Evaluation of the Helicopter Emergency Breathing Apparatus on Egress Performance

BACKGROUND: Emergency helicopter landing at sea is dangerous. Specialized training, known as helicopter underwater escape training (HUET), prepares occupants to quickly exit the helicopter, which often inverts and sinks. In most jurisdictions, helicopter occupants are equipped with a helicopter underwater egress breathing apparatus (HUEBA) to provide sufficient air for escape. HUET trainees report that the HUEBA is easy to use, but it is well known that learners are often overconfident in their judgement of learning. To better understand how the HUEBA affects HUET sequence performance, we investigated whether using the HUEBA influences the sequence movement time and number of errors.METHODS: Twelve participants (7 men and 5 women, mean age 25.33 9.57 SD) with no prior experience with HUET performed consecutive trials of the HUET sequence, 5 with the HUEBA and 5 without the HUEBA. Video of each trial recorded the total movement time and enabled movement time analyses of each component of the sequence: crossing arms, tucking the head, pushing the window, inserting the regulator, and releasing the seatbelt. These recordings were also used to score performance errors according to a checklist.RESULTS: Analyses revealed that using a HUEBA increased the total movement time and time to release the seatbelt by 0.36 and 0.39 s, respectively, in comparison to without the HUEBA.DISCUSSION: Our study illustrates that using the HUEBA during the HUET sequence increases total movement time and time to release the seatbelt. However, this difference is marginal and unlikely to have practical significance during underwater escape.King M, Sanli E, Mugford K, Martina S, Brown R, Carnahan H. Evaluation of the helicopter emergency breathing apparatus on egress performance. Aerosp Med Hum Perform. 2020; 91(12):962965.

Countermovement-Jump-Phase Characteristics of Senior and Academy Rugby League Players

Purpose:Gross measures of countermovement-jump (CMJ) performance are commonly used to track maturational changes in neuromuscular function in rugby league (RL). The purpose of this study was to conduct both a gross and a more detailed temporal-phase analysis of the CMJ performances of senior and academy RL players, to provide greater insight into how neuromuscular function differs between these groups.Methods:Twenty senior and 14 academy (under-19) male RL players performed 3 maximal-effort CMJs on a force platform, with forward dynamics subsequently employed to allow gross performance measures and entire kinetic– and kinematic–time curves to be compared between groups.Results:Jump height (JH), reactive strength index modified, concentric displacement, and relative concentric impulse (C-IMP) were the only gross measures that were greater for senior players (d = 0.58–0.91) than for academy players. The relative force- and displacement–time curves were similar between groups, but the relative power– and velocity–time curves were greater (d = 0.59–0.97) for the senior players at 94–96% and 89–100% of the total movement time, respectively.Conclusions:The CMJ distinguished between senior and academy RL players, with seniors demonstrating greater JH through applying a larger C-IMP and thus achieving greater velocity throughout the majority of the concentric phase and at takeoff. Therefore, academy RL players should train to improve triple (ie, ankle, knee, and hip) extension velocity during the CMJ to bring their JH scores in line with those attained by senior players.

Investigating the Difficulty of One Degree of Freedom Positioning: Associating Movement Phases with Regions

Positioning an object within specified bounds is a common daily computer task, for example making selections using a touch screen or positioning icons relative to each other. This experiment measured times for participants ( n = 145) to position rectangular cursors with various widths, p, within rectangular targets with various tolerances, t, in one dimension. The analysis divides the total movement time into three parts, the time for the cursor to touch the target, the time to enter the target after touching, and the centering time, the remaining time for participants to indicate that the cursor is completely within the target by clicking on the mouse button. The time to touch the target was modeled well by the initial cursor-target separation, r2/sup> = 0.95. The entering time was modeled well by log2( p/t + 1), r2/sup> = 0.99, and the centering time was modeled well by r2/sup> = 0.94

Control of sequential movements: evidence for generalized motor programs

The neuromotor processes underlying the control of rapid sequential limb movements were investigated. Subjects learned to pronate and supinate their forearms rapidly to four target locations in a specific spatio-temporal pattern under two movement-time conditions. The response sequence was first performed in a total movement time of 600 ms. Subjects were then told to produce the movement as quickly as possible while ignoring any timing pattern that they had previously learned. Electromyographic (EMG) signals were recorded from the biceps brachii and pronator teres muscles. Kinematic and EMG analyses were performed to investigate the temporal characteristics underlying the two movement-time conditions. When subjects produced the response as quickly as possible, average movement time to perform each reversal movement decreased while average peak velocity increased. Average total movement time was reduced by approximately 100 ms. Although movement time decreased, the proportion of total time to perform each movement of the sequence remained essentially invariant between movement-time conditions. Similar results were obtained for velocity. The time at which peak velocity was achieved occurred earlier in absolute time, although when normalized to the proportion of total movement time, the time to reach peak velocity was also invariant. Thus subjects proportionally compressed the entire movement sequence in time. The EMG analysis demonstrated that total EMG time decreased 89 ms on the average when subjects sped up the movement sequence. Thus average burst durations for both the biceps and pronator teres muscles decreased when movement speed increased. When burst durations were normalized to a proportion of total EMG time, the average proportion of time each muscle was active remained invariant. Therefore, the temporal pattern of activity for the biceps and pronator teres muscles were also proportionally compressed. The present experiment provided additional evidence for the structure of generalized motor programs consisting of invariant and variant features. Movement speed was considered a variant feature, which is specified each time the program is executed. Relative timing, the proportion of total time to produce each segment of the response, was considered to be an invariant feature and inherent in the structure of the motor program. Support for the invariance of relative timing was observed at both the kinematic and neuromuscular levels of analyses. Alternative models (9-11, 24) were found inadequate to account for the invariance of relative timing with the variation in movement time observed in the present experiment.

Age Differences in Integration of Components of a Motor Task

To study effects of practice on the ability of 6-, 11-, and 18-yr.-old Ss to integrate the components of the Rho task 3 groups of 50 boys performed 30 consecutive trials. (a) With practice all age groups improved in total movement time; (b) 11-yr.-old Ss attained the 18-yr.-olds' level of performance in both components, initial differences existing only in the linear component; (c) relative to the 18-yr.-old Ss, the 6-yr.-olds achieved proportionally less improvement in the linear component; (d) unlike 11- and 18-yr.-old Ss, the 6-yr.-olds evidenced increasing specificity of task components across trials. Unlike the two older age groups, the 6-yr.-old Ss were unable to achieve a high degree of integration of task components. The findings were discussed in light of Pascual-Leone's neo-Piagetian model of learning and development.