The Skeletal System

What the Skeleton Actually Does

The skeleton is far more than a structural frame. It provides the attachment points that allow muscles to produce movement, protects vital organs — the skull shields the brain, the ribcage the heart and lungs — and serves as the body's primary mineral reservoir, storing ninety-nine per cent of its calcium. It is also the site of blood cell production in the red bone marrow. Understanding this range of functions makes clear why skeletal health is not merely an orthopaedic concern but central to overall physiological function — including the ability to train effectively as you age.

Bone Is Living Tissue

The most important thing to understand about bone is that it is not inert. It is living tissue, constantly being remodelled — broken down by cells called osteoclasts and rebuilt by cells called osteoblasts. In healthy adults, this remodelling cycle takes roughly three to four months and the net result is determined by the mechanical demands placed on the skeleton. When load is applied to bone — through impact, through the pull of contracting muscles, through resistance training — osteoblast activity increases and bone mineral density improves. When load is absent — as in prolonged bed rest or in astronauts living in microgravity — bone density falls rapidly. The skeleton adapts to demand. It always has.

Why the Squat Is the Best Thing You Can Do for Your Bones

The squat loads the skeleton axially — the force passes down through the spine and into the hips, knees and ankles — while simultaneously requiring significant muscular tension at multiple joints. This combination of axial compression and muscular pull creates a uniquely powerful stimulus for bone remodelling throughout the lower skeleton and lumbar spine. Research consistently shows that people who perform regular loaded squats have significantly higher bone mineral density in the lumbar spine and hip compared to those who do not. Given that osteoporosis — the progressive loss of bone density — is one of the leading causes of fracture and loss of independence in older adults, this is not a minor finding.

Osteoporosis — The Silent Consequence of Inactivity

Bone density peaks in the late twenties to early thirties and then begins a gradual decline. In sedentary individuals this decline is significant — particularly in postmenopausal women, where the loss of oestrogen accelerates bone resorption dramatically. Osteoporosis — bone density low enough to substantially increase fracture risk — currently affects over three million people in the United Kingdom. Hip fractures in older adults are associated with a thirty per cent mortality rate within one year. This is not a condition that appears suddenly. It develops over decades of insufficient mechanical loading and inadequate nutrition, and it is largely preventable through exactly the kind of resistance training this site is built around.

The evidence is clear and consistent: people who strength train throughout their adult life maintain significantly higher bone mineral density than those who do not. The skeleton responds to load at any age — studies in adults in their seventies and eighties show meaningful improvements in bone density from resistance training programmes. It is never too late to begin, and the consequences of not beginning at all are severe.

Tendons, Ligaments and Cartilage

The skeletal system includes three connective tissues that are critical to training and injury prevention. Tendons connect muscle to bone — they are strong, relatively inelastic, and transmit muscular force to the skeleton. Explosive movements require careful warm-up precisely because cold tendons have reduced elasticity and are more vulnerable to strain. Ligaments connect bone to bone and provide joint stability — they do not stretch significantly, which is why a torn ligament does not spontaneously heal to its original length without surgical intervention. Cartilage covers the ends of bones within joints, providing a smooth surface and absorbing compressive force — but it has limited blood supply, repairs slowly, and does not regenerate fully once significantly damaged. These tissues can be strengthened through progressive loading, but the timeline is longer than muscle adaptation — tendons and ligaments adapt over months to years rather than weeks.

A Coaching Observation

Two ACL (anterior cruciate ligament) reconstructions gave me a level of respect for connective tissue that I did not fully possess before them. When an ACL fails there is a moment of absolute clarity — the joint simply stops working as it should, and everything that depended on its integrity suddenly does not function. The rehabilitation from ACL surgery takes the best part of a year done properly — and most people do not do it properly, which is why re-injury rates are high. What I learned across both episodes is that the musculature surrounding a joint is its primary protection. Strong quadriceps and hamstrings, trained consistently over years, protect the knee in a way no brace or surgical intervention can fully replicate. Train the muscles and you protect the skeleton. There is no other way.