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Oulun yliopiston väitöskirjat


Kustantaja:Oulun yliopisto 
Oppiaine:Lääketiede, farmasia 
Sijainti:Print Tietotalo 

20.00 €

It is known that exercise strengthens bone and can prevent bone loss. However, the optimalamount and intensity of exercise beneficial to bones is not known, because there have been nolong-term methods to evaluate the osteogenic features of exercise. The aim of the study was toreveal the determinants of physical activity or exercise beneficial for the bone, using novelaccelerometer-based measurement of bone loading. Additionally, the study tested the applicabilityof a previously developed bone exercise regimen in Japanese women, using the samemeasurement technology. Acceleration data obtained in two exercise trials were analyzed. Thesubjects were healthy women aged 25–50 years who participated in 12-month high-impactexercise trials either in Finland or in Japan. The individual daily bone loading was assessed witha waist-worn accelerometer-based bone exercise recorder. Vertical acceleration peaks caused byimpacts on the ground were recorded. Different key characteristics of the acceleration peaks wereanalyzed. A Daily Impact Score was developed to describe individual daily osteogenic loading.Bone mineral density was measured with dual x-ray absorptiometry at the proximal femur andlumbar spine, and cross-sectional geometry of mid-femur was assessed with spiral computedtomography. Calcaneus was assessed with quantitative ultrasound. Bone changes were analyzedwith respect to the acceleration data. The results showed that the number of impacts during thefirst six months of exercise was associated with the 12-month bone changes at the hip and mid-femur. The slope, area and energy of the acceleration signal were significant determinants of bonedensity changes. The threshold of acceleration slope for improving bone mineral density at the hipwas 100 g/s, which can be achieved during exercise including fast movements such as running andjumping. Daily Impact Score was able to describe the osteogenic potential of daily mechanicalloading with a single score. The results also showed that bone exercise can be applied to Japanesepremenopausal women. A brief high-impact exercise program with 50 jumps prevented bone lossat the femoral neck. The study gives new information on the measurement of bone-specificexercise. This information can be used in designing new feasible training programs for women toprevent osteoporosis and fracture risk factors.