Osteoporosis occurs due to an imbalance in the normal bone remodelling process, which involves the resorption of old bone tissue by specialized cells called osteoclasts and the formation of new bone tissue by cells called osteoblasts. Several factors contribute to this imbalance, leading to a decrease in bone strength and density characteristic of osteoporosis. The key mechanisms involved in the development of osteoporosis include:

1. Increased Bone Resorption: In osteoporosis, there is often an increase in the activity of osteoclasts, the cells responsible for breaking down old bone tissue. This excessive bone resorption leads to the removal of more bone than can be replaced by new bone formation, resulting in a net loss of bone mass.
2. Decreased Bone Formation: Osteoblasts, the cells responsible for building new bone tissue, may become less active or less efficient in osteoporosis. This reduction in bone formation further contributes to the loss of bone density.
3. Hormonal Changes: Hormonal changes play a significant role in bone remodelling. Estrogen, in particular, plays a crucial role in maintaining bone density by inhibiting bone resorption. As women age and their estrogen levels decline, there is an acceleration of bone loss. Similarly, in men, age-related declines in testosterone levels can contribute to bone loss.
4. Nutritional Deficiencies: Inadequate intake of calcium and vitamin D, essential nutrients for bone health, can contribute to the development of osteoporosis. Calcium is a key component of bone tissue, while vitamin D helps in the absorption of calcium from the intestines. Without sufficient levels of these nutrients, bone remodelling processes can be impaired. People with a history of eating disorders or disordered eating are more likely to be diagnosed with osteoporosis later in life.
5. Aging: As individuals age, bone remodelling becomes less efficient, and bone density naturally declines. This age-related bone loss is more pronounced in women after menopause due to hormonal changes but also occurs in men.
6. Lifestyle Factors: Certain lifestyle factors can increase the risk of osteoporosis. These include sedentary behaviour, smoking, excessive alcohol consumption, and a diet low in calcium and vitamin D. Lack of weight-bearing exercise can also contribute to bone loss.
7. Genetic Factors: Genetic factors can influence bone density and susceptibility to osteoporosis. Individuals with a family history of osteoporosis are at higher risk of developing the condition themselves.
8. Medical Conditions and Medications: Certain medical conditions and medications can affect bone health. Examples include chronic conditions such as rheumatoid arthritis, hyperthyroidism, and gastrointestinal disorders, as well as long-term use of corticosteroids and certain other medications that can interfere with bone remodelling.

Exercise plays a crucial role in both the treatment and prevention of osteoporosis, a condition characterized by weakening of bones, leading to increased risk of fractures. Here are some key exercise recommendations for individuals with osteoporosis.

1. Weight-bearing activities: These are activities that make you move against gravity while staying upright and typically involve bearing your body weight. Examples include walking, jogging, dancing, stair climbing, and hiking. These exercises help to improve bone density and strength.
2. Strength Training: Resistance exercises using weights, resistance bands, or body weight help to build muscle strength, which in turn supports and protects bones. Focus on exercises targeting major muscle groups, such as squats, lunges, push-ups, and weightlifting.
3. Posture and Balance Exercises:These exercises help to improve balance and coordination, reducing the risk of falls and fractures. Tai chi, yoga, and Pilates are excellent for enhancing balance, flexibility, and posture. Postural along with strength exercises also assist in keeping the posture upright, shifting the centre of gravity closer to the body. 
4. Flexibility Exercise: Stretching exercises improve flexibility and range of motion, which can help prevent injuries and maintain mobility. Incorporate stretches for all major muscle groups into your routine, holding each stretch for 15-30 seconds without bouncing.
5. Functional Exercises:Activities that mimic daily movements, such as bending, lifting, and reaching, help to maintain independence and reduce the risk of falls. Examples include gardening, carrying groceries, and household chores.

When prescribing exercise for individuals with osteoporosis, it’s essential to consider the load or intensity of the activity. Here are some recommendations for load:

1. Progressive overload: Gradually increase the intensity, duration, or frequency of your exercises over time to continually challenge your bones and muscles. This gradual progression stimulates bone remodelling and strengthens muscles.
2. Individualised Approach: The load of exercise should be tailored to each person’s fitness level, bone density, and overall health. Consult with an Exercise Physiologist professional to have your personalized exercise program designed.
3. Low to Moderate Impact: While weight-bearing exercises are beneficial for bone health, it’s essential to start with low to moderate impact activities, especially for individuals with osteoporosis or those at risk of fractures. Avoid high-impact activities that may increase the risk of injury, such as jumping or running on hard surfaces.
4. Resistance Training:When performing strength training exercises, choose a weight or resistance level that allows you to complete 8-12 repetitions with proper form before reaching fatigue. This moderate resistance helps to stimulate bone growth without causing excessive strain on joints.
5. Gradual Progression: Increase the load of your exercises gradually as your strength and bone density improve. However, listen to your body and avoid pushing yourself too hard, especially if you experience pain or discomfort. 

Overall, a well-rounded exercise program that includes a variety of weight-bearing, strength, balance, flexibility, and functional exercises, with a focus on gradual progression and individualisation, can be highly effective in the treatment and prevention of osteoporosis. It is a good idea to discuss your intentions to exercise with your GP and always consult with an Exercise Physiologist to assist in establishing a safe and effective graded program to targeted to osteoporosis management.