The effects of morning preconditioning protocols on testosterone, cortisol and afternoon sprint cycling performance [conference presentation]

Opportunities exist for athletes to undertake morning exercise protocols in an attempt to potentate afternoon performance. Four sub elite track sprint cyclists completed a morning cycling (Cyc) or weights-based protocol (WP) prior to an afternoon cycling time trial (500m) in a repeated measures, counterbalance crossover design. Measured variables included heart rate, blood lactate, cycling peak power, salivary testosterone (T) and cortisol levels along with time trial performance. Standardised differences in means via magnitude-based inferences were calculated using paired samples T-tests in SPSS version 24 with statistical significance set at p < 0.05. The WP produced significantly faster times in the final 250m in comparison to CycP. The anticipated circadian decline of T was observed after the CycP but was however mitigated following the WP. While slight decreases in 500m times were experienced during the WP, they were not significant and were considered within the normal variations experienced between performances by elite athletes. The effect of the WP on the circadian rhythm of T could be linked to a greater recruitment of muscle fibres. Results suggest a morning resistance protocol can positively affect testosterone levels for afternoon performance. Possible gender and individual responses from conducting a W over Cyc protocol were observed and require further investigation

GPS analysis of a team competing at a national Under 18 field hockey tournament

The purpose of this study was to utilise global-positioning system (GPS) technology to quantify the running demands of national Under 18 field hockey players competing in a regional field hockey tournament. Ten male players (mean ± SD; age 17.2 ± 0.4 years; stature 178.1 ± 5.2 cm; body mass 78.8 ± 8.8 kg) wore GPS units while competing in six matches over seven days at the 2018 New Zealand national under 18 field hockey tournament. GPS enabled the measurement of total distance (TD), low-speed activity (LSA; 0 -14.9 km/hr), and high-speed running (HSR; ≥ 15 km/hr) distances. Differences in running demands (TD, LSA, HSR) between positions were assessed using effect size and percent difference ± 90% confidence intervals. Midfielders covered the most TD and LSA per game and strikers the most HSR during the 6 matches. There were “very large” differences between strikers and midfielders for TD and LSA, strikers and defenders for LSA and HSR, and defenders and midfielders for LSA. These results suggest that these playing positions are sufficiently different to warrant specialised position-specific conditioning training leading into a field hockey tournament

Human athletic paleobiology; using sport as a model to investigate human evolutionary adaptation

The use of sport as a conceptual framework offers unprecedented opportunities to improve our understanding of what the body does, shedding new light on our evolutionary trajectory, our capacity for adaptation, and the underlying biological mechanisms. This approach has gained traction over recent years. To date, sport has facilitated exploration not only of the evolutionary history of our species as a whole, but also of human variation and adaptation at the interindividual and intraindividual levels. At the species level, analysis of lower and upper limb biomechanics and energetics with respect to walking, running and throwing have led to significant advances in the understanding of human adaptations relative to other hominins. From an interindividual perspective, investigation of physical activity patterns and endurance running performance is affording greater understanding of evolved constraints of energy expenditure, thermoregulatory energetics, signaling theory, and morphological variation. Furthermore, ultra-endurance challenges provoke functional trade-offs, allowing new ground to be broken in the study of life history trade-offs and human adaptability. Human athletic paleobiology-the recruitment of athletes as study participants and the use of contemporary sports as a model for studying evolutionary theory-has great potential. Here, we draw from examples in the literature to provide a review of how the use of athletes as a model system is enhancing understanding of human evolutionary adaptation

The Intrusiveness of Sensor-Suit Components on the Postures Associated with Performing Repeated Whole-Body Manual Lifting Tasks

Ergonomics can be defined as the responsibility to ensure that the demands of a job do not exceed the capabilities of a worker (Garg, Chaffin, and Herrin, 1978). Evaluating physiological demands on workers, particularly individuals performing highly varied tasks or monitoring their work in the field, can be a complex problem. Using on-person sensors to record kinematic and physiological measurements throughout extended is one proposed method by which to collect data necessary to evaluate the demands placed on the workers. In order to assess the efficacy of the data that would be collected, it is critical to evaluate the intrusive effects of the on-person sensors on the manner in which the work is performed. For the purpose of this study, various outfit ensembles, consisting of combinations of Clo, Mass, and Banding, were analyzed in order to determine whether or not they affect the posture while individuals perform a repetitive lifting task. Thirty-two paid volunteers participated in this study. Each subject was randomly assigned one of eight experimental ensembles. VICON MX-13 near-infrared cameras were used to capture whole-body kinematics. Subjects were asked to perform a cyclic work protocol that consisted of six twenty-minute cycles, including five-minutes each of 30 ground-to-waist lifts and lowers, 30 standing arm lifts and lowers, continuous walking on a treadmill, and a rest period. A 23 factorial, between-subjects design was used, producing 8 experimental ensemble conditions for combinations of Clo, Mass, and Banding. Statistical analyses were performed with a stepwise regression and general linear model (GLM). The bilateral angles for the hips, knees, and ankles were the dependent variables; independent variables were Banding, Clo, Mass, Part, Phase, and Cycle. From the stepwise regression (alpha=0.10 to remove), Part and Phase were removed from the model. From the GLM, the adjusted R2 values indicated that a good fit existed between the variables in the model. ANOVA results indicated that the main effects and all interactions effects of the ensemble conditions were significant, but the significance varied across lower body joints. Results indicate that Banding and Clo have significant effects on posture, but their effects are less than the nominally fatiguing aspect of the tasks performed. As expected, adding mass to the subjects caused significant changes to their posture over time, suggesting elevated levels of fatigue. Future studies should include other populations, fitness and experience constraints, and tasks with a lower physiological burden