Background: Insufficient physical activity (PA) is a risk factor for several noncommunicable chronic diseases. The World Health Organization stresses the need for national PA trend data to help inform strategies to arrest noncommunicable chronic disease incidence. The Active Australia Survey questionnaire quantifies leisure-time physical activity. Despite being used repeatedly in large population surveys, these data have never been analyzed as a single dataset. This study established temporal trends for aerobic PA sufficiency prevalences in the Australian adult (18–75+ y) population, 2002–2012, based on leisure-time physical activity. Methods: Individuals’ records from 58 surveys were merged into a master database (N = 443,211) and categorized according to sufficiency of PA (150 minutes of PA per week). Data were age/sex standardized to the 2011 Australian population. PA sufficiency trends were determined for the whole sample and sociodemographic subgroups. Results:Sufficient PA prevalences 2002–2012 increased from 55.9% (95% CI, 55.893–55.897) to 61.2% (95% CI, 61.223–61.267). No reported PA prevalences decreased from 16.1% (95% CI, 16.095–16.101) to 13.8% (95% CI, 13.745–13.811). This pattern persisted across most sociodemographic subgroups. Disparities between age groups, male/female, metropolitan/rural, and advantaged/disadvantaged categories, although present, were not diverging further. Conclusions: Levels of adult leisure-time physical activity are slowly increasing, but a substantial proportion of the population is still at increased risk of adverse health outcomes due to insufficient PA.
Katherine Reta Devonshire-Gill and Kevin Ian Norton
Darren Burgess, Geraldine Naughton and Kevin Norton
The understanding of the gap between Under 18 y (U18) and senior-level competition and the evolution of this gap in Australian Football lack a strong evidence base. Despite the multimillion dollars invested in recruitment, scientific research on successful transition is limited. No studies have compared individual players’ movement rate, game statistics and ball speed in U18 and senior competition of the Australian Football League across time. This project compared differences in player movement and ball speed between matches from senior AFL competitive matches and U18 players in the 2003 and 2009 seasons.
TrakPerformance Software and Global Positioning System (GPS) technology were used to analyze the movement of players, ball speed and game statistics. ANOVA compared the two levels of competition over time.
Observed interactions for distance traveled per minute of play (P = .009), number of sprints per minute of play (P < .001), time spent at sprint speed in the game (P < .001), time on field (P < .001), and ball speed (P < .001) were found. Subsequent analysis identified increases in movement patterns in senior AFL competition in 2009 compared with the same level of competition in 2003 and U18 players in 2003 and 2009.
Senior AFL players in 2009 were moving further, sprinting relatively more frequently, playing less time and playing at game speeds significantly greater than the same senior competition in 2003 as well as compared with both cohorts of U18 players.
Jim Dollman, Kevin Norton and Graeme Tucker
The aim of this study was to compare urban and rural South Australian primary schoolchildren on measures of anthropometry, fitness, and environmental mediators of physical activity. The sample was comprised of 445 urban and 205 rural boys and 423 urban and 158 rural girls, all age 10–11 yrs at the time of testing. After controlling for socioeconomic status and ethnicity, rural girls and boys were faster over 1.6 k than their urban counterparts while rural girls were also faster over 50 m. Rural residence independently predicted participation in organized activity, increasing involvement in club sport, and decreasing involvement in school sport. Rural children reported a greater likelihood of participating in two or more physical education classes per week. It is evident that urban and rural South Australia differ in ways which impact on fitness and physical activity patterns of upper primary age children.
Milos Mallol, David J. Bentley, Lynda Norton, Kevin Norton, Gaizka Mejuto and Javier Yanci
Purpose: To investigate changes in physiological and performance variables in triathletes following a 4-wk period of reduced training volume and increased training intensity. Methods: Sixteen moderately trained triathletes were randomly allocated to 2 groups: a control (CON) group, which followed their usual training, or a high-intensity interval training (HIIT) group, which completed 2 HIIT sessions per week during 4 wk of reduced training volume Results: Maximal oxygen consumption (VO2max) increased significantly in the HIIT group (P = .03, d = 0.5) but remained unchanged in the CON group. Cycling power at first and second ventilatory thresholds increased significantly in the HIIT subjects (P = .03, d = 1.0) and was unchanged in the CON participants (P = .57). During the simulated triathlon test, pretest–posttest cycling times and average power were unchanged in both groups (P > .05). No significant interactive effects between groups were observed for running time (P = .50). Conclusion: After a 4-wk HIIT program, VO2max and power at first and second ventilatory thresholds were found to have increased significantly while cycling and running performance were unchanged, despite an overall reduction in training time. In the present study, performance was only shown to improve with usual (high-volume) training. Summarizing, in order to improve running or cycling performances, high-volume training programs are highly recommended.
Jim Dollman, Tim Olds, Kevin Norton and David Stuart
There is evidence that fitness has been declining and fatness increasing in Australian schoolchildren over the last generation. This study reproduced the methods of a national survey of Australian schoolchildren conducted in 1985. Anthropometric and performance tests were administered to 1,463 10- and ll-year-old South Australians. Compared to the 1985 sample, the 1997 children were heavier (by 1.4−2.9 kg), showed greater weight for height (by 0.13−0.30 kg · m−2.85), and were slower over 1.6 km (by 38−48.5 s). Furthermore, the distribution of values was markedly more skewed in the 1997 data. While there was little difference between the fittest and leanest quartiles in 1997 and their 1985 counterparts, the least fit and fattest quartiles were markedly worse in 1997. This suggests that the decline in fitness of Australian schoolchildren is not homogeneous and that interventions should target groups where the decline is most marked.
Samuel Chalmers, Adrian Esterman, Roger Eston and Kevin Norton
Athletes often seek the minimum required time that might elicit a physiological or performance change. It is reasonable to suggest that heat training may improve aerobic-based performance in mild conditions. Therefore, rather than providing a traditional heat-exposure stimulus (ie, 7–10 × 60–100 min sessions), the current article details 2 studies that aimed to determine the effect of brief (≤240 min exposure) heat training on the second lactate threshold (LT2) in mild conditions.
Forty-one participants completed 5 (study 1, n = 18) or 4 (study 2, n = 23) perceptually regulated treadmill exercise training sessions in 35°C and 30% relative humidity (RH) (experimental group) or 19°C and 30% RH (control group). Preincremental and postincremental exercise testing occurred in mild conditions (19°C and 30% RH). Linear mixed-effects models analyzed the change in LT2.
Heat training did not substantially change LT2 in either study 1 (+1.2%, d = 0.38, P = .248) or study 2 (+1.9%, d = 0.42, P = .163). LT2 was not substantially changed in the control group in study 1 (+1.3%, d = 0.43, P = .193), but a within-group change was evident in study 2 (+2.3%, d = 1.04, P = .001).
Brief heat training was inadequate to improve the speed at LT2 in mild conditions more than comparable training in mild conditions. The brief nature of the heattraining protocol did not allow adaptations to develop to the extent required to potentially confer a performance advantage in an environment that is less thermally stressful than the training conditions.
Samuel Chalmers, Adrian Esterman, Roger Eston and Kevin Norton
The purpose of this study was to test the reliability and validity of 2 standardized methods for calculating speed at the second lactate-threshold point (LT2) based on the preexisting Dmax (LTD) and modified Dmax (LTMOD) procedures.
13 trained male road runners and triathletes completed 2 incremental laboratory running tests to determine LT2, followed by separate time trials (5, 10, 15 km) on an outdoor running track. Two new methods were proposed for calculating the speed at LT2: (1) the single standardized lactate threshold (LTSDs) and (2) the paired standardized lactate threshold (LTSDp) for quantifying changes over time.
The LTSDs and LTSDp methods had high relative (ICC ≥ .98) and absolute (CV ≤ 1.9%) reliability in identifying the speed at LT2. The speed at LT2 according to the LTSDs and LTSDp methods had a strong correlation and was not different to the performance speed during the 10- and 15-km time trials (≤2.3%; ρc > 0.8; P > .05). The following natural logbased formula was created to estimate the percentage of LT2 speed (using the LTSDs method) that could be sustained for events ~15–75 min: y = –7.256(ln x) + 157.64, where y = %LT2 speed, x = time-trial performance (s), and ln = natural log.
The standardized methods are reliable for determining LT2. The LTSDs and LTSDp methods for calculating the speed at LT2 from a near-maximal incremental test calculated speeds similar to those exhibited in 10- and 15-km running time trials. A prediction equation for estimating the percentage of LT2 that can be sustained for events of ~15–75 min was generated.
Jason C. Bartram, Dominic Thewlis, David T. Martin and Kevin I. Norton
Purpose: With knowledge of an individual’s critical power and W′, the SKIBA 2 model provides a framework with which to track W′ balance during intermittent high-intensity work bouts. There are fears that the time constant controlling the recovery rate of W′ (τ W′) may require refinement to enable effective use in an elite population. Methods: Four elite endurance cyclists completed an array of intermittent exercise protocols to volitional exhaustion. Each protocol lasted approximately 3.5–6 min and featured a range of recovery intensities, set in relation to the athlete’s critical power (D CP). Using the framework of the SKIBA 2 model, the τ W′ values were modified for each protocol to achieve an accurate W′ at volitional exhaustion. Modified τ W′ values were compared with equivalent SKIBA 2 τ W′ values to assess the difference in recovery rates for this population. Plotting modified τ W′ values against D CP showed the adjusted relationship between work rate and recovery rate. Results: Comparing modified τ W′ values against the SKIBA 2 τ W′ values showed a negative bias of 112 (46) s (mean ± 95% confidence limits), suggesting that athletes recovered W′ faster than predicted by SKIBA 2 (P = .0001). The modified τ W′–D CP relationship was best described by a power function: τ W′ = 2287.2 × D CP –0.688 (R 2 = .433). Conclusions: The current SKIBA 2 model is not appropriate for use in elite cyclists, as it underpredicts the recovery rate of W′. The modified τ W′ equation presented will require validation but appears more appropriate for high-performance athletes. Individual τ W′ relationships may be necessary to maximize the model’s validity.
Jason C. Bartram, Dominic Thewlis, David T. Martin and Kevin I. Norton
New applications of the critical-power concept, such as the modeling of intermittent-work capabilities, are exciting prospects for elite cycling. However, accurate calculation of the required parameters is traditionally time invasive and somewhat impractical. An alternative single-test protocol (3-min all-out) has recently been proposed, but validation in an elite population is lacking. The traditional approach for parameter establishment, but with fewer tests, could also prove an acceptable compromise.
Six senior Australian endurance track-cycling representatives completed 6 efforts to exhaustion on 2 separate days over a 3-wk period. These included 1-, 4-, 6-, 8-, and 10-min self-paced efforts, plus the 3-min all-out protocol. Traditional work-vs-time calculations of CP and anaerobic energy contribution (W′) using the 5 self-paced efforts were compared with calculations from the 3-min all-out protocol. The impact of using just 2 or 3 self-paced efforts for traditional CP and W′ estimation was also explored using thresholds of agreement (8 W, 2.0 kJ, respectively).
CP estimated from the 3-min all-out approach was significantly higher than from the traditional approach (402 ± 33, 351 ± 27 W, P < .001), while W′ was lower (15.5 ± 3.0, 24.3 ± 4.0 kJ, P = .02). Five different combinations of 2 or 3 self-paced efforts led to CP estimates within the threshold of agreement, with only 1 combination deemed accurate for W′.
In elite cyclists the 3-min all-out approach is not suitable to estimate CP when compared with the traditional method. However, reducing the number of tests used in the traditional method lessens testing burden while maintaining appropriate parameter accuracy.
Joel M. Garrett, Stuart R. Graham, Roger G. Eston, Darren J. Burgess, Lachlan J. Garrett, John Jakeman and Kevin Norton
Purpose: To determine the typical variation of variables from a countermovement jump (CMJ) test and a submaximal run test (SRT), along with comparing the sensitivity of each test for the detection of practically important changes within high-performance Australian rules football players. Methods: A total of 23 professional and semiprofessional Australian rules football players performed 6 CMJs and three 8-second 50-m runs every 30 seconds (SRT), 7 days apart. Absolute and trial-to-trial reliability was represented as a coefficient of variation, CV (±90% confidence intervals). Test–retest reliability was examined using the magnitude of the difference (effect size [±90% confidence interval]) from week 1 to week 2. The smallest worthwhile change was calculated as 0.25 × SD. Results: Good reliability (CVs = 6.6%–9.3%) was determined for all variables except eccentric displacement (CV = 12.8%), with no clear changes observed in any variables between week 1 and week 2. All variables from the SRT possessed a CV less than smallest worthwhile change, indicating an ability to detect practically important changes in performance. Only peak velocity from the CMJ test possessed a CV less than smallest worthwhile change, exhibiting a limitation of this test in detecting practically meaningful changes within this environment. Conclusions: The results suggest that while all variables possess acceptable reliability, a SRT might offer to be a more sensitive monitoring tool than a CMJ test within high-performance Australian rules football, due to its greater ability for detecting practically important changes in performance.