James B. Crabbe

Emotional responsiveness after low- and moderate-intensity exercise and seated rest.

PURPOSE Few experiments have been conducted regarding the effects of exercise on emotional responsiveness. The aim of this experiment was to determine whether anxiety-reducing conditions of low- and moderate-intensity cycling exercise lead to changes in emotional responsiveness to pictures designed to elicit pleasant, neutral, and unpleasant emotions. METHODS 24 healthy college women completed counterbalanced conditions of 25 min of low- and moderate-intensity cycling exercise and seated rest. Indices of emotional responsiveness, including the acoustic startle eyeblink and corrugator supercilii responses, as well as baseline corrugator supercilii electromyographic (EMG) activity, were measured immediately before and 20 min after each condition while participants viewed pleasant, neutral, and unpleasant pictures from the International Affective Picture System. RESULTS State anxiety was significantly reduced 20 min after each condition. Startle response magnitude was modulated by the affective content of the pictures and was reduced after each condition in response to each type of picture. Baseline corrugator EMG activity did not change after seated rest but decreased in an exercise intensity-dependent fashion after cycling. Corrugator EMG responses during the pictures were not different between conditions or from pre- to post-conditions. CONCLUSION The findings suggest that cycling exercise results in decreased baseline activity of facial muscles involved in the expression of emotion but does not lead to changes in appetitive or defensive responses to emotional stimuli. Furthermore, anxiolytic conditions of low- and moderate-intensity cycling exercise and seated rest are related to decreased startle magnitude in healthy college women.

The influence of acute exercise on sleep following high caffeine intake

The purpose of this study was to examine the influence of vigorous acute exercise on nocturnal sleep that had been disrupted by high doses (1200 mg) of caffeine throughout the daytime. Eight moderately fit, young males with a history of moderate caffeine use completed four conditions in a within-subjects, counterbalanced design: 60 min of (i) cycling at 60% VO(2peak) or (ii) quiet rest following placebo consumption, (iii) cycling, or (iv) quiet rest following the consumption of a high dose of caffeine. Each condition was performed twice from 1615-1715 h and followed by all-night polysomnographic recording. Subjects consumed two blinded 200-mg capsules of either lactose placebo or caffeine upon awakening, at 1600 h, and 2 h before bedtime. State anxiety was assessed at bedtime. Criterion scores consisted of the mean data across the two days in each condition. Sleep data were analyzed using a condition (exercise versus quiet rest) by drug (caffeine versus placebo) repeated-measures ANOVA. Caffeine-elicited sleep disturbance that was less than previously reported. Exercise attenuated selected sleep disturbances to a small degree. In general, the effects of exercise on sleep were not greater following caffeine compared to placebo. Indeed, increases in slow-wave sleep after exercise were approximately 1/3 smaller following caffeine treatment compared to placebo.

Acute exercise reduces caffeine-induced anxiogenesis.

PURPOSE This experiment examined the influence of acute exercise on anxiety following caffeine-induced elevations in self-rated anxiety. METHODS Eleven physically active, moderately fit males aged 25.1 +/- 3.8 yr completed four conditions in a within-subject, counterbalanced design involving 60 min of (1) cycling at 60% VO2peak or (2) quiet rest following placebo consumption (800 mg of lactose), as well as (3) cycling at 60% VO2peak and (4) quiet rest following 800 mg of caffeine. State anxiety and blood pressure were assessed 10 min before and 10 and 20 min after the conditions. RESULTS A main effect for drug (caffeine vs placebo) determined by repeated measures ANOVA, (F(1,8) = 9.77; P = 0.01), indicated that state anxiety was elevated by caffeine. Drug effects were not obtained for blood pressure. Experimental hypotheses were tested by drug-by-condition (exercise vs quiet rest)-by-time (10 and 20 min postcondition) repeated measures ANOVA of change scores from the precondition baseline. A main effect for drug (F(1,8) = 5.81; P = 0.043) indicated that reductions in state anxiety were larger after caffeine ingestion. A condition-by-time effect (F(1,8) = 5.02; P = 0.055) indicated greater reductions in state anxiety 20 min after exercise compared with quiet rest. A condition effect for systolic blood pressure (F(1,10) = 4.56; P = 0.058) and condition-by-time interactions for diastolic (F(1,10) = 8.87; P = 0.014) and mean arterial blood pressures (F(1,10) = 8.46; P = 0.016) indicated reductions after exercise but not after quiet rest following both caffeine and placebo. CONCLUSIONS We conclude that exercise can reduce anxiety elevated by a high dose of caffeine.

Emotional & electroencephalographic responses during affective picture viewing after exercise.

We examined the effects of 30 min of cycling exercise at a moderate intensity of 50% peak oxygen uptake, compared to 30 min of rest, on changes in emotional responses to pictorial foreground stimuli that reliably elicit unpleasant, neutral, and pleasant affect. Emotional responses were measured by self-reports of valence (unpleasant to pleasant) and arousal (low to high) and by hemispheric asymmetry (R-L) of frontal and parietal brain electroencephalographic (EEG) activity in 13 females and 21 males (24+/-3 y). Compared to after rest, self-reports of arousal in response to unpleasant slides were diminished after exercise, but self-reports of valence and frontal asymmetry of alpha frequencies were generally unchanged. Even so, there were differential responses in asymmetry in the beta frequencies in the frontal region and for alpha and beta frequencies in the parietal region, indicative of decreased activity in the left frontal and right parietal regions after exercise compared to after rest. We conclude that moderately intense cycling exercise generally does not alter emotional responding to pleasant and neutral pictures, but may reduce emotional arousal during exposure to unpleasant stimuli.

Antidepressant-like effects of physical activity versus imipramine: Neonatal clomipramine model.

The clomipramine (CLI) model of depression was used to examine whether exercise has antidepressant-like effects. Male Sprague-Dawley pups were injected with CLI-HCl (40 mg/kg/day) from age 8 to 21 days. At age 4 weeks, rats were assigned to one of five conditions: (1) sedentary; (2) 24-h access to an activity wheel; (3) sedentary + imipramine-HCl (10 mg/kg/twice daily) during the last 10 days of the experiment; (4) wheel running + imipramine; (5) daily treadmill running. At age 16 weeks, rats underwent sex behavior testing. The rate of copulation was lower in the sedentary CLI-treated group than in the saline controls. Reductions in measures of sexual arousal and levels of monoamines were consistent with the CLI model of depression but were smaller than expected. Wheel runners had more frequent mounts, intromissions, and ejaculations relative to the other groups. Norepinephrine levels in brain frontal cortex were higher in all running groups and the imipramine group relative to the sedentary CLI and saline groups. Radioligand [125I] binding density (BMax) of β-adrenoceptors in frontal cortex was lower for the wheel running, imipramine, and wheel running + imipramine groups. Activity wheel running equaled imipramine treatment for increasing norepinephrine and decreasing BMax, and it exceeded imipramine treatment for increasing male copulatory performance. We conclude that activity wheel running favorably influences several hallmark pharmaco-physiological and behavioral measures of an antidepressant effect but did not alter sexual arousal, a surrogate measure of anhedonia. The weaker than expected effects of CLI treatment indicate that the generalizability of the CLI model requires further elucidation using convergent behavioral, biochemical, and pharmacological measures.

Failure of neonatal clomipramine treatment to alter forced swim immobility: chronic treadmill or activity-wheel running and imipramine.

We examined whether chronic running on a treadmill or activity wheel would attenuate the increased swim immobility that has been reported after neonatal clomipramine (CLI) treatment. Male Sprague-Dawley pups (N = 60) were injected with the monoamine reuptake inhibitor clomipramine hydrochloride (40 mg/kg per day i.p.) from 8 to 21 days of age. Another group (N = 12) received saline vehicle. At age 4 weeks, the CLI pups were randomly assigned to experimental conditions: (1) sedentary; (2) 24-h access to an activity wheel; (3) sedentary that received the antidepressant drug imipramine hydrochloride (10 mg/kg twice daily) during the last 10 days of the experiment; (4) activity wheel + imipramine; (5) treadmill running (30 m/min for 1 h at 0 degrees incline, 6 days/week). At age 16 weeks, rats underwent the Porsolt swim test 48 h after the last imipramine injection and/or the last exercise session. The increase in swim immobility among CLI-treated rats was small (one quarter of SD) and not statistically significant (p>0.10). The results are not consistent with our previous finding of antidepressant-like effects of activity-wheel running based on brain noradrenergic adaptations and enhanced male copulatory performance after neonatal CLI treatment. The lack of change in swim performance after clomipramine questions the generalizability of the CLI model of depression and the validity of the forced swim test as a behavioral measure of depression when it is used after neonatal CLI injection or chronic activity-wheel running.