METHODS: In experiment 1 (n = 10), we tested the direction of force exerted in an isometric aiming task before and after 40 repetitions of 2-s maximal-force ballistic contractions toward a single directional target. In experiment 2 (n = 12), each participant completed three training conditions in a counterbalanced crossover design. In two conditions, both the aiming task and the training were conducted in the same (neutral) forearm posture. In one of these conditions, the training involved weak forces to determine whether the level of neural drive during training influences the degree of bias. In the third condition, high-force training contractions were performed in a 90° pronated forearm posture, whereas the low-force aiming task was performed in a neutral forearm posture. This dissociated the extrinsic training direction from the pulling direction of the trained muscles during the aiming task.
RESULTS: In experiment 1, we found that aiming direction was biased toward the training direction across a large area of the work space (approximately ±135°; tested for 16 targets spaced 22.5° apart), whereas in experiment 2, we found systematic bias in aiming toward the training direction defined in extrinsic space, but only immediately after high-force contractions.
CONCLUSION: Our findings suggest that bias effects of training involving strong neural drive generalize broadly to untrained movement directions and are expressed according to extrinsic rather than muscle-based coordinates.
METHODS: A cross-sectional randomized intervention study over 12 months' duration was conducted in university hospital simulation lab. ACLS-certified medical doctors were assigned to run 2 standardized simulated resuscitation code as RTL from a head-end position (HEP) and leg-end position (LEP). They were evaluated on leadership qualities including situational attentiveness (SA), errors detection (ED), and decision making (DM) using a standardized validated resuscitation-code-checklist (RCC). Performance was assessed live by 2 independent raters and was simultaneously recorded. RTL self-perceived performance was compared to measured performance.
RESULTS: Thirty-four participants completed the study. Mean marks for SA were 3.74 (SD ± 0.96) at HEP and 3.54 (SD ± 0.92) at LEP, P = .48. Mean marks for ED were 2.43 (SD ± 1.24) at HEP and 2.21 (SD ± 1.14) at LEP, P = .40. Mean marks for DM were 4.53 (SD ± 0.98) at HEP and 4.47 (SD ± 0.73) at LEP, P = .70. The mean total marks were 10.69 (SD ± 1.82) versus 10.22 (SD ± 1.93) at HEP and LEP respectively, P = .29 which shows no significance difference in all parameters. Twenty-four participants (71%) preferred LEP for the following reasons, better visualization (75% of participants); more room for movement (12.5% of participants); and better communication (12.5% of participants). RTL's perceived performance did not correlate with actual performance CONCLUSION:: The physical position either HEP or LEP appears to have no influence on performance of RTL in simulated cardiac resuscitation. RTL should be aware of the advantages and limitations of each position.