Osteoporosis is a multifactorial, chronic and progressive disease. It is a skeletal disorder that leads to reduced bone strength and thus increases the risk of stress fractures. It is characterized by low bone mineral density that leads to an alteration in the microstructure of the bone and predisposes an individual to fragility fractures that occur due to minor impact or trauma.
Dual-energy X-ray absorptiometry (DEXA) scans is a technique used to measure the bone mineral density with relatively low exposure to radiation. It usually measures the bone mineral density at the hip and spine, however research has shown that BMD at one site is predictive of fractures at another site and thus can be used as a measure of osteoporosis; the results of which are reported as a T-score. According to the WHO, a T-score of -1 and above is considered as normal, between -1 and -2.5 is a sign of osteopenia and below -2.5 is considered as osteoporosis.
Osteoporosis predisposes an individual to one or more fractures, which in turn affect the quality of life, both physically and mentally. It mainly affects the entire skeleton which is known as generalized osteoporosis. However, it can also occur locally due to an injury or reduced muscle forces on the bone.
Prevalence
Osteoporosis can be classified into primary and secondary:
Primary osteoporosis is the most common and prevalent in the geriatric population as a result of bone loss and structural damage to the bone as the person ages. It commonly affects the postmenopausal women and is rare in children and young adults. Juvenile osteoporosis occurs in healthy young children between the ages of 8-14 years of age which could either be mild affecting one or two vertebral bodies or severe affecting the entire spine. Osteoporosis occurs both in men and women, but women are 2-3 times more prone to the disease.
Secondary osteoporosis can occur in young as well as older individuals as a result of a predisposing condition or medications used.
Effect of Exercise
Bone tissue is constantly undergoing remodelling in response to stimuli such as physical activity and mechanical vibrations. During weight bearing exercises, ground reaction force exerts mechanical stress on the bone along with the muscle contraction during activity. This helps maintain or gain bone mass. Studies show that athletes participating in non-weight bearing sports such as swimming or cycling had lower BMD as compared to athletes undertaking high impact sports despite generating high levels of muscle contractions due to the fact that gravitational loading is critical for bone remodelling and stimulation.
Non-weight bearing High intensity resistance exercises has shown positive effects on BMD in the femoral neck and spine. During resistance training, at the bone tendon junction multiple forces are generated that can induce a bone osteogenic response which in turn stimulates metabolism and mineral deposition at these sides increasing BMD and reducing bone resorption.
Parameters
Frequency: moderate intensity 5 days weekly, 3x weekly for high intensity exercises and 2-3x weekly for weight bearing exercises.
Intensity: Moderate intensity 5-6 on RPE scale and 7-8 on RPE scale for high intensity.
Time: 30-60 minutes for moderate intensity exercises and 20-30 minutes for high intensity exercises with 8-10 exercises targeting major muscle groups and 1-3 sets of 8-12 reps each for non-weight bearing exercises
Type: walking, jogging, running for weight bearing and progressive non weight bearing resistance exercises using resistance bands, machines and calisthenics for non weight bearing exercises.
Potential risk factors to be considered while prescribing exercises
The elderly can present with various medical conditions and care must be taken to ensure exercises do not have an adverse effect on it and therefore, it is vital to know what medications they are on to avoid any adverse effects on the medications.
Most of the elderly population lives a sedentary lifestyle and directly prescribing moderate intensity exercises can be detrimental. Care should be taken to first assess and determine the capabilities of the individual and gradually tailor the plan as per their abilities.
Exercises that require sudden twisting motions of the spine should be avoided as they can cause excessive shearing forces on the facet joints of the spine subsequently leading to fractures.The resting and maximal heart rate should be monitored before, during and after the sessions.
Very well tied shoes and with adherent soles are recommended; and incorporation of warm up in the session like organic activity, e.g. walking; joint rotations or gentle stretching is beneficial. An individual should maintain a good posture to prevent muscle pain and fractures.
An individual using an unstable surface for a particular exercise like trampoline, wobble board, standing close to the wall is a must to prevent falls.
This blog was written by Dee Jogani (Physiotherapist), from our Morphett Vale practice.
References
1) Office of the Surgeon General (US) (2004) Bone health and osteoporosis: a report ofthe Surgeon General. Office of the Surgeon General (US), Rockville (MD). Available from: http://www.ncbi.nlm.nih.gov/books/NBK45513/. Accessed March 2014.
2) RABA&A KF. The Relation Between T-score, Z-score, Bone Mineral Density and Body Mass Index. Relation. 2013;3(5).
3) Senderovich H, Kosmopoulos A. An insight into the effect of exercises on the prevention of osteoporosis and associated fractures in high-risk individuals. Rambam Maimonides medical journal. 2018 Jan;9(1).
4) Howe TE, Shea B, Dawson LJ, Downie F, Murray A, Ross C, et al. Exercise for preventing and treating osteoporosis in postmenopausal women. Cochrane database of systematic reviews. 2011;2011(7):CD000333–CD000333.
5) American College of Sports Medicine. ACSMs resource manual for guidelines for exercise testing and prescription. Lippincott Williams & Wilkins; 2012 Dec 26.
6) Shojaa M, Von Stengel S, Kohl M, Schoene D, Kemmler W. Effects of dynamic resistance exercise on bone mineral density in postmenopausal women: a systematic review and meta-analysis with special emphasis on exercise parameters. Osteoporosis International. 2020 Aug;31(8):1427-44.
7) Moreira LD, Oliveira ML, Lirani-Galvão AP, Marin-Mio RV, Santos RN, Lazaretti-Castro M. Physical exercise and osteoporosis: effects of different types of exercises on bone and physical function of postmenopausal women. Arquivos Brasileiros de Endocrinologia & Metabologia. 2014;58:514-22.