Jeffrey D. Graham

Cognitive task performance causes impaired maximum force production in human hand flexor muscles.

The purpose of this study was to investigate effects of demanding cognitive task performance on intermittent maximum voluntary muscle contraction (MVC) force production. Participants performed either a modified Stroop or control task for 22 min. After the first min and at 3-min intervals thereafter, participants rated fatigue, perceived mental exertion and performed a 4-s MVC handgrip squeeze. A mixed ANOVA showed a significant interaction, F(7, 259)=2.43, p=.02, with a significant linear reduction in MVC force production over time in the cognitively depleting condition (p=.01) and no change for controls. Ratings of perceived mental exertion, F(7, 252)=2.39, p<.05, mirrored the force production results with a greater linear increase over time in the cognitive depletion condition (p<.001) compared to controls. Findings support current views that performance of cognitively demanding tasks diminishes central nervous system resources that govern self-regulation of physical tasks requiring maximal voluntary effort.

Self-control training leads to enhanced cardiovascular exercise performance

Abstract The purpose of the study was to investigate the effects of two weeks of self-control strength training on maximum cardiovascular exercise performance. Forty-one participants completed a cognitive self-control depletion task (Stroop task) followed by a maximal graded cycling test and were randomized to training (maximal endurance contractions of spring handgrip trainers, twice daily) or no-treatment control groups. At follow-up (2 weeks), half of each group completed either a time-matched or trial-matched Stroop task followed by another maximal graded cycling test. Results showed a significant 2-way (training X time) interaction (P < 0.001), and a trend for the 3-way (training X time X cognitive task) interaction (P = 0.07). Decomposition of the interactions revealed that across sessions cycling performance increased in both training groups, did not change in the trial-matched cognitive task control group, and declined in the time-matched control group. We conclude that isometric handgrip training leads to self-control strength adaptations that enhance maximal cardiovascular exercise performance or tolerance of exercise at maximal levels of effort.

Self-control strength depletion reduces self-efficacy and impairs exercise performance.

The purpose of this study was to investigate the role of task self-efficacy as a psychological factor involved in the relationship between self-control depletion and physical endurance. Participants (N = 37) completed two isometric handgrip endurance trials, separated by a Stroop task, which was either congruent (control) or incongruent (causing depletion). Task self-efficacy for the second endurance trial was measured following the Stroop task. Participants in the depletion condition reported lower task self-efficacy and showed a greater reduction in performance on the second endurance trial when compared with controls. Task self-efficacy also mediated the relationship between self-control depletion and endurance performance. The results of this study provide evidence that task self-efficacy is negatively affected following self-control depletion. We recommend that task self-efficacy be further investigated as a psychological factor accounting for the negative change in self-control performance of physical endurance and sport tasks following self-control strength depletion.

Exertion of self-control increases fatigue, reduces task self-efficacy, and impairs performance of resistance exercise.

The purpose of this study was to investigate sequential indirect pathways by which self-control exertion affects resistance exercise performance through fatigue and task self-efficacy. Participants (N = 50) completed 2 sets of maximum repetitions at submaximal loads on bench press and leg extension resistance exercises separated by a Stroop task, which was either congruent (control) or incongruent (self-control exertion). Fatigue was assessed using the State Self-Control Capacity Scale following the Stroop task and participants rated their task self-efficacy for bench press and leg extension prior to performing the second sets of tasks. The self-control exertion condition reported greater fatigue, lower task self-efficacy, and showed a greater reduction in resistance exercise performance compared to controls. Results supported a serial mediation model indicating that exertion of self-control causes increased fatigue, which in turn leads to reduced self-efficacy to exert self-control and subsequent reductions in self-controlled task performance.

Using self-reported and objective measures of self-control to predict exercise and academic behaviors among first-year university students:

Thirty students (mean age = 18 ± 0.5 years) completed self-report (Self-Control Scale) and objective (isometric handgrip squeeze performance) measures of self-control, provided their exercise and academic (study/schoolwork) plans for the next month, and then logged these behaviors over the subsequent 4-week period. Trait self-control predicted exercise and academic behavior. Handgrip squeeze performance predicted academic behavior and adherence to academic plans. Further, regression analysis revealed that trait self-control and handgrip performance explained significant variance in academic behavior. These findings provide a new understanding of how different self-control measures can be used to predict first-year students’ participation in, and adherence to, exercise and academic behaviors concurrently.

Cognitive control exertion leads to reductions in peak power output and as well as increased perceived exertion on a graded exercise test to exhaustion

ABSTRACT We investigated effects of a brief (10.5 min) cognitively demanding task on graded exercise test performance. Untrained, university students (N = 15) completed two graded exercise tests in counterbalanced, randomised order. One test was preceded by restful viewing of a documentary video (control); the other by a stop-signal task. Cardiorespiratory functions and perceived exertion were monitored during exercise. Peak power output (W) was lower following the stop-signal task (M = 240.03, SD = 53.37) compared to control (M = 246.03, SD = 52.60), P = 0.002, ηP2 = 0.493, as was (P = 0.042, Cohen’s d = 0.55). Perceived exertion was significantly higher at 50% (d = 0.77) and 75% (d = 0.83) of iso-time following the cognitive task (Ps ≤ 0.01). Results are consistent with research showing negative carryover effects of cognitively demanding tasks on whole-body endurance performance. Results also support the psychobiological model of exercise as performance of the cognitive task did not affect perceived exertion when exercise task demands were lower, but lead to greater perceived exertion and earlier withdrawal of effort at higher levels of exercise task demand. Findings have implications for understanding psychological determinants of exercise performance and conditions that may lead to underestimation of .

Imagery and Endurance: Does Imagery Impair Performance by Depleting Self-Control Strength?

Abstract Although mental imagery has been shown to have beneficial effects on performance, imagery has been shown to negatively affect physical performances under some conditions. The limited strength model of self-regulation posits that self-control strength is depleted when people regulate their thoughts, impulses, emotions, and behaviours. Research shows depletion of self-control strength in one task domain (e.g., controlling thoughts or images) leads to poorer self-control within similar and dissimilar domains (e.g., controlling physical endurance). The purpose of the present study was to investigate the aftereffects of performing mental imagery on two self-control tasks, physical endurance and response inhibition. Sedentary undergraduates (N = 37) were randomly assigned to either an imagery condition (n = 15), attention-placebo condition (n = 13), or a quiet rest control (n = 9). Participants performed two isometric endurance tasks (30% of maximum handgrip squeeze) separated by their respective study manipulation, and followed by the Wisconsin Card Sort Test (WCST). It was expected that participants in the mental imagery condition would show greater decrements in performance on the second endurance trial (when compared to baseline) and more perseverative errors on the WCST compared to the control conditions. All of the participants’ endurance performances declined over time (p < .05), however, no between group differences were found on endurance performances (p > .05) or on WCST scores (p > .05). Performing a basic 6 minute imagery session involving moderately-intense aerobic exercise does not appear to deplete self-control resources when compared to the attention-placebo and quiet rest control groups. However, the unanticipated decline in the endurance performances observed within the control conditions suggests that future research is needed to better understand the relationship between mental imagery and self-control depletion effects.

Are Canadian-born Major League Baseball players more likely to bat left-handed? A partial test of the hockey-influence on batting hypothesis.

It has been suggested that Canadian-born Major League Baseball (MLB) players are more likely to bat left-handed, possibly owing to the fact that they learn to play ice hockey before baseball, and that there is no clear hand-preference when shooting with a hockey stick; approximately half of all ice hockey players shoot left. We constructed a database on active (i.e., October, 2016) MLB players from four countries/regions based on place of birth (Canada, United States of America [USA], Dominican Republic and South Asia [i.e., Japan, Taiwan and South Korea]), including information on which hand they use to bat and throw. We also extracted information on all Canadian-born MLB players, dating back to 1917. Our results confirm that the proportion of left-handed batters born in Canada is higher when compared to the other countries selected; also, since 1917, the proportion of Canadian MLB players who bat left has been consistently higher than the league average. We also compared the proportion of left-handed batters in Canada with players born in states in the USA grouped into high, average and low based on hockey participation. The proportion of MLB players born in states with a high level of hockey participation were more likely to bat left, although the differences were significant at trend level only (p < .10). Lastly, we found that while Canadians were more likely to bat left-handed, this did not correspond with a greater left-hand dominance, as determined by throwing hand. In conclusion, the present study confirms that Canadian-born MLB players are more likely to bat left-handed when compared to American, Dominican Republic and South Asian-born MLB players, providing partial support for the hockey influence on batting hypothesis.

Moderating Effects of Physical Activity and Global Self-Worth on Internalizing Problems in School-Aged Children With Developmental Coordination Disorder

School-aged children with developmental coordination disorder (DCD) are at greater risk for physical inactivity, lower global self-worth, and internalizing problems, such as depression and anxiety. Based on the environmental stress hypothesis (ESH), recent research has shown that physical inactivity and lower global self-worth sequentially mediate the relationship between DCD and internalizing problems, suggesting that DCD leads to lower levels of physical activity, which in turn leads to lower levels of global self-worth, and ultimately, a greater amount of internalizing problems. However, physical activity and global self-worth may also buffer (i.e., moderate) the adverse effect of DCD on internalizing problems. To date, this has yet to be tested. Participants were 1206 children aged 12–14 years [611 boys, 79 with probable DCD (pDCD)]. All children received assessments of motor coordination, physical activity, global self-worth, and internalizing problems. Children with pDCD were less physically active, had lower self-worth, and experienced more internalizing problems compared to typically developing (TD) children (p’s < 0.05). Furthermore, the moderated moderating effect (three-way interaction) of physical activity and global self-worth was also evident (p < 0.05), indicating that internalizing problems in both TD and pDCD groups decreased with concurrent increases in physical activity and global self-worth. Importantly, when compared to TD children, increases in physical activity and global self-worth were associated with a greater reduction in internalizing problems among children with pDCD. The findings support several pathways in the ESH and highlight that, in addition to improving motor skills, interventions should also target both physical activity and global self-worth to mitigate potential mental health issues for children with motor difficulties.

Effects of cognitive control exertion and motor coordination on task self-efficacy and muscular endurance performance in children

Emerging research shows a strong connection between brain areas governing cognition and motor behavior. Indeed, research based on the Strength Model has shown that people perform worse on physical tasks following the exertion of high (compared to low) cognitive control which has been attributed to the dysregulation of neurophysiological processes within areas of the brain responsible for cognition. Yet, research investigating the negative aftereffects of high cognitive control (HCC) exertion on task performance has not considered the potential role of areas governing motor behavior. The present study investigated the effects of HCC exertion on task self-efficacy and exercise performance in children. A secondary purpose was to investigate whether motor coordination influences the change in exercise performance differently following low versus HCC exertion. Participants (N = 70) performed two isometric handgrip endurance trials separated by a Stroop task, which was either congruent low cognitive control (LCC) or incongruent (HCC). Motor coordination was assessed prior to the first endurance trial. Task self-efficacy for performing the second endurance trial was assessed following the Stroop task. Participants in the HCC condition reported lower task self-efficacy and showed a reduction in endurance exercise performance. Task self-efficacy mediated the cognitive control—performance relationship. Participants scoring lower on motor coordination showed the greatest declines in exercise performance following HCC, whereas motor coordination did not affect performance following LCC. The results of this study provide evidence that task self-efficacy and exercise performance are also negatively affected in children following HCC, and interestingly, these effects are exacerbated among those scoring lower in motor coordination. We recommend future research investigate motor coordination as a potential mechanism for the reductions in both cognitive and physical task performance following the prolonged exertion of HCC.