Lower extremity power during the squat jump with various barbell loads

The purpose of this study was twofold: (1) to determine the barbell load that maximised the system power as well as the ankle, knee, and hip joint powers during the squat jump, and (2) to compare the system powers computed from two different methods: the centre of mass (COM) method and the barbell method. Seven male throwers were recruited in this study. The system power (COM method) and the ankle, knee, and hip joint powers were determined with the load incrementally set at 0%, 10%, 30%, 50%, 70%, and 90% of one repetition maximum. The largest system power was observed at the load of 30% (p < 0.008) while the largest ankle and knee powers were observed at 70% and 0% (p < 0.05). The barbell method overestimated the system power (p < 0.001) when compared to the COM method. It was concluded that the barbell method could influence load optimisation in squat jump. The optimal barbell load which maximised the system power did not maximise the ankle, knee, or hip power simultaneously.     

Population differences in constructive memory

An experiment was conducted to evaluate constructive memory in fourth-grade low-SES black and middle-SES white children. The children were read nine short passages; each passage was composed of two premise statements and a filler sentence. The children were tested by a recognition procedure. Thirty-six test sentences were presented randomly. Four sentences were associated with each passage (true premise, false premise, true inference, and false inference). Subjects were asked to make yes/no recognition decisions based on whether the test sentence was identical to a sentence presented at study. Middle-SES white children made few errors, except to true inference test sentences. This pattern of performance is consistent with the constructive view of memory. Low-SES black children also had a high error rate to true inference items. However, this outcome may not reflect constructive memory because they also had a high error rate to some of the other types of test sentences.