Abstract
Movement screening has become increasingly popular among tactical professionals. This popularity has motivated the design of interventions that cater to improving outcomes on the screens themselves, which are often scored in reference to an objective norm. In contrast to the assumptions underlying this approach, dynamical systems theory suggests that movements arise as a function of continuously evolving constraints and that optimal movement strategies may not exist. To date, few data address behavioral complexity in the fundamental movement tasks commonly used in clinical screenings. To provide evidence of complex variability during movement screens and test the role of modifiable-that is, trainable-constraints in mediating loss of complexity during experimental-task manipulations. Crossover study. Research laboratory. Twenty-five male (age = 23.96 ± 3.74 years, height = 178.82 ± 7.51 cm, mass = 79.66 ± 12.66 kg) and 25 female (age = 22.00 ± 2.02 years, height = 165.40 ± 10.24 cm, mass = 63.98 ± 11.07 kg) recreationally active adults. Participants performed tests of balance, range of motion, and strength. Additionally, they performed cyclical movement tasks under a control (C) condition and while wearing an 18.10-kg weight vest (W). Ground reaction forces were sampled at 1000 Hz and used to calculate center of pressure during cyclical movement tests. Multivariate multiscale entropy (MMSE) for the center-of-pressure signal was then calculated. Condition effects (C versus W) were analyzed using paired t tests, and penalized varying-coefficients regression was used to identify models predicting entropy outcomes from balance, range of motion, and strength. The MMSE decreased during the W condition (MMSEC > MMSEW; t49 range = 3.17-5.21; all P values < .01). Moderate evidence supported an association between modifiable constraints and behavioral complexity, but a role in mediating load-related loss of complexity was not demonstrated.
Highlights
The order in which variables were retained in a given model as the penalty parameter was adjusted from a maximum value, under which all coefficients were shrunk to zero, to the value at which the final variable was retained is presented in Tables 3 (MMSECI models) and 4 (CV models)
Multivariate empirical mode decomposition-enhanced MMSECI during dynamical postural-control tasks decreased when those tasks were performed with an external load
With respect to main effects, the pattern suggested that certain covariates related to range of motion, and to a lesser extent balance, were relevant contributors to the cyclic movement behaviors tested. For both MMSECI and CV, 3 of the 4 models presented in Table 5 feature significant effects related to range of motion
Summary
All participants provided written informed consent before data collection began. Fifty recreationally active adults (25 men: age 1⁄4 23.96 6 3.74 years, height 1⁄4 178.82 6 7.51 cm, mass 1⁄4 79.66 6 12.66 kg; 25 women: age 1⁄4 22.00 6 2.02 years, height 1⁄4 165.40 6 10.24 cm, mass 1⁄4 63.98 6 11.07 kg) were recruited to participate in this investigation. This population was chosen to reflect the candidate demographic for tactical professions
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