Previous studies indicate that rifle shooting performance while standing is compromised when fatigued. Apprehension of suspects by police officers may involve foot pursuit and firing a weapon from a standing position. The purpose of the current study was to investigate pistol shooting performance in police officers under similar conditions of physical fatigue. Participants (mean age: 30.1 years; 4.4 years of experience as police officer) completed two shooting trials separated by an acute bout of exercise on a cycle ergometer to voluntary exhaustion. Each trial consisted of three rounds of five rapid-fire shots at a target, each round separated by a 15-s rest. Participants’ backs were turned to the target between rounds. Despite physical exertion, with an average heart rate of 164 bpm, shooting accuracy (mean distance of the closest 4 shots from the center of the target) and precision (diameter of the tightest 4-shot grouping) remained unchanged on postexercise trials relative to preexercise trials. This suggests that automatic shooting reactions override the adverse consequences of fatiguing exercise on shooting performance.
Melissa J. Brown, Richard D. Tandy, Gabriele Wulf and John C. Young
Michele L. Hobson and W. Jack Rejeski
This investigation examined the role that different doses of acute aerobic exercise (AE) have on psychophysiological responses to mental stress. Eighty women participated in one of four experimental conditions: (a) attention control, (b) 10 min of exercise, (c) 25 min of exercise, or (d) 40 min of exercise. All exercise sessions were performed at 70% of each subject's heart rate reserve. Following each condition, subjects rested for 20 min and then completed a modified Stroop test. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were monitored at rest and during the stressor. Positive and negative affect were assessed upon entry to the laboratory, postexercise (after the 20-min rest), prior to the stressor, and after a 5-min recovery period. A priori comparisons of the 40-min exercise condition versus the attention control manipulation revealed that a demanding bout of acute AE lowered DBP and MAP reactivity to the Stroop; however, there were no significant linear trends between the dose of exercise and the extent of blood pressure (BP) reactivity. Analysis of the positive and negative affect data revealed no differences between any of the four treatment groups either prior to performing the Stroop task or following a 5-min period of recovery.
Rebecca E. Hasson, Kirsten E. Granados, David Xavier Marquez, Gary Bennett, Patty Freedson and Barry Braun
Racial differences in psychological determinants of exercise exist between non-Hispanic blacks (blacks) and non-Hispanic whites (whites). To date, no study has examined racial differences in the psychological responses during and after exercise. The objective of this study was to compare psychological outcomes of single exercise bouts in blacks and whites.
On 3 separate occasions, sedentary black (n = 16) and white (n = 14) participants walked on a treadmill at 75%max HR for 75 minutes. Questionnaires assessing mood, state anxiety, and exercise task self-efficacy were administered before and after each exercise bout. In-task mood and rating of perceived exertion (RPE) were measured every 5 minutes during exercise.
Exercise self-efficacy and psychological distress significantly improved in both blacks and whites. However during exercise blacks reported more positive in-task mood and lower RPE compared with whites.
These data suggest that racial differences exist in psychological responses during exercise. Further research should confirm these findings in a larger, free-living population.
Karen Davranche, Ben Hall and Terry McMorris
This study aimed to determine how cognitive control, engaged in a task requiring selective inhibition, is affected by acute steady-state exercise. An adapted version of the Eriksen flanker task, involving three types of trials that varied according to their level of congruency (congruent trials, stimulus-incongruent trials, and response-incongruent trials) was performed during 2 periods of 20-min cycling at a carefully controlled intensity (50% of maximal aerobic power). The results indicated that moderate exercise improves reaction time (RT) performance on the Eriksen flanker task. This facilitating effect appeared to be neither dependent on the nature of the interference (stimulus level conflict vs. response level conflict) nor on the amount of cognitive control engaged in the task (congruent vs. incongruent trials). Distributional RT analyses did not highlight any sign of impairment in the efficiency of cognitive control.
Torunn Bodin and Egil W. Martinsen
Physical activity is associated with an antidepressant effect in clinical depression. Self-efficacy is one mechanism proposed to explain this effect. In this study we compared the changes in mood following exercise sessions with high and stable self-efficacy (stationary bike exercise) to exercise sessions with initially low but increasing self-efficacy (martial arts). The experimental design incorporated repeated measures and counter-balancing. Twelve clinically depressed participants completed 45-min exercise sessions consisting of stationary bike use and martial arts. A waiting control condition of 30 minutes was conducted before each exercise session. During martial arts, statistically significant increases in positive affect, reductions in negative affect and state anxiety, and increased self-efficacy were observed. During the stationary bike exercise no statistically significant changes were found. The results indicate that an increase in self-efficacy may be important for mood benefits to occur.
Phillip D. Tomporowski
A review of the literature indicates that acute bouts of physical activity exert short-term positive benefits on the behavior and cognitive functioning of youths without clinical disorders and on youths who have difficulty focusing attention, controlling impulsive actions, or who evidence high levels of motor activity. Prior research conducted has been largely atheoretical. Information-processing models are suggested to provide a framework for assessing the impact of physical activity and cognition and behavior.
Maple Liu and Brian W. Timmons
The adaptive effects of exercise-induced inflammation and reactive oxygen species production has been well studied in adults, but not in children. Characterizing the exercise responses in children compared with adults will start clarifying the transition from the child phenotype to that of an adult. Ten children aged 8–10 and 12 adults aged 19–21 performed 2 × 30-min bouts of continuous cycling, separated by a 6-min rest period, at a target work rate of 60% of their maximum aerobic capacity. Blood samples were collected pre- and immediately postexercise, and analyzed for neutrophil count, systemic oxidative and inflammatory markers, and intracellular neutrophil-derived reactive oxygen species. Although postexercise absolute neutrophils increased by approximately twofold in men (2.72 ± 0.49 × 109/L to 4.85 ± 2.05 × 109/L; p = .007), boys showed no such change (3.18 ± 0.67 × 109/L to 3.57 ± 0.73 × 109/L; p = .52). Contrary to these findings, boys did show an increase in overall intracellular neutrophil ROS production, whereas men did not. Boys also demonstrated higher overall protein carbonyl levels (0.07 nmol/mg vs 0.04 nmol/mg; boys vs men respectively), whereas men showed higher overall malondialdehyde (0.24 μM vs 0.67 μM; boys vs men respectively). The differences observed in the exercise-induced inflammatory and oxidative stress response may indicate growth-mediated adaptive responses to exercise during childhood development.
Zekine Lappalainen, Jani Lappalainen, David E. Laaksonen, Niku K.J Oksala, Savita Khanna, Chandan K. Sen and Mustafa Atalay
Thioredoxin (TRX) is a protein disulfide reductase that plays an important role in many thiol-dependent cellular reductive processes, antioxidant protection, and signal transduction. Moreover, TRX reduces and maintains the function of many proteins during oxidative stress, which is increased in diabetes. The authors recently reported that diabetes impairs brain redox status and TRX response to exercise training. As a continuation of their studies, they hypothesized that alpha-lipoic acid, a natural thiol antioxidant, has a favorable effect on the brain TRX and glutathione (GSH) system in diabetes. Streptozotocin-induced diabetes was used as a chronic model and exhaustive exercise as an acute model for disrupted redox balance. Half the diabetic and nondiabetic animals were subjected to a bout of exhaustive exercise after 8 wk with or without lipoic acid and analyzed for key thiol antioxidants. Lipoic acid neither altered diabetes-induced oxidative stress as assessed by the increased ratio of oxidized to total GSH nor had any impact on the antioxidant protein response to exercise. However, lipoic acid increased mRNA of TRX-interacting protein, an inhibitor of TRX-1, and glutaredoxin-1 in diabetes. Exercise increased TRX-1 mRNA in both diabetic and nondiabetic animals but had no effect on TRX-1 protein. Cytosolic superoxide dismutase mRNA was only increased in diabetes, whereas exercise increased the protein levels in nondiabetic animals. The findings suggest that exhaustive exercise induces mRNA of TRX-1 in the brain and that lipoic acid cannot prevent diabetes-induced disturbances in GSH homeostasis. Because lipoic acid increased TRX-interacting protein transcription in diabetes, high doses may impair TRX-1 homeostasis.
Jocelyn F. Hafer and Katherine A. Boyer
The link between age-related changes in muscle strength and gait is unclear. We tested if knee extensor functional demand differs by age and physical activity status and if functional demand increases with walking speed or after exercise. Gait and knee extensor muscle torque were collected from young adults and highly and less active older adults before and after treadmill walking. Functional demand was the ratio of knee moments during gait to knee extensor muscle torques estimated from participant-specific torque–velocity curves. Functional demand at the peak knee flexion moment was greater in less active older adults than young adults (29.3% [14.3%] vs 24.6% [12.1%]) and increased with walking speed (32.0% [13.9%] vs 22.8% [10.4%]). Functional demand at both knee extension moments increased ∼2% to 3% after exercise. The low functional demand found in this study suggests that healthy adults maintain a reserve of knee extensor strength.
Roger G. Bounds, Steven E. Martin, Peter W. Grandjean, Barbara C. O’Brien, Cindi Inman and Stephen F. Crouse
To test the effect of diet on the short-term lipid response to exercise, fourteen moderately trained (VO2max: 50.2 ± 6.7 ml/kg/min), healthy men (mean age: 28 ± 4 years) were alternately fed a high fat (60±6.7% fat) and a high carbohydrate (63 ± 3.2% carbohydrate) isoenergetic diet for 2 weeks in a randomized crossover design. During the last 4 days of the treatments, fasting total cholesterol, triglyceride. HDL-cholesterol, and