All I really needed to know I learned during gastrulation

Note from the Editor     

Differences in activation patterns between eccentric and concentric quadriceps contractions.

Previous studies analysing electromyograms (EMGs) from indwelling electrodes have indicated that fast-twitch motor units are selectively recruited for low-intensity eccentric contractions. The aim of this study was to compare the frequency content of surface EMGs from quadriceps muscles during eccentric and concentric contractions at various contraction intensities. Electromyograms were recorded from the rectus femoris, vastus lateralis and vastus medialis muscles of 10 men during isokinetic (1.05 rad x s(-1)) eccentric and concentric knee extension contractions at 25%, 50%, 75% and 100% of maximal voluntary contraction (MVC) for each contraction mode. Additionally, isometric contractions (70 degrees) were performed at each intensity. The mean frequency and root mean square (RMS) of the surface EMG were computed. Mean frequency was higher for eccentric than concentric contractions at 25% (P < 0.01), 50% (P < 0.01) and 75% (P < 0.05) but not at 100% MVC. It increased with increasing contraction intensity for isometric (P < 0.001) and concentric (P < 0.01) contractions but not for eccentric contractions (P = 0.27). The EMG amplitude (RMS) increased with increasing contraction intensity similarly in each contraction mode (P < 0.0001). Higher mean frequencies for eccentric than concentric contractions at submaximal contraction intensities is consistent with more fast-twitch motor units being active during eccentric contractions.     

Prediction of maximum oxygen consumption from walking, jogging, or running

The purpose of this study was to develop a submaximal, 1.5-mile endurance test for college-aged students using walking, jogging, or running exercise. College students (N = 101: 52 men, 47 women), ages 18-26years, successfully completed the 1.5-mile test twice, and a maximal graded exercise test. Participants were instructed to achieve a "somewhat hard" exercise intensity (rating of perceived exertion = 13) and maintain a steady pace throughout each 1.5-mile test. Multiple linear regression generated the following prediction equation: VO2 max = 65.404 + 7.707 x gender (1 = male; 0 =female) - 0.159 x body mass (kg) - 0.843 x elapsed exercise time (min; walking, jogging orrunning). This equation shows acceptable validity (R = .86, SEE = 3.37 ml x kg(-1) min(-1)) similar to the accuracy of comparable field tests, and reliability (ICC = .93) is also comparable to similar models. The statistical shrinkage is minimal (R(press) = 0.85, SEE(press) = 3.51 ml x kg(-) x min(-1)); hence, it should provide comparable results when applied to other similar samples. A regression model (R =.90, and SEE = 2.87 ml x kg(-1) min(-1)) including exercise heart rate was also developed: VO2 max = 100.162 +/- 7.301 x gender(1 = male; 0 =female) - 0.164 x body mass (kg) - 1.273 x elapsed exercise time -0.156 x exercise heart rate, for those who have access to electronic heart rate monitors. This submaximal 1.5-mile test accurately predicts maximal oxygen uptake (VO2max) without measuring heart rate and is similar to the 1.5-mile run in that it allowsfor mass testing and requires only a flat, measured distance and a stopwatch. Further, it can accommodate a wide range of fitness levels (from walkers to runners).     

Multi-informant assessment of maltreated children: convergent and discriminant validity of the TSCC and TSCYC

OBJECTIVE: This study examined the convergent and discriminant validity of two trauma symptom measures, the Trauma Symptom Checklist for Children (TSCC) [Briere, J. (1996). Trauma Symptom Checklist for Children (TSCC). Odessa, FL: Psychological Assessment Resources] and the Trauma Symptom Checklist for Young Children (TSCYC) [Briere, J. (2005). Trauma Symptom Checklist for Young Children (TSCYC). Odessa, FL: Psychological Assessment Resources]. METHODS: Children's scores on the TSCC and their caretakers' ratings on the TSCYC were analyzed in a study of 310 children presenting to one of two child abuse treatment centers. RESULTS: TSCC and TSCYC scales generally converged in their assessment of symptomatology in maltreated children. Equivalent scales measuring anxiety, depression, anger, dissociation, and sexual concerns were generally most correlated with one another. Similarly, the Posttraumatic Stress-Intrusion (PTS-I) scale of the TSCYC correlated highest with the Posttraumatic Stress (PTS) and Anxiety (ANX) scales of the TSCC, the TSCYC Posttraumatic Stress-Arousal (PTS-AR) scale was correlated with the TSCC ANX scale, and the TSCC PTS scale was most correlated with the TSCYC ANX, PTS-I, and Sexual Concerns (SC) scales. The TSCYC Posttraumatic Stress-Avoidance scale was unrelated to any TSCC scale. Discriminant function analysis revealed that the TSCC PTS scale was the best single predictor of sexual abuse-related PTSD status as identified by the TSCYC. CONCLUSIONS: The TSCC and TSCYC display moderate convergent and discriminant validity with respect to one another, despite different information sources. Nevertheless, the relatively small association between relevant TSCC and TSCYC scales indicates that different symptom informants may have different perspectives on the child's symptomatology; an outcome that may be beneficial when both measures are administered simultaneously. PRACTICE IMPLICATIONS: These results reinforce the notion that both child- and parent/caretaker report measures should be used in the evaluation of traumatized children, so that multiple sources of information can be considered simultaneously. In the current context, administration of the TSCC to the child and the TSCYC to the caretaker, when appropriate (i.e., in children 8-12 years of age) may yield more clinical information on the child's symptomatology than either measure would alone-perhaps especially in cases when one of the two respondents under- or over-reports the child's distress.     

Child peer sexual abuse: preliminary data on outcomes and disclosure experiences

OBJECTIVE: This study compared experiences of children sexually abused by peers to those of children abused by adolescents/adults. Variables examined included perceived negativity of the abuse, self-reported outcomes, overall psychological functioning, and disclosure. METHOD: An archival data set containing retrospective reports of childhood sexual experiences was culled for instances of sexual abuse by child peers and adolescents/adults. An equivalent nonabused comparison group was identified. The Self-Report Outcome Checklist (SROC; Gilbert, 1994b), the MMPI-Hugo Short Form (Hugo, 1971) and a disclosure survey were also retrieved from these data. RESULTS: Compared to abuse by peers, abuse perpetrated by adolescents/adults was more intrusive and intrafamilial. Both groups rated their experiences as equally negative, and reported equally pervasive outcomes. Those abused by adolescents/adults reported significantly higher scores on the Psychopathic Deviate, Psychasthenia, and Schizophrenia scales compared to nonabused controls; similar findings did not emerge for those abused by child peers. Less than a fourth in either abuse group reported disclosing their experience to a parent. Among those who did not disclose, participants abused by child peers anticipated less support from both parents and more anger from their mothers. CONCLUSIONS: The findings suggest that child peer sexual abuse may be associated with adverse outcomes.