Effect of Preexercise Ingestion of Modified Amylomaize Starch on Glycemic Response While Cycling.

Amylomaize-7 is classified as a resistant corn starch and is 68% digestible. When modified by partial hydrolysis in ethanol and hydrochloric acid its digestibility is 92%, yet retains its low glycemic and insulinemic properties. The purpose of this study was to characterize the metabolic response when modified amylomaize-7 or dextrose is consumed in the hour before exercise, and to compare the effect on performance of a brief high-intensity cycling trial. Ten male, trained cyclists were given 1 g/kg body mass of dextrose (DEX) or modified amylomaize-7 (AMY-7) or a flavored water placebo (PL) 45 min prior to exercise on a cycle ergometer. A 15-min ride at 60% Wmax was immediately followed by a self-paced time trial (TT) equivalent to 15 min at 80% Wmax. When cyclists consumed DEX, mean serum glucose concentration increased by 3.3 ± 2.1 mmol/L before exercise, compared to stable serum glucose observed for AMY-7 or PL. Glucose concentrations returned to baseline by pre-TT in all treatments. However, the mean post-TT glucose concentration of the DEX group was significantly lower than baseline, AMY-7, or PL. Serum insulin concentration increased nine-fold from baseline to preexercise in the DEX trial, whereas PL or AMY-7 remained unchanged. Time required to complete the performance trial was not significantly different between DEX, AMY-7 or PL. Preexercise ingestion of modified amylomaize-7 compared to dextrose resulted in a more stable serum glucose concentration, but did not offer a performance advantage in this high-intensity cycling trial.

Effect of preexercise soup ingestion on water intake and fluid balance during exercise in the heat.

PURPOSE: To determine whether chicken noodle soup before exercise increases ad libitum water intake, fluid balance, and physical and cognitive performance compared with water. METHODS: Nine trained men (age 25 ± 3 yr, VO2peak 54.2 ± 5.1 ml · kg-1 · min-1; M ± SD) performed cycle exercise in the heat (wet bulb globe temperature = 25.9 ± 0.4 °C) for 90 min at 50% VO2peak, 45 min after ingesting 355 ml of either commercially available bottled water (WATER) or chicken noodle soup (SOUP). The same bottled water was allowed ad libitum throughout both trials. Participants then completed a time trial to finish a given amount of work (10 min at 90% VO2peak; n = 8). Cognitive performance was evaluated by the Stroop color-word task before, every 30 min during, and immediately after the time trial. RESULTS: Ad libitum water intake throughout steady-state exercise was greater in SOUP than with WATER (1,435 ± 593 vs. 1,163 ± 427 g, respectively; p < .03). Total urine volume was similar in both trials (p = .13), resulting in a trend for greater water retention in SOUP than in WATER (87.7% ± 7.6% vs. 74.9% ± 21.7%, respectively; p = .09), possibly due to a change in free water clearance (-0.32 ± 1.22 vs. 0.51 ± 1.06 ml/min, respectively; p = .07). Fluid balance tended to be improved with SOUP (-106 ± 603 vs. -478 ± 594 g, p = .05). Likewise, change in plasma volume tended to be reduced in SOUP compared with WATER (p = .06). Only mild dehydration was achieved (<1%), and physical performance was not different between treatments (p = .77). The number of errors in the Stroop color-word task was lower in SOUP throughout the entire trial (treatment effect; p = .04). CONCLUSION: SOUP before exercise increased ad libitum water intake and may alter kidney function.

Effect of preexercise electrolyte ingestion on fluid balance in men and women.

PURPOSE: This article aimed to study the effect of preexercise ingestion of an electrolyte-containing beverage and meal on fluid balance during exercise in men and women. METHODS: Twenty healthy, college-aged people (10 males, 10 females; mean +/- SD = 51.2 +/- 9.8 mL x kg x min(-1)) exercised at 58 +/- 4% V O 2 peak for 90 min, 45 min after ingesting 355 mL of chicken noodle soup (SOUP; 167 mmol x L(-1) Na +), carbohydrate-electrolyte beverage (CE; 16 mmol x L(-1) Na+), or water (WATER). After 90 min of exercise, participants completed a physical performance task (PPT) consisting of the calculated work that would be completed in 30 min at 60% V O 2 peak (n = 19). Water was allowed ad libitum throughout all trials. RESULTS: Fluid balance was improved in SOUP compared with WATER (-251 +/- 418 vs -657 +/- 593 g, respectively; P = 0.002) because of greater water intake and retention throughout the trial. Water intake was also greater in CE compared with WATER mostly because of an increase during the PPT. Plasma osmolality increased after ingestion of SOUP and remained elevated throughout exercise compared with both CE and WATER. Men and women had similar fluid balance results, with women having lower relative water intake and evaporative water losses compared with men. Physical performance was similar in all trials. CONCLUSIONS: SOUP ingested before exercise improves fluid balance because of increased ad libitum water intake and reduced proportional urinary water loss. The increase in water intake and, subsequently, the improved fluid balance may be because of a greater plasma osmolality before and throughout exercise.

Testosterone prohormone supplements.

Testosterone prohormones such as androstenedione, androstenediol, and dehydroepiandrosterone (DHEA) have been heavily marketed as testosterone-enhancing and muscle-building nutritional supplements for the past decade. Concerns over the safety of prohormone supplement use prompted the United States Food and Drug Administration to call for a ban on androstenedione sales, and Congress passed the Anabolic Steroid Control Act of 2004, which classifies androstenedione and 17 other steroids as controlled substances. As of January 2005, these substances cannot be sold without prescription. Here, we summarize the current scientific knowledge regarding the efficacy and safety of prohormone supplementation in humans. We focus primarily on androstenedione, but we also discuss DHEA, androstenediol, 19-nor androstenedione, and 19-nor androstenediol supplements. Contrary to marketing claims, research to date indicates that the use of prohormone nutritional supplements (DHEA, androstenedione, androstenediol, and other steroid hormone supplements) does not produce either anabolic or ergogenic effects in men. Moreover, the use of prohormone nutritional supplements may raise the risk for negative health consequences.

Urinary excretion of steroid metabolites after chronic androstenedione ingestion.

Urinary steroid excretion after androstenedione intake has been examined after a single dose of 50 mg and single doses of 100 or 300 mg/d for 7 d. We evaluated the effects of 28 d of 100 mg three times a day (t.i.d.) androstenedione intake on urinary steroid excretion. Twenty healthy men, ages 30-39 yr (33.5 +/- 0.6), consumed 100 mg androstenedione t.i.d. or placebo for 28 d. Urine samples were analyzed for testosterone, epitestosterone, androsterone, and etiocholanolone via HPLC/tandem mass spectrometry on d 0 and 28. Androstenedione intake increased (P < 0.05) urinary testosterone 35.1 +/- 10.5 ng/ml vs. 251.6 +/- 87.5 ng/ml, epitestosterone 35.3 +/- 8.8 ng/ml vs. 99.7 +/- 28.7 ng/ml, androsterone 2,102 +/- 383 ng/ml vs. 15,767 +/- 3,358 ng/ml, and etiocholanolone 1,698 +/- 409 ng/ml vs. 11,329 +/- 2,656 ng/ml (means +/- se). Although the testosterone to epitestosterone ratio (T/E) tended to increase with androstenedione intake (1.2 +/- 0.3 vs. 4.0 +/- 1.6; P = 0.12), only one subject had a urinary T/E greater than the current Olympic criteria (>6.0) for a positive drug test. Chronic intake of 100 mg androstenedione t.i.d. increases the urinary excretion of steroid metabolites. Due to inconsistent increases in the T/E ratio, the T/E ratio may not effectively detect androstenedione use.

Isoflavone-rich soy protein prevents loss of hip lean mass but does not prevent the shift in regional fat distribution in perimenopausal women.

OBJECTIVE: Menopause-induced estrogen deficiency increases the risk of cardiovascular disease, which is related to a shift in regional fat distribution. We tested the hypothesis that estrogen-like isoflavones in soy protein isolate (SPI+) would lessen both regional fat gain and lean loss compared with isoflavone-poor soy (SPI-). DESIGN: Perimenopausal participants (N = 69) were randomly assigned (double-blind) to 24 weeks of treatment (40 g soy or whey protein per day): SPI+ (n = 24), SPI- (n = 24), or whey control (n = 21); each participant had blood drawn in the fasted (12 hours) state, had physical activity assessed, and kept a 5-day food diary. Dual-energy x-ray absorptiometry was used to examine the effects of SPI+ on regional fat and lean tissue distribution changes in the waist, hip, and thigh regions. RESULTS: Mean body mass increased (P < 0.01) in each group, but treatment had no effect on gain in overall body mass, fat mass, or lean mass using analysis of variance. In all treatment groups combined, lean mass increased in each region; fat mass increased only in the waist region. Treatment had an effect (P = 0.039) on hip lean mass and a marginal effect (P = 0.077) on thigh fat. Regression analyses revealed that SPI+ diminished the increase in thigh fat (P = 0.018) and heightened the increase in hip lean (P = 0.035) mass. Carbohydrate intake (P = 0.006) and cohort (reflective of season; P = 0.011) contributed to the gain in thigh fat. Total protein intake (P = 0.0012), plasma insulin (P = 0.0034), and physical activity (P = 0.047) contributed to the gain in hip lean mass. CONCLUSIONS: Gain in hip lean mass was greater (P = 0.014) in SPI+ than other groups, but SPI+ did not reduce the disease-promoting menopausal shift in regional fat mass.

Acute hormonal response to sublingual androstenediol intake in young men.

The effectiveness of orally ingested androstenediol in raising serum testosterone concentrations may be limited because of hepatic breakdown of the ingested androgens. Because androstenediol administered sublingually with cyclodextrin bypasses first-pass hepatic catabolism, we evaluated the acute hormonal response to sublingual cyclodextrin androstenediol supplement in young men. Eight men (22.9 +/- 1.2 yr) experienced in strength training consumed either 20 mg androstenediol in a sublingual cyclodextrin tablet (Sl Diol) or placebo (Pl) separated by at least 1 wk in a randomized, double-blind, crossover manner. Blood samples were collected before supplementation and at 30-min intervals for 3 h after supplementation. Serum hormone concentrations did not change with Pl. Serum androstenedione concentrations were increased (P < 0.05) above baseline (11.2 +/- 1.1 nmol/l) with Sl Diol from 60 to 180 min after intake and reached a peak concentration of 25.2 +/- 2.9 nmol/l at 120 min. Serum free testosterone concentrations were increased from 86.2 +/- 9.1 pmol/l with Sl Diol from 30 to 180 min and reached a peak concentration of 175.4 +/- 12.2 pmol/l at 60 min. Serum total testosterone concentrations increased above basal (25.6 +/- 2.3 nmol/l) from 30 to 180 min with Sl Diol and reached a peak concentration of 47.9 + 2.9 nmol/l at 60 min. Serum estradiol concentrations were elevated (P < 0.05) above baseline (0.08 +/- 0.01 nmol/l) from 30 to 180 min with Sl Diol and reached 0.14 +/- 0.02 nmol/l at 180 min. These data indicate that sublingual cyclodextrin androstenediol intake increases serum androstenedione, free testosterone, total testosterone, and estradiol concentrations.