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David W. Brown, David R. Brown, Gregory W. Heath, David G. Moriarty, Lina Balluz and Wayne H. Giles

Background:

Hypertension (HTN), which affects more than 65 million Americans, is associated with poor health-related quality of life (HRQOL). Regular physical activity (PA) has been shown to reduce blood pressure and is associated with higher levels of HRQOL.

Methods:

Using self-reports from 60,321 hypertensive adults age 18 y or older who participated in the 2003 Behavioral Risk Factor Surveillance Survey, we examined the independent relationship between engaging in recommended levels of moderate or vigorous PA and four measures of HRQOL developed by the Centers for Disease Control and Prevention.

Results:

For all age and racial/ethnic groups and both sexes, the proportion of hypertensive adults with 14 or more unhealthy days (physical or mental) in the past month was significantly lower among those who attained recommended levels of PA than among physically inactive adults.

Conclusions:

Participation in regular PA is one of several lifestyle strategies available to control and prevent HTN. These results suggest that PA is associated with higher levels of HRQOL among adults with HTN and highlight the importance of health programs that promote participation in regular PA.

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David Giles, Joel B. Chidley, Nicola Taylor, Ollie Torr, Josh Hadley, Tom Randall and Simon Fryer

Purpose: To determine if the mathematical model used for the estimation of critical force (CF) and the energy store component W′ are applicable to intermittent isometric muscle actions of the finger flexors of rock climbers, using a multisession test. As a secondary aim, the agreement of estimates of CF and W′ from a single-session test was also determined. The CF was defined as the slope coefficient, and W′ was the intercept of the linear relationship between total “isometric work” (W lim) and time to exhaustion (T lim). Methods: Subjects performed 3 (separated by either 20 min or >24 h) tests to failure using intermittent isometric finger-flexor contractions at 45%, 60%, and 80% of their maximum voluntary contraction. Results: Force plotted against T lim displayed a hyperbolic relationship; correlation coefficients of the parameter estimates from the work–time CF model were consistently very high (R 2 > .94). Climbers’ mean CF was 425.7 (82.8) N (41.0% [6.2%] maximum voluntary contraction) and W′ was 30,882 (11,820) N·s. Good agreement was found between the single-session and multisession protocol for CF (intraclass correlation coefficient [ICC3,1] = .900; 95% confidence interval, .616–.979), but not for W′ (ICC3,1 = .768; 95% confidence interval, .190–.949). Conclusions: The results demonstrated the sensitivity of a simple test for the determination of CF and W′, using equipment readily available in most climbing gyms. Although further work is still necessary, the test of CF described is of value for understanding exercise tolerance and to determine optimal training prescription to monitor improvements in the performance of the finger flexors.

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David Giles, Vanesa España Romero, Inmaculada Garrido, Alejandro de la O Puerta, Keeron Stone and Simon Fryer

Purpose:

To examine differences in oxygenation kinetics in the nondominant and dominant flexor digitorum profundus (FDP) of rock climbers.

Methods:

Participants were 28 sport climbers with a range of on-site abilities (6a+ to 8a French Sport). Using near-infrared spectroscopy, oxygenation kinetics of the FDP was assessed by calculating the time to half recovery (t 1/2 recovery) of the tissue-saturation index (TSI) after 3–5 min of ischemia.

Results:

A 2-way mixed-model ANOVA found a nonsignificant interaction (P = .112) for TSI by sex. However, there was a significant main effect (P = .027) of handedness (dominant vs nondominant FDP). The dominant forearm recovered 13.6% faster (t 1/2 recovery mean difference = 1.12 s, 95% CI 0.13–2.10 s) than the nondominant FDP. This was not affected by 6-mo on-site climbing ability or sex (P = .839, P = .683).

Conclusions:

Significant intraindividual differences in oxygenation kinetics of the FDP were found. Improvements in oxygenation kinetics in the FDP are likely due to the abilities of the muscle to deliver, perfuse, and consume oxygen. These enhancements may be due to structural adaptations in the microvasculature, such as an increase in capillary density and enhanced improvement in capillary filtration.

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David Ogilvie, Billie Giles-Corti, Paula Hooper, Lin Yang and Fiona Bull

Modifying the built environment is increasingly recommended as a means of increasing physical activity, but there is currently little evidence from intervention studies to support this approach. From a discussion of 3 natural experiments in this area (RESIDE, iConnect, and Commuting and Health in Cambridge), several common lessons emerged. First, researchers should anticipate delays in the implementation of interventions that are outside their control, and research funders need to exercise a degree of flexibility to accommodate changing research timetables. Second, new built environments develop and evolve over time, and so do their effects on human behavior. Study designs and exposure measures should take account of this, and long term outcomes should be measured wherever possible to allow for potential sleeper, snowball, or threshold effects emerging over time. Third, it may be difficult to identify suitable control areas for a conventional parallel-group intervention–control design, and it may be necessary to draw on other study designs to provide a counterfactual comparison. Fourth, the effort and cost required to recruit, retain and obtain repeated measurements from participants over a period of years should not be underestimated. Finally, comprehensive process evaluation measures may be required to assess the level and quality of interventions.

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Natasha Schranz, Tim Olds, Dylan Cliff, Melanie Davern, Lina Engelen, Billie Giles-Corti, Sjaan Gomersall, Louise Hardy, Kylie Hesketh, Andrew Hills, David Lubans, Doune Macdonald, Rona Macniven, Philip Morgan, Tony Okely, Anne-Maree Parish, Ron Plotnikoff, Trevor Shilton, Leon Straker, Anna Timperio, Stewart Trost, Stewart Vella, Jenny Ziviani and Grant Tomkinson

Background:

Like many other countries, Australia is facing an inactivity epidemic. The purpose of the Australian 2014 Physical Activity Report Card initiative was to assess the behaviors, settings, and sources of influences and strategies and investments associated with the physical activity levels of Australian children and youth.

Methods:

A Research Working Group (RWG) drawn from experts around Australia collaborated to determine key indicators, assess available datasets, and the metrics which should be used to inform grades for each indicator and factors to consider when weighting the data. The RWG then met to evaluate the synthesized data to assign a grade to each indicator.

Results:

Overall Physical Activity Levels were assigned a grade of D-. Other physical activity behaviors were also graded as less than average (D to D-), while Organized Sport and Physical Activity Participation was assigned a grade of B-. The nation performed better for settings and sources of influence and Government Strategies and Investments (A- to a C). Four incompletes were assigned due to a lack of representative quality data.

Conclusions:

Evidence suggests that physical activity levels of Australian children remain very low, despite moderately supportive social, environmental and regulatory environments. There are clear gaps in the research which need to be filled and consistent data collection methods need to be put into place.