Changes in Intragastric Temperature Reflect Changes in Heat Stress Following Tepid Fluid Ingestion But Not Ice Slurry Ingestion

This study examined the effects of fluid and ice slurry ingestion on the relationship between intragastric temperature and rectal temperature in humans during physical activity. The purpose was to identify a technique to quantify changes in heat stress in situations when temperature probes are not feasible and when time constraints do not allow for a period long enough for an indigestible temperature capsule to reach the lower gastrointestinal tract. Eight moderately trained male runners inserted a rectal probe and ingested a telemetric capsule before randomized, crossover, pre-exercise ingestion of 7.5 mL x kg-1 x BM-1tepid fluid (22°C) or ice slurry (-1°C). Beverage ingestion was followed by a self-paced endurance running time trial. Average intragastric temperature was significantly lower than average rectal temperature across the run following both fluid (37.9 +/- 0.4°C vs. 38.4 +/- 0.2°C; p=0.003) and ice slurry ingestion (37.2 +/- 0.9 vs. 38.3 +/- 0.2; p=0.009). However, a strong relationship was observed between measurements following fluid (r=0.89) but not ice slurry (r=0.18). The average bias +/- limits of agreement during the run was 0.46 +/- 0.50 following fluid and 1.09 +/- 1.68 following ice slurry ingestion, which improved to 0.06 +/- 0.76 and 0.65 +/- 1.42, respectively when analyzed as delta scores. Intragastric temperature appears to not be a valid measure of absolute core body temperature at baseline or during exercise following either fluid or ice slurry ingestion. However, the relative changes in intragastric temperature during endurance exercise appears to be a strong indicator of systemic heat stress during exercise following ingestion of fluid at 22°C, but not ice slurry at -1°C

Development of the Basketball Exercise Simulation Test: A match-specific basketball fitness test

The aim of this study was to develop a reliable and valid field test that simulates the match-specific activity demands of male basketball competition. Fourteen male basketball players (mean ± SD, age: 24.9 ± 2.3 yr; stature: 187.8 ± 7.7 cm; body mass: 88.8 ± 10.5 kg) from state- (n = 6) and regional-level (n = 8) Australian competitions volunteered to participate. The Basketball Exercise Simulation Test (BEST) was developed using notational data describing the current activity demands of male basketball competition. Participants completed a repeat-sprint protocol, Yo-Yo Intermittent Recovery Test (Yo-Yo IRT) and 12-min BEST trial. Nine participants completed a further BEST trial at least 7 days later. Measures taken across the BEST included mean sprint and circuit time (s), sprint and circuit decrement (%) and total distance covered (m). Test-retest reliability was determined by calculating the intra-class correlation coefficient (ICC), typical error of measurement, coefficient of variation (CV) and 95% confidence intervals (CI) across the two BEST trials. Criterion validity was calculated using Pearson Correlation analysis between each BEST measure and performance in the repeat-sprint protocol and Yo-Yo IRT. Mean sprint and circuit time and sprint and circuit decrement possessed high ICCs (0.92-0.99), while all measures except sprint (14.6%) and circuit decrement (16.8%) exhibited low CVs (<5%). Significant (p < 0.01) relationships were reported between mean sprint time, sprint decrement, mean circuit time and circuit decrement during the BEST and repeat-sprint performance (r = 0.80-0.92), as well as Yo-Yo IRT distance (r = -0.71-0.85). The present results suggest that the BEST is a reliable and valid match-specific test for the combined assessment of basketball-related anaerobic and aerobic fitness

Peak match acceleration demands differentiate between elite youth and professional football players

Youth footballers need to be developed to meet the technical, tactical, and physical demands of professional level competition, ensuring that the transition between competition levels is successful. To quantify the physical demands, peak match intensities have been measured across football competition tiers, with team formations and tactical approaches shown to influence these physical demands. To date, no research has directly compared the physical demands of elite youth and professional footballers from a single club utilising common formations and tactical approaches. The current study quantified the total match and peak match running demands of youth and professional footballers from a single Australian A-League club. GPS data were collected across a single season from both a professional (n = 19; total observations = 199; mean ± SD; 26.7 ± 4.0 years) and elite youth (n = 21; total observations = 59; 17.9 ± 1.3 years) team. Total match demands and peak match running demands (1–10 min) were quantified for measures of total distance, high-speed distance [>19.8 km-h-1] and average acceleration. Linear mixed models and effect sizes identified differences between competition levels. No differences existed between competition levels for any total match physical performance metric. Peak total and high-speed distances demands were similar between competitions for all moving average durations. Interestingly, peak average acceleration demands were lower (SMD = 0.63–0.69) in the youth players across all moving average durations. The data suggest that the development of acceleration and repeat effort capacities is crucial in youth players for them to transition into professional competition

Foreign Capital Inflow, Skilled-Unskilled Wage Inequality and Unemployment of Unskilled Labour in a Fair Wage Model

This paper has developed a three-sector general equilibrium framework that explains unemployment of both skilled and unskilled labour. Unemployment of unskilled labour is of the Harris-Todaro (1970) type while unemployment of skilled labour is caused due to the validity of the FWH in the high-skill sector. There are two types of capital one of which is specific to the primary export sector while the other moves freely among the different sectors. Inflows of foreign capital of either type unambiguously improve the economic conditions of the unskilled working class. However, the effects on the skilled-unskilled wage inequality and the extent of unemployment of both types of labour crucially hinge on the properties implied by the efficiency function of the skilled workers

Feasibility of a school-based physical activity intervention for adolescents with disability

Background: Adolescents with disability are less active and have lower levels of physical fitness than their typically developing peers. Schools are ideal settings to address this; however, few school-based interventions have been designed and evaluated among this group. Therefore, the aim of this pilot study was to determine the feasibility of a time-efficient school-based physical activity intervention for adolescents with disability. Methods: A non-randomized pilot trial was conducted with adolescents in the special education unit at one secondary school in New South Wales, Australia. Sixteen grade 11 and 12 students (aged 17.3 ± 0.7 years) participated in the 2-month physical activity intervention. Two classroom teachers were trained to facilitate the delivery of a high-intensity interval training (HIIT) program, known as Burn 2 Learn adapted (B2La). Teachers were asked to deliver 2–3 weekly HIIT sessions for a period of 2 months. Four domains of feasibility (acceptability, implementation, adaptability, and practicality) were assessed using quantitative measures at the student and teacher levels (e.g., observations, process evaluation questionnaires, and heart rate [HR] monitoring). Data were also collected from three learning and support teachers who assisted classroom teachers with intervention delivery. Preliminary efficacy of the intervention on measures of adolescents’ functional capacity (6-min walk/run test) and muscular fitness (sit-to-stand test and modified push-up test) were analyzed using paired sample t-tests. Results: Moderate-to-high levels of program satisfaction were reported by both students (80% rated “Good” or “Excellent”) and teachers (100% rated “Good” or “Excellent”). Teachers reported delivering 2.5 ± 0.7 sessions per week during the study. Based on researcher session observations, the program was delivered effectively by teachers (14/20). However, HR data indicated session intensity was lower than intended. The program was considered “adaptable” by teachers, with several observed modifications to HIIT sessions to cater for the needs of adolescents with disability. No adverse events were reported. We observed improvements in preliminary efficacy measures. Conclusions: Our findings suggest it is feasible to train teachers to deliver a school-based HIIT program for adolescents with disability. Evaluation of B2La within a larger-scale effectiveness trial is warranted

Cooling during exercise: an overlooked strategy for enhancing endurance performance in the heat

It is well established that endurance performance is negatively affected by environmental heat stress due to a complex interaction of physical, physiological and psychological alterations. Numerous scientific investigations have attempted to improve performance in the heat with pre-cooling (cooling prior to an exercise test), and as such this has become a well-established ergogenic practice for endurance athletes. However, the use of mid-cooling (cooling during an exercise test) has received considerably less research attention in comparison, despite recent evidence to suggest that the advantage gained from mid-cooling may outweigh that of pre-cooling. A range of mid-cooling strategies are beneficial for endurance performance in the heat, including the ingestion of cold fluids and ice slurry, both with and without menthol, as well as cooling of the neck and face region via a cooling collar or water poured on the head and face. The combination of pre-cooling and mid-cooling has also been effective, but few comparisons exist between the timing and type of such interventions. Therefore, athletes should experiment with a range of suitable mid-cooling strategies for their event during mock competition scenarios, with the aim to determine their individual tolerable limits and performance benefits. Based on current evidence, the effect of mid-cooling on core temperature appears largely irrelevant to any subsequent performance improvements, while cardiovascular, skin temperature, central nervous system function and psychophysiological factors are likely involved. Research is lacking on elite athletes, and as such it is currently unclear how this population may benefit from mid-cooling

Factors relating to the decision-making performance of Australian football officials

Team sport officials are charged with the responsibility to enforce the laws of the game and their performance is based upon the quality of their decisions during a match. The current investigation examined the effects of positioning and retrospective physical demands had on the decision- making accuracy of Australian football officials. Match decision-making statistics and time motion data from 20 elite Australian football matches and the factors related to improved decision-making during match play were examined. Most decisions were made from a distance between 11-15 m, however distance from play had no significant effect on accuracy. There was no significant effect of movement velocity at the time of a decision on accuracy. There was a significant (P<0.05) difference between correct and incorrect decisions in the running speed across the 5 s prior to the decision being made. These findings determine that there is no effect of distance from play or instantaneous velocity on decision-making accuracy during match play. However, higher relative running speeds prior to a decision increases the likelihood of a decisional error. Superior anticipatory skill may reduce the running demands immediately prior to a decision, and therefore possibly improve the decision-making accuracy of umpires

Time-motion analysis of a 2-hour surfing training session

Purpose : To provide a descriptive and quantitative time–motion analysis of surfing training with the use of global positioning system (GPS) and heart-rate (HR) technology. Methods : Fifteen male surfing athletes (22.1 ± 3.9 y, 175.4 ± 6.4 cm, 72.5 ± 7.7 kg) performed a 2-h surfing training session, wearing both a GPS unit and an HR monitor. An individual digital video recording was taken of the entire surfing duration. Repeated-measures ANOVAs were used to determine any effects of time on the physical and physiological measures. Results : Participants covered 6293.2 ± 1826.1 m during the 2-h surfing training session and recorded measures of average speed, HR average , and HR peak as 52.4 ± 15.2 m/min, 128 ± 13 beats/min, and 171 ± 12 beats/ min, respectively. Furthermore, the relative mean times spent performing paddling, sprint paddling to catch waves, stationary, wave riding, and recovery of the surfboard were 42.6% ± 9.9%, 4.1% ± 1.2%, 52.8% ± 12.4%, 2.5% ± 1.9%, and 2.1% ± 1.7%, respectively. Conclusion : The results demonstrate that a 2-h surfing training session is performed at a lower intensity than competitive heats. This is likely due to the onset of fatigue and a pacing strategy used by participants. Furthermore, surfing training sessions do not appear to appropriately condition surfers for competitive events. As a result, coaches working with surfing athletes should consider altering training sessions to incorporate repeated-effort sprint paddling to more effectively physically prepare surfers for competitive events

Utility of global positioning system to measure active transport in urban areas

Purpose: The purpose of this study was to determine test–retest reliability of Global Positioning System (GPS) units for measuring distance traveled when walking and cycling (AT), and to determine whether GPS unit placement influences accuracy. Methods: Participants (N = 19) completed two walking and cycling trials at self-selected speeds on a measured 1489-m course wearing two Garmin GPS units, worn in lanyard and waistband placements. GPS estimates of travel distance were compared with actual distance, and test–retest reliability was examined. Data-cleaning protocols were developed to remove signal noise. Results are presented for both raw and cleaned data. Results: For both raw and cleaned data, no significant differences were observed between trials (trial 1 vs trial 2), unit placement (lanyard vs waistband), or AT mode (walk vscycle) (P Q 0.05). Both lanyard and waistband units significantly overestimated distance traveled during walking trials (P e 0.05), but not cycling trials (P Q 0.05). The relative technical error of measurement (TEM) of the raw data ranged from 3.74 to 15.51%, and average absolute errors ranged from 5.03 to 8.53% for all trials. A significant position by AT mode interaction was observed for clean data (P G 0.05). Relative TEM for the clean data ranged from 1.42 to 1.98%, and average absolute errors ranged from 0.32 to 1.97%. Intraclass correlations (ICC) were poor to fair for all trials using raw and cleaned data. Conclusion: Signal noise during unitinitialization may adversely affect unit performance; however, application of data-cleaning procedures to remove data associated with signal noise improves unit ability to measure distance. Results suggest that the lanyard position is the optimal placement for units during data collection