Longitudinal changes in physical capacity from adolescence to middle age in men and women.

The aim was to investigate how physical capacity changes from adolescence through early adulthood to middle age with focus on early aging. The aim was also to study if physical capacity in middle age could be predicted by factors in adolescence or early adulthood. A cohort of men and women in Sweden (SPAF-1958, n = 425) have been followed for 36 years, at 16, 34, and 52 years of age. The study includes, among other variables, objective measures of physical capacity. At age 52, 50% of the original cohort participated in exercise testing. Physical capacity increased from 16 to 34 years. From 34 to 52 years, physical capacity decreased in both genders by 15-20% in all but one test. Physical capacity at 16 and 34 years of age were better predictors of physical capacity at age 52 than body dimensions, school grades and life style factors. In conclusion, present data confirm earlier cross-sectional studies regarding the decrease in aerobic capacity and muscular strength during the early ageing period in both genders. The study has also generated novel data that show a smaller decline in muscular endurance than previously reported. Finally, physical capacity is fairly stable from adolescence to middle age.

The Swedish physical activity and fitness cohort born in 1958 - dropout analysis and overview at 36-year follow-up.

The main aim of the Swedish physical activity and fitness cohort study (SPAF-1958) was to describe physical fitness, physical activity, health, and lifestyle across part of the lifespan, and to assess the influences on these factors from the environment, personal factors, and genetics. There is inevitable dropout from longitudinal studies, and it may be systematic. The aim of this first paper of the second follow-up of SPAF-1958 was to provide a dropout analysis to consider to what extent the participants, at 52 years of age, remain a representative sample of the original adolescent study population. Additional aims were to provide an overview of the study protocol and the ongoing study population. Ongoing study participants in SPAF born in 1958 were, at the second follow-up at the age of 52, still representative of the study cohort in terms of sex, adolescent geographical area, upper secondary school program, adolescent body composition, muscular strength, and muscular endurance. However, a higher physical activity and, among women, a higher aerobic capacity in adolescence decreased the risk for dropout. It is important when interpreting results from longitudinal studies to adjust for the systematic dropout that could bias the conclusions drawn from the results.

Striking a balance--health experiences of male ambulance personnel with musculoskeletal symptoms: a grounded theory.

BACKGROUND: Musculoskeletal disorders (MSD) are a dominant cause to long-term sick leave and early retirement. Some occupational groups are more affected than others and ambulance personnel are among them. Despite a vast amount of research, only a small part focuses the experiences of the affected. OBJECTIVES: The aim of the study was to explore the experience of illness and wellness in ambulance personnel with musculoskeletal symptoms. DESIGN: An emerging design was used in accordance with Grounded Theory. PARTICIPANTS: Informants in the study were ten men with musculoskeletal symptoms, working as ambulance personnel at an ambulance station located in a mid-sized city in Sweden. METHODS: Narrative interviews were performed, parallel to a constant comparative analysis. RESULTS: The study resulted in a model, which describes the experience of illness and wellness as characterised by an effort to strike a balance. Wellness through nurturing appeared parallel to encountering illness as an experience and a threat. Accepting and handling illness was of importance to maintaining wellness, and wellness through nurturing was the motivation for accepting and handling illness. CONCLUSIONS: Enhancing the understanding of wellness and illness makes it possible to avoid undermining the meaningfulness that support accepting and handling illness, and by understanding different aspects of illness prevention can become facilitated. This is of importance as other aspects than solely physical have shown to be similarly important in the development of MSD.

Relationships between physical activity and physical capacity in adolescent females and bone mass in adulthood.

This study investigates whether physical activity and physical performance in adolescence are positively related to adult bone mineral density (BMD). In 1974, physical activity, endurance, and muscular strength were measured in 204 randomly selected female students, age 16.1 +/- 0.3 year (range 15-17 years). Twenty years later, 36 of the women volunteered to undergo a measurement of their BMD. Women who were members in a sports club in adolescence had significantly higher adult BMD (mean differences of 5% to 17% depending on site) compared with subjects who were not engaged in a sports club. Furthermore, women with persistent weight-bearing activity in adulthood had significantly higher BMD compared with women who had stopped being active or had never been active. The differences ranged between 5% and 19% with the highest difference found in trochanter BMD. Stepwise regression analyses showed that membership in a sports club at baseline was a significant independent predictor of BMD in the total body, lumbar spine, legs, trochanter, and femoral neck, explaining 17-26% of the variation in BMD. Change in body weight was a strong independent predictor of BMD of the total body and arms, explaining 8% of the variation in both sites. In addition, running performance at baseline was an independent predictor of total body BMD, whereas the two-hand lift performance significantly predicted BMD of the total body, legs and trochanter. The hanging leg-lift and handgrip were both significant predictors of arm BMD. In conclusion, membership in a sports club and site-specific physical performance in adolescence together with the change in body weight were significantly associated with adult BMD in premenopausal women.

Low physical activity among adolescents in practical education.

The aim of this study was to investigate physical activity levels and factors related to physical activity among 16-year-old girls and boys in secondary school practical and theoretical programs. An additional aim was to identify factors contributing to differences in physical activity patterns between the educational programs. Sixteen-year-old students in the first year of secondary school in Sweden (n=585) were systematically selected and 93% agreed to complete a questionnaire. Compared with students in theoretical programs, those in practical programs spent less time and energy per day in physical activity. Girls in practical programs were the least physically active, and boys in theoretical programs the most physically active students. Statistical analysis showed that, among students in practical programs, the influence of educational program on physical activity level was explained by lower socio-economic level, less parental support, lower perceived health level, and negative attitudes toward outdoor physical activities. These data suggest that promotion of physical activity should focus on students, especially girls, in practical programs. Because the difference in physical activity levels between educational programs was partly an effect of less positive parental influence, school-based programs may be especially influential in increasing physical activity levels among secondary school students.

Short-term effects of repetitive arm work and dynamic exercise on glucose metabolism and insulin sensitivity.

AIM: To determine whether repetitive arm work, with a large component of static muscle contraction alters glucose metabolism and insulin sensitivity. METHOD: Euglycemic clamps (2 h) were started in ten healthy individuals 15 min after 37 min periods of: (1) repetitive arm work in a simulated occupational setting; (2) dynamic concentric exercise on a cycle ergometer at 60% of VO(2max) and (3) a resting regime as a control. During the experimental periods, blood samples were collected, blood pressure was measured repeatedly and electrocardiogram (ECG) was recorded continuously. During the clamps, euglycemia was maintained at 5 mmol l(-1) and insulin was infused at 56 mU m(-2) min(-1) for 120 min. RESULTS: The insulin-mediated glucose disposal rate (M-value) for the steady-state period (60-120 min) of the clamp, tended to be lower following arm work than for both cycling and resting regimes. When dividing the steady-state period into 20-min intervals, the insulin sensitivity index (ISI) was significantly lower for arm work compared with the resting control situation between 60-80 min (P = 0.04) and 80-100 min (P = 0.01), respectively. Catecholamines increased significantly for arm work and cycling compared with resting regime. Data from heart rate variability (HRV) measurements indicated significant sympathetic activation during repetitive arm work. CONCLUSION: The results indicate that repetitive arm work might acutely promote insulin resistance, whereas no such effect on insulin resistance was produced by dynamic concentric exercise.

Prediction of development of fatigue during a simulated ambulance work task from physical performance tests.

The aims of this study were (1) to identify which physical performance tests could best explain the development of fatigue during a simulated ambulance work task, (2) to investigate the effect of height and weight and (3) to investigate in what respects these findings differ between female and male ambulance personnel. Forty-eight male and 17 female ambulance personnel completed a test battery assessing cardio-respiratory capacity, muscular strength and endurance, and co-ordination. The subjects also completed a simulated ambulance work task -- carrying a loaded stretcher. The work task was evaluated by development of fatigue. Univariate and multiple regression analyses were used to investigate to what extent the tests in the test battery were able to explain the variance of developed fatigue. The explained variance was higher for female than for male ambulance personnel (time > 70% of HRpeak: R2 = 0.75 vs 0.10, accumulated lactate: R2 = 0.62 vs 0.42, perceived exertion: R2 = 0.75 vs 0.10). Significant predictors in the models were VO2max, isometric back endurance, one-leg rising, isokinetic knee flexion and shoulder extension strength. Height, but not weight, could further explain the variance. The high physical strain during carrying the loaded stretcher implies the importance of investigating whether improved performance, matching the occupational demands, could decrease the development of fatigue during strenuous tasks.

No evidence for genetic linkage between development of multiple sclerosis and components of the IFN system and the JAK-STAT pathway.

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the central nervous system (CNS). Several observations suggest that the interferon system may be of interest in the study of MS development To investigate whether polymorphism in components of the IFN system and the JAK-STAT pathway influence susceptibility to MS, we performed a linkage analysis between polymorphic loci in or close to the IFN gamma, IFN gamma receptor, IFN alpha/beta receptor, JAK 1, STAT 1 and STAT 3 genes in 27 Swedish families with at least two members having MS. Tests for transmission disequilibrium and nonparametric linkage analysis gave negative results. We found no evidence for linkage between MS and any of these loci.

Secular trends in sports: participation and attitudes among adolescents in Sweden from 1974 to 1995.

AIM: To study the secular trend (time changes) in participation in leisure-time sports activities and in attitudes towards sports activities and physical education in a representative sample of Swedish adolescents between 1974 and 1995. METHODS: A questionnaire was distributed to 16-y-old girls and boys (n = 395 in 1974, n = 542 in 1995) to assess participation in leisure-time sports activity, attitudes towards sports activities and attitudes towards physical education at school. Height and weight were measured and body mass index (BMI) was calculated. RESULTS: Compared with 1974, more subjects in 1995 answered that they were engaged in leisure-time sports activities, and that they were members of sports clubs. BMI increased from 1974 to 1995. By 1995, adolescents participated in and had become more interested in individual sports activities, including keep-fit activities (e.g. strength training and aerobics) compared with 1974. A gender difference in the feeling of anxiety towards physical education, with more girls experiencing it, appeared in 1995, but not in 1974. CONCLUSION: Although more adolescents participated in leisure-time sports activity in 1995 than in 1974, the lifestyle of adolescents between sports training sessions may have become more sedentary. This is negative in a health perspective, since the benefits of physical activity on health are largely correlated to the total energy expenditure. However, the increased interest in keep-fit activities is important, since these activities have the potential to be continued into adulthood.

Secular trends in body dimensions and physical fitness among adolescents in Sweden from 1974 to 1995.

AIM: To investigate changes over time in body dimensions, and muscular and aerobic fitness in a representative sample of 16-year-old-girls and boys in secondary schools in Sweden from 1974 to 1995 (n = 855). METHOD: Height and weight were measured and five tests were performed: run-walk, two-hand-lift, Sargent jump, sit-ups, and bench-press. RESULTS: In 1995, girls and boys had higher body mass index (BMI) than in 1974. Girls and boys performed less well in bench-press, sit-ups, and run-walk-tests in 1995. Boys, but not girls, performed better in Sargent jump in 1995 than in 1974. Girls and boys performed better in two-hand-lift in 1995 than in 1974. However, after adjustment for body dimensions, there were no differences in performance in two-hand-lift or run-walk-tests between 1974 and 1995. CONCLUSION: There was a decreased aerobic fitness and an increased maximal static strength among adolescents in Sweden between 1974 and 1995. These changes were partly due to increased BMI. However, decreased daily physical activity level cannot be excluded as a contributing factor to the decreased aerobic fitness. The reduced performance in muscular endurance in 1995 was not related to increased BMI. Instead, it is suggested that it is to be related to a specific decrease in hip flexion and arm muscle endurance.

Serological differences in monozygotic twin pairs discordant for multiple sclerosis.

OBJECTIVES: The etiology of MS is unknown but genetic factors are supported by a high concordance in twins. Geographic distribution and migration studies indicate, however, the importance of environmental factors. MATERIAL AND METHODS: We studied 3 pairs of genetically identical twins who had shared the same environment but were discordant for MS. Serum samples were assayed for antibodies against 21 viruses, 4 bacteria and Toxoplasma gondii. RESULTS AND CONCLUSION: No common factor present only in the affected twins was identified but differences were found in serum titers against some neurotropic microorganisms. In general the serum titers were strikingly similar in the twins, indicating no major disturbances of the humoral immune system in MS.

Adolescent determinants of cardiovascular risk factors in adult men and women.

AIMS: To investigate how physical activity, physical performance and sociodemographic characteristics at the age of 16 are related to adult health habits (physical activity, dietary intake, smoking) and biological risk factors for cardiovascular diseases (being overweight, low aerobic fitness, unfavorable levels of serum lipids, high blood pressure). METHODS: A randomly selected group of 220 male and 205 female students at 16 years of age was tested in 1974, and reinvestigated 18 years later. RESULTS: The predictive health profiles for adult lifestyle and biological risk factors were different in men and women. Leisure sports activity along with high performance in the nine-minute run among the boys and in the two-hand lift test among the girls were significant predictors of adult physical activity. A positive attitude to aerobic exercise and high performance in the nine-minute run test among the boys and high marks in physical education among the girls decreased the risk of smoking. Leisure sports activities together with body mass index at young ages were the most powerful predictors of adult biological risk factors, but attitudes to sports and educational level were also significant determinants. CONCLUSION: These results contribute to the knowledge of which factors at young ages may promote adult healthy habits in particular physical activities.

Laser-triggered high-voltage plasma switching with diffractive optics.

High-power lasers can be used to induce ionization of gases and thereby enable rapid triggering of electrical discharge devices, potentially faster than any devices based on mechanical or solid-state switching. With diffractive optical elements (DOEs) the laser light can conveniently be directed to positions within the gas so that an electrical discharge between two high-voltage electrodes is triggered reliably and rapidly. Here we report on two different types of DOE used for creating an electrical discharge in pure argon for potential high-voltage applications. One is the diffractive equivalent of a conventional axicon that yields an extended, and continuous, high-intensity focal region between the electrodes. The other is a multiple-focal-distance kinoform--a DOE that is designed to produce a linear array of 20 discrete foci, with high peak intensities, between the electrodes. We show that DOEs enable efficient, rapid switching and may provide increased flexibility in the design of novel electrode configurations.

Cancer risk in the reindeer breeding Saami population of Sweden, 1961-1997.

The Saami people are the natives of northern Scandinavia and the Kola Peninsula. In a cohort of 2033 Swedish reindeer breeding Saamis, the cancer risks between 1961 and 1997 were studied. In total, 193 cases of cancer were observed versus 322 expected in the general Swedish population and 249 in a geographically matched reference population of non-Saamis. In comparison to non-Saamis living in the same area, the reindeer breeding Saamis showed a statistically significant lower risk of developing cancer of the prostate and of malignant lymphoma, whereas the risk of stomach cancer was significantly higher. Although there were no statistically significant changes of cancer risks over time, temporal trends were indicated towards a decreased risk of cancer in the stomach and the prostate. The results suggest that the explanations of the low cancer risk of the reindeer breeding Saamis, in relation to the non-Saamis in the same environment, are to be found among lifestyle and/or genetic factors.

Prediction of physical fitness and physical activity level in adulthood by physical performance and physical activity in adolescence--an 18-year follow-up study.

The aim of the study was to investigate relationships between physical fitness and self-reported physical activity in adulthood and to what extent the level of physical fitness and leisure-time physical activity in adulthood can be explained by anthropometric measures, physical performance, physical activity, attitudes to sports activities and socio-demographic characteristics at the age of 16. A group of 157 men and 121 women was tested at the ages of 16 and 34 by means of questionnaires and fitness tests. Physically active men and women had higher estimated VO2 max and performed better in curl ups and bench press than those who were inactive. Performance in physical tests, height, weight and physical activity at the age of 16 contributed best to explain adult physical performance and physical activity. The magnitude of explanation varied between 10% (9-min run test) and 56% (bench press test); it was in general lower in the men than in the women. The various fitness tests and physical activity were explained by different predictors and the predictors also differed between men and women. The findings about attitudes to sports and socio-demographic factors at a young age that influence adult physical activity habits and fitness are very complex and further research is required to identify specific inactivity risks.

TM-AFM Threshold Analysis of Macromolecular Orientation: A Study of the Orientation of IgG and IgE on Mica Surfaces.

Adsorption and orientation properties of two different types of immunoglobulin molecules on derivatized and native mica surfaces were investigated using TM-AFM. The analyses included height measurements at two different pH values and a new technique, presented here as threshold analysis, which displays the outer mantle shape of an adsorbed protein. A major difference in preferential orientation is observed upon comparing the adsorption of the two proteins onto the different surfaces. The characteristics of both the adsorbed immunoglobulin and the surface are important for any preferential orientation of the adsorbed protein. Copyright 1998 Academic Press.

Determinants of self-reported neck-shoulder and low back symptoms in a general population.

STUDY DESIGN: A combined cross-sectional and longitudinal design. OBJECTIVES: To investigate relation between, on one hand, self-reported neck-shoulder symptoms and, on the other hand, low back symptoms and self-reported work-related physical load, psychosocial factors, and individual characteristics and to study the influence of physical capacity in adolescence on neck-shoulder and low back symptoms in adulthood. SUMMARY OF BACKGROUND DATA: Heavy physical work and exposure to vibration constitute risk factors for low back problems, and repetitive and static work are risk factors for neck-shoulder symptoms in many jobs. The interplay between individual factors and work-related psychosocial and physical exposure, however, is not well documented. This study addresses effects of adolescent capacity on this interplay in a general population. METHODS: A random sample of 425 Swedish students was investigated when the students were 16 years and 34 years of age. Sixty-five percent participated in both examinations; only those who worked > or = 16 hours/week at the follow-up period, 148 men and 90 women, were included in these analyses. Data about musculoskeletal symptoms, work, and sociodemographic and individual characteristics were collected at the age of 34 years; physical performance data were collected at the ages of 16 years and 34 years. RESULTS: Among the men, self-employment and worry were associated with neck-shoulder symptoms; among the women, monotonous work and high decision latitude were associated with neck-shoulder symptoms. Low back problems were related to monotonous work among men and women and to exposure to vibration among men. Performance in certain fitness tests at the ages of 16 years and 34 years was negatively associated with musculoskeletal symptoms. CONCLUSIONS: The inverse relationships between performance at the age of 16 years and adult musculoskeletal symptoms may imply benefits of early fitness training.

Physical activity pattern in men and women at the ages of 16 and 34 and development of physical activity from adolescence to adulthood.

The aim of this study was to investigate gender-related differences in physical activity patterns at the ages of 16 and 34 and to analyse those factors that might contribute to an explanation of physical activity habits in adulthood. A randomly selected group, consisting of 220 boys and 205 girls, was tested in 1974 and reinvestigated in 1992 by means of a questionnaire. Eighty-eight per cent participated in the reinvestigation. At the age of 16 more boys (69%) than girls (51%) participated in some sports activity in their leisure time. The results showed an overall decrease in participation in vigorous physical activity, although participation in light physical activity remained relatively constant. At the age of 34, there was no difference in overall physical activity between men and women, but the men exercised more vigorously (44% vs. 29%). Early experience of physical activity at the age of 16 decreased the risk of becoming inactive in adulthood. At the age of 34 cohabiting for the men, and having children and high socio-economic class for the women, increased the risk of being physically inactive in adulthood, whereas positive beliefs about health effects of exercise decreased the risk for both men and women.

Development of muscular endurance and strength from adolescence to adulthood and level of physical capacity in men and women at the age of 34 years.

This study investigated the development of muscular endurance and strength from the age of 16 to the age of 34 and the fitness components at the age of 34 in men and women. A randomly selected group consisting of 220 boys and 205 girls was tested in 1974 and reinvestigated 18 years later. Muscular endurance and strength increased significantly in 4 of the 5 remeasured tests for the men; bench press increased by 58%, two-hand lift by 20%, hand grip by 16% and Sargent jump by 8%. For the women there was a significant increase in bench press and two-hand lift by 25% and 7% respectively, but hand grip and Sargent jump decreased with a few per cent. The hip and trunk flexion test, sit-up, decreased remarkably in both men (58%) and women (78%). At the age of 16 physical capacity was significantly higher in all tests in the men. This was also the situation at the age of 34 except for VO2 max in ml.kg-1.min-1 and muscular endurance in the back muscles. There were no differences in flexibility between men and women except for less flexibility in the hamstring muscles in the men. The result of the balance test was significantly better in the men.

No genetic linkage between multiple sclerosis and the interferon alpha/beta locus.

Multiple sclerosis (MS) is probably caused by an interaction of genetic and environmental factors. The genetic component is reflected by a ten-fold higher concordance rate in monozygotic (27%) compared to dizygotic (3%) twin pairs. Treatment with interferon was recently reported to have a favorable effect in patients with relapsing-remitting MS. In the present familial study, we have investigated the possibility of a genetic association between the highly polymorphic Interferon alpha beta locus and the development of MS. Based on our data, we conclude that there is no linkage between the Interferon alpha beta locus and MS.