Does self-efficacy predict performance in experienced weightlifters?

Previous studies that have examined self-efficacy-performance relationships have used novice performers. It is unclear if these findings would generalize to "experienced" performers. Based on Bandura's self-efficacy theory, this study was designed to investigate (a) the effects of false information feedback on self-efficacy beliefs and subsequent weightlifting performance, and (b) whether self-efficacy or past performance is most related to subsequent weightlifting performance. Experienced weightlifters engaged in six performance sessions, each consisting of a one-repetition-maximum bench press. Male subjects (N = 36) were randomly assigned to one of three treatment groups: accurate performance information, false information that they lifted more than their actual lift, or false information that they lifted less than their actual lift. Before each session, subjects indicated the amount of weight they were 100%, 75%, and 50% confident they could lift. Results replicated existing research findings regarding deception and performance; false positive feedback increased future bench press performance. In addition, results indicated that past weightlifting performance accounted for nearly all of the variance in subsequent performance. This finding is discussed in light of the difficulty in extending the predictions of self-efficacy theory to sport settings where athletes have gained experience by undergoing repeated training trials.

Effect of supplemental ascorbic acid in a case of torsion dystonia.

Determinations of various catecholamines and their metabolites have been performed on 24-hr urine collecions obtained from a patient with torsion dystonia and compared to values obtained in a control population. This study was initiated following significant symptomatic worsening by the patient with supplemental ascorbic acid at a dosage of 2 g/day. Compared to base-line values, there resulted no significant alteration in urinary excretion of DOPA, dopamine, norepinephrine, epinephrine, or VMA for either the patient or a group of controls, receiving 1 g/day vitamin C. MHPG is the glycol metabolite of norepinephrine, and is produced both in central and systemic tissues, whereas VMA is not synthesized in brain. The MHPG excretion for the patient increased 150% with supplemental ascorbate, whereas the control individuals demonstrated a mean increase of 19.6%. It is possible that the symptomatic worsening by the patient and the increased excretion of MHPG in response to supplemental ascorbic acid are causally related. Ascorbic acid affects catecholamine biosynthesis at two metabolic loci; it is the necessary cofactor for dopamine-beta-hydroxylase and, by maintaining biopterin in reduced form, facilitates tyrosine hydroxylase holoenzyme activity. Thus, the vitamin may have effected increased central synthesis or turnover of norepinephrine, or both, with resultant clinical worsening.