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Biomedical subjects

A Heinonen

Publications and source records attributed to A Heinonen.

49 records · Page 3Linked to original sources
PubMed1995

Bone mineral density in female athletes representing sports with different loading characteristics of the skeleton.

To address the hypothesis that osteogenic effect of physical loading increases with increasing strain rates and peak forces, we examined 59 competitive Finnish female athletes (representing three sports with different skeletal loading characteristics), physically active referents (they reported an average of five various types of exercise sessions per week), and sedentary referents (two sessions per week) using dual energy X-ray absorptiometry. The measured anatomic sites were at the lumbar spine, femoral neck, distal femur, patella, proximal tibia, calcaneus, and distal radius. The athlete group consisted of aerobic dancers (N = 27), squash players (N = 18), and speed skaters (N = 14). The squash players had the highest values for weight-adjusted bone mineral density (BMD) at the lumbar spine (13.8% p < 0.001 as compared with the sedentary reference group), femoral neck (16.8%, p < 0.001), proximal tibia (12.6%, p < 0.001) and calcaneus (18.5%, p < 0.001). Aerobic dancers and speed skaters also had significantly higher BMD values at the loaded sites than the sedentary reference group, the difference ranging from 5.3% to 13.5%. The physically active referents' BMD values did not differ from those of the sedentary referents at any site. The results support the concept that training, including high strain rates in versatile movements and high peak forces, is more effective in bone formation than training with a large number of low-force repetitions.

Adult↗
PubMed1994

Long-term unilateral loading and bone mineral density and content in female squash players.

We examined 19 female Finnish national level squash players and 19 healthy female controls with a dual energy x-ray absorptiometric (DXA) scanner for the determination of the association between long-term unilateral activity and bone mineral density (BMD) and content (BMC) of the upper extremities. In players, the BMDs and the BMCs were significantly higher in each bone site of the playing extremity. The side-to-side difference was largest in the proximal humerus (BMD 15.6%, BMC 17.8%) and smallest in the ulnar shaft (BMD 5.6%, BMC 7.3%). In sex-, age-, weight-, and height-matched controls, the side-to-side differences were significantly smaller, ranging from 1.6% to 4.1%. The number of training years and elbow flexion strength correlated positively with the relative BMD and BMC in the humerus of the playing arm (r = 0.632-0.685). The starting age of training in turn correlated negatively (r = -0.483 to -0.577) with these bone parameters. Significantly larger side-to-side differences (average 22%) were found in players who had started their career before or during menarche than in those who had begun the training 1 year or more after the menarche (9%). These findings suggest that the bones of the playing extremity clearly benefit from active squash playing. The benefit is largest in humerus and smaller in the bone of the forearm. The benefit of playing is stronger if the athlete has started the training at or before menarche than after it.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1994

Effects of unilateral strength training and detraining on bone mineral density and content in young women: a study of mechanical loading and deloading on human bones.

This study assessed the effect of unilateral strength training at 80% one repetition maximum and of detraining on bone mineral density (BMD, g/cm-2) and bone mineral content (sigma BMC, g) in young women. Twelve female physiotherapy students trained their left limb by leg press an average of four times per week for 1 year followed by 3 months of detraining. Twelve students served as controls. Repeated bone measurements were performed by dual energy X-ray absorptiometry of the lumbar spine, femoral neck, distal femur, patella, proximal tibia, and calcaneus. The training increased the muscle strength of the trained limb, and the BMD of the same limb showed a nonsignificant but systematic increase in distal femur, patella, and proximal tibia, and in sigma BMC of the five measured limb sites (considered an index of the total osteogenic effectiveness of the training). Simultaneously, the muscle strength increased in the untrained limb as an evidence of cross-training effect. A corresponding small but systematic increase was also seen in BMD of this limb as well as in sigma BMC. After the cessation of training, leg extension strength was retained but BMD and sigma BMC of the trained and untrained limbs declined towards baseline values in 3 months. The BMD and sigma BMC values in the control group showed an increasing tendency during the follow-up but the changes were less than 1%. The differences of the changes in BMD and sigma BMC between the left and right limb in the control group, as well as between the same limb in the training and control groups were nonsignificant.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1994

Reproducibility of computer measurement of maximal isometric strength and electromyography in sedentary middle-aged women.

The objectives of this study were (i) to determine the reproducibility of computer measurements of isometric strength and related electromyography in several muscle groups in sedentary middle-aged women, (ii) to evaluate the effects of different digital signal averaging methods on the reproducibility, (iii) to determine the final test score to be preferred in terms of improved reproducibility of isometric strength measurements, and (iv) to evaluate potential advantages provided by the computer measurement. Fifteen subjects were measured three times within a 2-week period. The measurements consisted of recordings of maximal isometric strength and rate of force production during trunk extension and flexion, leg extension and dominant forearm flexion with simultaneous recordings of surface electromyography, except in the trunk flexors. The following four final test scores were determined for each trial: the maximum of the three scores, the mean of the two highest scores, the median of the three scores and the mean of the three scores. The scores for the strength measurement were generally more reproducible (coefficient of variation, CV, approximately 6% and intraclass correlation coefficient ICCC, approximately 0.90) than those of the other measurements (CV > 10%, ICCC 0.13-0.97). There was no obvious preference for any type of final test score or for the width of the averaging window in the computer analysis. For isometric strength the reproducibility of the computer measurements was comparable to that of the voltmeter assessments. Computer analysis seems to be a versatile method for determining parameters of neuromuscular performance with reasonable reproducibility.

Computers↗
PubMed1993

Bone mineral density of female athletes in different sports.

Anthropometry, training history, cardiorespiratory and muscular performance capacity, and bone mineral density (BMD) were studied in female orienteers (n = 30), cross-country skiers (n = 28), cyclists (n = 29), weight lifters (n = 18) and in a reference group (n = 25). BMD was measured at lumbar spine, femoral neck, distal femur, patella, proximal tibia, calcaneus and distal radius by dual energy X-ray absorptiometry. The weight lifters had significantly higher weight adjusted BMD (P < 0.001) than the referents at all sites (9-26%) except in femoral neck and calcaneus. Of the endurance athletes, the orienteers were the only group which had significantly higher BMD (P < 0.05) than referents, only at distal femur (5%) and proximal tibia (5%). BMD did not differ significantly at any skeletal site between subjects with different calcium intake. Weight training seems to provide more effective osteogenic stimulus than endurance training. The differences in BMD at different sites between the groups were consistent with specificity of the stimulus to the training of the studied sports.

Adult↗
PubMed1992

A cruciate ligament injury produces considerable, permanent osteoporosis in the affected knee.

Bone mineral density (BMD) and clinical status of 42 patients treated surgically 10-11 years earlier for an acute knee ligament injury were determined. The BMD was measured at the spine (L2-4) and the femoral neck, distal femur, patella, proximal tibia, and calcaneus of both lower extremities using dual-energy x-ray absorptiometric (DXA) scanner. The relative BMD results of the injured knee were correlated with sex, age, activity level, knee stability, and functional scores of the patient. In the 11 patients with moderate injury (isolated rupture of the medial collateral ligament), the BMDs of the injured and uninjured extremities were equal. In the 31 patients with severe injury (cruciate ligament rupture), the BMDs were significantly lower in the injured knee: distal femur, -6.0% (p = 0.0000); patella, -9.0% (p = 0.0000); and proximal tibia, -3.3% (p = 0.0012). Neither the femoral neck nor the calcaneus showed any differences. There were no significant differences either between men and women or between patients with different activity levels. The relative BMDs of the injured knee did not correlate with age or static knee stability but correlated significantly (r = 0.42-0.78, p < 0.01-0.001) with the functional scores of the same knee: the better the knee function in comparison with the healthy knee, the higher the relative BMD. The spinal BMDs corresponded with the age-adjusted reference values of the used densitometry. In conclusion, a severe knee ligament injury results in permanently decreased BMD in the injured knee. Other parts of the same extremity and lumbar spine are not affected.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1988

Rheumatoid factor isotypes in patients with rheumatoid arthritis and in subjects with "false-positive" reactions.

The appearance of RFs, as detected by standard serological techniques, often precedes the onset of clinical RA by years. This pre-rheumatoid immunological reactivity is not associated with C-reactive protein response or occurrence of antibodies against native type II collagen. The profile of RF isotypes appeared to be similar between pre-rheumatoid and rheumatoid sera. RA sera contained somewhat more frequently IgG and IgA class RFs than "false-positive" sera from a community-based population sample. 7S IgM could be detected at about the same frequency in rheumatoid sera, in RF-positive pre-rheumatoid sera and in sera with "false-positive" RF reactions. The significance of the findings in terms of the pathogenesis of RA will be discussed.

Adult↗
PubMedDate not supplied

Bone mineral density and muscle strength of lower extremities after long-term strength training, subsequent knee ligament injury and rehabilitation: a unique 2-year follow-up of a 26-year-old female student.

Physical training is shown to have potential to increase the mass of healthy bones. In contrast, immobilization, used as a treatment of soft tissue and bone injuries, is shown to result in atrophy of these tissues. In this unique 26-month follow-up of a 26-year-old female student, we determined the effects of a 1-year strenuous unilateral lower limb strength training and subsequent anterior cruciate ligament (ACL) rupture on bone mineral density (BMD) of lumbar spine and lower extremities (femoral neck, distal femur, patella, proximal tibia, calcaneus), measured repeatedly (11 times) by dual-energy X-ray absorptiometry (DXA). Also, the strength and functional characteristics of the lower extremities were repeatedly examined. This prospective study strikingly demonstrated the deleterious effects of an ACL rupture on the BMD of the affected limb in contrast to beneficial but modest effects of the preceding controlled training. The site-specific increases in the BMD were 1.8-3.1% during the training. The posttraumatic decrease in the BMD of the injured knee was rapid and corresponded to approximately 2 SD (approximately 20%) observed in the age- and sex-matched population. A year after the injury, the subject's knee function and muscular performance as well as the usage of the injured limb were completely recovered, but the site-specific BMDs were still approximately 1 SD below the subject's baseline BMD, although continuously increasing. This study suggests that considerable posttraumatic osteopenia at the affected bone sites occurs quickly regardless of appropriate preventive and rehabilitative actions, and the time needed for steady-state and recovery will be long.(ABSTRACT TRUNCATED AT 250 WORDS)

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↗