Protecting joints: cartilage, arthritis and what movement really does

How cartilage lives

Joint cartilage has no blood vessels. It is nourished like a sponge: under load fluid is pressed out, when unloaded it sucks nutrients from the joint fluid. Without this alternation it starves. That is why rest is almost always wrong with joint complaints: cartilage of people who move regularly is thicker and healthier than that of people who sit. Arthritis does not arise from wear like a tire but from an imbalance of load, inflammation, muscle weakness and weight.

Weight and joints

When walking, three to four times the body weight acts on the knee, when climbing stairs five times. Ten kilos of excess weight are thus 40 kilos more load with every step, millions of times a year. Belly fat also produces inflammatory substances that attack cartilage directly; that explains why overweight people also have more arthritis in the hands. Ten kilos less halve the risk of knee arthritis and clearly lower existing pain.

Muscles as shock absorbers

Arthritis guidelines name strength training as first-line therapy, before injections and surgery. Strong thigh and hip muscles stabilize the knee, distribute forces and dampen impacts. Studies show that twelve weeks of leg training lower pain in knee arthritis by 30 to 40 percent, about as much as painkillers, without their side effects. Squats, leg press, lunges, hip raises, in the pain-free range, with slow progression.

The right movement

Joint-friendly does not mean movement-poor: cycling, swimming, rowing, cross-trainer, brisk walking and strength training are ideal, also with existing arthritis. Running is no risk for healthy joints; runners have no more arthritis than non-runners in long-term studies, often less. Problematic are sports with rotation under load and impacts without preparation, so weekend football after five days in an office chair. Mobility training preserves the range of motion that arthritis otherwise restricts step by step.

What to make of supplements

Glucosamine and chondroitin show no or minimal effects in independent studies; whoever takes them and feels improvement may, but should not hope for miracles. Omega-3 measurably reduces joint inflammation. Vitamin D with deficiency improves muscle strength around the joint. Turmeric extract has small studies with pain reduction. Hyaluronic acid injections work for some for months, cortisone briefly and with cartilage damage when repeated. The best remains: weight, strength, movement.