Assisted Cycle Therapy (ACT) Improved Self-Efficacy and Exercise Perception in Middle-Age Adults with Down Syndrome.

Alzheimer's disease is prevalent in persons with Down syndrome (DS) as early as their 30s and presents as decreased social interaction, coordination, and physical activity. Therefore, changing attitudes and beliefs about exercise is key to increasing motivation for physical activity especially in middle-age adults with DS. The aim of this study was to examine the effects of Assisted Cycle Therapy (ACT) on self-efficacy and exercise perception in middle-age adults with Down syndrome (DS) following an exercise intervention three times a week for 8 weeks. Twelve participants were in the ACT group in which a motor assisted their cycling to be performed at least 30% faster than voluntary cycling (VC), 10 participants were in the voluntary cycling group, and two participants were in the no cycling (NC) group. The results showed that both exercise groups (i.e., ACT and VC) improved in their self-efficacy after the 8-week intervention. In addition, exercise perception improved following ACT, but not VC or NC. Our results are discussed with respect to their future implications for exercise in the DS population. The results can be attributed to differences in effort required by each intervention group as well as the neurotrophic factors that occur when muscle contractions create synaptic connections resulting in improvement in cognition and feelings of satisfaction.

Choice of end-state comfort is dependent upon the time spent at the beginning-state and the precision requirement of the end-state.

Choice of posture while grasping an object typically depends upon several factors including the time spent in that posture, what postures were held prior to choosing that posture, and the precision required by the posture. The purpose of this study was to test choice of end-state thumb-up posture based on time spent at the beginning-state and the precision requirement of the end-state. To determine choice of thumb-up based on time or precision, we varied how long a subject had to hold the beginning state before moving an object to an end location. We made end-state precision either small or large and eliminated the precision needed to stand the object up at the end of the movement. A choice between "comfort" at the beginning or precision at the end-state would be demanded by the conditions with long beginning-state hold times and high precision demands. We aimed to determine which aspect of movement was of greater importance to individuals, overall "comfort" or precision. When the requirement was to hold the initial grasp longer, and the end-target was large, we predicted that we would see more thumb-up postures adopted at the beginning state. When the final placement was small and the initial posture was not constrained, we predicted we would see thumb-up postures adopted at the end state. On average, we found that, as beginning-state grasp time increased, more individuals chose beginning-state thumb-up postures. Perhaps, not surprisingly, we found distinct individual differences within our sample. Some individuals seemed to choose beginning-state thumb-up postures nearly 100% of the time, while other individuals chose end-state thumb-up postures nearly 100% of the time. Both the time spent in a posture and its precision requirements influenced planning, but not necessarily in a systematic way.

Effects of Flywheel Resistance Training on Muscle Function and Sport-Specific Performance in Collegiate Club Water Polo Players.

Purpose: This study investigated the effects of flywheel squat training on lower body muscle function adaptations and sport-specific performance in collegiate club water polo players. Methods: Thirteen collegiate club water polo athletes (5 women, 8 men) performed flywheel squat training for 4 weeks. Isokinetic knee extension (KE) peak power (PP) and peak torque (PT), flywheel squat peak power (FPP) and mean power (FMP), countermovement jump (CMJ), in-water jump height (WJH) and foot speed were assessed at baseline (Pre1), 4 weeks (Pre2), and 8 weeks (Post) with the first 4 week block being a control period and the second 4 week block being the experimental training. Throughout the training period muscle soreness was assessed using a VAS scale, and FPP and FMP were assessed during every other session. Results: Isokinetic KE PP and PT increased from Pre1 to Post, and FPP and FMP increased between Pre1 and Post, and Pre2 and Post. CMJ and foot speed were unchanged. WJH displayed a change between Pre1 and Post. FPP increased 19% from session 2 to 4 and FMP increased 27% from session 2 to 6, and each remained elevated through session 8. Conclusion: 4 weeks of flywheel squat training in collegiate club water polo players elicited large gains (47-52%) in flywheel-specific squat power, but did not influence sport-specific performance measures including CMJ, WJH, and foot speed. Water-based exercises and stretch-shortening cycle movements (plyometrics) in combination with effective resistance training programs, which may include flywheel-based training, are likely needed for marked sport skill improvements.

Visual feedback is not important for bimanual human interval timing.

The clock variance of intervals produced by one finger is reduced when that finger taps along with another finger (termed the bimanual advantage). The multiple-timekeeper model proposes a coupling of internal clocks, leading to reduced clock variance for bimanual timing. Alternatively, reduced variance for bimanual timing could result from additional sensory feedback from two fingers as opposed to one. We aimed to test the role of visual feedback in reducing temporal variability. Participants tapped unimanually and bimanually (with no table contact) in three conditions: full vision, blindfolded, and with additional visual feedback provided via a mirror reflecting the right hand. We predicted that temporal variability would be reduced for tapping with vision versus no vision, and when the left hand was represented by a mirror but did not actually tap. Additional, redundant visual information did not reduce temporal variability for any condition, suggesting that visual feedback is not crucial for bimanual advantage. These findings support the role of sensory feedback (namely, tactile, auditory, and proprioceptive) in reducing timekeeper variability during bimanual timing and argue against a strictly multiple-timekeeper model.

The influence of time constraints on posture choices during an end-state comfort task.

People adopt comfortable postures for the end states of motor actions (end-state comfort; Rosenbaum & Jorgensen, 1992). The choice to end comfortably often elicits adoption of uncomfortable beginning states, demonstrating that a sequence of movement is planned in advance of movement onset. Many factors influence the choice of comfortable end-state postures including the greater precision and speed afforded by postures at joint angle mid-ranges (Short & Cauraugh, 1999). To date, there has been little evaluation of the hypothesis that postures are chosen based on minimizing the time spent in uncomfortable postures. The aim of this experiment was to examine how the relative time required to hold beginning and end-state postures influenced the choice of posture. Participants moved a two-toned wooden dowel from one location to another with the requirement to grasp the object and place a specified color down. Participants completed four conditions where no postures were held, only one posture was held, or both postures were held. We predicted more thumb-up postures for positions held longer regardless of whether these postures were at the end or beginning state. Results verified that the constraint of holding the initial posture led to decreased end-state comfort supporting the hypothesis that estimation of time spent in postures is an important constraint in planning. We also note marked individual differences in posture choices, particularly when the object was moved to the left.

Preliminary Evidence That Motor Planning Is Slower and More Difficult for Children With Autism Spectrum Disorder During Motor Cooperation.

Children with autism spectrum disorder (ASD) exhibit impairment in helping someone else with a motor action, which may arise from impairment in selecting and preparing motor responses. Five children with ASD and five typically developing children performed a cooperative motor planning task that required them to reach for, lift, and hand an object (hammer or stick) to a researcher. The response, movement, and grasp time were measured. Children with ASD grasped the object longer on trials where they helped, indicating that the action was planned in sequence versus as a whole (i.e., prior to the onset of movement). The hammer object elicited a quicker response than the stick, suggesting the facilitation of planning by tools with inherent action properties. Finally, the increased helping of children with ASD was not mirrored by changes in the response, movement, or grasp time.

Gender differences in nonlinear motor performance following concussion.

PURPOSE: To quantify differences in nonlinear aspects of performance on a seated visual-motor tracking task between clinically asymptomatic males and females with and without a self-reported mild traumatic brain injury history. METHODS: Seventy-three individuals with a self-reported concussion history (age: 21.40 ± 2.25 years, mean ± SD) and 75 without completed the visual-motor tracking task (age: 21.50 ± 2.00 years). Participants pressed an index finger against a force sensor, tracing a line across a computer screen (visual-motor tracking). The produced signal's root-mean-square error (RMSE), sample entropy (SampEn, a measure of regularity), and average power (AvP) between 0 and 12 Hz were calculated. RESULTS: Males with a history of 0 or 1 concussion had greater RMSE (worse performance) than females with 0 (p < 0.0001) and 1 concussion (p = 0.052). Additionally, females with 2+ concussions exhibited lower SampEn than females with no history (p = 0.001) or a history of 1 concussion (p = 0.026). Finally, females with 2+ concussions had lower 8-12 Hz AvP than males with 2+ concussions (p = 0.031). Few differences were observed in the male participants. CONCLUSION: Females with a self-reported history of multiple concussions exhibited lower SampEn in the visual-motor tracking-task force output structure as compared to those with no reported history of concussion and their male counterparts. Lower SampEn and lower power between 8 and 12 Hz indicated persistent impairment in visual processing and feed-forward or predictive motor control systems.

Experience with Event Timing Does not Alter Emergent Timing: Further Evidence for Robustness of Event and Emergent Timing.

Although, event and emergent timings are thought of as mutually exclusive, significant correlations between tapping and circle drawing (Baer, Thibodeau, Gralnick, Li, & Penhune, 2013 ; Studenka, Zelaznik, & Balasubramaniam, 2012 ; Zelaznik & Rosenbaum, 2010 ) suggest that emergent timing may not be as robust as once thought. We aimed to test this hypothesis in both a younger (18-25) and older (55-100) population. Participants performed one block of circle drawing as a baseline, then six blocks of tapping, followed by circle drawing. We examined the use of event timing. Our hypothesis that acute experience with event timing would bias an individual to use event timing during an emergent task was not supported. We, instead, support the robustness of event and emergent timing as independent timing modes.

Concussion history is negatively associated with visual-motor force complexity: evidence for persistent effects on visual-motor integration.

OBJECTIVES: Long-term monitoring of concussion recovery requires time- and cost-effective methods. Physiologic complexity may be useful in evaluating visual-motor integration following concussion. The purpose of this study was to quantify the extent to which prior number of concussions influenced visual-motor tracking force complexity. METHODS: Thirty-five individuals with a self-reported concussion history (age: 20.92 ± 1.98) and 15 without (age: 20.92 ± 2.21) performed an isometric visual-motor tracking task, using index finger force to trace a straight line across a computer screen. Finger force root mean square error (RMSE), multi-scale complexity, and average power from 0 to 12 Hertz (Hz) were calculated. Individual multiple regressions were fit to these outcomes. RESULTS: Force complexity decreased linearly with an increasing number of concussions (R2 = 0.101). Males had more complex force overall (R2 = 0.219) and greater 4-8 Hz average power (R2 = 0.193). The 8-12 Hz average power decreased significantly for individuals with prior loss of consciousness (LOC) and increasing numbers of concussions (R2 = 0.143). CONCLUSION: Individuals exhibited linear decreases in visual-motor tracking force complexity with increasing numbers of concussions, influenced by both gender and a history of LOC. These findings indicate cumulative changes in the ways in which previously concussed individuals process and integrate visual information to guide behaviour.

The role of multiple internal timekeepers and sources of feedback on interval timing.

The aim of this experiment was to document the role of multiple internal clock mechanisms and external sources of temporal feedback on reducing timing variability when two fingers tap instead of one (a phenomenon known as the bimanual advantage). Previous research documents a reduction in timed interval variability when two effectors time instead of one. In addition, interval variability decreases with multiple sources of feedback. To date, however, no research has explored the separate roles of feedback and internal timing on the bimanual advantage. We evaluated the bimanual advantage in a task that does not utilise an internal clock (circle drawing). Participants performed both unimanual and bimanual timing while tapping or drawing circles. Both tasks were performed with and without tactile feedback at the timing goal. We document reduced bimanual timing variability only for tasks that utilise internal clock-like timing (tapping). We also document reduced timing variability for timing with greater sensory feedback (tactile vs no-tactile feedback tapping). We conclude that internal clock mechanisms are necessary for bimanual advantage to occur, but that multiple sources of feedback can also serve to improve internal timing, which ties together current theories of bimanual advantage.

Motor and verbal perspective taking in children with Autism Spectrum Disorder: Changes in social interaction with people and tools.

BACKGROUND: Children with Autism Spectrum Disorder (ASD) have difficulty communicating with others nonverbally, via mechanisms such as hand gestures, eye contact and facial expression. Individuals with ASD also have marked deficits in planning future actions (Hughes, 1996), which might contribute to impairments in non-verbal communication. Perspective taking is typically assessed using verbal scenarios whereby the participant imagines how an actor would interact in a social situation (e.g., Sally Anne task; Baron-Cohen, Leslie, & Frith, 1985). METHOD: The current project evaluated motor perspective taking in five children with ASD (8-11 years old) as they participated in a narrative intervention program over the course of about 16 weeks. The goal of the motor perspective-taking task was to facilitate the action of an experimenter either hammering with a tool or putting it away. RESULTS: Initially, children with ASD facilitated the experimenter's action less than neurotypical control children. As the narrative intervention progressed, children with ASD exhibited increased motor facilitation that paralleled their increased use of mental state and causal language, indicating a link between verbal and motor perspective taking. CONCLUSIONS: Motoric perspective taking provides an additional way to assess understanding and communication in children with ASD and may be a valuable tool for both early assessment and diagnosis of children with ASD.

Narrative Intervention for Children With Autism Spectrum Disorder (ASD).

PURPOSE: This study was conducted to determine whether a narrative intervention program that targeted the use of mental state and causal language resulted in positive gains in narrative production for children with autism spectrum disorder (ASD). METHOD: Five children (2 girls and 3 boys) who had been diagnosed with ASD participated in the study. Children ranged in age from 8 to 12 years and were recruited through an autism clinic. Intervention was provided for two 50-min individual sessions per week for a total of 21-33 sessions (depending on the student). Children's spontaneous stories, collected weekly, were analyzed for overall story complexity, story structure, and the use of mental state and causal language. Following a multiple-baseline across-participants design, data were collected for lagged baseline and intervention phases over a 6-month period. RESULTS: All of the children made gains on all 3 measures of narration after participating in the instruction, with clear changes in level for all 5 children and changes in trend for 4 of the 5 children. The gains were maintained after intervention was discontinued. CONCLUSION: The results demonstrate the efficacy of the 3-phase narrative instruction program for improving the fictional narration abilities of children with ASD.

Visual information about past, current and future properties of irregular target paths in isometric force tracking.

In visual-motor tracking, information about past, current, and future properties of a target path can be available but, because they are typically manipulated independently, the relative contribution of these information categories to tracking performance is not well understood. The aim of the current study was to investigate the role of visual information pertaining to past, current, and future states of the target path in guiding isometric tracking performance as a function of the irregularity of the target path (sine wave, brown/pink noise, white noise). The findings from local and global properties of the force output showed that the role of visual information about the past, current, and future states of target paths is dependent on the regularity of the signal to be tracked. The brown/pink noise pathway condition was most strongly influenced by future and past-future visual information for both local error properties (lead/lag, root mean square error (RMSE)) and global properties of the force output (ApEn, cross correlation). The highly irregular white noise pathway did not benefit from past or future information and the highly regular sine wave was only influenced for the local error properties of RMSE and lead/lag. It appears that visual information about past and future tracking states is more effective with a pathway that is middling with respect to regularity/irregularity. This is consistent with the role of visual information in tracking to be dependent on the potential adaptability for change in the dimension of the motor output.

Response to period shifts in tapping and circle drawing: a window into event and emergent components of continuous movement.

Synchronization of movement to a metronome is a well-studied task for both discretely and smoothly produced rhythmic movement. In particular, behavioral responses to unexpected changes in a regular metronome can reveal both the strength and the completeness of error correction mechanisms and temporal control. Clock-like control is exhibited by discretely produced movement and movement with discrete perceptual information, whereas smoothly produced movement does not rely on internal clock mechanisms. Documented differences in error correction between discretely and smoothly produced movements have been attributed to this different underlying control. In this study, error correction mechanisms were examined by inducing changes in the pace of rhythmic movement. An overshoot response following the pace change for both tapping and circle drawing is documented, and suggests the presence of phase and period correction in both tasks. The presence of phase correction in circle drawing also suggests that clock and non-clock timing may co-exist within the same movement. Furthermore, a sub-group of participants emerged who appropriately changed pace, but were not able to correct the phasing of their movement while performing the circle drawing task, supporting that phase and period maintenance in timing are independently controlled processes.

Differential time scales of change to learning frequency structures of isometric force tracking.

Multiple processes support the persistent (learning) and transient (adaptive) change in behavior over time. We investigated whether practice and rest influence similarly the learning and adaptation of slow and fast frequency structures in isometric force tracking of pathways that varied in their regularity. Participants practiced 25 trials on each of 5 days in either a constant force target or 1 with the 1/f distributional properties of brown or pink noise. There was a reduction in root mean squared error (RMSE) as well as an increasing positive correlation between force output and the target pathway for all noise conditions over days. The spectral frequency analysis of force output and RMSE revealed task dependent outcomes of learning and adaptation as a function of the relatively slow (0-4 Hz) and fast (8-12 Hz) oscillatory time scales. These contrasting findings show that the persistent and transient properties of learning occur across different timescales and dimensions of behavior (force output and outcome-RMSE).

Crossing the arms confuses the clocks: sensory feedback and the bimanual advantage.

The bimanual advantage refers to the finding that tapping with two fingers on opposite hands exhibits reduced timing variability, as compared with tapping with only one finger. Two leading theories propose that the bimanual advantage results from the addition of either sensory (i.e., enhanced feedback) or cognitive (i.e., multiple timekeeper) processes involved in timing. Given that crossing the arms impairs perception of tactile stimuli and modulates cortical activation following tactile stimulation, we investigated the role of crossing the arms in the bimanual advantage. Participants tapped unimanually or bimanually with their arms crossed or uncrossed on a tabletop or in the air. With arms crossed, we expected increased interval timing variance. Similarly, for air tapping, we expected reduced bimanual advantage, due to reduced sensory feedback. A significant bimanual advantage was observed for the uncrossed, but not the crossed posture in tabletop tapping. Furthermore, removing tactile feedback from taps eliminated the bimanual advantage for both postures. Together, these findings suggest that crossing the arms likely impairs integration of internal (i.e., effector-specific) and external (i.e., environment-specific) information and that this multisensory integration is crucial to reducing timing variability during repetitive coordinated bimanual tasks.

End-state comfort trumps handedness in object manipulation.

A goal of research on human perception and performance is to explore the relative importance of constraints shaping action selection. The present study concerned the relative importance of two constraints that have not been directly contrasted: (1) the tendency to grasp objects in ways that afford comfortable or easy-to-control final postures; and (2) the tendency to grasp objects with the dominant rather than the nondominant hand. We asked participants to reach out and grasp a horizontal rod whose left or right end was to be placed into a target after a 90° rotation. In one condition, we told participants which hand to use and let them choose an overhand or underhand initial grasp. In another condition, we told participants which grasp to use and let them choose either hand. Participants sacrificed hand preference to perform the task in a way that ensured a comfortable or easy to control thumb-up posture at the time of object placement, indicating that comfort trumped handedness. A second experiment confirmed that comfort was indeed higher for thumb-down postures than thumb-up postures. A third experiment confirmed that the choice data could be linked to objective performance differences. The results point to the importance of identifying constraint weightings for action selection and support an account of hand selection that ascribes hand preference to sensitivity to performance differences. The results do not support the hypothesis that hand preference simply reflects a bias to use the dominant hand.

Choosing actions.

Actions that are chosen have properties that distinguish them from actions that are not. Of the nearly infinite possible actions that can achieve any given task, many of the unchosen actions are irrelevant, incorrect, or inappropriate. Others are relevant, correct, or appropriate but are disfavored for other reasons. Our research focuses on the question of what distinguishes actions that are chosen from actions that are possible but are not. We review studies that use simple preference methods to identify factors that contribute to action choices, especially for object-manipulation tasks. We can determine which factors are especially important through simple behavioral experiments.

Motor interactions with another person: do individuals with Autism Spectrum Disorder plan ahead?

Interpersonal motor interactions (joint-actions) occur on a daily basis. In joint-action situations, typically developing (TD) individuals consider the end-goal of their partner and adjust their own movements to accommodate the other person. The movement planning processes required for joint-action may, however, be difficult for individuals with an Autism Spectrum Disorder (ASD) given documented difficulties in performance on theory of mind (ToM) and motor tasks. The goal of this experiment was to determine if individuals with ASD exhibit end-state comfort behaviors similar to their TD peers in joint-action situations. Participants were asked to either pass, place, or use three common tools: a wooden toy hammer, a stick, or a calculator. These tools were selected because the degree of affordance they offer (i.e., the physical characteristics they posses to prompt proper use) ranges from direct (hammer) to indirect (calculator). Participants were asked to pass the tool to a confederate who intended to place the tool down, or use the tool. Variables of interest included beginning and end-state grip orientations of the participant and confederate (comfortable or uncomfortable) as a function of task goal, and the side to which the tool was placed or passed. Similar to Gonzalez et al. (2011), some individuals with ASD maximized their partner's beginning-state comfort by adopting personally uncomfortable postures. That said, their performance was more variable than their TD peers who consistently passed tools in a manner that facilitated comfortable use by the confederate. Therefore, the movement planning processes used to prepare to pass a tool are not stereotypical across all individuals with ASD. We propose that the novel joint-action task described herein provides the basis for testing an important link between motor performance and more complex social and communication behaviors.

Visual information for prospective control of tracking irregular target paths with isometric force production.

The prospective control of isometric force tracking was investigated as a function of the duration of visual information about past and future properties of target paths that varied in regularity. Longer duration of information specifying future behavior significantly enhanced performance when past information was not available. Furthermore, target path regularity differentially influenced local and global performance properties as the duration of prospective information increased. For more regular target paths, longer duration of prospective visual information improved local properties (e.g., decreased error), whereas, for less regular target paths, longer duration of prospective visual information enhanced global properties of force production (e.g., spectral slope). The strategies of prospective control depend on the interaction of the regularity of motor output and the available informational support.