.

Bone building

New bone is formed by osteoblasts in a process called ossification. Here’s how they function within the remodelling cycle:

Osteoblasts are responsible for synthesising and secreting new bone matrix, which is primarily composed of collagen. This matrix serves as the framework for new bone. Osteoblasts then deposit calcium and phosphate into the matrix in a process called mineralisation to harden bone.

Some osteoblasts become trapped in the matrix and differentiate into osteocytes. Osteocytes are mature bone cells that maintain the bone matrix and communicate with other bone cells to regulate bone health. 

diagram of osteoblast and osteoclast
balancing scales

Balance

During the bone remodelling cycle, resorption by osteoclasts is tightly linked to formation by osteoblasts. 

Osteoblasts and osteoclasts produce hormonal signalling molecules that influence the activity of the other. For instance, when osteoclasts are active, they will send signals that attract osteoblasts to the site where bone needs to be rebuilt4. Osteoblasts can also control the activity of osteoclasts by releasing molecules that either promote or inhibit bone breakdown5

This balance ensures that bone formation and resorption are coordinated, and net bone mass is preserved. 

The role of oestrogen

Oestrogen plays a crucial role in the bone remodelling cycle by regulating the activity of osteoclasts. It inhibits excessive bone breakdown by reducing osteoclast formation and activity6, helping to maintain a balance between bone resorption and formation.

balancing scales

Balance

During the bone remodelling cycle, resorption by osteoclasts is tightly linked to formation by osteoblasts. 

Osteoblasts and osteoclasts produce hormonal signalling molecules that influence the activity of the other. For instance, when osteoclasts are active, they will send signals that attract osteoblasts to the site where bone needs to be rebuilt4. Osteoblasts can also control the activity of osteoclasts by releasing molecules that either promote or inhibit bone breakdown5

This balance ensures that bone formation and resorption are coordinated, and net bone mass is preserved. 

The role of oestrogen

Oestrogen plays a crucial role in the bone remodelling cycle by regulating the activity of osteoclasts. It inhibits excessive bone breakdown by reducing osteoclast formation and activity6, helping to maintain a balance between bone resorption and formation.

Imbalance

Disruption of the bone remodelling cycle can lead to osteopenia and osteoporosis. When bone resorption exceeds bone building, bones become weaker and more likely to fracture. 

Some factors that can influence this imbalance include:

  • Hormones – decreased levels of oestrogen, such as after menopause, can increase bone resorption
  • Ageing – As you age, your number of osteoblasts decrease7
  • Lifestyle factors such as smoking, drinking alcohol and poor nutrition can inhibit osteoblast activity and increase osteoclast activity
  • Certain cancers – cancer cells can inhibit osteoblasts and stimulate osteoclasts to accelerate bone loss8
  • Conditions such as rheumatoid arthritis, inflammatory bowel disease, celiac disease, lung inflammation, renal disease, and diseases affecting nerves and muscles can all interrupt the bone remodelling cycle9
female doctor holding anatomical model of the human spine

Imbalance

Disruption of the bone remodelling cycle can lead to osteopenia and osteoporosis. When bone resorption exceeds bone building, bones become weaker and more likely to fracture. 

Some factors that can influence this imbalance include:

  • Hormones – decreased levels of oestrogen, such as after menopause, can increase bone resorption
  • Ageing – As you age, your number of osteoblasts decrease7
  • Lifestyle factors such as smoking, drinking alcohol and poor nutrition can inhibit osteoblast activity and increase osteoclast activity
  • Certain cancers – cancer cells can inhibit osteoblasts and stimulate osteoclasts to accelerate bone loss8
  • Conditions such as rheumatoid arthritis, inflammatory bowel disease, celiac disease, lung inflammation, renal disease, and diseases affecting nerves and muscles can all interrupt the bone remodelling cycle9
female doctor holding anatomical model of the human spine
woman stood on marodyne liv device on low pile carpet floor

Maintaining healthy bones

Maintaining a balanced bone remodelling cycle is crucial for long-term skeletal health and the prevention of conditions like osteoporosis. Here are some tips to help you achieve that:

Adequate nutrition – consume a diet rich in calcium, vitamin D, protein, magnesium and phosphorus to give osteoblasts the right building blocks to lay down new bone. 

Lifestyle choices – avoid smoking and limit alcohol consumption to prevent unnecessary inhibition of osteoblasts.

Hormonal balance – consider talking to your doctor about HRT to keep oestrogen levels up during menopause. 

Regular weight-bearing exercise – strength-training, weight-bearing aerobics and balance and flexibility exercises can all encourage osteoblast activation.

Low-intensity Vibration therapy – Low-intensity Vibration therapy with the Marodyne LiV mimics the natural mechanical stresses experienced by bones during physical activity. These vibrations stimulate osteoblasts and reduce the activity of osteoclasts, promoting bone formation and reducing bone loss. 

Backed by decades of research, Low-intensity Vibration therapy with the Marodyne LiV is safe, non-invasive and only requires 10-minutes of use per day, making it a convenient and efficient way to support your bone health. Find out more here

 

Make sure to check out our Bone Health Glossary for definitions of commonly used words throughout this article and the Marodyne LiV website.

woman stood on marodyne liv device on low pile carpet floor

Maintaining healthy bones

Maintaining a balanced bone remodelling cycle is crucial for long-term skeletal health and the prevention of conditions like osteoporosis. Here are some tips to help you achieve that:

Adequate nutrition – consume a diet rich in calcium, vitamin D, protein, magnesium and phosphorus to give osteoblasts the right building blocks to lay down new bone. 

Lifestyle choices – avoid smoking and limit alcohol consumption to prevent unnecessary inhibition of osteoblasts.

Hormonal balance – consider talking to your doctor about HRT to keep oestrogen levels up during menopause. 

Regular weight-bearing exercise – strength-training, weight-bearing aerobics and balance and flexibility exercises can all encourage osteoblast activation.

Low-intensity Vibration therapy – Low-intensity Vibration therapy with the Marodyne LiV mimics the natural mechanical stresses experienced by bones during physical activity. These vibrations stimulate osteoblasts and reduce the activity of osteoclasts, promoting bone formation and reducing bone loss. 

Backed by decades of research, Low-intensity Vibration therapy with the Marodyne LiV is safe, non-invasive and only requires 10-minutes of use per day, making it a convenient and efficient way to support your bone health. Find out more here

 

Make sure to check out our Bone Health Glossary for definitions of commonly used words throughout this article and the Marodyne LiV website.

References

References