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Yi-Ching Chen, I-Chen Lin, Yen-Ting Lin, Wei-Min Huang, Chien-Chun Huang and Ing-Shiou Hwang

One of the manifestations of aging is that a given function loses its specialization and becomes simplified, known as age-related loss of complexity ( Baltes & Lindenberger, 1997 ). Numerous studies have demonstrated age-related reduction in complexity in the cardiovascular ( Bartzokis, 2004

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Yumeng Li, Melissa A. Mache and Teri A. Todd

physiological complexity. 18 Multiscale entropy is a nonlinear analysis tool to quantify complexity or irregularity of a time-series signal over multiple time scales. Compared with approximate entropy and sample entropy, multiscale entropy quantifies the overall complexity of a system and allows researchers to

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Marcel Mutsaarts, Bert Steenbergen and Harold Bekkering

Anticipatory planning was examined in detail for a complex object manipulation task by capitalizing on both the complexity and the number of elements in the movement sequences in seven individuals with hemiparetic cerebral palsy (HCP) and seven left-handed control participants. Participants had to grasp a hexagonal knob using one of five possible grasping patterns as quicklly as possible following a starting cue (condition I), and sometimes, they had to rotate it subsequently either 60˚ or 120˚ clockwise or counterclockwise (condition II). In the first condition, the HCP participants appear to anticipate the comfort of the different grasping patterns before movement onset, as controls did. However, when the task consisted of more than one movement part, HCP participants did not complete their planning processes before movement onset, which was contrary to controls. Instead, the results suggest that they use a step-by-step planning strategy, that is, they planned the latter parts of a movement sequence as the movement unfolds. The results are discussed in the light of possible capacity limitations of an internal model for grip selection, and a recent model on the planning and on-line control of movement performance.

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Fatemeh Azadinia, Ismail Ebrahimi-Takamjani, Mojtaba Kamyab, Morteza Asgari and Mohamad Parnianpour

), 731 – 735 . PubMed ID: 25737236 doi:10.1016/j.gaitpost.2015.01.008 Rhea , C.K. , Silver , T.A. , Hong , S.L. , Ryu , J.H. , Studenka , B.E. , Hughes , C.M. , & Haddad , J.M. ( 2011 ). Noise and complexity in human postural control: Interpreting the different estimations of entropy

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Anne Sofie B. Malling, Bo M. Morberg, Lene Wermuth, Ole Gredal, Per Bech and Bente R. Jensen

, Bode, & Wermuth, 2014 ; Uhrbrand, Stenager, Pedersen, & Dalgas, 2015 ). Physical rehabilitation for persons with PD is therefore important to minimize motor deficits due to disease progression. The complexity of a motor task may be defined by the number of task components and the connections between

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Nicholas Stergiou, Jenny A. Kent and Denise McGrath

An optimal level of variability enables us to interact adaptively and safely to a continuously changing environment, where often our movements must be adjusted in a matter of milliseconds. A large body of research exists that demonstrates natural variability in healthy gait (along with variability in other, healthy biological signals such as heart rate) and a loss of this variability in aging and injury, as well as in a variety of neurodegenerative and physiological disorders. We submit that this field of research is now in pressing need of an innovative “next step” that goes beyond the many descriptive studies that characterize levels of variability in various patient populations. We need to devise novel therapies that will harness the existing knowledge on biological variability and create new possibilities for those in the grip of disease. We also propose that the nature of the specific physiological limitation present in the neuromuscular apparatus may be less important in the physiological complexity framework than the control mechanisms adopted by the older individual in the coordination of the available degrees of freedom. The theoretical underpinnings of this framework suggest that interventions designed to restore healthy system dynamics may optimize functional improvements in older adults. We submit that interventions based on the restoration of optimal variability and movement complexity could potentially be applied across a range of diseases or dysfunctions as it addresses the adaptability and coordination of available degrees of freedom, regardless of the internal constraints of the individual.

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Maria Kosma, David Buchanan and Jan Hondzinski

acknowledge the complexity of exercise behavior. Based on the study findings, the following implications for physical activity promoters (practitioners) are recommended whenever applicable: (a) although exercise training is typically linked to physical effort and mobility, individual variations need to be

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Tami Abourezk and Tonya Toole

Thirty-four women ages 60 to 75 years were divided into two groups based on self-reported physical activity levels. The presence of significant fitness differences between the two activity groups was confirmed by testing all subjects on a well-established submaximal mile walking test. Both groups performed a reaction time task under two levels of task complexity: simple reaction time (SRT) and complex choice reaction time (CCRT). Time to react in milliseconds was recorded for both levels of task complexity. Analysis of variance revealed that the active group reacted faster (p < .05) than the less active group on CCRT (active M, 1.100 sec; less active M, 1.818 sec). However, SRT times did not differ between groups (active M, .345 msec; less active M, .374 msec). This finding lends support to the hypothesis that cognitive task complexity influences the strength of the association between physical fitness and cognitive performance in older adults.

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W. Jack Rejeski and Elizabeth Kenney

This study examined how exercise endurance was influenced by varying the task complexity of dissociative coping. In Trial 1, 60 subjects were randomly assigned to one of three conditions: a simple cognitive task (SCT), a complex cognitive task (CCT), or a control group (CG). All subjects were instructed to maintain an isometric contraction of 40% maximum on a handgrip dynamometer for as long as possible. Results revealed that subjects in the SCT and CCT conditions had greater endurance than those in the CG; however, varying the complexity of the task made no difference. Trial 2, a within-subjects design, was implemented to examine the potential mediating effects of task preference on cognitive coping. The protocol was identical to Trial 1 except that subjects previously assigned to the SCT condition were given the CCT and vice versa. Upon completion of Trial 2, subjects were asked which coping style they had preferred. A two-way mixed ANO-VA resulted in a significant coping style X preference interaction term. Specifically, subjects who preferred the complex task did equally well in both conditions, whereas subjects who preferred the simple task performed significantly better with the simple than with the complex task.

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Amanda Louise Lewis and Frank F. Eves

Background/Objective:

While point-of-choice prompts consistently increase stair climbing, experimental comparisons of message content are rare. Here, the effects of 2 messages differing in complexity about the health outcomes obtainable from stair climbing were compared.

Methods:

In a UK train station with 2 independent platforms exited by identical 39-step staircases and adjacent escalators, observers recorded travelers ascent method and gender from 8:00 A.M. to 10:00 A.M. on 2 weekdays during February/March 2008 (n = 48,697). Baseline observations (2-weeks) preceded a 3-week poster phase. Two posters (594 × 841mm) that differed in the complexity of the message were positioned at the point-of-choice between ascent methods, with 1 placed on each side of the station simultaneously. Logistic regression analysis was conducted in April 2010.

Results:

Omnibus analysis contained main effects of the intervention (OR = 1.07, CI = 1.02–1.13, P = .01) and pedestrian traffic volume (OR = 5.42, CI = 3.05–9.62, P < .001). Similar effects occurred for complex (OR = 1.10, CI = 1.02–1.18, P = .01) and simple messages (OR = 1.07, CI = 1.01–1.13, P = .02) when analyses controlled for the influence of pedestrian traffic volume. There was reduced efficacy for the complex message during busier periods (OR = 0.36, CI = 0.20–0.66, P = .001), whereas the simple message was immune to these effects of traffic volume.

Conclusions:

Pedestrian traffic flow in stations can influence message effectiveness. Simple messages appear more suitable for busy sites.