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P Oja

Publications and source records attributed to P Oja.

At least 55 records · Page 3Linked to original sources
PubMed1998

Assessment of energy expenditure in overweight women.

PURPOSE: To compare field measures of average daily energy expenditure (ADEE) against criterion data by the doubly labeled water method (DLW) in overweight women. METHODS: The subject were 20 overweight (BMI 29.9 +a- 3.0 kg.m-2) premenopausal women. Energy expenditure was measured by DLW and by the factorial method (activity diary, two techniques differing by method to obtain resting energy expenditure, REE), heart-rate monitoring (HR, two techniques differing by the FLEX-point to discriminate sedentary and activity HR), accelerometer, and pedometer. RESULTS: The ADEE(DLW) was 10.26 +a- 1.1 MJ.d-1. The mean bias (ADEE by the alternative minus ADEE(DLW) was smallest for the accelerometer (+ 0.08 +a- 1.63 MJ) and HR-FLEX10 (+ 0.11 +a- 1.67 MJ). The HR-FLEX(0) technique (lower FLEX-point) overestimated ADEE by + 1.18 (+a- 1.97 MJ). However, the random error (SD of bias) was smaller for both factorial techniques (REE measured: -0.48 +2- 0.81 MJ; REE calculated from the WHO equation: -0.22 +2- 0.88 MJ). CONCLUSION: The results show that simple factorial methods may assess ADEE with small random errors in population with a rather narrow range of physical activity. The accelerometer and HR with the higher FLEX-point have comparable results with smaller bias but larger random error compared with the factorial techniques.

Adult↗
PubMed1998

Effects of walking training on health-related fitness in healthy middle-aged adults--a randomized controlled study.

The effects of walking training on VO2max, serum lipoproteins and plasma fibrinogen were studied in 119 healthy middle-aged persons. Training prescription was 65-75% of VO2max, 50 min/session, four times a week for 15 weeks. The net difference (between pre-posttraining changes in the walking and control group) was statistically significant for VO2max (0.14 l .min-1, 95% CI 0.04, 0.23), total cholesterol (-0.20 mmol.l-1, CI -0.34, -0.06), LDL cholesterol (-0.17 mmol.l-1, CI -0.29, -0.05), ratio of HDL cholesterol to total cholesterol (0.014, CI 0.005, 0.023), and triglycerides (-0.15 mmol.l-1, CI -0.26, -0.04). No statistically significant changes occurred in fibrinogen. The findings indicate that walking training of moderate intensity resulted in a modest increase in VO2max and minor but consistently favorable changes in serum lipoproteins.

Adult↗
PubMed1998

Associations of physical activity and calcium intake with bone mass and size in healthy women at different ages.

Weight-bearing exercise and calcium intake are known to contribute to bone density. However, the relative significance of physical activity and calcium intake in the development of bone characteristics in functionally different weight-bearing and nonweight-bearing bone sites at different ages is poorly known. A total of 422 women in three age groups (25-30, 40-45, and 60-65 years) were screened from 1017 women and divided into four groups by their level of physical activity (high [PA+] and low [PA-]) and calcium intake (high [Ca+] and low [Ca-]). Total body bone mineral content (TBBMC), areal bone mineral density (BMD) of the femoral neck and distal radius, and selected dimensions and estimated strength variables (bone width, cortical wall thickness, cross-sectional moment of inertia, and section modulus of the femoral and radial shafts) were measured with dual-energy X-ray absorptiometry. Both high physical activity and high calcium intake were associated with a higher TBBMC when compared with low activity and calcium intake (1.8% and 4.6%, respectively). The BMD of the weight-bearing femoral neck was 5% higher in the PA+ groups than in the PA- groups, whereas calcium intake showed no such significant association. Neither physical activity nor calcium intake was associated with the BMD of the nonweight-bearing radius. However, both high physical activity and high calcium intake were related to larger and mechanically more competent bones in the femoral and radial shafts, the association for physical activity being stronger with increasing age. No significant interaction between physical activity and calcium intake was found with respect to any of the bone variables. These data from a cross-sectional study suggest that a moderate level of physical activity or a sufficient level of calcium intake, if maintained from childhood, can result in considerable long-term improvement in the mechanical competence of the skeleton. The clinical relevance of these findings is further emphasized by the fact that the observed patterns of physical activity and calcium intake pertain to customary lifestyle and are thus feasible targets for the primary prevention of osteoporosis.

Absorptiometry, Photon↗
PubMed1998

Effect of long-term unilateral activity on bone mineral density of female junior tennis players.

High peak bone mass in early adulthood is an important protective factor against osteoporotic fractures in later life, but little is known about the effects of exercise on growing bone. The purpose of this cross-sectional study was to determine at which state of maturity (Tanner stage), the areal bone mineral density (BMD) differences between the playing and nonplaying arms of junior tennis players become obvious, and to clarify in each developmental stage which training and background variables, if any, could explain the interindividual differences in bones' response to mechanical loading. Ninety-one 7- to 17-year-old female tennis players and 58 healthy female controls were measured. In each Tanner stage, differences in BMD in playing and nonplaying (dominant and nondominant) arms (proximal humerus, humeral shaft, and distal radius) and BMD of the lumbar spine and nondominant distal radius were compared between the controls and players. Within each Tanner stage of players, the associations between training and background variables and BMD differences were analyzed with Spearman rank correlation coefficients. In players, BMD differences between the playing and nonplaying arms were significant (P < 0.05- < 0.001) in all Tanner stages, with the mean difference ranging from 1.6 to 15.7%. In controls, these dominant-to-nondominant arm differences were clearly smaller (ranging from -0.2 to 4.6%), but significant at some measured sites. In comparison with the relative side-to-side arm differences between the players and controls (i.e., examination of the training effect), the mean difference was not obvious and significant until the adolescent growth spurt (i.e., the girls in Tanner stage III with a mean age of 12.6 years). In the lumbar spine, significant BMD differences between players and controls were not found until Tanner stage IV (mean age 13.5 years; 8.7%, P < 0.05) and V (mean age 15.5 years; 12.4%, P < 0.05). In a nonloaded site of the skeleton (nondominant distal radius), no significant BMD differences were found between the players and controls in any Tanner stage. In the correlation analysis, the Tanner I and II players (mean ages 9.4 and 10.8 years) showed no significant associations between any of the predictive variables and the side-to-side BMD differences, while in Tanner stages III, IV, and V, such associations could be found; the total amount of training hours during the playing career and the number of training sessions per week showed a significant and systematic correlation (rs ranging from 0.43 to 0.80) with the side-to-side BMD differences in several measured bone sites. In conclusion, this study suggests that in a majority of female junior tennis players, the benefit of unilateral activity on bone density does not become clearly evident until the adolescent growth spurt or Tanner stage III. The total amount of training during the player's career and the current training frequency (sessions per week) seem to best explain the training effect on bone tissue, leaving, however, room for speculation on the still unknown factors that modulate the loading response of a growing bone.

Absorptiometry, Photon↗
PubMed1998

Effect of two training regimens on bone mineral density in healthy perimenopausal women: a randomized controlled trial.

The aim of this randomized controlled trial was to evaluate the effects of 18 months of calisthenics and endurance training regimens on bone mineral density (BMD) in perimenopausal women. Clinically healthy sedentary female volunteers (n = 105) aged 52-53 years were randomly assigned to a calisthenics (n = 36), endurance (n = 34), or control (n = 35) group. The calisthenics training (2.6 times per week on average, 50 minutes per session) consisted of rhythmic strength-endurance exercises by large muscle groups, and the endurance training (3.2 times per week, 50 minutes) consisted of walking, stair climbing, ergometer cycling, and jogging at a controlled heart rate zone corresponding to 55-75% of the individual maximal oxygen uptake (VO2max) of the subjects. The control subjects performed a light stretching program once a week The BMD of the lumbar spine (L2-L4), right femoral neck, calcaneus, and distal radius was measured by dual-energy X-ray absorptiometry at 0, 4, 8, 10, 14, and 18 months, and the maximal isometric strength during trunk extension and flexion, leg extension, and arm flexion and the VO2max by ergospirometry were evaluated at 0, 8, 10, and 18 months of intervention. The VO2max improved significantly (p = 0.021) in the endurance group. The linear trend of the femoral neck BMD in the endurance group, as determined by generalized linear models, was significantly different (p = 0.043) from that of the control group, the trend indicating a maintenance of the prestudy BMD. In the calisthenics group, the training effect was not significant. However, the distal radius BMD of the endurance group showed a significant negative trend (p = 0.006). These results suggest that multiexercise endurance training maintains the BMD the clinically important femoral neck of perimenopausal women. This form of endurance training proved also to be feasible for healthy perimenopausal women.

Absorptiometry, Photon↗
PubMed1997

Agreement between questionnaire data and medical records of chronic diseases in middle-aged and elderly Finnish men and women.

The agreement between self-reported diseases in a questionnaire survey and data from medical records was assessed in a representative sample of Finnish men and women (n = 596) aged 45-73 years. The accumulated medical record information was abstracted from the records in the health centers and the central hospital in the study region. The agreement between the two information sources was substantial (kappa 0.73-0.80) for cardiovascular diseases as a group, hypertension, angina pectoris, myocardial infarction, and diabetes. The lowest agreement (kappa < 0.55) was found for lower back disorder, hip and knee arthrosis, and claudication. These results showed that the agreement between questionnaire data and medical records was good for well-known chronic diseases that have clear diagnostic criteria and are easily communicated to the patient. Conversely, the agreement was poor for diseases with nonestablished diagnostic criteria and a fluctuating course.

Adult↗
PubMed1997

Self-rated health status as a health measure: the predictive value of self-reported health status on the use of physician services and on mortality in the working-age population.

The validity of various self-reported health assessments in predicting physician contracts and all-cause mortality was investigated in a prospective study in Finland. The follow-up periods were one year for the use of physician services and ten years ten months for the mortality. The study cohort comprised 1340 men and 1500 women, 35-63 years of age at the beginning of the study. The initial health assessments were derived from postal questionnaires in 1980 (response rate 77.5%). The survey was repeated one year later to verify the stability of the respondents' perceived health status. The data on the physician contacts and mortality were registered independently. The stability of perceived health status was relatively good and the perceived health was inversely associated with the number of physician contacts per year. A consistent inverse association, standardized by age, sex and social status, was observed between perceived health status and perceived physical fitness and mortality, while the predictive value of self-reported chronic diseases was low. The results suggest that the subjective health assessments are valid health status indicator in middle-aged populations, and they can be used in cohort studies and population health monitoring.

Adult↗
PubMed1997

Determinants of bone mineralization in 8 to 20 year old Finnish females.

OBJECTIVES: To study the determinants of bone mass and density in Finnish girls and young women. DESIGN: A cross-sectional study. SUBJECTS: One hundred and seventy six 8 to 20 year old female volunteers living in the city of Tampere, Finland. METHODS: Calcium intake was estimated from a 7 d calcium intake diary (CaD). Bone mineral content (BMC) and areal density (BMD) were measured by dual-energy X-ray absorptiometry (DXA) at the lumbar spine, femoral neck and distal radius. Volumetric bone mineral apparent density (BMAD) was estimated from these DXA data. In addition, anthropometric characteristics, isometric muscle strength, and the Tanner stage were determined. Menstrual status and physical activity level were assessed by a questionnaire and personal interview. RESULTS: Body weight and Tanner stage were the most important determinants of BMC and BMD. Physical activity was the only not growth-related factor associated with BMC, BMD and BMAD. Therefore, it was examined in detail between the PA and NA groups. Site-specific benefits varied from 5-7% for the BMC (lumbar spine and radius) and BMD (lumbar spine and femoral neck) and was about 5% for the BMAD (femoral neck). CONCLUSIONS: Body weight seems to be the most important determinant of the BMC and BMD of growing Finnish girls, but during puberty exercise may beneficially affect BMD at the loaded skeletal sites. Exercise may increase femoral BMAD during peripubertal years. There was no association between calcium intake and the bone variables, but the high level so calcium intake in all age groups of the study was likely to explain the lack of association.

Absorptiometry, Photon↗
PubMed1997

Association between leisure time physical activity and 10-year body mass change among working-aged men and women.

OBJECTIVE: To determine whether habitual leisure time physical activity and body mass change of working-aged men and women are associated. DESIGN: Prospective 10 y follow-up study. SUBJECTS: A regionally representative cohort of 19-63 y old men (n = 2564) and women (n = 2695) in three municipalities in Finland. MEASUREMENTS: The main outcome measures were average body mass change during the 10 y of follow-up and the clinically significant body mass gain defined as a body mass gain of 5 kg or more during the follow-up and a body mass index of 26 or higher at the end of the follow-up. Leisure time physical activity was determined from self-administered questionnaires. RESULTS: After adjustment for the potential confounders, the logistic regression analysis showed that the men and women with no regular weekly activity at the end of the follow-up had an odds ratio of 2.59 (95% confidence interval, 1.69-3.97) and 2.67 (1.65-4.31), respectively for clinically significant body mass gain in comparison with the most active groups. The men who had decreased their activity during the 10 y follow-up had an odds ratio of 1.96 (1.39-2.75), and the men who were physically inactive all the time had an odds ratio of 1.62 (1.18-2.20) for clinically significant body mass gain when compared with the subjects who were active all the time. Among the women the odds ratios for clinically significant body mass gain after adjustment for potential confounders were 2.49 (1.72-3.60) and 1.61 (1.17-2.21), respectively. CONCLUSION: These findings are consistent with the hypothesis that regular physical activity prevents body mass gain and physical inactivity is a risk factor for body mass gain and obesity among adults.

Adult↗
PubMed1997

Variation of ambulatory blood pressure in healthy middle-aged men.

The majority of the reference data on ambulatory blood pressure (ABP) monitoring is based on fixed, predefined times for waking hours and sleep. Our aim was to determine the level of ABP according to diary entries when awake, at work, at home and during sleep in a sample of normotensive, middle-aged men. The dipping-status was also determined. All measurements were taken with a non-invasive auscultatory device on a normal working day. A total of 62 clinically healthy, normotensive men without a history of elevated BP were included. The mean resting BP of the group was 122/73 mm Hg. The 24-h systolic BP (SBP) was 114.4 +/- 8.6 mm Hg (95% CI 112.3, 116.6), while the diastolic BP (DBP) was 80.4 +/- 7.2 mm Hg (95% CI 78.5, 82.2). SBP when awake was 120.5 +/- 9.4 mm Hg (95% CI 118.1, 122.9) and diastolic pressure 84.4 +/- 7.7 mm Hg (95% CI 82.5, 86.4). The corresponding values for systolic and diastolic pressures during sleep were 101.2 +/- 8.5 mm Hg (95% CI 99.1, 103.4) and 71.7 +/- 7.7 mm Hg (95% CI 69.7, 73.6). The difference between day and night was 19.2 +/- 7.0 mm Hg for systolic and 12.7 +/- 6.0 mm Hg for diastolic pressure. The number of men whose systolic and diastolic pressure dropped less than 10% while asleep (non-dippers) was eight (13%) and 15 (24%), respectively. If the mean +/- 2 standard deviation interval is considered, the range of normality averaged 102-139/69-100 mm Hg when awake, 84-118/56-87 mm Hg when asleep and 97-132/66-95 over 24 h. The awake-sleep pressure difference did not correlate with the 24-h average.

Blood Pressure↗
PubMed1997

Association of leisure time physical activity with the risk of coronary heart disease, hypertension and diabetes in middle-aged men and women.

BACKGROUND: The association of physical activity and the risk of coronary heart disease (CHD), hypertension and diabetes has previously been studied mostly in separate follow-up studies. The present analysis focuses on the association between physical activity and these three metabolic diseases in a representative adult cohort. METHODS: The effect of the total amount and intensity of leisure time physical activity on the risk of the three diseases was studied in a cohort of 1340 men and 1500 women aged 35-63 years. RESULTS: During the 10 years of follow-up the incidence rates per 1000 person-years for CHD, hypertension and diabetes were 108, 142 and 64 for men and 75, 117 and 54 for women, respectively. In the Cox proportional hazards model the men's total amount of activity was inversely associated with the risk of CHD and hypertension. An age- and smoking-adjusted relative risk of 1.98 (95% confidence interval [CI]: 1.22-3.23) for CHD and age-adjusted risk of 1.73 (95% CI: 1.13-2.65) for hypertension were found for the lowest third total activity group compared with the highest third of total activity. Vigorous activity once or more often a week was inversely associated with the risk of hypertension. For the women both a higher total amount of activity and weekly vigorous activity had an inverse association with the risk of diabetes. An age-adjusted relative risk of 2.64 (95% CI: 1.28-5.44) for diabetes was found for the lowest third activity group compared with the highest third. CONCLUSIONS: The results suggest a preventive effect of leisure time physical activity on CHD, hypertension and diabetes. This effect may differ among middle-aged men and women and the relative importance of the total amount and the intensity may vary depending on the outcome measure.

Adult↗
PubMed1996

Randomised controlled trial of effect of high-impact exercise on selected risk factors for osteoporotic fractures.

BACKGROUND: Osteoporotic fractures among the elderly are common, and without preventive measures the burden of these fractures on health-care systems will increase further. The purpose of this randomised controlled study was to evaluate, in premenopausal women, the effects of high-impact loading on several determinants osteoporotic fractures. METHODS: 98 healthy, sedentary female volunteers aged 35-45 years were randomly assigned to either a training (n = 49) or a control group (n = 49). Progressive high-impact exercises were done three times per week for 18 months. We measured bone mineral density (BMD) in specific axial and lower-limb sites, by dual-energy X-ray absorptiometry, at baseline and after 12 and 18 months. Maximum isometric strength, muscular and cardiovascular performance, and dynamic balance were also assessed. FINDINGS: BMD at the femoral neck, a weightbearing site, increased significantly more in the training group (mean 1.6% [95% CI 0.8-2.4]) than in the control group (0.6% [-0.2 to 1.4], p = 0.006). By contrast, at non-weightbearing sites, such as the distal radius, there was no significant difference between the training and control groups (-1.5% [-2.7 to -0.3] vs -0.7% [-1.9 to -0.5], p = 0.60). In the training group there was a significant improvement in vertical jump and predicted oxygen consumption per min at maximum exercise compared with controls. INTERPRETATION: High-impact exercises that load bones with a rapidly rising force profile in versatile movements improve skeletal integrity, muscular performance, and dynamic balance in premenopausal women. If done on a regular basis, this type of exercise may help decrease the risk of osteoporotic fractures in later life. Long-term studies are required to show whether these 18-month results can be translated into long-term benefit.

Adult↗
PubMed1996

Characteristics of leisure time physical activity associated with decreased risk of premature all-cause and cardiovascular disease mortality in middle-aged men.

The association between leisure time physical activity and the risk of all-cause and cardiovascular disease mortality was analyzed in a Finnish cohort of 1,072 men age 35-63 years who were followed up for 10 years and 10 months. During the period, 168 deaths were recorded, 93 of which were the result of cardiovascular diseases. Leisure time physical activity was assessed by several measures: 1) a single question combining an estimate of the frequency and intensity of the total amount of leisure time physical activity, 2) a compiled measure of leisure time physical activity derived from three separate questions concerning the intensity and frequency of activity, 3) a physical energy expenditure index computed as an estimate of weekly energy expenditure for leisure time activity and commuting to work, 4) 16 separate specified activities of daily living and domestic chores included in the leisure time physical activity index. The association between baseline leisure time physical activity and the risk of death was assessed using the Cox proportional hazards model. After adjustment for potential confounders, the leisure time physical activity energy expenditure index and participation in several specific activities of daily living and domestic chores showed that the mortality risk for all causes and cardiovascular diseases was highest in the most sedentary men. With respect to the leisure time physical activity energy expenditure index, sedentary men ( those with an estimated weekly energy expenditure in leisure time physical activity of < 800 kcal) had an increased risk of 2.74 (95% confidence interval 1.46-5.14) for all-cause mortality and a risk of 3.58 (95% confidence interval 1.45-8.85) for cardiovascular disease mortality compared with the most active persons (those with an estimated weekly energy expenditure in leisure time physical activity of at least 2,100 kcal) when age, initial health status, marital status, employment status, and smoking were controlled.

Adult↗
PubMed1996

Effects of unilateral strength training and detraining on bone mineral mass and estimated mechanical characteristics of the upper limb bones in young women.

The aims of this study were to examine the effects of 12 months unilateral high-resistance strength training and 8-month detraining on bone mineral content (BMC), density (BMD) and estimated mechanical characteristics of upper limb bones, and also to estimate consequent loading induced strains on forearm bone shafts. Thirteen female physiotherapy students (mean 23.8 +/- 5.0 yrs, 166 +/- 7 cm, 64.4 +/- 7 cm, 64.4 +/- 13.3 kg) trained their left upper limbs with dumbbells on average 2.8 times per week for 12 months, followed by eight months detraining. Nineteen students served as controls (mean 25.7 +/- 5.2 yrs, 165 +/- 4 cm, 62.1 +/- 7.0 kg). BMC, BMD, and bone width and estimated cortical wall thickness (CWT) were measured at five different sites in both upper extremities (proximal humerus, humeral shaft, radial shaft, ulnar shaft, and distal forearm) using dual energy x-ray absorptiometry (DXA) scanner. In addition, cross-sectional moment of inertia (CSMI) was estimated from DXA data. The maximal isometric strength of the upper extremities was measured with an arm flexion-extension dynamometer. The training increased significantly the flexion strength by 14% (p = 0.001). During the detraining period, all measured strength values in the training group decreased in both limbs with respect to values after training. Despite the clear effect on muscular strength, no significant intergroup differences were observed in BMC, BMD, bone width, CWT, or CSMI values at any measured site after the training or detraining period. The estimated loading-induced strains remained within customary loading, and the change in strain level was only 15%. In conclusion, this study indicated that using high-resistance strength training may not provide an effective osteogenic stimulus for bone formation and geometric changes in upper limb bones of young, healthy, adult women. The interaction of bones and muscles may play an important and relatively unrecognized role in the development of bone strength, suggesting that the entire biomechanical environment should be carefully considered when evaluating the osteogenic efficiency of physical loading.

Absorptiometry, Photon↗
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↗
PubMed1996

Development of mass, density, and estimated mechanical characteristics of bones in Caucasian females.

Three hundred and thirty healthy Finnish girls and premenopausal women, aged 7-47 years, were examined to evaluate the natural development of bone mineral mass and density from early childhood to menopause. Bone mineral content (BMC,g) and areal density (BMD, g/cm2) were measured from the spine (L2-L4), femoral neck, trochanter region of the femur, and distal radius using dual-energy X-ray absorptiometry (DXA). In addition, the bone mineral apparent density (BMAD, g/cm3) was assessed from the above described skeletal sites, and the mechanical competence of the femoral neck was estimated. Special attention was paid to the timing of the peak values of these bone parameters as well as to the evidence of premenopausal bone loss. The BMC, BMD, and BMAD of the spine, femoral neck, and trochanter region of the femur achieved peak values around the age of 20, and the bone loss seemed to start soon thereafter. In contrast, the bone mass of the distal radius slightly increased between the ages of 20 and 47. In the femoral neck, the estimated bending strength achieved its peak value around the age of 20 and showed a slight decrease during the following decades. The highest body weight and neck-length adjusted strength values of the femoral neck were, however, found in early childhood, with the values decreasing linearly thereafter. In conclusion, this study supports previous findings of rapid bone mineral accumulation in late adolescence, and occurrence of the peak bone mass and density around the age of 20. Premenopausal bone loss seems to occur in the proximal femur and lumbar spine. Our observations of femur strength development imply that from childhood to menopause the mechanical strength of the femoral neck is well adjusted to the biomechanical loading requirements of the body.

Adolescent↗
PubMed1996

Estimation of various mechanical characteristics of human bones using dual energy X-ray absorptiometry: methodology and precision.

The mechanical competence of bone is determined by its macroscopic geometric characteristics [size, shape, apparent density (BMAD), cortical thickness (CWT), cross-sectional area, trabecular architecture], intrinsic material properties (stiffness, strength), and loading conditions (mode, direction, rate) at a given skeletal site. The main objective of this study was to introduce precise methods for further analysis of dual energy X-ray absorptiometric (DXA) data and for estimating macroscopic mechanical characteristics of bone at several skeletal sites representing both the axial and appendicular skeleton. This study showed that using computational BMAD, CWT and dimensional parameters, different site-specific mechanical characteristics (stiffness and strength indices) of a typical long bone (a bone consisting of both the cortical shaft and trabecular metaphyses and epiphyses at both ends) can be approximated with a low precision error (generally < 2%). The efficacy of a study applying DXA may be further enhanced by applying relevant site-specific parameters (different parameters for bone ends and shafts) for evaluation, the parameters based on the anatomic ROIs. Evidently high-quality operator performance is a prerequisite for effective accomplishment of longitudinal studies, especially when small changes in bone characteristics are expected. It should be kept in mind that to some extent the inherent two-dimensional nature of the DXA measurement compromizes the potential efficacy of the presented methods since some simple assumptions had to be made regarding the geometry and structure of bone. Nevertheless, in this study the observed values were consistent with those found by other investigators. Further experimental studies are needed for direct site-specific validation of the proposed analytic methods.

Absorptiometry, Photon↗