The episodic/semantic memory distinction as an heuristic in the study of instructional effects on cognitive structure

Previous attempts to measure the effects of instruction on students' cognitive structure have produced inconsistent and ambiguous findings. One reason may be that researchers have not distinguished between well-learned, abstracted information and memorized facts or formulas. Using the distinction between episodic and semantic memory as an heuristic, a procedure was designed to increase the likelihood that student performance on structure tasks was indicative of semantic rather than episodic memory. Significant correlations between measures of cognitive structure and performance on achievement test items were observed. In addition, partial correlations revealed that the measures of cognitive structure are correlated with the achievement items tapping higher-order cognitive processes and not with items tapping lower-order processes. These results are interpreted as supporting the argument that related research needs to be guided by theory-based definitions of cognitive structure.     

Acute effects of passive muscle stretching on sprint performance

The results of previous research have shown that passive muscle stretching can diminish the peak force output of subsequent maximal isometric, concentric and stretch-shortening contractions. The aim of this study was to establish whether the deleterious effects of passive stretching seen in laboratory settings would be manifest in a performance setting. Sixteen members (11 males, 5 females) of a Division I NCAA track athletics team performed electronically timed 20 m sprints with and without prior stretching of the legs. The experiment was done as part of each athlete's Monday work-out programme. Four different stretch protocols were used, with each protocol completed on a different day. Hence, the test period lasted 4 weeks. The four stretching protocols were no-stretch of either leg (NS), both legs stretched (BS), forward leg in the starting position stretched (FS) and rear leg in the starting position stretched (RS). Three stretching exercises (hamstring stretch, quadriceps stretch, calf stretch) were used for the BS, FS and RS protocols. Each stretching exercise was performed four times, and each time the stretch was maintained for 30 s. The BS, FS and RS protocols induced a significant (P < 0.05) increase (approximately 0.04 s) in the 20 m time. Thus, it appears that pre-event stretching might negatively impact the performance of high-power short-term exercise.