Purpose This study investigated the effects of a 10-day heat acclimation (HA) programme on the time course of changes in thermoneutral maximal oxygen uptake ($$\dot{V}$$ V ˙ O2max) during and up to 10 days post-HA. Methods Twenty-two male cyclists were assigned to a HA or control (Con) training group following baseline ramp tests of thermoneutral $$\dot{V}$$ V ˙ O2max. Ten days of fixed-intensity (50% baseline $$\dot{V}$$ V ˙ O2max) indoor cycling was performed in either ~ 38.0 °C (HA) or ~ 20 °C (Con). $$\dot{V}$$ V ˙ O2max was re-tested on HA days 5, 10 and post-HA days 1, 2, 3, 4, 5 and 10. Results $$\dot{V}$$ V ˙ O2max initially declined across time in both groups during training (P < 0.05), before increasing in the post-HA period in both groups (P < 0.05). However, $$\dot{V}$$ V ˙ O2max was higher than control by post-HA day 4 in the HA group (P = 0.046). Conclusions The non-linear time course of $$\dot{V}$$ V ˙ O2max adaptation suggests that post-testing should be performed 96-h post-training to identify the maximal change for most individuals. In preparation for training or testing, athletes can augment their aerobic power in thermoneutral environments by performing 10 days HA, but the full effects will manifest at varying stages of the post-HA period.

This mean TDEE was approximately 25% lower than that reported in a previous study (14.5 vs. 19.3 MJ/day) for a 13-day leg of a fully crewed offshore race. The difference in results was probably due to the fact that in the previous study, the crew operated in "watches" (work shifts), affording each crew member greater opportunity to eat, rest and sleep. Effective planning and efficient management of resources is essential to the success of the solo sailor. However, the extent to which maintenance of energy balance underpins competitive success remains to be established. To maintain energy balance during the race, a mean daily energy intake of 14.5 MJ/day was necessary for the subject in this study. However, this mean value for energy intake would have been inadequate to match the peak energy expended during the most physically demanding 24 hours of the race.

BACKGROUND:The roles of the emergency services are challenging and often physically demanding. Readiness to meet these challenges and demands is a fundamental requirement for staff to deliver their roles safely and effectively. Furthermore, employers are required by law to demonstrate every reasonable effort to protect their staff from undue risk of work-related injury. Implementing Physical Employment Standards (PES) enables employers to assign staff to roles for which they are physically-suited whilst contributing to such duty-of-care. However, for PES to be successful and legally-defendable, standards must reflect the demands of those job-tasks which are truly critical to the readiness of these services.OBJECTIVE:To determine whether a standardised approach to identifying critical job-tasks exists in the development of PES for the emergency services.METHODS:Studies which conducted analysis of job-tasks to develop PES within the emergency services were reviewed.RESULTS:Forty-two reported studies (i.e. records) met the inclusion criteria. Methods to determine job-tasks varied but were typically criteria-based incorporating one, or all, of 9 reported techniques. Methods were subjective and based upon reference to past or present job-task performance.CONCLUSION:Correctly determining critical job-tasks is essential for effective, legally-defendable PES. A standardised method to define job-tasks remains to be established.

Background The ergogenic effects of dietary supplements on endurance exercise performance are well-established; however, their efficacy in hot environmental conditions has not been systematically evaluated. Objectives (1) To meta-analyse studies investigating the effects of selected dietary supplements on endurance performance and core temperature responses in the heat. Supplements were included if they were deemed to: (a) have a strong evidence base for ‘directly’ improving thermoneutral endurance performance, based on current position statements, or (b) have a proposed mechanism of action that related to modifiable factors associated with thermal balance. (2) To conduct meta-regressions to evaluate the moderating effect of selected variables on endurance performance and core temperature responses in the heat following dietary supplementation. Methods A search was performed using various databases in May 2020. After screening, 25 peer-reviewed articles were identified for inclusion, across three separate meta-analyses: (1) exercise performance; (2) end core temperature; (3) submaximal core temperature. The moderating effect of several variables were assessed via sub-analysis and meta-regression. Results Overall, dietary supplementation had a trivial significant positive effect on exercise performance (Hedges’ g = 0.18, 95% CI 0.007–0.352, P = 0.042), a trivial non-significant positive effect on submaximal core temperature (Hedges’ g = 0.18, 95% CI − 0.021 to 0.379, P = 0.080) and a small non-significant positive effect on end core temperature (Hedges’ g = 0.20, 95% CI − 0.041 to 0.439, P = 0.104) in the heat. There was a non-significant effect of individual supplements on exercise performance (P = 0.973) and submaximal core temperature (P = 0.599). However, end core temperature was significantly affected by supplement type (P = 0.003), which was attributable to caffeine’s large significant positive effect (n = 8; Hedges’ g = 0.82, 95% CI 0.433–1.202, P < 0.001) and taurine’s medium significant negative effect (n = 1; Hedges’ g = − 0.96, 95% CI − 1.855 to − 0.069, P = 0.035). Conclusion Supplements such as caffeine and nitrates do not enhance endurance performance in the heat, with caffeine also increasing core temperature responses. Some amino acids might offer the greatest performance benefits in the heat. Exercising in the heat negatively affected the efficacy of many dietary supplements, indicating that further research is needed and current guidelines for performance in hot environments likely require revision.