Contrasting gender differences on two measures of exercise dependence.

OBJECTIVE: Recent studies using multidimensional measures have shown that men (Exercise Dependence Scale; EDS-R) are more exercise-dependent than women, whereas others have found that women (Exercise Dependence Questionnaire; EDQ) are more exercise-dependent than men. This study investigated whether there may be sex differences in exercise dependence or whether the questionnaires may be measuring different dimensions of exercise dependence. DESIGN: Regular exercisers voluntarily completed the EDS-R, EDQ and Drive for Thinness (DFT) subscale before or after a workout. SETTING: A local health club in the eastern USA. PARTICIPANTS: Male (n = 102) and female (n = 102) exercisers completed the three questionnaires, but 11 participants (1 man, 10 women) were excluded from further analysis because scores indicated possible secondary exercise dependence (eating disorder). PRIMARY OUTCOME MEASURES: Eight subscales of the EDQ, seven subscales of the EDS, the DFT subscale, and several demographic variables served as dependent measures. RESULTS: A multivariate analysis of variance (MANOVA) on the EDS-R showed that men were significantly higher than women on the Withdrawal, Continuance, Tolerance, Lack of Control, Time, and Intention Effect subscales. Another MANOVA on the EDQ indicated that women scored significantly higher than did men on the Interference, Positive Rewards, Withdrawal, and Social Reasons subscales. Statistical analysis using t tests revealed that men had significantly higher total EDS-R scores than women, but women had significantly higher EDQ and DFT scores. CONCLUSION: These results suggest that both questionnaires measure different aspects of exercise dependence that favour either gender. It remains for further research to determine whether these instruments are equally viable for measurement of ED in both men and women.

Abnormal neurotransmission in mice lacking synaptic vesicle protein 2A (SV2A).

Synaptic vesicle protein 2 (SV2) is a membrane glycoprotein common to all synaptic and endocrine vesicles. Unlike many proteins involved in synaptic exocytosis, SV2 has no homolog in yeast, indicating that it performs a function unique to secretion in higher eukaryotes. Although the structure and protein interactions of SV2 suggest multiple possible functions, its role in synaptic events remains unknown. To explore the function of SV2 in an in vivo context, we generated mice that do not express the primary SV2 isoform, SV2A, by using targeted gene disruption. Animals homozygous for the SV2A gene disruption appear normal at birth. However, they fail to grow, experience severe seizures, and die within 3 weeks, suggesting multiple neural and endocrine deficits. Electrophysiological studies of spontaneous inhibitory neurotransmission in the CA3 region of the hippocampus revealed that loss of SV2A leads to a reduction in action potential-dependent gamma-aminobutyric acid (GABA)ergic neurotransmission. In contrast, action potential-independent neurotransmission was normal. Analyses of synapse ultrastructure suggest that altered neurotransmission is not caused by changes in synapse density or morphology. These findings demonstrate that SV2A is an essential protein and implicate it in the control of exocytosis.

Measurement of exercise dependence in bodybuilders.

OBJECTIVE: The purpose of this study was to explore exercise dependence in bodybuilders, and undertake preliminary validation of a measurement instrument. EXPERIMENTAL DESIGN: A comparative analysis of self-report indices between groups. PARTICIPANTS: Forty-seven bodybuilders, 31 individuals who weight trained for general fitness purposes and 24 weightlifters participated in the study. MEASURES: Each subject completed the following: demographic information, bodybuilding-specific versions of the social identity and exclusivity scales of the Athletic Identity Measurement Scale, the physical strength and body attractiveness subscales of the Physical Self-Perception Profile, a short form of the Marlowe-Crowne Social Desirability Scale, and a 9-item Bodybuilding Dependence Scale. RESULTS: Factor analysis on the BDS revealed 3 subscales (social dependency, training dependency and mastery) which accounted for 68.4% of the variance. Internal consistency was satisfactory for each subscale (Chronbach's alpha = 0.76, 0.75 and 0.78 respectively). The BDS social dependency and PSPP body attractiveness scores of the bodybuilders were higher than those of the weightlifters, whose scores were higher than those of the fitness trainers. The bodybuilders scored higher on both AIMS subscales than the other groups. The bodybuilders and weightlifters scored higher on PSPP physical strength than the fitness trainers. BDS social dependency correlated with both AIMS and both PSPP subscales, and BDS training dependency correlated with AIMS exclusivity. All three BDS subscales correlated with training frequency. Discriminant analysis found the combination of AIMS social identity, BDS social dependency and years training experience enabled correct classification of 92% of the respondents. CONCLUSIONS: These results support the construct and concurrent validity of the BDS social dependency subscale, but do not wholly support the validity of the other two subscales.

Calbindin-D28k immunoreactivity within the cholinergic and GABAergic projection neurons of the basal forebrain.

The purpose of this study was to determine whether the calcium binding protein calbindin-D28k was present within the cortically projecting basal forebrain neurons of various rodent species not previously examined. Double-label immunocytochemistry was performed using antibodies against calbindin-D28k and choline acetyltransferase (ChAT) to detect the presence of the calcium binding protein within the cholinergic basal forebrain neurons of various species (i.e., humans, rats, mice, gerbils, guinea pigs). Antibodies against calbindin-D28k, ChAT, and glutamic acid decarboxylase (GAD) were also used in combination with a cortically injected retrograde tracer (Fluoro-Gold) to determine whether calbindin-D28k immunoreactive (IR) neurons within the basal forebrain projected to the frontoparietal cortex. The nucleus basalis of rats was examined for the presence of calbindin-D27k IR within the GABAergic basal forebrain neurons. All species examined had cholinergic, GABAergic, and calbindinergic neurons within the basal forebrain; however, only the cholinergic neurons within the human nucleus basalis of Meynert were also immunoreactive for calbindin-D28k. Although all rodent species had both cholinergic and GABAergic basal forebrain neurons that contained the Fluoro-Gold dye, none of the calbindin-D28k IR neurons, detected using monoclonal and polyclonal antibodies, were found to contain the retrograde tracer. These results indicate that the cortically projecting cholinergic and GABAergic basal forebrain neurons within these rodent species do not contain calbindin-D28k. Therefore, age- and disease-related loss of nucleus basalis projection neurons may not be mediated by alterations in calbindin-D28k.(ABSTRACT TRUNCATED AT 250 WORDS)

The self-efficacy-performance link in maximum strength performance.

To examine whether manipulating self-efficacy affects strength performance on a bench press, and to see if these situation-specific changes would affect levels of physical self-efficacy, 24 undergraduates untrained in weightlifting were randomly assigned to three groups: 'light', who lifted less weight than they believed; 'heavy', who lifted more weight than they believed; and control, for whom there was no manipulation. Self-efficacy measures were taken before and after the manipulation. Physical self-efficacy was measured using the Physical Self-Efficacy Scale (PSE). 'Light' subjects lifted significantly greater increases in weight than the other subjects. 'Heavy' subjects significantly decreased self-efficacy following the manipulation. Initial self-efficacy was found to be a significant predictor of baseline maximum, while manipulated self-efficacy was significant for performance change. The PSE scores did not change pre- to post-study. The results suggest that self-efficacy is a situation-specific construct which can be manipulated, and which relates to both past performance experience and future performance.

Iris pigmentation and fractionated reaction and reflex time.

Recent investigations indicate that an iris pigmentation-motor behavior exists, but may be limited to the reaction time component of a motor task. The absence of differences in peripheral nervous conduction (Wolf and Landers, 1978) suggests that a central nervous system mechanism may be operating, possibly dependent on the characteristics of neuromelanin or catecholamine turnover. Experiment 1 tested this notion by fractionating simple reaction time into the premotor and motor components by electromyography. ANOVA revealed that dark-eyed subjects had faster total reaction times and premotor times, but only the premotor time component approached significance (p < 0.07). Experiment 2 fractionated patellar reflex time of light-eyed and dark-eyed subjects into reflex lagency and motor components. There were no eye color differences for any of the reflex time measures. The results of Experiments 1 and 2 support a central nervous system explanation for the iris pigmentation-reaction time phenomenon.