Inherent work suit buoyancy distribution:effects on lifejacket self-righting performance

Introduction: Accidental immersion in cold water is an occupational risk. Work suits and life jackets (LJ) should work effectively in combination to keep the airway clear of the water (freeboard) and enable self-righting. We hypothesized that inherent buoyancy, in the suit or LJ, would be beneficial for enabling freeboard, but its distribution may influence LJ self-righting. Methods: Six participants consented to complete nine immersions. Suits and LJ tested were: flotation suit (FLOAT; 85 N inherent buoyancy); oilskins 1 (OS-1) and 2 (OS-2), both with no inherent buoyancy; LJs (inherent buoyancy/buoyancy after inflation/total buoyancy), LJ-1 50/150/200 N, LJ-2 0/290/290 N, LJ-3 80/190/270 N. Once dressed, the subject entered an immersion pool where uninflated freeboard, self-righting performance, and inflated freeboard were measured. Data were compared using Friedman’s test to the 0.05 alpha level. Results: All suits and LJs enabled uninflated and inflated freeboard, but differences were seen between the suits and LJs. Self-righting was achieved on 43 of 54 occasions, irrespective of suit or LJ. On all occasions that self-righting was not achieved, this occurred in an LJ that included inherent buoyancy (11/54 occasions). Of these 11 failures, 8 occurred (73% of occasions) when the FLOAT suit was being worn. Discussion: LJs that included inherent buoyancy, that are certified as effective on their own, worked less effectively from the perspective of self-righting in combination with a work suit that also included inherent buoyancy. Equipment that is approved for use in the workplace should be tested in combination to ensure adequate performance in an emergency scenario

Moving in extreme environments:what’s extreme and who decides?

Humans work, rest and play in immensely varied extreme environments. The term ‘extreme’ typically refers to insufficiency or excess of one or more stressors, such as thermal energy or gravity. Individuals’ behavioural and physiological capacity to endure and enjoy such environments varies immensely. Adverse effects of acute exposure to these environments are readily identifiable (e.g. heat stroke or bone fracture), whereas adverse effects of chronic exposure (e.g. stress fractures or osteoporosis) may be as important but much less discernable. Modern societies have increasingly sought to protect people from such stressors and, in that way, minimise their adverse effects. Regulations are thus established, and advice is provided on what is ‘acceptable’ exposure. Examples include work/rest cycles in the heat, hydration regimes, rates of ascent to and duration of stay at altitude and diving depth. While usually valuable and well intentioned, it is important to realise the breadth and importance of limitations associated with such guidelines. Regulations and advisories leave less room for self-determination, learning and perhaps adaptation. Regulations based on stress (e.g. work/rest cycles relative to WBGT) are more practical but less direct than those based on strain (e.g. core temperature), but even the latter can be substantively limited (e.g. by lack of criterion validation and allowance for behavioural regulation in the research on which they are based). Extreme Physiology & Medicine is publishing a series of reviews aimed at critically examining the issues involved with self- versus regulation-controlled human movement acutely and chronically in extreme environments. These papers, arising from a research symposium in 2013, are about the impact of people engaging in such environments and the effect of rules and guidelines on their safety, enjoyment, autonomy and productivity. The reviews will cover occupational heat stress, sporting heat stress, hydration, diving, extreme loading, chronic unloading and high altitude. Ramifications include factors such as health and safety, productivity, enjoyment and autonomy, acute and chronic protection and optimising adaptation

Adaptation of the Cold Shock Response and Cooling Rates on Swimming Following Repeated Cold Water Immersions in a Group of Children Aged 10 – 12 years

Habituation of the cold shock response, and adaptation in deep body cooling with prolonged cold water immersion is well documented in adults. This study aimed to determine whether children exhibit similar responses. Eight children aged 10-11 years underwent a 5 min static immersion in 15°C (59°F) water, five then swam for up to 40 minutes, before and after a year of regular cold water swim training. Following acclimatization, no differences were found in heart rates or respiratory frequencies on initial immersion, despite a smaller relative VO2. Children reported feeling warmer (p \u3c .01) and more comfortable (p \u3c .05), implying acclimatization of subjective perception of cold. No difference was found in cooling rates while swimming. On comparison with data of adults swimming in 12°C (36°F) water, no difference was found in cooling rates, but the trend in both acclimatized groups to a slower rate of cooling was significant (p \u3c .026) when the data were pooled. These data may support a theory of insulative adaptation

The Physiological Response on Immersion in Cold Water and the Cooling Rates on Swimming in a Group of children Aged 10 – 11 years

Swimming is a popular sport in the United Kingdom (UK); however, cold water immersion often found in open waters in the UK is not without increased risk. Drowning is among the leading cause of accidental death in 1-14 year-olds in most countries. We examined whether children and adults exhibit similar cold shock responses; their rate of cooling while swimming; and subjective recognition of cooling. Nineteen children aged 10-11 years voluntarily undertook a 5 min static immersion in 15 °C (59 °F) water. Ten of them then completed a swim of up to 40 min. Resting heart rate, respiratory frequency and inspiratory volume increased in all participants on initial immersion. The mean (+SD) cooling rate while swimming was 2.5 °C hr1 (+3.1)). No significant correlation was found between cooling rate and thermal sensation or comfort, implying a lack of subjective awareness in children. On comparing data from unacclimatized adults in 12°C (53.6 °F) water, children showed a smaller ‘cold shock’ response (p \u3c .05), and no difference was found in cooling rates during swimming