Menstrual cycle phase affects temperature regulation during endurance exercise.

We investigated whether menstrual cycle phase would affect temperature regulation during an endurance exercise bout performed at room temperature (Ta) of 22 degrees C and 60% relative humidity. Nine eumenorrheic women [age 27.2 +/- 3.7 yr, peak O2 uptake (VO2) 2.52 +/- 0.35 l/min] performed 60 min of cycle exercise at 65% of peak VO2. Subjects were tested in both midfollicular (F) and midluteal (L) phases, although one woman did not show a rise in serum progesterone (P4) that is typically evident 1 wk after ovulation. VO2, rectal (Tre) and skin (Tsk) temperatures, heart rates (HR), and ratings of perceived exertion (RPE) were measured throughout exercise. Sweat loss (SL) was estimated from pre- and postexercise body weight differences. VO2, SL, and Tsk were not affected by menstrual cycle phase. Preexercise Tre was 0.3 degrees C higher during L than during F conditions, and this difference increased to 0.6 degrees C by the end of exercise (P less than 0.01). Compared with F, HRs during L were approximately 10 beats/min greater (P less than 0.001) at all times, whereas RPE responses were significantly greater (P less than 0.01) by 50 min of cycling. No differences in any measured values were found in the subject whose P4 was low in both test conditions. Results indicate that thermoregulation (specifically, regulation of Tre), as well as cardiovascular strain and perception of exercise, was adversely affected during the L phase.

A one-year follow-up to physical activity and health. A report of the Surgeon General.

OBJECTIVES: A telephone survey of over 2000 American adults was conducted to determine their awareness of Physical Activity and Health: A Report of the Surgeon General and their knowledge of the health messages contained within the report. A related purpose was to determine if awareness and knowledge were a function of age, ethnicity, gender, and education level. METHODS: A random sample of American adults was drawn and a national telephone survey was conducted in the 48 contiguous states and the District of Columbia. RESULTS: Approximately one third of the adult population had heard of the report. Awareness was a function of age, ethnicity, and educational level. Knowledge of the relationship between physical inactivity and specific chronic diseases was a function of age, ethnicity, and gender. CONCLUSIONS: Differential awareness of the Report and its contents by various segments of the population has significant implications for the messages transmitted and interventions developed to help individuals adopt and maintain active lifestyles.

Strength comparisons in untrained men and trained women athletes.

The purpose was to compare untrained college men with trained collegiate women basketball and volleyball players in terms of absolute and relative upper and lower body strength. Absolute and relative strength comparisons were also made between the two groups of women athletes. Eighty subjects were included in each group. Relative strength was expressed per unit of weight, height, biacromium, and biiliac widths. It was hypothesized that while men are significantly stronger than trained women athletes, such differences may be removed once body size characteristics are controlled. MANOVA and MANCOVA were utilized to test hypotheses. Results indicate that untrained men have greater upper and lower body strength than trained women athletes in terms of both absolute and relative strength. Women basketball players have greater upper and lower body strength than women volley players. The two groups of women athletes are alike in terms of upper body absolute and relative strength.

Caltrac versus calorimeter determination of 24-h energy expenditure in female children and adolescents.

The purpose of this study was to determine the validity of the Caltrac accelerometer for estimating 24-h energy expenditure (EE) in children and adolescents. EE for 40 girls (13.0 +/- 1.8 yr) was assessed for 24 h via indirect calorimetry in whole-room calorimeters. EE and activity level were estimated concurrently by two Caltrac accelerometers placed on the subjects at each hip. Significant correlations (P < 0.001) resulted between Caltrac estimates and calorimeter values for 24-h total EE (TEE, r = 0.80), sedentary daily EE (SDEE, r = 0.84), and waking EE (WEE, r = 0.85). Nonetheless, the Caltrac significantly (P < 0.001) underestimated EE in all experimental conditions (TEE: -13.3 +/- 8.6%; SDEE: -6.8 +/- 7.3%; WEE: -30.4 +/- 8.5%). A significant multiple correlation between calorimeter values and a combination of Caltrac activity counts and body weight (R = 0.86, P < 0.001) suggested these variables could be useful for daily EE estimation. Additional analyses indicated that as EE increased, the absolute difference between Caltrac and calorimeter values also increased. The significant correlations between Caltrac and calorimeter values suggest the Caltrac may be useful for assessing daily caloric expenditure for groups of children.

Accuracy of measured and predicted residual lung volume on body density measurement.

The effects of measured and predicted residual lung volume on the accuracy of body density and percent fat (%Fat) were investigated. Adult fitness subjects (N = 46) had residual lung volume measured with the oxygen dilution method while those from an athlete sample (N = 134) utilized the nitrogen washout technique. Residual lung volume was also predicted with gender-specific regression equations using height and age and from 24% of vital capacity (%FVC). Residual lung volume alpha reliability for the average of four residual lung volume trials exceeded 0.90 (SEM less than = 161 ml) for the oxygen dilution method and 0.99 (SEM = 30 ml) for the average of two nitrogen washout measures. The standard errors for predicted residual lung volume were 579 and 355 ml, respectively, for the men and women in the adult sample and 288 ml for the trained athlete sample. Estimating residual lung volume from %FVC yielded a SEE of 318 ml for the trained athlete sample. Measured residual lung volume errors resulted in errors of 1.04%Fat, 0.87%Fat, and 0.21%Fat for the men, women, and trained athlete samples, respectively. In contrast, predicted residual lung volume measurement errors resulted in errors of 3.70%Fat, 2.85%Fat, and 1.98%Fat for the respective samples and 2.18%Fat when using %FVC with the trained athletes. Measured residual lung volume introduces little %Fat error while predicted residual lung volume introduces a substantial source of measurement error.

The energy cost of horizontal walking and running in adolescents.

PURPOSE: This study developed and cross-validated generalized equations for predicting VO2 (mL x kg(-1) x min(-1)) and caloric expenditure (kcal x kg(-1) x min(-1)) during horizontal walking and running in adolescents. METHODS: Subjects were 47 male and 35 female adolescent volunteers, ages 12-18. Each subject underwent a submaximal treadmill exercise test to determine VO2 at randomly selected walking and jogging speeds (67-215 m x min(-1)). Caloric expenditure was estimated from VO2 and RER. Multiple regression was used to develop prediction equations for estimating VO2 and caloric expenditure from a derivation sample of 77 random observations, both walking and running. RESULTS: The group relationship between running speed and energy cost in the derivation sample was linear, whereas the relationship between walking speed and energy cost was quadratic. Gender, age, and height each failed to account for significant additional variation in energy cost after speed and mode were considered. Skinfolds accounted for a small yet significant amount of additional variation in energy cost. The derived equations were cross-validated on a sample of 76 separate random observations. The cross-validation statistics are: for VO2, R = 0.95, error = 3.58 mL x kg(-1) x min(-1), and for caloric expenditure, R = 0.94, error = 0.019 kcal x kg(-1) x min(-1). Most selected adult equations consistently underestimated both VO2 and caloric expenditure in the cross-validation sample. CONCLUSIONS: These results suggest that in adolescents, within the range of speeds tested, the relationship between speed of movement and energy cost for running is linear, but for walking is curvilinear. Also, adult models for estimating VO2 or caloric expenditure do not account for the higher relative energy cost of walking and running in adolescents.

Variables related to meeting the CDC/ACSM physical activity guidelines.

PURPOSE: The purpose of this study was to investigate the relation between perceived importance of physical activity and demographic variables and current physical activity level with specific reference to the CDC/ACSM guidelines for sufficient physical activity for a health benefit. METHODS: Physical activity levels were assessed by a telephone survey of 2002 households throughout the continental United States and the District of Columbia to determine whether the individuals met the CDC/ACSM physical activity guidelines. RESULTS: Results indicate that 68% of the respondents are physically active below the CDC/ACSM criterion. Chi-square analysis revealed significant relationships between meeting the CDC/ACSM physical activity guidelines and 1) perceived importance of physical inactivity as a health risk (P < 0.0001), and 2) gender (P < 0.0001). Logistic regression analysis revealed that having a greater awareness of the health risks of physical inactivity improved the odds ratio (OR = 1.40, 95% CI = 1.21-1.62) of being sufficiently physically active for a health benefit by 40% (P < 0.0001) and being a male improved the odds ratio (OR = 1.45, 95% CI = 1.17-1.79) of being sufficiently physically active for a health benefit by 45% (P < 0.0006). CONCLUSIONS: Implications for health and physical fitness researchers and practitioners are that they need to improve awareness of life span fitness benefits and develop intervention programs based on individuals' current physical activity levels.

Instructional design strategies for developing an interactive video educational program for pregnant teens: a pilot study.

One hundred forty-six teens attending an urban maternity hospital's prenatal clinic completed a questionnaire designed to assist in the development of educational programs utilizing computer-assisted television instruction or interactive video. Ninety-five percent of the teens agreed that additional information about desirable health behaviors during pregnancy would be helpful. Forty-six percent preferred obtaining information from a health professional at the hospital. Although 90% said that the race of the narrator for a film show was unimportant, responses regarding racial preference corresponded to the racial distribution of participants. Seventy-six percent of the teens preferred the narrator to be younger than 35 years of age, and 54% preferred a female narrator. Race was associated with video game experiences, preferences about the narrator's age and race, and favorite television shows. Age was not associated with responses to any of the questions. Although only 19% had ever used a computer, 98% stated they would like to try a computer with assistance. More than half (55%) knew how to type and 83% had played video games; of those who had played video games, 93% said they enjoyed doing so. Eighty-three percent of the respondents always or sometimes enjoyed cartoons. Favorite television shows and cartoon characters were identified. The design implications of the teens' preferences to the development of instruction using computers coupled with other emerging technologies are discussed.

Assessing adolescent health needs: a factor analytic approach.

Advances in technology are rapidly expanding health educators' resources for presenting information tailored to meet individual health needs and interests. A self-administered questionnaire was given to 510 youths in grades 6 through 9 to ascertain adolescents' health concerns and thus develop more appropriate educational programs. Smoking, diet and weight control, physical fitness, and general health items were included. Factor analysis methods identified ten concerns; smoking, weight control, exercise effects, peer approval of appearance, preparatory health behaviors, planning and maintaining a personal health program, feeling good about oneself, communication issues, comparisons with others, and resistance to negative peer influences. Sex and grade were significantly associated with particular responses. Recommendations include the value of addressing each area of the content domain as it relates to health lessons to ensure that information is relevant to the needs and interests of individual adolescents.

Work-related activities to improve quality of life in HIV disease.

The authors conducted an ethnographic analysis of various ways that persons with AIDS (PWAs) manage their illness in order to improve quality of life. According to Anselm Strauss (1975), illness management involves "work": The activities associated with work change as disease-related symptomatology presents different responses. Strauss' concept of work served as the theoretical orientation for this study. The researchers interviewed the respondents (N = 19) while they were hospitalized for problems related to their diagnosis of AIDS. Analysis was guided by grounded theory. Several categories of management activities emerged. The participants perceived all work-related activities as very important to life in the hospital. They perceived nurses as confederates who were involved in many of the work activities. Quality of life was enhanced when PWAs were able to conduct activities they felt were important and when the healthcare team supported their work.

Health locus of control among HIV-positive indigent women.

The authors explored the multidimensional construct of health locus of control among 14 indigent HIV-positive women who attended one of two southwestern city health clinics. An exploratory survey design was used to compare the mean responses of the subjects on the Multidimensional Health Locus of Control (MHLC) Scales with established normative data. The women believed they had control over their health, yet felt powerful others and chance determine their health outcomes. These findings are drawn from high scores on both the Internal and External MHLC Scales. Findings imply that these women may not view themselves as having any control in the dichotomous world of acute and chronic illness. Authors recommend that nurses should encourage their patients to participate in the management of their health care.

Relations of sit-up and sit-and-reach tests to low back pain in adults.

The sit-up and sit-and-reach tests are found on nearly all youth and adult fitness tests because of the perceived relation between performance on these tests and low back pain. However, this relationship has not been well validated. Therefore, the purpose of the study was to examine the relationship between performance on these two common field tests of muscular strength and flexibility (the sit-up and the sit-and-reach tests) and self-reported low back pain (LBP). The sample included 2,747 adults with a mean age of 44.6 +/- 9.8 years. The 1-minute sit-up (mean = 30.9 +/- 10.6) and sit-and-reach tests (mean = 39.88 +/- 10.49 cm) were administered to participants as part of a voluntary clinical health and fitness evaluation between 1980 and 1990. Participants completed a mail-back survey in 1990 on musculoskeletal health problems. Low back pain was quantified by developing on ordinal variable from questionnaire responses which represented a range of severity of LBP from none (0) to LBP which required medical care (3). With an average of 6.1 (+/- 2.0) years of follow-up, LBP was reported by 54% of the study participants (men = 45%, women = 54%). Pearson correlations between sit-up (r = .002; p = .94), sit-and-reach (r = -.043; p = .03), and LBP indicated poor LBP criterion-related validity from the sit-up and sit-and-reach tests. Partial correlations, where age, gender, percent of body fat, and time between testing and survey response were controlled, displayed no increase in the relationship. This study does not support the validity of sit-up and sit-and-reach test items for health-related fitness batteries because they were unrelated to LBP.

Artificial ribonucleases.

Many inorganic and organic compounds promote the reactions catalyzed by RNase A. Both the transesterification step, where a 2',3'-cyclic phosphate is formed with concomitant cleavage of RNA, and the hydrolysis step, where the 2',3'-cyclic phosphate is converted to a phosphate monoester, may be mimicked with compounds that are readily synthesized in the laboratory. Electrophilic activation of the phosphate ester and charge neutralization are generally important means by which artificial RNases promote phosphate diester displacement reactions. Several artificial RNases operate by a bifunctional general acid/general base mechanism, as does RNase A. Provision of an intramolecular nucleophile appears to be an important pathway for metal complex promoted phosphate diester hydrolysis. In contrast to the successful design of compounds that promote the reactions catalyzed by RNase A, there are no artificial nucleases to date that will cleave the 3' P-O bond of RNA or hydrolyze an oligonucleotide of DNA. Artificial RNases based on both metal complexes and organic compounds have been described. Metal complexes may be particularly effective catalysts for both transesterification and hydrolysis reactions of phosphate diesters. Under physiological conditions (37 degrees C and neutral pH), several metal complexes catalyze the transesterification of RNA. Future work should involve the development of metal complexes which are inert to metal ion release but which maintain open coordination sites for catalytic activity. The design of compounds containing multiple amine or imidazole groups that may demonstrate bifunctional catalysis is a promising route to new artificial RNases. Further design of these compounds and careful placement of catalytic groups may yield new RNase mimics that operate under physiological conditions. The attachment of artificial RNases to recognition agents such as oligodeoxynucleotides to create new sequence-specific endoribonucleases is an exciting field of endeavor. Applications for such sequence-specific endoribonucleases include in vitro manipulations of RNA and the destruction of gene transcripts in vivo. Further work will require the development of new synthetic methodologies for attachment of catalytic cleaving groups to oligodeoxynucleotides.

Exercise and VO2 max in children: a meta-analysis.

Despite widespread belief that children are aerobically trainable, studies examining the ability of a child to improve maximal oxygen uptake (VO2max) have yielded inconsistent findings. The present investigation, using meta-analysis, examined the effects of physical activity, gender, experimental design, and sufficiency of exercise on the VO2 max of child subjects. Sixty-nine studies examining the effects of training on children were originally located; 28 met criteria for inclusion. From these studies, 70 effect sizes (ESs) were calculated. Some studies employed cross-sectional (XS) designs involving comparisons of intact groups of subjects; the others used a pretest-posttest (PP) design, which followed subjects throughout a specified training program. Average ES indicated a considerable difference between trained and untrained subjects though several possible sources of confounding (e.g., subject self-selection) in XS studies were identified. Effect sizes of .94 (+/- 1.00) and .35 (+/- 0.82) were achieved for XS and PP designs, respectively. Further analyses were conducted with the PP design studies. In these studies, subjects improved approximately 2 ml.kg 1 x min-1. In the PP studies, effect sizes were not significantly affected by (a) gender, (b) "sufficient" and "insufficient" training protocol, or (c) test mode. Results indicated that reported changes in VO2max in children are small to moderate and are a function of the experimental design used.