Philip J. Buckenmeyer

Response of patients with coronary artery disease stratified by ejection fraction following short-term training

The purpose of this study was to investigate the response of patients with ischemic heart disease and varied left ventricular function following 6 weeks of exercise training. We studied the oxygen consumption (VO2), and central hemodynamic and metabolic responses of 14 patients with coronary artery disease (CAD) stratified by left ventricular ejection fraction (EF). There were two groups of patients: normal EF (NEF), EF = 64 +/- 9.9 (mean +/- S.E.M.); n = 7, and diminished EF (DEF), EF = 36 +/- 11.6; n = 7. The patients ranged in age from 42 to 72 years (54.9 +/- 2.2), and were evaluated prior to and then following training. Measures of VO2, cardiac output (Qt) stroke volume (SV), heart rate (HR), exercise duration (XTIME) and intensity (XI), as well as plasma lactate (LA), and the catecholamines epinephrine (E) and norepinephrine (NE) were obtained in response to maximal cycle ergometry. Subjects trained three times per week, 30 min per session, at an intensity equal to 70% of their peak oxygen consumption. Repeated measures analysis of variance (ANOVA) revealed no interaction between groups suggesting a similar training response. Significant post-training changes (P < 0.05) were observed in peak VO2 (VO2peak) NEF, 11.8% increase, (16.0 +/- 1.3 to 17.9 +/- 1.1 ml/kg/min) and DEF, 9.3% increase (15.1 +/- 1.6 to 16.5 +/- 1.2 ml/kg/min); submaximal HR, 4% decrease in the NEF (95.57 +/- 4.58 to 92 +/- 4.43 beats/min) and a 6% decrease in the DEF (107.29 +/- 7.44 to 101.43 +/- 6.77 beats/min); XTIME NEF, 11.2% increase (7.8 +/- 0.57 to 8.67 +/- 0.61 min) and DEF, 16.6% increase (7.3 +/- 0.91 to 8.51 +/- 0.69 min); and XI NEF, 19.2% increase (104.3 +/- 11.3 to 124.3 +/- 12.9 W) DEF, 21.2% increase (94.3 +/- 18.5 to 114.3 +/- 16.9 W), and a 15% decrease in resting NE (350 +/- 26 to 296.9 +/- 19 pg/ml). There were no changes in Qt, SV, LA, E, peak NE or peak HR for either group. These findings suggest short-term endurance training at 70% VO2peak provide the necessary stimulus for individuals with CAD and NEF or DEF to display an improvement in XI, XTIME, and VO2peak. The lack of a significant enhancement in Qt with short-term training may indicate that the mechanism by which both study groups were able to attain significantly higher levels of VO2peak may have been attributable to peripheral mechanisms rather than any alterations in Qt, a central mechanism.

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.