Análisis del riesgo de ahogamiento asociado al entorno acuático y competencia natatoria / Analysis of the Drowning Risk Associated with Aquatic Environment and Swimming Ability

Un alto nivel de natación puede ser un factor protector ante el ahogamiento, sin embargo, esta relación todavía no ha sido empíricamente demostrada, en base al nivel de habilidad y entorno acuático. Este estudio diseñó una matriz de riesgo de ahogamiento en base al análisis probabilístico de un cuestionario respondido por 3.181 participantes. Se analizó la ocurrencia de Estrés/Distrés acuático (EDA) en base a 5 niveles de competencia y tres entornos acuáticos: a) Piscina sin olas ni corrientes, b) Lagos, embalses, ríos y playas sin olas ni corrientes, c) Ríos, playas o piscinas con olas y/o corrientes. Los resultados se expresaron en Odds Ratio (OR). El riesgo de EDA superó el OR de 25 en el entorno más peligroso y se incrementó para todos los escenarios conforme la competencia acuática era peor. Tres de cada cuatro nadadores han sufrido EDA y este evento pudo ser un incentivo para mejorar sus competencias acuáticas. (AU)

A high level of swimming can be a protective factor against drowning, however, this relationship has not yet been empirically demonstrated, based on water competence level and aquatic environment. This study designed a drowning risk matrix based on the probabilistic analysis of a questionnaire answered by 3,181 participants. The occurrence of Aquatic Stress/Distress (EDA) was analysed based on 5 skill levels and three aquatic scenarios: a) Pool without waves or currents, b) Lakes, reservoirs, rivers and beaches without waves or currents, c) Rivers, beaches or pools with waves and/or currents. The results were expressed in Odds Ratio (OR). EDA risk exceeded OR of 25 in the most dangerous environment and increased for all scenarios as aquatic competency worsened. Three out of four swimmers have suffered from EDA and this event could have been an incentive to improve their water competence. (AU)

Methodological approaches used to assess the relationship between parental supervision and child injury risk.

OBJECTIVE: To describe and rate the quality of methodological approaches used to measure parental supervision in relation to injury risk in children aged 0-14 years. DESIGN: A systematic review of the literature related to supervision and injury risk. METHODS: A comprehensive search of electronic databases from the earliest records available to the end of 2007, and supplemental hand-searching of relevant journals, reference lists of studies identified through database searches, and bibliographies of systematic and non-systematic reviews. A classification scale was used to rate the methodological quality of studies. RESULTS: 30 papers met the inclusion criteria. They varied substantially in quality, and no meta-analyses or randomised controlled trials were identified. Fifteen studies used self-report approaches, asking parents or care givers to report through recording diaries, interviews and questionnaires and were considered of low quality; 11 studies reconstructed injury outcomes retrospectively. Observational studies were conducted in both laboratory and natural settings (n = 6), and these studies were generally of higher quality than self-report methods. CONCLUSIONS: The quality of many supervision and child injury risk studies is low to moderate. Further development of methodological approaches is needed to improve studies of the relationship between supervision and child injury risk.

Treadmill Velocity Best Predicts 5000-m Run Performance.

In this study, we aimed to investigate physiological determinants of endurance performance that best predict 5000-m average run velocity before and after endurance training. Thirty-nine previously untrained participants completed a 5000-m run; a constant velocity test (measuring running economy); and an incremental treadmill test to determine maximal oxygen uptake, final treadmill velocity, and velocity and oxygen uptake at lactate threshold, before and after six weeks of endurance training. Maximal oxygen uptake, final treadmill velocity, and velocity and oxygen uptake at threshold all increased significantly after training (p < 0.05). Average velocity for 5000 m increased significantly (p < 0.05). Running economy was not significantly altered. Correlation analysis revealed final treadmill velocity was most strongly related to 5000-m performance, in both untrained and trained states (r = 0.89, 0.83). Lactate threshold velocity (r = 0.73, 0.76), maximal oxygen uptake (r = 0.55, 0.51) and oxygen uptake at threshold (r = 0.45, 0.45) also showed significant correlations. In contrast, running economy was not significantly related to performance. These results demonstrate that final treadmill velocity in an VO2max test is the single best predictor of 5000-m performance in untrained and trained states. Furthermore, stepwise regression analysis showed that only velocity at lactate threshold significantly improved the accuracy of prediction provided by final treadmill velocity alone.

Long term retention of safe diving skills.

This short report describes a 20-month follow-up of safe diving skills, extending the 8-month retention period previously published in this journal. Thirty-four recreational swimmers with poor diving skills were evaluated before and immediately after a diving skills intervention program. Twenty-two returned for the eight-month follow-up evaluation and 16 returned 20 months post. As with the earlier study, Treadwater, Deck, Block and Running dives were video-recorded, and maximum depth, distance, velocity, entry angle and flight distance were compared. Underwater hand and arm positions were examined. Pre-intervention, a breaststroke arm action before maximum depth occurred in 18% of all dives and 38% of Treadwater dives. This was eliminated post-intervention, improving head protection. The Treadwater dive elicited the greatest mean maximum depth, and ANOVA showed depth for this entry decreased (improved) following intervention and remained shallower at the eight-month and 20-month post follow-ups. The Block dive also became shallower following intervention while the Deck dive remained unchanged. As seven 10-minute skills sessions resulted in shallower dives with safer hand and arm positions, and these skills were retained over a 600 day non-practice period, it is reliable to consider that the inclusion of safe diving skills in learn-to-swim programs can provide a diving spinal cord injury prevention strategy.

Retention of safe diving skills.

This study investigated diving skill maintenance over an eight-month retention period following an intervention program. Thirty-four recreational swimmers with poor diving skills were measured before and immediately after a diving skills intervention program. Twenty-two returned for follow-up evaluation. Treadwater, Deck and Block dives were video-recorded, and maximum depth, distance, velocity, entry angle and flight distance were compared. Underwater hand and arm positions were examined. Pre-intervention, a breaststroke arm action before maximum depth occurred in 18% of all dives and 38% of Treadwater dives. This was eliminated post-intervention, improving head protection. The Treadwater dive elicited the greatest mean maximum depth, and ANOVA showed depth for this entry decreased (improved) following intervention and remained shallower at follow-up. Deck and Block dives also became shallower following intervention. As seven 10-minute skills sessions resulted in shallower dives with safer hand and arm positions, including safe diving skills in learn-to-swim programs can provide a diving spinal cord injury prevention strategy.

Risk reduction in diving spinal cord injury: teaching safe diving skills.

Thirty-four recreational swimmers underwent an intervention program to improve diving skills. Participants with low diving skills completed seven 10-minute sessions which emphasised locking thumbs and holding arms extended beyond the head, and steering and gliding skills. Various dive entries were video-recorded and maximum depth reached was used as the criterion measure. A one-way repeated measures analysis of variance was conducted for each dive condition. Maximum depth decreased for all dives. Velocity at maximum depth was greater for the Treadwater, Deck and Block conditions. Improved streamlining and increased 'spring' were evident in more confident participants. Hands separated in 71% of pre-intervention dives but only in 3% of post-intervention dives. Preintervention, arms were pulled backward before. or at, maximum depth in 30% of participants but none did this post-intervention. Diving skills were improved following participation in the intervention program.

Characteristics of 'low risk' and 'high risk' dives by young adults: risk reduction in spinal cord injury.

STUDY DESIGN: To establish benchmark normative data for dive entries performed by young adults of the age range most likely to sustain a diving spinal cord injury. Data acquired from analysis of the dives performed, along with survey information, were used to determine which factors make the most contribution to the level of risk in diving. OBJECTIVES: To identify influential variables which could contribute to risk of spinal cord injury for each of four types of dives. The types of dives investigated were: dive entries from deck level to tread water (Treadwater); deck level to swim 25 m (Deck); starting block height to swim 25 m (Block); and a running dive entry to swim 25 m (Running). SETTING: Victoria, Australia. METHODS: Ninety-five first year university students (average age 19.9 years) performed three or four dives which were video-recorded for later analysis. Maximum depth reached was used as an indicator of risk, and velocity at maximum depth, distance at maximum depth, angle of entry and flight distance were measured for each dive. Participants also completed a questionnaire designed to elicit information about their swimming and diving background. Unlike previous diving studies, participants were recreational rather than competitive swimmers. They were not aware that the dive was the focal point, assuming that the researchers were investigating their swimming and treadwater ability. RESULTS: A stepwise multiple regression was applied to predict depth for each dive condition, and demonstrated that four variables were able to account for 56% of the variance for Treadwater, 68% for Deck; 73% for Running and 79% for Block. In all conditions involving swimming after the dive (ie Deck, Block and Running), beta weights showed that distance at maximum depth had the greatest influence on the depth of a dive. Flight distance and angle of entry were the next most influential variables. For the Treadwater condition, beta weights showed angle of entry was the most influential variable, followed by velocity at maximum depth, distance at maximum depth and swim rank. CONCLUSION: It is recommended that divers strive to surface in as short a distance as possible by maximising flight distance and aiming for a low entry angle. Implementation of steering-up techniques will assist in minimising dive depth.

Aetiology and occurrence of diving injuries. A review of diving safety.

This paper examines multifaceted aspects of diving entries into water which are the cause of many critical injuries (costed at $A150 million) and therefore have important safety ramifications. Wedge and compression fractures are most commonly found in the cervical area of the spine with off-centre impacts with the pool or sea bottom. Diving-related injuries range from 2.3 in a South African study to 21% of spinal cord injuries in Poland. Alcohol and diving do not mix because of diminished awareness and information processing. Children aged under 13 years suffer fewer cervical injuries (1 to 4%), but complication rates are relatively high for this group. Sports trauma (diving-related in particular) is one of the more prevalent causes of spinal cord injury in children aged 6 to 15 years. The highest incidence occurs among those aged 10 to 14, followed by the group aged 5 to 9 years. This contradicts the common perception that 15-to 19-year-olds comprise the highest risk group. Boys are more frequently injured, and swimming pools are more common as an injury location then is the case with adults. The role played by water depth has been conclusively ascertained; technique, and therefore education, appear to be more important considerations in injury prevention. Although 89% of injuries occur in water < 1.52m, injuries are rare in water of 0.46 to 0.61m. Care with pool design to avoid sudden depth changes and the resultant "spinal wall' is necessary. Minimum depth values for diving vary from 1 to 1.52 m. Velocities and angles of entry are considered to ascertain the body's decelerative capacity upon entry. The scoop, racing start dive has been shown to require at least 1.22 m of water even when practised by trained divers; the risks involved must therefore be weighed against the fact that it may be no faster than more conventional dives. While it may be safe to perform kneeling and crouching dives into shallowers water, standing dives by untrained divers require a greater margin of error. Lack of education is an issue which needs to be addressed and this paper makes recommendations for safety practices such as steering up to the surface, head protection with the arms and only diving when absolutely necessary.

The effect of running training on exercise-induced asthma.

A running training program had no effect upon the severity of exercise-induced asthma, however, it appeared as if the children benefitted not only from a decrease in the frequency and duration of asthma in daily life, but also by improvement in self-confidence and ability to participate in group activities.