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Biomedical subjects

H Sievanen

Publications and source records attributed to H Sievanen.

5 recordsLinked to original sources
PubMed2000

Structural trends in the aging femoral neck and proximal shaft: analysis of the Third National Health and Nutrition Examination Survey dual-energy X-ray absorptiometry data.

Hip scans of U.S. adults aged 20-99 years acquired in the Third National Health and Nutrition Examination Survey (NHANES III) using dual-energy X-ray absorptiometry (DXA) were analyzed with a structural analysis program. The program analyzes narrow (3 mm wide) regions at specific locations across the proximal femur to measure bone mineral density (BMD) as well as cross-sectional areas (CSAs), cross-sectional moments of inertia (CSMI), section moduli, subperiosteal widths, and estimated mean cortical thickness. Measurements are reported here on a non-Hispanic white subgroup of 2,719 men and 2,904 women for a cortical region across the proximal shaft 2 cm distal to the lesser trochanter and a mixed cortical/trabecular region across the narrowest point of the femoral neck. Apparent age trends in BMD and section modulus were studied for both regions by sex after correction for body weight. The BMD decline with age in the narrow neck was similar to that seen in the Hologic neck region; BMD in the shaft also declined, although at a slower rate. A different pattern was seen for section modulus; furthermore, this pattern depended on sex. Specifically, the section modulus at both the narrow neck and the shaft regions remains nearly constant until the fifth decade in females and then declined at a slower rate than BMD. In males, the narrow neck section modulus declined modestly until the fifth decade and then remained nearly constant whereas the shaft section modulus was static until the fifth decade and then increased steadily. The apparent mechanism for the discord between BMD and section modulus is a linear expansion in subperiosteal diameter in both sexes and in both regions, which tends to mechanically offset net loss of medullary bone mass. These results suggest that aging loss of bone mass in the hip does not necessarily mean reduced mechanical strength. Femoral neck section moduli in the elderly are on the average within 14% of young values in females and within 6% in males.

Absorptiometry, Photon↗
PubMed1997

Reproducibility of the ST-segment depression/heart rate analysis of the exercise electrocardiographic test in asymptomatic middle-aged population.

The reproducibility of the ST-segment depression against heart rate (ST/HR) hysteresis, ST/HR index, and end-exercise ST depression between the repeated exercise electrocardiographic tests were determined in 61 asymptomatic middle-aged subjects. The findings support the clinical utility of the ST/HR hysteresis, but it is noteworthy that the results also suggest that the magnitude of change in the exercise electrocardiographic variables, which has to be observed to make the clinician confident that a real diagnostic change has occurred, is surprisingly large.

Electrocardiography↗
PubMed1996

Dimensions and estimated mechanical characteristics of the humerus after long-term tennis loading.

This study evaluated the effects of long-term unilateral physical activity (tennis) on the playing arm humerus. Total lengths of both humeri, site-specific widths, and the bone mineral contents (BMC) at the proximal, middle, and distal parts of the bones were measured using dual-energy X-ray absorptiometry (DXA). Bone mineral apparent density (BMAD), cortical wall thickness (CWT), cross-sectional moment of inertia (CSMI), and section modulus (Z) were approximated from the DXA data for describing the bone's mechanical characteristics more concretely. The study population consisted of 67 healthy, competitive tennis players (17 young men with a mean age [+/- SD] of 25 +/- 5 years, 30 young women with a mean age of 19 +/- 3 years, and 20 older women with a mean age of 43 +/- 5 years) and 57 sedentary controls (16 young men with mean age of 25 +/- 5 years, 25 years, 25 young women with a mean age of 21 +/- 3 years, and 16 older women with mean age of 39 +/- 6 years). All the players had competitive playing histories greater than 4 years. The young male and female players had started their playing careers in childhood (men at the age of 10 +/- 3 years, women 9 +/- 2 years), while the older female players started the training at adulthood (29 +/- 6 years). The playing-to-nonplaying or dominant-to-nondominant arm differences in humeral length ranged from +0.2 to +1.4%, the difference being significant in young male players (+1.4%), young female controls (+1.1%), and older female players (+0.7%). When comparing players' relative side-to-side length differences with those of the controls, no significant differences were found. Significant side-to-side differences in humeral width were observed in all groups except male controls. Compared with the controls, the relative side-to-side width differences were significantly larger at the proximal humerus of the young male players (controls +1.2%, players +3.7%) and the distal humerus of young female players (controls -0.2%, players +1.6%). Compared with the controls, the players' relative side-to-side differences in BMC (range, +7.6 to +25.2%), BMD (+5.8 to +22.5%), BMAD (+5.5 to +20.4%), CWT (+6.9 to +45.2%), CSMI (+7.8 to +26.4%), and Z (+3.0 to +21.7%) were significantly larger in all measured humeral sites except BMAD in the distal humeri of the older female players. These relative side-to-side differences were clearly and significantly larger in the young players (+11.7 to +45.2%) than in the older players (+3.0 to +12.4%). In conclusion, long-term intensive tennis playing, especially if started in childhood or adolescence, clearly increases the humeral BMC, BMD, and CWT but seems to have only a minor effect on the width of this particular bone. In this respect, there seems to be no sex difference. However, along with the increases in mineral mass and density, the changes in bone width are important in increasing the bending stiffness and strength of the humerus. In older players, the relative side-to-side differences are at the same level or only slightly larger than those in their age-matched controls. This suggests that even intense physical loading of a mature bone is only marginally better in increasing the bone mass, bone density, and CWT of the target bone than the normal daily use of the dominant extremity.

Absorptiometry, Photon↗
PubMedDate not supplied

Factors predicting dynamic balance and quality of life in home-dwelling elderly women.

BACKGROUND: Proper balance seems to be a critical factor in terms of fall prevention among the elderly. OBJECTIVE: The purpose of this cross-sectional study was to examine factors that are associated with dynamic balance and health-related quality of life in home-dwelling elderly women. METHODS: One hundred and fifty-three healthy postmenopausal women (mean age: 72 years, height: 159 cm, weight: 72 kg) were examined. General health and physical activity were assessed by a questionnaire. Quality of life was measured using a health-related quality of life questionnaire (Rand 36-Item Health Survey 1.0). Dynamic balance (agility) was tested by a figure-of-eight running test. Static balance (postural sway) was tested on an unstable platform. Maximal isometric strength of the leg extensors was measured with a leg press dynamometer. Dynamic muscle strength of lower limbs was tested by measuring ground reaction forces with a force platform during common daily activities (sit-to-stand and step-on-a-stair tests). RESULTS: Concerning physical activity, 33% of the subjects reported brisk exercise (walking, Nordic walking, cross-country skiing, swimming and aquatic exercises) at least twice a week, and 22% some kind of brisk activity once a week in addition to lighter physical exercise. The remaining 45% did not exercise regularly and were classified as sedentary. The correlations of step-on-a-stair and sit-to-stand ground reaction forces, and leg extensor strength to dynamic balance were from -0.32 to -0.43 (the better the strength, the better the balance). In the regression analysis with backward elimination, step-on-a-stair and sit-to-stand ground reaction forces, and leg extensor strength, age, brisk physical activity, number of diseases and dynamic postural stability explained 42% of the variance in the dynamic balance. Similarly, dynamic balance (figure-of-eight running time), number of diseases and walking more than 3 km per day explained 14% of the variance in the quality of life score. Of these, figure-of-eight running time was the strongest predictor of the quality of life score, explaining 9% of its variance. CONCLUSION: This study emphasizes the concept that in home-dwelling elderly women good muscle strength in lower limbs is crucial for proper body balance and that dynamic balance is an independent predictor of a standardized quality of life estimate. The results provide important and useful information when planning meaningful contents for studies related to fall prevention and quality of life and interventions in elderly women.

Accidental Falls↗