Use of heart rate to predict energy expenditure from low to high activity levels.

This study evaluated the ability to use the relationship between heart rate (HR) and oxygen uptake (VO2 ) to estimate energy expenditure (EE) from low to high physical activity with different HR-based prediction equations. General prediction equations were established based on the individual relations between HR and EE. Possibilities to improve the EE estimation with using alternatives for respective HR were also assessed. The alternatives were % of HR reserve: 100 x [(activity HR - resting HR)/(maximal HR - resting HR)], (HRR), and the difference between activity HR and resting HR (activity HR - resting HR), (HRnet). Forty-two men (age mean 36.5 [sd 7.6] y, BMI 24.5 [2.4] kg x m(-2), VO2 max 45.2 [6.5]) kg x ml x min(-1) and 47 women (mean age 37.5 [9.5], BMI 23.3 [3.4], VO2 max 36.3 [5.4]) performed an exercise test consisting of physically low-activity tasks and a maximal treadmill uphill walking test. Respiratory gases were obtained from indirect calorimetry. HR was registered by electrocardiography and EE was calculated from (VO2 ) and carbon dioxide (VCO2 ) production. Generalised linear models with random effects were used for the prediction of EE. EE values of the tests (one value at each intensity level) were predicted in separate models by the respective HR, HRR or HRnet values. The other predictors used in all models were body weight, sex and the intensity of exercise. The standard error of estimate (SEE) was 1.41 kcal x min(-1) (5.89 kJ) in the model with HR variable as a predictor, 1.01 kcal x min(-1) (4.22 kJ) with HRR variable, and 1.08 (4.51 kJ) with HRnet variable. The results show that the prediction of EE is more accurate if HRR or HRnet are used in prediction equation instead of HR.

Improved functional status in 16 years of follow up of middle aged and elderly men and women in north eastern Finland.

STUDY OBJECTIVE: To investigate age, period, and cohort effects on functional status. DESIGN: A prospective cohort study with measurements in 1981, 1990, and 1996. SETTING: Three municipalities in north east Finland. PARTICIPANTS: A regionally representative sample of 19 to 63 year old men and women was drawn from the census data in 1979, of which 758 men and 1033 women initially aged 39-63 years entered the study in 1980 and completed the follow up in 1996 (90.9% of the alive cohort). MEASUREMENTS AND MAIN RESULTS: Functional status was determined based on self estimated disabilities (difficulties or not able) to walk 2 km, climb several flights of stairs, and run 100 m. The age adjusted odds of disability in stair climbing and running were lower among the men and the women in 1990 and 1996 than among the men and the women in 1981. There was a declining trend in the odds of disability with succeeding birth cohorts among both the men (odds ratios (OR) 0.79 and 95% confidence intervals (CI) 0.70 to 0.88 for stair climbing and OR 0.88 and 95% CI 0.78 to 0.98 for running) and the women (OR 0.85 and 95% CI 0.77 to 0.93 for stair climbing and OR 0.85 and 95% CI 0.76 to 0.94 for running). No statistically significant differences in walking disability were found between the study periods or the study cohorts. CONCLUSIONS: The findings depict an improved time trend in functional status in the study population, with implications for future health and social care planning.

Does previous participation in high-impact training result in residual bone gain in growing girls? One year follow-up of a 9-month jumping intervention.

The skeletal response to exercise and training on bone is exceptionally good during the growing years. However, it is not known whether the benefit of training on bone is maintained after the training. This 20-month follow-up study assessed the effect of a 9-month jumping intervention on bone gain and physical performance in 99 girls (mean age 12.5 +/- 1.5 years at the beginning of the study) one year after the end of the intervention. Both bone mineral content (BMC), by dual energy X-ray absorptiometry (DXA) at the lumbar spine and proximal femur, and physical performance parameters (standing long jump, leg extension strength, and shuttle run tests) were measured at baseline and at 20 months. A multivariate regression analysis was first used to determine the best predictors of the BMC accrual by time. Analysis showed that age at baseline and square of age, changes in height and weight, and pubertal development into Tanner stages 4 and 5 during the follow-up explained the majority of the BMC gain. Then, the effect of participation in the 9-month exercise intervention on BMC accrual and physical performance was analysed adding this variable (participation: yes/no) into the model. The regression analysis showed that the trainees (N = 50) had 4.9 % (95 % CI, 0.9 % to 8.8 %, p = 0.017) greater BMC increase in the lumbar spine than the controls (N = 49). The mean 20-month BMC increase in the lumbar spine was 28 % (SD 19) in the trainees compared to 22 % (12) increase in the controls. In the proximal femur, the trend was similar but the obtained 2 to 3 % higher BMC accrual in the trainees (compared to that in controls) were statistically insignificant. Among the performance variables, using the same model that best predicted the BMC accrual, the only statistically significant between-groups difference, in favour of the trainees, was the improvement in the standing long jump test (6.4 %, 95 % CI, 2.3 % to 10.4 %, p = 0.002). Improvements in the leg extension strength and shuttle run tests showed no between-groups difference. In conclusion, although the greatest proportion of bone mineral accrual in growing girls is attributable to growth, an additional bone gain achieved by jumping training is maintained at the lumbar spine at least a year after the end of the training.

Test-retest reproducibility and inter-rater reliability of a motor skill test battery for adults.

The purpose of this study was to evaluate the test-retest and inter-rater reliability of nine selected tests for the following basic motor skills: balance, orientation, sense of rhythm, kinaesthetic precision and flexibility. Twenty-five healthy, non-sporting volunteers (14 men, 11 women, aged 36-72 years) were tested in three sessions at one-week intervals by two raters. For the tests of balance on a bar, tandem walking backwards and forwards and ball bouncing, the within-participant and between-session repeatability, as assessed by the intraclass correlation coefficient (ICC), was high (ICC 0.83-0.96), and for the rhythm test it was fair (ICC 0.70). The inter-rater reliability was also high for all the tests (ICC 0.88-0.96) except that for rhythm (ICC 0.76). In a test-retest design, these tests were sensitive enough to produce sufficient variation between participants in terms of differentiating between individuals. The learning effect was the most remarkable between the pretest and test sessions, and the reliability was better for the test-retest session although a statistically significant difference existed only for tandem walking forwards (p<0.02) and balance on a bar (p<0.004). The tests with quantitative scores had a smaller margin of error than those with qualitative scores. These tests provide reliable alternatives for assessing basic motor skills of non-sporting adults in the context of physical activity promotion.

Bone mineral density during reduction, maintenance and regain of body weight in premenopausal, obese women.

Weight loss may lead to bone loss but little is known about changes in bone mass during regain of reduced weight. We studied changes in bone mineral density (BMD) and bone mineral content (BMC) during voluntary weight reduction and partial regain. The study consisted of three phases: a 3 month weight reduction with very-low-energy diet (VLED), a 9 month randomized, controlled walking intervention period with two training groups (target energy expenditure 4.2 or 8.4 MJ/week) and a 24-month follow-up. The participants were premenopausal women with a mean body mass index of 34.0 (SD 3.6) kg/m2. Seventy-four of 85 subjects completed the whole study. Total body, lumbar spine, proximal femur and dominant radius BMD and BMC were measured with dual-energy X-ray absorptiometry (DXA). The mean weight loss during VLED was 13.2 (3.4) kg, accompanied by unchanged total body BMC and decreased lumbar, trochanteric and radial BMD (p < 0.05). During months 3-36, an average of 62% of the weight loss was regained, total body BMC decreased and trochanteric BMD increased (p < 0.05). At the end of the study, total body BMC and lumbar and femoral neck BMD were lower than initially (p < 0.05). Weight change throughout the study correlated significantly with the change in radial (r = 0.54), total body (r = 0.39) and trochanteric (r = 0.37) BMD. Exercise-group assignment had no effect on BMD at weight-bearing sites. In conclusion, the observed changes in BMD and BMC during weight reduction and its partial regain were clinically small and partly reversible. More studies are needed to clarify whether the observed weight changes in BMD and BMC are real or are artifacts arising from assumptions, inaccuracies and technical limitations of DXA.

Prediction of change in maximal aerobic power by the 2-km walk test after walking training in middle-aged adults.

The aim was to study the 2-km walk test's accuracy in predicting maximal aerobic power (VO2max) and its changes during 15-week walking training in 108 healthy middle-aged adults. Training prescription was 65-75% of VO2max 50 min/session, four times weekly. VO2max was measured walking on a treadmill and predicted from the 2-km walk test using gender-specific equations including age, body mass index, performance time and heart rate. The difference in VO2max between the walk test and the maximal exercise test before training was -0.9 ml x min(-1) x kg(-1) (SD 4.4) in men and -2.2 (3.5) in women. The total error was from 4.1 to 4.5 ml x min(-1) x kg(-1). After training the increase in measured VO2max was 2.9 ml x min(-1) x kg(-1) more in the walkers compared to the controls. The difference between the predicted and measured changes in VO2max during training ranged from -1.8 to -1.0 ml x min(-1) x kg(-1) between the study groups except in walking men, for whom the walk test overestimated the difference. The total error was from 3.1 to 4.9 ml x min(-1) x kg(-1). The 2-km walk test can be used as a reasonably accurate field test to predict changes in VO2max due to aerobic training in healthy nonathletic adults.

Health-related fitness test battery for middle-aged adults: associations with physical activity patterns.

To evaluate the validity of a health-related fitness (HRFI) test battery with respect to physical activity (PA), we studied how PA patterns of adults are related to different components of HRFI with special interest in musculoskeletal and motor fitness. Subjects (n = 498) were middle-aged (37-57 years) men and women, evenly selected from five age cohorts of a representative population sample. PA was assessed with a questionnaire and classified into three PA groups. Fitness assessment included 9 simple field tests. The odds ratio of low fitness (least fit 40 %) of the measured dimension of HRFI for three PA groups with reference to inactive group were analysed. All PA groups were strongly related to Walk Test results in both genders, and to BMI in women. Muscular type exercise was associated with modified push-ups strength and static back extension endurance in both genders, and with one-leg standing balance in women. One-leg squat for leg strength, jump-and-reach for leg power, trunk side-bending flexibility and hamstring muscle extensibility tests were not associated with PA. Five of the nine fitness tests demonstrated plausible associations with PA patterns among adults suggesting activity-related validity. An exercise intervention study is needed to evaluate the sensitivity of the tests to fitness changes.

Health-related fitness test battery for adults: associations with perceived health, mobility, and back function and symptoms.

OBJECTIVE: To evaluate the health-related content validity of nine fitness tests by studying how low, mid, and high levels of fitness are associated with perceived health and musculoskeletal functioning. DESIGN: Cross-sectional methodological study. SETTING: A research institute for health promotion. PARTICIPANTS: Middle-aged (37 to 57 years) men (n = 245) and women (n = 253), evenly selected from five age cohorts of a random population sample. MAIN OUTCOME MEASURES: The odds ratios (ORs) of selected health outcomes for low (least fit 20%), mid (next 40%), and high (most fit 40%) fitness categories in the different tests adjusted for several possible confounders. RESULTS: Cardiorespiratory fitness, as measured by 2-km walk test, was strongly and consistently associated with perceived health and mobility (stair climbing) in both genders (range of ORs, 2.4 to 17.6), and a somewhat weaker relationship was found with leg power and with leg strength (ORs, 2.5 to 7.2). Low fitness in back muscular endurance and upper-body strength were associated with mobility disability (ORs, 2.8 to 8.5) and with back dysfunction and pain (ORs, 2.9 to 6.1). High fitness in back endurance in men and in balance in women were related to positive back health (ORs, 2.5 to 3.7). Body mass index was associated with musculoskeletal disability in women (ORs, 2.4 to 5.3). Balance, leg strength, and leg flexibility in men; and leg power, trunk and leg flexibility in women were not associated with health outcomes. CONCLUSIONS: Among a middle-aged population, the majority of the evaluated fitness tests demonstrated health-related validity by strong associations with perceived health and musculoskeletal functioning, and by weaker associations with back symptoms.

Safety and feasibility of a health-related fitness test battery for adults.

BACKGROUND AND PURPOSE: Health-related fitness (HRFI) assessment may be useful in promoting physical activity. Health-related fitness refers to those components of fitness that are related to health status. The safety and feasibility of a test battery designed for the assessment of HRFI were evaluated. SUBJECTS AND METHODS: Middle-aged men (n = 246) and women (n = 254), evenly selected from five age cohorts of a random sample (N = 826), were tested. The subjects had a mean age of 47.0 years (SD = 7.9, range = 37-57). Screening to identify subjects with health limitations was conducted by fitness testers who had master's degrees in sport or health sciences. Safety was assessed in terms of acute complications, delayed-onset muscle soreness (DOMS), and heart rate after each test. Subject exclusion and time costs were evaluated for feasibility. RESULTS: No acute complications occurred. The leg function test caused severe DOMS among inactive women. The overall exclusion rate increased with age. Up to 27% of subjects aged 52 and 57 years were excluded from muscle endurance tests, mainly due to self-reported heart disease or elevated blood pressures. Over 90% of the subjects, however, qualified for balance, flexibility, muscle force, and walk tests. CONCLUSION AND DISCUSSION: The test battery offers a safe and feasible method for the assessment of HRFI in working-aged adults, with the limitation that the one-leg squat function test may cause DOMS, particularly in inactive women.

Health-related fitness test battery for adults: aspects of reliability.

OBJECTIVE: In two studies, the reliability of 3 balance, 2 flexibility, and 4 muscular strength tests proposed as test items were investigated in a health-related fitness (HRF) test battery for adults. DESIGN: Methodological study. SETTING: A health promotion research institute. SUBJECTS: In study A, volunteers (n=42) from two worksites participated. In study B, a population sample (n=510) of 37-to 57-year-old men and women was selected. MAIN OUTCOME MEASURES: Intraclass correlation coefficient of repeated measures was used to assess inter-rater reliability. The degree of measurement error was expressed as the standard error of measurement. The mean difference with 95% confidence intervals between the testing days or test trials was used to assess test-retest or trial-to-trial reproducibility. The coefficient of variation(CV=[SD/mean] x 100%) from day to day was also calculated. RESULTS: The following tests appeared to provide acceptable reliability as methods for field assessment of HRF: standing on one leg with eyes open for balance, side-bending of the trunk for spinal flexibility, modified push-ups for upper body muscular function, and jump and reach and one leg squat for leg muscular function. CONCLUSIONS: This reliability assessment provided useful information on the characteristics of potential test items in a HRF test battery for adults and on the limitations of its practical use. Testers must be properly trained to ensure reliable assessment of HRF of adults.

Feasibility of a 2-km walking test for fitness assessment in a population study.

A simple 2-km Walking Test has been developed for determining the cardiorespiratory fitness of healthy adults. In the present study the following aspects of the feasibility of this test for population assessment were investigated: participation willingness, the percentage of test qualified subjects, the percentage of acceptable test performances and the resources needed for field test administration. A representative sample was drawn from the 27 to 65-year-old population in a rural municipality in northeastern Finland. Subjects were recruited on the basis of the results of health questionnaires and interviews. One fourth of the volunteers were excluded from the test because of health problems. The 2-km walking tests were administered outdoors in the municipality center. More than 50% of the subjects successfully completed two consecutive walking tests. This study indicated that the 2-km Walking Test is a feasible alternative as a measure of cardiovascular fitness for large population groups and could potentially be used in exercise related health promotion programmes.

Training effects of cross-country skiing and running on maximal aerobic cycle performance and on blood lipids.

Two experiments were carried out to compare the cardiorespiratory and metabolic effects of cross-country skiing and running training during two successive winters. Forty-year-old men were randomly assigned into skiing (n = 15 in study 1, n = 16 in study 2), running (n = 16 in study 1 and n = 16 in study 2) and control (n = 17 in study 1 and n = 16 in study 2) groups. Three subjects dropped out of the programme. The training lasted 9-10 weeks with 40-min exercise sessions three times each week. The training intensity was controlled at 75%-85% of the maximal oxygen consumption (VO2max) using portable heart rate metres and the mean heart rate was 156-157 beats.min-1 in the training groups. In the pooled data of the two studies the mean increase in the VO2max (in ml.min-1.kg-1) on a cycle ergometer was 17% for the skiing group, 13% for the running group and 2% for the control group. The increase in VO2max was highly significant in the combined exercise group compared to the control group but did not differ significantly between the skiing and running groups. The fasting serum concentrations of lipoproteins and insulin did not change significantly in any of the groups. These results suggested that training by cross-country skiing and running of the same duration and intensity at each session for 9-10 weeks improved equally the cardiorespiratory fitness of untrained middle-aged men.

Negative controls of cell proliferation: human prostate cancer cells and androgens.

LNCaP cells represent a useful tool to explore the mechanism of sex hormone action on cell proliferation in an "in culture-in animal" model. Results indicated that: (a) these cells were inhibited from proliferating for extended periods (up to 30 days) when placed in charcoal-dextran-stripped sera; they remained, however, viable because they proliferated when sex hormones were added to this medium; (b) the inhibitory effect of sera was reversed by the addition of 5 alpha-dihydrotestosterone at 3 x 10(-10) M, 17 beta-estradiol at 3 x 10(-8) M and higher concentrations, and progesterone at 3 x 10(-10) M and higher concentrations; (c) while the dose response to androgens was biphasic (i.e., 5 alpha-dihydrotestosterone at concentrations higher than 3 x 10(-10) M resulted in progressively lower cell yields), estrogens and progestagens exhibited a monophasic pattern; (d) these cells were exceedingly sensitive to the nutritional environment in which they grew; (e) while these cells have androgen receptors (68 fmol/mg protein; Kd = 2 x 10(-9) M), estrogen and progestagen receptors could not be detected by biochemical and immunocytochemical techniques; (f) tumors grew at the site of inoculation in castrated nude mice carrying 17 beta-estradiol and progesterone pellets and in intact male nude mice implanted with placebo pellets, while tumors did not grow in castrated nude mice implanted with a 5 alpha-dihydrotestosterone pellet. Taken together the data collected are compatible with the following conclusions: (a) the proliferative response in LNCaP cells seems not to be directly mediated by their intracellular androgen receptors; (b) plasma-borne trypsin-sensitive inhibitors of the proliferation of these cells (androcolyone I) appear to play a significant role in the proliferative event; (c) natural and synthetic androgens, estrogens, and progestagens cancelled the inhibition by charcoal-dextran-stripped human sera; (d) only androgens were able to trigger an inhibition of cell proliferation (shutoff effect) at concentrations higher than those that affected maximal cell yields (direct negative hypothesis); and (e) a faulty shutoff response is probably a crucial event for the tumorigenesis of these human prostate cells.