The psychological significance of secondary sexual characteristics in nine- to eleven-year-old girls

82 9-11-year-old girls were seen in order to study the onset of puberty as represented by breast and pubic hair growth. Girls filled out self-report scales, mothers rated their daughters' breast and pubic hair development using schematic representations of the Tanner stages, and height was measured by a nurse practitioner. Breast growth, but not pubic hair growth, was expected to be associated with a positive body image, positive peer relationships, superior adjustment, and the rating of adult roles as important (marriage, children, and careers). These expectations were confirmed for all but the adult role measures. Controlling for pubic hair growth did not alter the findings for breast development. Associations with height also were examined. Height was linked to superior adjustment and career importance. These findings are discussed in terms of possible roles that different pubertal events may play in the self-definitions of young adolescents as well as the meaning of various physical changes to the girl and to others.     

Memory for Preselected and Constrained Short Movements

Abstract

The present experiment investigated the recall of terminal location and distance of both preselected and constrained short movements (12 cm ± 4 cm approximately) following 5 second and 30 second unfilled retention intervals. Systematic alteration of the magnitude and direction of the starting position for recall movements revealed that the distance moved markedly interfered with the recall of the terminal location, but distance was essentially recalled independently of terminal location. Recall of distance was superior to terminal location for both the unfilled retention intervals, and there was a decrease in location recall performances following the longer 30 second delay when compared to recall attempts after the shorter 5 second delay. The Findings are discussed in terms of recent proposals to account for the memory for, and control of, discrete limb movements.     

Effects of agonist–antagonist complex resistance training on upper body strength and power development

Abstract

The objective of this study was to examine the chronic effects on strength and power of performing complex versus traditional set training over eight weeks. Fifteen trained males were assessed for throw height, peak velocity, and peak power in the bench press throw and one-repetition maximum (1-RM) in the bench press and bench pull exercises, before and after the eight-week programme. The traditional set group performed the pulling before the pushing exercise sets, whereas the complex set group alternated pulling and pushing sets. The complex set training sessions were completed in approximately half the time. Electromyographic (EMG) activity was monitored during both test sessions in an attempt to determine if it was affected as a result of the training programme. Although there were no differences in the dependent variables between the two conditions, bench pull and bench press 1-RM increased significantly under the complex set condition and peak power increased significantly under the traditional set condition. Effect size statistics suggested that the complex set was more time-efficient than the traditional set condition with respect to development of 1-RM bench pull and bench press, peak velocity and peak power. The EMG activity was not affected. Complex set training would appear to be an effective method of exercise with respect to efficiency and strength development.     

The relationship between inertial measurement unit-derived ‘force signatures’ and ground reaction forces during cricket pace bowling

Abstract

This study assessed the reliability and validity of segment measured accelerations in comparison to front foot contact (FFC) ground reaction force (GRF) during the delivery stride for cricket pace bowlers. Eleven recreational bowlers completed a 30-delivery bowling spell. Trunk- and tibia-mounted inertial measurement units (IMUs) were used to measure accelerations, converted to force, for comparisons to force plate GRF discrete measures. These measures included peak force, impulse and the continuous force–time curve in the vertical and braking (horizontal) planes. Reliability and validity was determined by intra-class correlation coefficients (ICC), coefficient of variation (CV), Bland–Altman plots, paired sample t-tests, Pearson’s correlation and one-dimensional (1D) statistical parametrical mapping (SPM). All ICC (0.90–0.98) and CV (4.23–7.41%) were acceptable, except for tibia-mounted IMU braking peak force (CV = 12.44%) and impulse (CV = 18.17%) and trunk vertical impulse (CV = 17.93%). Bland–Altman plots revealed wide limits of agreement between discrete IMU force signatures and force plate GRF. The 1D SPM outlined numerous significant (p < 0.01) differences between trunk- and tibia-located IMU-derived measures and force plate GRF traces in vertical and braking (horizontal) planes. The trunk- and tibia-mounted IMUs appeared to not represent the GRF experienced during pace bowling FFC when compared to a gold-standard force plate.     

Interpreting the differences: A reply to Kaufman

Kaufman's critique of our article was based on a misunderstanding of our purpose and procedures. This reply clarifies those points and suggests further areas of concern regarding the McCarthy Screening Test.