The count versus METs relationship for accelerometry was found to be dependent on the type of activity performed, which may be due to the inability of accelerometers to detect increased energy cost from upper body movement, load carriage, or changes in surface or terrain. This may introduce error in attempts to use accelerometry to assess point estimates of physical activity energy expenditure in free-living situations.

No abstract

Explosive devices have been the most frequent cause of traumatic brain injury (TBI) among deployed contemporary U.S. service members. The purpose of this study was to examine the influence of previous cumulative blast exposures (that did or did not result in TBI) on later post-concussion and post-traumatic symptom reporting after sustaining a mild TBI (MTBI). Participants were 573 service members who sustained MTBI divided into four groups by number of blast exposures (1, 2, 3, and 4-10) and a nonblast control group. Post-concussion symptoms were measured using the Neurobehavioral Symptom Inventory (NSI) and post-traumatic stress disorder (PTSD) symptoms using the Post-traumatic Checklist-Civilian version (PCL-C). Results show groups significantly differed on total NSI scores ( p < 0.001), where symptom endorsement increased as number of reported blast exposures increased. Total NSI scores were significantly higher for the 3-and 4-10 blast groups compared with the 1-and 2-blast groups with effect sizes ranging from small to moderate (d = 0.31 to 0.63). After controlling for PTSD symptoms using the PCL-C total score, NSI total score differences remained between the 4-10-blast group and the 1-and 2-blast groups, but were less pronounced (d = 0.35 and d = 0.24, respectively). Analyses of NSI subscale scores using PCL-C scores as a covariate revealed significant between-blast group differences on cognitive, sensory, and somatic, but not affective symptoms. Regression analyses revealed that cumulative blast exposures accounted for a small but significant amount of the variance in total NSI scores (4.8%; p = 0.009) and total PCL-C scores (2.3%; p < 0.001). Among service members exposed to blast, post-concussion symptom reporting increased as a function of cumulative blast exposures. Future research will need to determine the relationship between cumulative blast exposures, symptom reporting, and neuropathological changes.

Past experience of MTBI may be a risk factor for increased symptom difficulty for several months postinjury. Clinicians should ascertain lifetime history of brain injury when evaluating patients for MTBI.

Baseline GOS score was a reliable predictor of outcome in patients with an initial score of 5 (no disability) or 4 (mild disability), but not in patients with an initial score of 3 (severe disability). Patients who remained unconscious for more than 24 hours did not have significantly lower outcome scores than those who experienced loss of consciousness for less than 24 hours at 15 months postinjury. Interestingly, the duration of unconsciousness did not affect the likelihood of an improved score during the study period in patients with a GOS score of 3 or 4 at baseline. An updated evaluation conducted after the early phases of treatment is needed to provide a realistic prognosis of severe TBI.

Maximal oxygen uptake (VO2max) in females, expressed as ml x kg(-1) x min(-1), declines steadily during the first three decades of life. The contribution of diminished cardiovascular function to this apparent fall in aerobic fitness is unknown. Cardiac responses to maximal cycle exercise were compared in 24 premenarcheal females (mean age 11.7 years) and 17 young adult women (mean age 27.4 years) using Doppler echocardiography. Mean VO2max was 40 ml x kg(-1) x min(-1) and 34.7 ml x kg(-1) x min(-1) in the girls and women, respectively (p < 0.05). When VO2max was expressed relative to allometrically-derived mass(0.52), however, no significant difference was observed in aerobic fitness between the two groups. Similar allometric analyses revealed no significant differences in average maximal cardiac output (10.50 vs 10.07 L x min(-1) BSA(-1.11) for girls and women, respectively) nor maximal stroke volume (53 vs 56 ml BSA(-1.13) respectively). These findings suggest that 1) allometric scaling is important in eliminating the effects of body size on VO2max, 2) body dimension differences can account for variations in VO2 in young females, and 3) cardiac functional reserve is similar in premenarcheal girls and young adult women.

Needs for services following TBI are associated with poor symptomatic and functional outcomes and may persist for years after injury in military service members and veterans. The study suggests service members' needs post TBI for improved cognition, support for emotional issues, and resources for vocational skills. Information about available services should be made accessible to those recovering from TBI to reduce the incidence of long-term unmet needs.

These findings indicate that 1) maximal stroke volume is the critical determinant of the high VO2max in child cyclists and 2) factors that influence resting stroke volume are important in defining VO2max differences between child endurance athletes and untrained boys.