Physical fitness and performance. Fatigue responses during repeated sprints matched for initial mechanical output

PURPOSE: To compare muscle fatigability during two sets of repeated cycling sprints matched for initial mechanical output in a nonfatigued and fatigued state. METHODS: Eight young men performed 10, 6-s all-out sprints on a cycle ergometer interspersed with 30 s of recovery, followed, after 6 min of passive recovery, by five 6-s sprints, again interspersed by 30 s of recovery. RESULTS: On the basis of total work (TW), performance in sprint 11 (79.8 +/- 4.8 J.kg) was not significantly different to performance in sprint 4 (80.3 +/- 5.3 J.kg; P = 0.81). The decrease in TW for the five sprints after sprint 4 (i.e., sprints 4 to 8) averaged 14.5% (P < 0.001), which was significantly less than the decrement in TW from sprints 11 to 15 (20.3%; P < 0.05). Despite no significant differences in TW values achieved in sprints 4 and 11, the amplitude of the electromyogram (EMG) signal (i.e., root mean square (RMS)) recorded during sprint 11 (0.398 +/- 0.03 V) was 12.0% lower (P < 0.05) than in sprint 4 (0.452 +/- 0.02 V). In contrast, values of EMG median frequency (MF) recorded during sprint 4 (85.5 +/- 5.5 Hz) and 11 (89.3 +/- 7.2 Hz) were not significantly different (P = 0.33). However, the rate of decrease in EMG activity (i.e., RMS and MF) was similar for the two set of sprints. CONCLUSIONS: These findings suggest that previous fatiguing repeated-sprint exercise, followed by a rest period, induces greater fatigability during subsequent repeated-sprint exercise, regardless of the initial mechanical output, and that these changes are associated with acute neuromuscular adjustments.     

Marital status,gender and cardiovascular mortality: Behavioural,psychological distress and metabolic explanations

The intermediate processes through which the various unmarried states can increase the risk of subsequent cardiovascular disease mortality are incompletely understood. An understanding of these processes and how they may vary by gender is important for understanding why marital status is strongly and robustly associated with subsequent cardiovascular disease. In a prospective study of 13,889 Scottish men and women (mean age 52.3, Standard Deviation: 11.8 yrs, range 35–95, 56.1% female) without a history of clinically diagnosed cardiovascular disease, we examined the extent to which health behaviours (smoking, alcohol, physical activity), psychological distress (General Health Questionnaire-12 item) and metabolic dysregulation (obesity levels, and the presence of hypertension and diabetes) account for the association between marital status and cardiovascular mortality. There were 258 cardiovascular deaths over an average follow up of 7.1 (Standard Deviation = 3.3) years. The risk of cardiovascular mortality was greatest in single, never married men and separated/divorced women compared with those that were married in gender stratified models that were adjusted for age and socio-economic group. In models that were separately adjusted, behavioural factors explained up to 33%, psychological distress explained up to 10% and metabolic dysregulation up to 16% of the relative change in the hazard ratios in the observed significant associations between marital status and cardiovascular mortality. Behavioural factors were particularly important in accounting for the relationship between being separated/divorced and cardiovascular mortality in both men and women (33% and 21% of the relative change in the hazard ratios, respectively). The findings suggest that health behaviour, psychological distress and metabolic dysregulation data have varying explanatory power for understanding the observed relationship between cardiovascular disease mortality and unmarried states.     

Blood levels of donor-specific human leukocyte antigen antibodies after renal transplantation: resolution of rejection in the presence of circulating donor-specific antibody

BACKGROUND: Accommodation to antibody is an important mechanism in successful ABO-incompatible transplantation, but its importance in human leukocyte antigen (HLA) antibody-incompatible transplantation is less clear, as sensitive techniques facilitating daily measurement of donor-specific HLA antibodies (DSAs) have only recently been developed. METHODS: We report 24 patients who had HLA antibody-incompatible kidney transplantation (21 living donors, 3 deceased), 21 of whom had pretransplant plasmapheresis. Eight had positive complement-dependent cytotoxic (CDC) crossmatch (XM) pretransplant plasmapheresis, nine had positive flow cytometric (FC) XM, and seven had DSA detectable by microbead analysis only. After transplant, DSA levels were monitored closely with microbead assays. RESULTS: Rejection occurred in five of eight (62.5%) CDC-positive cases, in three of nine (33%) FC-positive cases, and in two of seven (29%) of microbead-only cases at a median of 6.5 days after transplantation. Resolution occurred at a median of 15 days after transplantation, in 8 of 10 cases when the microbead level of DSA had median fluorescence intensity (MFI) >2000 U, in 6 of 10 when the microbead MFI >4000 U. In 8 of 10 cases, the microbead MFI at the time of resolution was greater than at the onset. DSA did not always cause clinical rejection. In five cases with a posttransplant DSA peaking at MFI >2000 U on microbead assay, rejection did not occur. CONCLUSION: These data suggest that the dominant method of successful transplantation was function of the transplant in the presence of circulating DSA, and they also define the period during which this occurred.     

Continuous phenobarbital treatment leads to recurrent plantar fibromatosis

Despite contrary recommendations by expert opinion and international guidelines phenobarbital remains the most widely prescribed anticonvulsant worldwide. Although associated connective tissue disorders were described in a timely way after its introduction, the association between plantar fibromatosis--also called Ledderhose syndrome--and phenobarbital seems not to be well known in general. Our case series uniquely demonstrates that continuous phenobarbital treatment leads to recurrent plantar fibromatosis and may result in long-term disability and numerous unnecessary operations. In general, the association between connective tissue disorders and phenobarbital most prominently appears in adult patients of northern European descent. However, our case series and data from the literature suggest that patient groups less susceptible to connective tissue disorders may as well develop Ledderhose syndrome or other associated syndromes as Dupuytren's contractures, frozen shoulder, Peyronie's disease or complex regional pain syndrome in the course of phenobarbital treatment.     

Application of flow cytometry to monitor antibody levels in ABO incompatible kidney transplantation

Current methods of measuring ABO antibody levels based on the hemagglutination (HA) titers have the disadvantages of relatively poor reproducibility and do not offer fine discrimination of antibody concentration. We therefore developed a simple and rapid method of measuring ABO antibody levels using flow cytometry (FC). For validation, we analyzed plasma samples from 79 blood donors. Both IgM and IgG were detected and measured with IgG essentially restricted blood group O donors. Forty-two successive samples were collected from a patient with blood group O undergoing antibody removal and subsequent transplantation from a group A2 donor and tested by both HA and FC. Changes in IgG measured by FC (relative median fluorescence) correlated well with HA titers and importantly rejection episodes were preempted by a rising relative median fluorescence. The method allowed quantitative discrimination in the range of antibody levels relevant to ABO incompatible transplantation and has the advantages over HA of objective measurement and reproducibility.     

Social support and regular physical activity: Does planning mediate this link?

Objectives . Social support for physical activity is reliably associated with regular physical activity, however the social cognitive processes, particularly post‐intentional processes, that can explain this link have not been well characterized. In this study, we examined the extent to which the relationship between social support for physical activity and subsequent physical activity can be accounted for by planning processes. Design and method . The design was prospective observational and the sample consisted of 903 university students. Participants completed standard theory of planned behaviour, planning, and physical activity measures at 2 time points, approximately 7 weeks apart. A gender stratified multiple mediation model was conducted to test the study hypotheses. Results . A significant interaction between social support and gender was observed. This indicated that lower levels of social support for physical activity were associated with lower levels of physical activity at Time 2, for women only. In multiple mediation analysis, this was partly explained by the indirect effects of social support through perceived behavioural control and coping planning. Conclusion . These findings highlight the importance of interpersonal processes in understanding the post‐intentional social cognitive determinants of regular physical activity. It is likely that planning processes relating to physical activity are often influenced by those in the ongoing immediate social environment who support this behaviour. Future development of theory and interventions should take account of the socially interactive nature of planning processes.