HYPOTHESIS:

- A multicomponent exercise program where strength exercises are performed with blood flow restriction obtains better values in densitometry and bone mass of osteoporotic patients with respect to the same multicomponent exercise program where strength is worked without flow restriction.

INTERVENTION:

The recruitment of the population will be carried out between July and November 2021, with the collaboration of the Consorci Sanitari de Terrassa (CST), which brings together a hospital center and different primary care centers (CAP). The primary care physicians and rheumatologists of the CST will receive an e-mail from the hospital management, informing them of the study to be carried out so that, if they consider it appropriate, they can inform their patients.

Intervention of the intervention and control group:

Each volunteer will be assigned to an intervention group either to the control group (CG) or experimental group (EG).

The control group and intervention group will receive the same multicomponent exercise program, based on specific literature for being an effective, safe and feasible training for both elderly people {{2091 Bouaziz, Walid 2016;}} {{2092 Fragala,M. S. 2019;}}, with or without frailty {{2093 Cadore, Eduardo L 2014;}} {{2094 Casas-Herrero, Alvaro 2019;}} {{2088 Fernández-García, Ángel Iván 2020;}} and/or with osteoporosis {{2089 Moradell, Ana 2020;}}. The main difference between both groups is that the experimental group (EG) will perform the strength exercises with flow restriction (BFR) while the control group (CG) will not have any restriction.

The periodicity of both groups will be 2 sessions per week, with a duration of 65 minutes per session and the duration of the intervention of 6 months and a follow-up 12 months after the beginning of the intervention (see scheme).

The training will be supervised at all times by a physiotherapist with more than 10 years of experience in multicomponent exercise. The sessions will include both limb and trunk work and will have a clear functional objective, focusing on activities of daily living (ADL). Each session will work on all the basic physical abilities (strength, balance, endurance, flexibility and coordination) and will be divided into:

• 10 minutes of initial warm-up. This is divided into 8 minutes walking on a treadmill or cyclohergometer with an intensity corresponding to 30% of heart rate reserve. Followed by 2 minutes of active mobilizations in both upper and lower extremities.
• 20 minutes of strength exercises. These will be interspersed with the rest of the exercises and will include the different extremities and trunk. During the first month, training will be carried out with loads corresponding to 20% of 1 repetition maximum (RM) and from the second month onwards it will be increased to 30-35% of 1 RM.
• 10 minutes of resistance exercises. These exercises will be interspersed with the rest to make the session much more enjoyable.
• 10 minutes of coordination and balance exercises. These exercises will be interspersed with the rest of the activities.
• 5 minutes of flexibility. These exercises will be performed interspersed with the strength and endurance exercises.
• 5 minutes of return to calm and relaxation. To facilitate the monitoring of the researcher who will apply the intervention, each group will be subdivided into smaller groups (ratio of 5 subjects per researcher).

BACKGROUND

According to the WHO, osteoporosis is a disorder of the skeleton characterized by impaired bone strength, primarily reflecting poor integration of bone density and quality {{2042 NIH Consensus Development Panel on Osteoporosis Prevention, Diagnosis, and Therapy 2001;}}}. There are two types of osteoporosis, the most common is considered primary or idiopathic and includes juvenile, postmenopausal and senile osteoporosis. Secondary osteoporosis is considered to be that in which the deterioration of bone quality is due to different types of systemic diseases or produced by the intake of certain drugs (mainly glucocorticoids, anticoagulants and diuretics) {{2164 Maggi, S 2006;}}. Primary osteoporosis can affect both sexes, but postmenopausal and older women are more vulnerable to this disease because they possess important risk factors such as the same age and estrogen depletion {{2043 Tella, Sri Harsha 2014;}}.

It is estimated that approximately 200 million women worldwide have osteoporosis, approximately 10% of women in their 60s, 20% of women in their 70s, 40% of women in their 80s, and 67% of women in their 90s {{2044 Kanis, John Anthony 2007;}}}. Double beam X-ray densitometry (DEXA) is the test to accurately determine bone mass {{2046 Curiel, M Diaz 1997;}}{{2045 Peris,P. 2000;}} and osteoporosis is considered to be present when densitometry values are below 2.5 standard deviations (SD) of peak bone mass {{2081 Kanis, John A 1994;}}, the maximum value reached in young women.

The reduced mass and altered microstructure of osteoporotic bone leads to increased bone fragility and an increased risk of bone fracture {{2047 Anonymous 1993;}} {{2048 Norohna, Judith A 2020;}}. It is estimated that an osteoporotic fracture occurs every 3 seconds and 8.9 million such fractures are considered to occur worldwide {{2049 Ribagin, Simeon 2016;}}, accounting in the European continent for 1.75% of noncommunicable diseases {{2051 Johnell, Olof 2006;}}. Fragility fractures are estimated to be associated with significant morbidity and mortality. Johnell and Kanis estimated that 740,000 deaths per year are associated with hip fracture due to osteoporosis {{2052 Johnell, Olof 2004;}}}. Despite advances in therapeutic procedures only 30-45% of those who survive a hip fracture recover pre-fracture function and 32-80% suffer some form of dysfunction {{2142 Rey-Rodriguez,M.M. 2020;}}} {{2144 Takahashi, Ai 2020;}}, thus representing a high economic and life cost for the countries that suffer from them. It is estimated that in 2050 the United States will spend $131.5 billion to treat fractures caused by osteoporosis {{2053 Burge, Russel 2007;}}}.

Associated with osteoporosis, numerous investigations, have observed a correlation between altered bone quality ( osteopenia or osteoporosis) and a decrease in strength and/or muscle mass (sarcopenia) thus increasing the frailty and deterioration of the patient suffering from it {{2054 Hirschfeld, HP 2017;}} {{2055 Hassan, Ebrahim Bani 2017;}} {{2056 Paintin, James 2018;}} {{2056 Paintin, James 2018;}}. Tokeshi et al. observed how patients with osteoporotic fracture had lower muscle mass compared to those patients without osteoporisis {{2057 Tokeshi, Soichiro 2020;}}}. Hoo Lee and Sik Gong describe that lower extremity muscle mass and loss of grip are closely related to the occurrence of osteoporotic vertebral fracture {{2058 Eguchi, Yawara 2019; }} and numerous investigations show the relationship between grip strength and osteoporotic fractures in older elderly {{2059 Kärkkäinen, M 2008;}} {{2060 Denk, Katharina 2018;}} {{2061 Kamiya, Kuniyasu 2019;}} {{2062 Samelson, Elizabeth J 2006;}} {{2062 Samelson, Elizabeth J 2006;}}.

Because of the morbidity, increased associated frailty, and high economic cost associated with osteoporosis, different therapeutic strategies have been proposed. Although the number of patients treated with pharmacology has been increasing in recent years {{2166 de Felipe,R. 2010;}} and treatment recommended in most clinical guidelines {{2167 Sanfélix-Genovés, José 2014;}}{{2165 Tarantino 2017;}}, more global approaches such as exercise and/or nutrition are increasingly gaining importance {{2165 Tarantino 2017;}} {{2168 Jang,H.D. 2020;}}

HYPOTHESIS:

- A multicomponent exercise program where strength exercises are performed with blood flow restriction obtains better values in densitometry and bone mass of osteoporotic patients with respect to the same multicomponent exercise program where strength is worked without flow restriction.

INTERVENTION:

The recruitment of the population will be carried out between July and November 2021, with the collaboration of the Consorci Sanitari de Terrassa (CST), which brings together a hospital center and different primary care centers (CAP). The primary care physicians and rheumatologists of the CST will receive an e-mail from the hospital management, informing them of the study to be carried out so that, if they consider it appropriate, they can inform their patients.

Intervention of the intervention and control group:

Each volunteer will be assigned to an intervention group either to the control group (CG) or experimental group (EG).

The control group and intervention group will receive the same multicomponent exercise program, based on specific literature for being an effective, safe and feasible training for both elderly people {{2091 Bouaziz, Walid 2016;}} {{2092 Fragala,M. S. 2019;}}, with or without frailty {{2093 Cadore, Eduardo L 2014;}} {{2094 Casas-Herrero, Alvaro 2019;}} {{2088 Fernández-García, Ángel Iván 2020;}} and/or with osteoporosis {{2089 Moradell, Ana 2020;}}. The main difference between both groups is that the experimental group (EG) will perform the strength exercises with flow restriction (BFR) while the control group (CG) will not have any restriction.

The periodicity of both groups will be 2 sessions per week, with a duration of 65 minutes per session and the duration of the intervention of 6 months and a follow-up 12 months after the beginning of the intervention (see scheme).

The training will be supervised at all times by a physiotherapist with more than 10 years of experience in multicomponent exercise. The sessions will include both limb and trunk work and will have a clear functional objective, focusing on activities of daily living (ADL). Each session will work on all the basic physical abilities (strength, balance, endurance, flexibility and coordination) and will be divided into:

• 10 minutes of initial warm-up. This is divided into 8 minutes walking on a treadmill or cyclohergometer with an intensity corresponding to 30% of heart rate reserve. Followed by 2 minutes of active mobilizations in both upper and lower extremities.
• 20 minutes of strength exercises. These will be interspersed with the rest of the exercises and will include the different extremities and trunk. During the first month, training will be carried out with loads corresponding to 20% of 1 repetition maximum (RM) and from the second month onwards it will be increased to 30-35% of 1 RM.
• 10 minutes of resistance exercises. These exercises will be interspersed with the rest to make the session much more enjoyable.
• 10 minutes of coordination and balance exercises. These exercises will be interspersed with the rest of the activities.
• 5 minutes of flexibility. These exercises will be performed interspersed with the strength and endurance exercises.
• 5 minutes of return to calm and relaxation. To facilitate the monitoring of the researcher who will apply the intervention, each group will be subdivided into smaller groups (ratio of 5 subjects per researcher).

Inclusion Criteria:

• A woman between 60 and 75 years of age with a medical diagnosis of osteoporosis by means of a femur or lumbar densitometry of less than 2.5 standard deviations (SD) of peak bone mass.
• No history of previous fracture in the last 10 years.

Exclusion Criteria:

• Secondary osteoporosis.
• Having suffered a bone fracture in the last year.
• Present primary osteoporosis but who presented juvenile osteoporosis in adolescence or youth.
• Uncontrolled arterial hypertension.
• Severe acute respiratory failure.
• Uncontrolled orthostatic hypotension.
• Diabetes mellitus with acute decompensation or uncontrolled hypoglycemia.
• Endocrine, hematological and other associated rheumatic diseases.
• Mental health problems (schizophrenia, dementia, depression, etc.) or not being in full mental capacity.
• Patients with pharmacological treatments of glucocorticoids, anticoagulants and/or diuretics.
• Patients with coagulation problems or previous cardiac pathology.
• People with a body mass index (BMI) equal to or higher than 30.
• Subjects who present a systemic disease or any other pathology in which therapeutic exercise could be contraindicated.

postmenopausal women