Betsy A. Keller

Impact of rapid weight loss on cognitive function in collegiate wrestlers.

PURPOSE The purpose of this study was to examine the effects of rapid weight loss (RWL) on cognitive function in collegiate wrestlers. METHODS Wrestlers (N = 14) and controls (N = 15) were college-aged males who were tested at three different times: baseline, RWL, and rehydration. Wrestlers practiced RWL in preparation for competition while controls maintained normal body weight and dietary practices throughout the study. At each test session, blood glucose, hemoglobin (Hgb), hematocrit (Hct), plasma volume (PV), and body weight were measured. Subjects also completed mood and hypoglycemic profiles as well as five short cognitive tests. RESULTS Two-way ANOVA and post-hoc tests revealed poorer performance for wrestlers than controls in two recall tests as well as greater mood negativity for the wrestlers after RWL. With RWL, between group differences were also evident in hypoglycemic profile, blood glucose, PV, and body weight. All measures returned to near baseline values after rehydration, suggesting that all physiological and cognitive effects associated with RWL were reversible. It is possible that precompetition anxiety may partially explain the results. CONCLUSIONS RWL in collegiate wrestlers before a competition appears to cause physiological effects that are accompanied by transient mood reduction and impairment of short-term memory. The potential negative impact of this practice on the student-athlete should be considered.

Noninvasive estimation of the maximal lactate steady state in trained cyclists

PURPOSE The purposes of this study were to estimate noninvasively the maximal lactate steady state (MLSS) in trained cyclists on a windload simulator with a velocity based technique and to determine whether the HR at MLSS (HR(MLSS)) elicited a similar blood lactate concentration (BLC) during field testing. METHODS To determine and verify MLSS, 10 male cyclists performed five to seven laboratory trials on separate days, including a VO2max test; a 5-km time trial (TT); and two or more 30-min trials at specific percentages of each subjects average 5-km TT speed (AVS5km). Mean+/-SD for the following variables were obtained at MLSS: velocity was 90.3+/-2.7% of the AVS5km, BLC was 5.4+/-1.6 mM, RPE was 15+/-2.1, VO2 was 80+/-6.3% of VO2max, and HR was 167+/-9.5 beats x min(-1), which was 88+/-3.8% of the mean maximum HR. Field tests included three laps of an 8-km road circuit at HR(MLSS) +/-3 beats x min(-1) and one lap at maximum sustainable velocity (a road TT). RESULTS There were no significant differences in BLC, HR, and RPE between the three steady-state road laps and the lab MLSS trial. There was also good agreement between the road and lab MLSS velocity/TT velocity ratios. CONCLUSIONS Our data suggest that 5-km TT cycling velocity, as measured on a windload simulator, may be used to estimate MLSS and the HR at MLSS for training purposes.

State of the Art Reviews: Development of Fitness in Children: The Influence of Gender and Physical Activity

The influences of gender and physical activity on the development of fitness are reviewed from early childhood to late adolescence. Changes in parameters of fitness prior to puberty are driven predominantly by neuroendocrine-mediated factors, although physical activity level may be influenced largely by sociocultural factors prior to and following puberty. Thus, it is still unclear to what extent environment versus genetics accounts for gender differences in fitness. Future studies need to account for all factors known to explain gender differences in fitness to better differentiate intrinsic versus environmental causes. Consequently, one must consider if and to what extent a gender comparison study actually reveals true, inherent gender differences compared with sociocultural and/or cultural influences. Nevertheless, differences in fitness between girls and boys that are influenced by sociocultural factors should be considered when devising programs to promote physical activity and enhance fitness in youth. Fundamentally, the role of parents and primary caregivers in modeling physical activity and influencing the fitness level of their child cannot be overestimated.

Effect of calcium supplementation on bone mineral density in female athletes

Abstract Females engaged in athletic activities frequently select to follow severe dietary restrictions, depriving their bodies of essential nutrients such as calcium in an effort to achieve some idealized body shape. Calcium poor diets are associated with stress fractures in the athlete and a rising prevalence in osteoporosis. The purpose of this study was to determine if calcium supplementation would enhance bone mineral density (BMD) in young (18–22 year old) female athletes. In this double blind study, thirty athletes from Division I and Division III teams were randomized to calcium supplementation (N = 17) and placebo (N = 13) groups. Treatment subjects were given tablets containing 1000 mg. elemental calcium for one year. Six BMD sites (lumbar spine, total hip, femoral neck, trochanter, Wards Triangle and radius) were assessed at baseline and 6 and 12 months utilizing the Hologic QDR 1000W scanner. Treatment groups were compared with respect to BMD and changes in BMD at baseline and 6 and 12 month intervals utilizing two way ANOVAs. The relationship between primary and secondary efficacy variables were investigated using Pearson and Spearman Rank Correlations. The impact of calcium supplementation on BMD was investigated using ANCOVA with average calcium intake serving as the covariate. No significant differences in BMD or changes in BMD between treatment groups were observed at baseline, 6 and 12 months. Mean reported compliance was 64 ± 4.8% for the calcium supplementation (CS) group and 73 ± 6.3% for the placebo group. Compliance data suggest that the CS group failed to consume the prescribed 1000 mg. daily intake of calcium. Furthermore, subjects in the placebo group reported a higher intake of calcium when compared with the CS group. Lumbar spine BMD increased in the CS group and remained stable in the placebo group. While significant differences in BMD were not achieved with calcium supplementation in these young athletes, study results reflect some benefit to BMD from higher calcium intakes. The potential cost-benefit of decreasing the prevalence of low bone mass in American women supports the need for further calcium supplementation studies in young females.

Eukaryotes in the gut microbiota in myalgic encephalomyelitis/chronic fatigue syndrome

Patients with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) often suffer from gastrointestinal symptoms and many are diagnosed with irritable bowel syndrome (IBS). Previous studies, including from our laboratory, have demonstrated that the ME/CFS gut bacterial composition is altered and less diverse when compared to healthy individuals. Patients have increased biomarkers of inflammation and leaky gut syndrome. To further investigate dysbiosis in the ME/CFS gut microbiome, we sought to characterize the eukaryotes present in the gut of 49 individuals with ME/CFS and 39 healthy controls. Using 18S rRNA sequencing, we have identified eukaryotes in stool samples of 17 healthy individuals and 17 ME/CFS patients. Our analysis demonstrates a small, nonsignificant decrease in eukaryotic diversity in ME/CFS patients compared to healthy individuals. In addition, ME/CFS patients show a nonsignificant increase in the ratio of fungal phyla Basidiomycota to Ascomycota, which is consistent with ongoing inflammation in ME/CFS. We did not identify specific eukaryotic taxa that are associated with ME/CFS disease status.

Cardiopulmonary Exercise Test Methodology for Assessing Exertion Intolerance in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Background: Concise methodological directions for administration of serial cardiopulmonary exercise testing (CPET) are needed for testing of patients with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). Maximal CPET is used to evaluate the coordinated metabolic, muscular, respiratory and cardiac contributions to energy production in patients with ME/CFS. In this patient population, CPET also elicits a robust post-exertional symptom flare (termed, post-exertional malaise); a cardinal symptom of the disease. CPET measures are highly reliable and reproducible in both healthy and diseased populations. However, evidence to date indicates that ME/CFS patients are uniquely unable to reproduce CPET measures during a second test, despite giving maximal effort during both tests, due to the effects of PEM on energy production. Methodology: To document and assess functional impairment due to the effects of post-exertional malaise in ME/CFS, a 2-day CPET procedure (2-day CPET) has been used to first measure baseline functional capacity (CPET1) and provoke post-exertional malaise, then assess changes in CPET variables 24 h later with a second CPET to assess the effects of post-exertional malaise on functional capacity. The second CPET measures changes in energy production and physiological function, objectively documenting the effects of post-exertional malaise. Use of CPET as a standardized stressor to induce post-exertional malaise and quantify impairment associated with post-exertional malaise has been employed to examine ME/CFS pathology in several studies. This article discusses the results of those studies, as well as the standardized techniques and procedures for use of the 2-day CPET in ME/CFS patients, and potentially other fatiguing illnesses. Conclusions: Basic concepts of CPET are summarized, and special considerations for performing CPET on ME/CFS patients are detailed to ensure a valid outcome. The 2-day CPET methodology is outlined, and the utility of the procedure is discussed for assessment of functional capacity and exertion intolerance in ME/CFS.