Effects of acute and multi-day low-dose sodium bicarbonate intake on high-intensity endurance exercise performance in male recreational cyclists.

PURPOSE: This study aimed to compare the effects of acute and multi-day low-dose sodium bicarbonate (SB) intake on high-intensity endurance exercise performance. METHODS: In a randomized, double-blind, cross-over design, twelve recreational male cyclists (age: 31.17 ± 4.91 years; V ˙ O2peak: 47.98 ± 7.68 ml·kg-1·min-1) completed three endurance performance tests following acute SB (ASB, 0.2 g·kg-1 SB), multi-day SB (MSB, 0.2 g·kg-1·day-1 SB for four days), and placebo (PLA) intake. The high-intensity endurance performance was assessed with a cycling exercise test, wherein participants cycled on a bicycle ergometer at 95% of the predetermined anaerobic threshold for 30 min, followed by a time-to-exhaustion test at 110% of the anaerobic threshold. Data were analyzed using one-way and two-way repeated-measures ANOVA. RESULTS: Significant main effects of supplementation protocol were evident in pre-exercise bicarbonate concentrations (F = 27.93; p < 0.01; partial eta squared (η2) = 0.72; false discovery rate (FDR)-adjusted p value = 0.001). Prior to performance test, blood bicarbonate concentrations were significantly higher in MSB (25.78 ± 1.63 mmol·L-1 [95% CI 26.55-28.44] (p < 0.001; FDR-adjusted p value = 0.001)) and ASB (27.49 ± 1.49 mmol·L-1 [95% CI 24.75-26.81] (p < 0.001; FDR-adjusted p value = 0.007)) compared to PLA (23.75 ± 1.40 mmol·L-1 [95% CI 22.86 to 24.64]). Time-to-exhaustion increased in MSB (54.27 ± 9.20 min [95% CI 48.43-60.12]) compared to PLA (49.75 ± 10.80 min [95% CI 42.89-56.62]) (p = 0.048); however, this increase in MSB did not reach the significance threshold of 1% FDR (FDR-adjusted p value = 0.040). No significant difference was noted in exhaustion times between ASB (51.15 ± 8.39 min [95% CI 45.82-56.48]) and PLA (p > 0.05). CONCLUSION: Both acute and multi-day administration of low-dose SB improves buffering system in cyclists; nevertheless, neither intervention demonstrates sufficient efficacy in enhancing high-intensity endurance performance.

Effects of step aerobics and aerobic dancing on serum lipids and lipoproteins.

BACKGROUND: To examine the effect of 8 weeks of step aerobics and aerobic dancing on blood lipids and lipoproteins. EXPERIMENTAL DESIGN: Comparative training. SETTING: Two months of physical fitness program. PARTICIPANTS: Forty-five sedentary female college student volunteers randomly assigned to one of the three groups as step aerobics (n=15), aerobic dancing (n=15) and the control group (n=15). The step aerobics and aerobic dancing groups participated in sessions of 45 min per day, 3 days per week for 8 weeks with 60-70 percent of their heart rate reserve. MEASURES: Total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol levels (HDL-C), the ratio of total cholesterol to high-density lipoprotein cholesterol (TC:HDL-C). RESULTS: At the end of the 8 week period, a significant difference has been found between the step aerobics group and the control group and between the aerobic dancing group and the control group in TC levels (F[2,44]=8.38; p<0.01). A significant difference in HDL-C levels (F[2,44]=3.65; p<0.05) and TC:HDL-C ratio (F[2,44]=11.56; p<0.01) has been found only between the step aerobics group and the control group. CONCLUSIONS: These results indicate that step aerobics training is an effective training mode for modifying lipid and lipoprotein profiles of female college-aged students.

The relationship of self-concept and perceived athletic competence to physical activity level and gender among Turkish early adolescents.

The purpose of this study was to examine the self-concept and perceived athletic competence of Turkish early adolescents in relation to physical activity level and gender. Self-concept was assessed using the Piers-Harris Children's Self-Concept Scale, and perceived athletic competence was assessed by means of the Athletic Competence subscale of Harter's Self-Perception Profile for Children. In addition, the Weekly Activity Checklist was used for assessing physical activity level. Males and females were assigned to low and high physical activity level groups based on their mean scores. Multivariate analysis of variance revealed significant main effects for gender and physical activity level, but there was no significant gender by physical activity interaction. Univariate analysis demonstrated a significant main effect for physical activity level on perceived athletic competence but not global self-concept. In addition, univariate analysis did not reveal a significant difference in either global self-concept or perceived athletic competence with respect to gender.