When discussing sports and the athletes who participate in them, it has long been recognized that fitness is a prerequisite for optimal performance. The goal of training to improve fitness levels in ...athletes is ultimately to minimize the stress that the body experiences during competition. When it comes to the topic of racecar drivers, however, drivers and their trainers have largely been left to their own devices to figure out the stressors and the areas of specific training focus. Unfortunately, racecar drivers have battled the stereotype that they are not athletes, and with little regard for them as athletes, drivers are seldom the focus of scientific research related to their performance. Like the cars they drive, driver-athletes are complex, but from a physiological perspective. However, unlike the cars they drive, driver-athletes have not been examined, evaluated, and tweaked to the same degree. The purpose of this review is two-fold: first, by examining the available literature, to make the case for new research into the driver's role in the driver-car system (i.e. driver science) and the stresses experienced; second, to make the case for more extensive use of microtechnology in the real-time monitoring of driver-athletes. With the miniaturization of sensors and the advent of portable data storage devices, the prospect of quantifying the stresses unique to the driver are no longer as daunting, and the relative impossibility and difficulties associated with measuring the driver-athlete in real-time no longer need to be as challenging. Using microtechnology in the assessment of the driver-athlete and with a more public discussion and dissemination of information on the topic of driver science, the scientific community has the opportunity to quantify that which has been largely assumed and speculated. The current article will offer the following recommendations: first, rather than examining a singular physiological stressor, to examine the interaction of stressors; second, to examine variables/stressors that are more representative of the changing driver demographics; third, to measure drivers in real-time during actual race events; lastly, to work to develop training programs that more accurately apply to the driver and the stresses experienced. In uncovering this information, there is an opportunity to contribute to racing becoming that much safer, that much more competitive, and that much more comprehensive for the driver, the team, and the sport.
The purpose of this study was to determine the effects of supplementation with a water-soluble cinnamon extract (Cinnulin PF(R)) on body composition and features of the metabolic syndrome.
Twenty-two ...subjects with prediabetes and the metabolic syndrome (mean +/- SD: age, BMI, systolic blood pressure SBP, fasting blood glucose FBG: 46.0 +/- 9.7 y; 33.2 +/- 9.3 kg/m2; 133 +/- 17 mm Hg; 114.3 +/- 11.6 mg/dL) were randomly assigned to supplement their diet with either Cinnulin PF(R) (500 mg/d) or a placebo for 12-weeks. Main outcome measures were changes in FBG, SBP, and body composition measured after 12-weeks of supplementation. The primary statistical analyses consisted of two factor (group x time), repeated-measures ANOVA for between group differences over time. In all analyses, an intent-to-treat approach was used and significance was accepted at P < 0.05.
Subjects in the Cinnulin PF(R) group had significant decreases in FBG (-8.4%: 116.3 +/- 12.8 mg/dL pre to 106.5 +/- 20.1 mg/dL post, p < 0.01), SBP (-3.8%: 133 +/- 14 mm Hg pre to 128 +/- 18 mm Hg post, p < 0.001), and increases in lean mass (+1.1%: 53.7 +/- 11.8 kg pre to 54.3 +/- 11.8 kg post, p < 0.002) compared with the placebo group. Additionally, within-group analyses uncovered small, but statistically significant decreases in body fat (-0.7%: 37.9 +/- 9.2% pre to 37.2 +/- 8.9% post, p < 0.02) in the Cinnulin PF(R) group. No significant changes in clinical blood chemistries were observed between groups over time.
These data support the efficacy of Cinnulin PF(R) supplementation on reducing FBG and SBP, and improving body composition in men and women with the metabolic syndrome and suggest that this naturally-occurring spice can reduce risk factors associated with diabetes and cardiovascular diseases.
We hypothesized that creatine supplementation would interfere with normal body fluid shifts that occur during exercise in a hot environment due to its osmotic effect intracellularly. This study ...examined the effects of acute creatine loading (20 g/d for 5 d) on the thermoregulatory response of the body during a bout of exercise at 39°C.
Subjects (15 men and 1 woman) performed a cycle test of maximum oxygen consumption to determine the proper work rate for the heat-stress test (40 min at 55% maximum oxygen consumption at 39°C) and were assigned to a creatine group (
n = 8) or a placebo group (
n = 8) in a double-blind fashion. Each group performed the heat-stress test on two separate occasions: before supplementation and after supplementation (20 g/d of creatine with Gatorade or Solka-floc plus Gatorade). Dependent variables included rectal temperature, mean skin temperature, mean body temperature, and perceived thermal sensation.
Repeated measure analysis of variance showed a significant (
P ≤ 0.05) increase in body weight in the group supplemented with Gatorade. Core temperature was significantly lower after supplementation for both groups combined (before supplementation at 37.85°C and after supplementation at 37.7°C), with no difference between groups. A significant three-way interaction (group × trial × time) was also found for rectal temperature, with both groups having significantly lower rectal temperature after supplementation. Mean body and mean skin temperatures showed no differences.
Short-term creatine supplementation (20 g/d for 5 d) did not have a negative effect on thermoregulatory responses during exercise at 39°C.
PURPOSE: The purpose of this study was to determine the accuracy of an air displacement plethysmography (ADP) body composition measure in estimating resting metabolic rate (RMR). The specific aim was ...to quantifiably compare the estimated metabolic rate from air displacement plethysmography to the actual metabolic rate measured using indirect calorimetry via a standard metabolic cart. METHODS: Fifty-eight apparently healthy (18-45 yrs) male (n=20) and female (n=38) subjects participated in the trial. All subjects were instructed to adhere to the following pretest instructions: 1) Fast 12 hours prior to the test 2) Avoid strenuous exercise 24 hours prior to the test 3) Wear tight fitting clothing (i.e. lycra or spandex material) and 4) refrain from nicotine and alcohol for 24 hours prior to testing. Each subject was required to lie down in a quiet room for a total of 30 minutes during the indirect calorimetry obtainment of resting metabolic rate (RMR) via the metabolic cart (MC) method. The first 15 minutes of the RMR data was discarded and the average VO sub(2) of the following 15 minutes was used as the subjects RMR. Upon completion of the MC RMR, subjects moved directly to ADP testing following the manufacturers standardized protocol whereby an estimated RMR was obtained. RESULTS: RMR measurements from the MC (1868.6+ or -487.1 kcals) and estimates from the ADP (1428.2+ or -306.7 kcals) were statistically significant (p< or =0.05). CONCLUSIONS: Significant differences in RMR measurements were found between indirect calorimetry and the estimated value obtained from the ADP measure. This could cause confusion and be prohibitive in proper nutritional recommendations for people wanting to alter body composition.
Targeting most-at-risk individuals with HIV preventive interventions is cost-effective. We developed gender-specific indices to measure risk of HIV among sexually active individuals in Rakai, Uganda.
...We used multivariable Cox proportional hazards models to estimate time-to-HIV infection associated with candidate predictors. Reduced models were determined using backward selection procedures with Akaike's information criterion (AIC) as the stopping rule. Model discrimination was determined using Harrell's concordance index (c index). Model calibration was determined graphically. Nomograms were used to present the final prediction models.
We used samples of 7,497 women and 5,783 men. 342 new infections occurred among females (incidence 1.11/100 person years,) and 225 among the males (incidence 1.00/100 person years). The final model for men included age, education, circumcision status, number of sexual partners, genital ulcer disease symptoms, alcohol use before sex, partner in high risk employment, community type, being unaware of a partner's HIV status and community HIV prevalence. The Model's optimism-corrected c index was 69.1 percent (95% CI = 0.66, 0.73). The final women's model included age, marital status, education, number of sex partners, new sex partner, alcohol consumption by self or partner before sex, concurrent sexual partners, being employed in a high-risk occupation, having genital ulcer disease symptoms, community HIV prevalence, and perceiving oneself or partner to be exposed to HIV. The models optimism-corrected c index was 0.67 (95% CI = 0.64, 0.70). Both models were well calibrated.
These indices were discriminative and well calibrated. This provides proof-of-concept that population-based HIV risk indices can be developed. Further research to validate these indices for other populations is needed.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Caenorhabditis elegans uses chemosensation to determine its course of development. Young larvae can arrest as dauer larvae in response to increasing population density, which they measure by a ...nematodeexcreted pheromone, and decreasing food supply. Dauer larvae can resume development in response to a decrease in pheromone and increase in food concentration. We show here that two novel G protein alpha subunits (GPA-2 and GPA-3) show promoter activity in subsets of chemosensory neurons and are involved in the decision to form dauer larvae primarily through the response to dauer pheromone. Dominant activating mutations in these G proteins result in constitutive, pheromone-independent dauer formation, whereas inactivation results in reduced sensitivity to pheromone, and, under certain conditions, an alteration in the response to food. Interactions between gpa-2, gpa-3 and other genes controlling dauer formation suggest that these G proteins may act in parallel to regulate the neuronal decision making that precedes dauer formation.
As a scientist, coach, athlete, or other fitness-type professional, knowledge of tests to measure specific physiologic characteristics that may ultimately contribute to performance in a sport or ...event is imperative. Baseline measurements of these factors influencing performance are critical for many different reasons. First, it is difficult to get to a predetermined end point if the baseline is unknown. Second, these specific physiologic characteristic, once measured, can be evaluated and used as a guide to develop appropriate training strategies for continued improvement. As such, this chapter explores and details the most widely used laboratory and field techniques used to measure human performance. Performance can be thought of as the way an individual or something functions. There are many levels of performance such as poor, average, or elite. Many times, performance is measured by the outcome of the game or event with wins and losses. So what determines an athlete’s ability to perform, or more importantly, excel at his or her sport? Of particular interest in this chapter are the physiologic components that comprise a portion of sport performance. Technical skill and tactical awareness are not considered here but are extremely important to overall sport performance. Certainly, genetic endowment is at the top of the list of physiologic parameters that affect sport performance. As has often been said, we must choose our parents wisely and realize that genetic predisposition to exercise performance is uncontrollable. Along with genetics, the overall health and nutritional status of an athlete can affect their performance. These factors of health and nutritional status are controllable and must be optimized. Another factor and arguably the most recognized influential and controllable component of performance is training. A tremendous amount of scientific study along with trial and error have produced increasingly better performances across the athletic spectrum through the improvement of training programs. A cornerstone to these improved training programs is the ability to monitor an athlete’s progress. This monitoring can be achieved by properly selecting and administering specific laboratory and field tests based on sport-specific physiologic demands.
The goa-1 gene encoding the alpha subunit of the heterotrimeric guanosine triphosphate-binding protein (G protein) Go from Caenorhabditis elegans is expressed in most neurons, and in the muscles ...involved in egg laying and male mating. Reduction-of-function mutations in goa-1 caused a variety of behavioral defects including hyperactive movement, premature egg laying, and male impotence. Expression of the activated Go alpha subunit (G alpha o) in transgenic nematodes resulted in lethargic movement, delayed egg laying, and reduced mating efficiency. Induced expression of activated G alpha o in adults was sufficient to cause these phenotypes, indicating that G alpha o mediates behavior through its role in neuronal function and the functioning of specialized muscles.
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