Robert E. Keith

Creatine supplementation and health variables : a retrospective study

PURPOSE Long-term safety of creatine supplementation has been questioned. This retrospective study was performed to examine markers related to health, the incidence of reported side effects and the perceived training benefits in athletes supplementing with creatine monohydrate. METHODS Twenty-six athletes (18 M and 8 F, 24.7 +/- 9.2 y; 82.4 +/- 20.0 kg; 176.5 +/- 8.8 cm) from various sports were used as subjects. Blood was collected between 7:00 and 8:30 a.m. after a 12-h fast. Standard clinical examination was performed for CBC and 27 blood chemistries. Testosterone, cortisol, and growth hormone were analyzed using an ELISA. Subjects answered a questionnaire on dietary habits, creatine supplementation, medical history, training history, and perceived effects of supplementation. Body mass was measured using a medical scale, body composition was estimated using skinfolds, and resting heart rate and blood pressure were recorded. Subjects were grouped by supplementation length or no use: Gp1 (control) = no use (N = 7; 3 F, 4 M); Gp2 = 0.8-1.0 yr (N = 9; 2 F, 7 M); and Gp3 = 1(+) (N = 10; 3 F, 7 M). RESULTS Creatine supplementation ranged from 0.8--4 yr. Mean loading dose for Gp2 and Gp3 was 13.7 +/- 10.0 and the maintenance dose was 9.7 +/- 5.7 g.d(-)1. Group differences were analyzed using one-way ANOVA. CONCLUSIONS Expected gender differences were observed. Of the comparisons made among supplementation groups, only two differences for creatinine and total protein (P < 0.05) were noted. All group means fell within normal clinical ranges. There were no differences in the reported incidence of muscle injury, cramps, or other side effects. These data suggest that long-term creatine supplementation does not result in adverse health effects.

Lipid-lowering effect of a dietary chromium (III)—Nicotinic acid complex in male athletes

Abstract Exercise-induced chromium (Cr) losses and marginal Cr intakes may place athletes in a suboptimal state for Cr nutritional status, possibly resulting in impaired insulin function. The purpose of this study was to assess the effects of a synthetic trivalent Cr-nicotinic acid (NA) supplement on insulin controlled variables in athletes. Thirty-four college-age male bodybuilders (BB) were randomly assigned to three groups: placebo (P), n=11; 200 μg Cr−1.8 mg NA (1X), n=12; or 800 μg Cr−7.2 mg NA (4X), n=11. Supplements were ingested daily for 8 weeks and training was controlled. Twelve hr fasting insulin, glucose, total cholesterol (TC), triglyceride, HDL-cholesterol, TC:HDL, LDL-cholesterol, and one hr post-challenge insulin and glucose values were determined at pre- and post-supplementation periods. All pre-supplementation values were within normal ranges. ANOVAs revealed two significant interactions. Mean TC in the P group increased from 139.9 to 153.4 mg/dl, yet decreased from 147.9 to 126.8 mg/dl and 159.2 to 131.3 mg/dl in the 1X and 4X groups, respectively (p

Alterations in dietary carbohydrate, protein, and fat intake and mood state in trained female cyclists

Seven highly trained female cyclists (age 22 +/- 5 yr, height 165 +/- 6 cm, weight 60 +/- 5 kg, VO2max 55 +/- 6 ml.min-1.kg-1, mean +/- SD) consumed, for 1 wk each, isocaloric diets containing varying levels of carbohydrate, protein, and fat designated as low carbohydrate (LCHO), moderate carbohydrate (MCHO), and high carbohydrate (HCHO). Diets were administered in random order, and each subject consumed all three diet treatments. At the end of each weekly diet treatment, subjects rode on a cycle ergometer at 80% VO2max until fatigued. Cyclists continued light training during the diet treatments. Following each diet treatment and immediately prior to the fatiguing cycle ergometer ride, cyclists completed a Profile of Mood States (POMS) questionnaire. The POMS yields measures of tension (T), depression (D), anger (A), vigor (V), fatigue (F), and confusion (C), as well as providing a total mood score (TMS). Results indicated that subjects on LCHO had significantly (P less than or equal to 0.05) greater T, D, A, and TMS and less V compared with MCHO and HCHO. There were no significant differences between MCHO and HCHO. In the present study, LCHO in conjunction with training and exercise adversely affected the mood state of trained female cyclists as compared with MCHO and HCHO diets.

Dietary carbohydrate intake and endurance exercise performance of trained female cyclists

Abstract Seven highly trained female cyclists (age 22±5 yr, x¯SD; wt:60±5 kg; ht:165±6 cm; V02 max: 55±6 ml/min/kg) rode on a cycle ergometer at 80% V02 max to fatigue following week-long consumption of isocaloric diets containing low (LCHO), moderate (MCHO) or high carbohydrate (HCHO) content (13%, 54%, 72% of total kcal). Total caloric intake was the normal intake for subjects. Subjects were randomly assigned to dietary treatments with all subjects eventually consuming all diets. Expired air and blood samples were taken before, during, and at the end of each exercise session. Respiratory exchange (R) values and plasma glucose and lactate concentrations were determined. Results indicated that mean exercise time to fatigue increased with increasing dietary carbohydrate content (LCHO:60±12 min; MCHO:98±13; HCHO:113±28). Exercise time on LCHO was significantly shorter (p

Non-Anemic Iron Depletion, Oral Iron Supplementation and Indices of Copper Status in College-Aged Females

Objectives: Indices of copper status, specifically serum copper and ceruloplasmin concentrations and erythrocyte superoxide dismutase activity, and iron status, including serum ferritin, transferrin receptors, hemoglobin and hematocrit, were studied in 27 college-aged females with adequate iron versus low iron stores. Methods: Serum copper and ceruloplasmin concentrations, erythrocyte superoxide dismutase activity, serum ferritin, transferrin receptors, hemoglobin and hematocrit were studied in 15 females with non-anemic iron depletion before and after five weeks of iron supplementation and in 12 healthy iron-adequate females aged 19 to 28 years. Results: Mean hemoglobin, hematocrit and ferritin concentrations of the control group (144 ± 11 g/L, 43 ± 3% and 38 ± 15 μg/L, respectively) were significantly higher than those of the iron depleted group prior to supplementation (134 ± 9 g/L, 39 ± 2% and 11 ± 6 μg/L, respectively). The serum transferrin receptor to serum ferritin ratio was significantly greater for the iron depleted group prior to supplementation (890 ± 753) versus the control group (151 ± 61). Mean serum copper and ceruloplasmin concentrations and erythrocyte superoxide dismutase activity of the iron-adequate control group (20.0 ± 5.7 μmol/L, 463 ± 142 mg/L and 527 ± 124 U/mL, respectively) were significantly higher than those of the iron depleted group (12.4 ± 3.8 μmol/L, 350 ± 108 mg/L and 353 ± 186 U/mL, respectively) prior to supplementation. Following iron supplementation, hematocrit and ferritin concentrations of the iron depleted group significantly increased to 42 ± 3% and 26 ± 8 μg/L, respectively. Mean serum transferrin receptor concentrations and the serum transferrin receptor to ferritin ratios significantly decreased in the iron depleted group following supplementation (6.1 ± 1.6 mg/L to 4.6 ± 1.5 mg/L and 890 ± 753 to 198 ± 114, respectively). Iron supplementation also significantly increased the mean serum copper concentration to 14.2 ± 5.4 μmol/L and, in subjects with serum ferritin concentrations ≤12 μg/L, the mean serum ceruloplasmin concentration. Conclusions: Non-anemic iron depletion characterized by low iron stores is associated with negative impacts on copper status. Iron supplements improved indices of iron status and serum copper and ceruloplasmin concentrations. Whether the diminished serum copper and ceruloplasmin concentrations and superoxide dismutase activity are associated with free radical damage to iron depleted cells requires further investigation.

Riboflavin status of female athletes consuming normal diets

Riboflavin (B2) status was determined in trained female athletes (n=13) and untrained female subjects (n=14). Groups were similar in age, height and weight. Subjects ingesting large quantities of supplemental or dietary riboflavin were excluded from the study. Dietary intake information was obtained and evaluated for B2 content. Riboflavin status was evaluated using the erythrocyte glutathione reductase activity coefficient (EGRAC) and urinary riboflavin excretion. Results indicated that total riboflavin intake per 24 hr was significantly greater (p<0.05) in the athletic group. However, no significant difference in intake was noted when B2 consumption was expressed as intake/ 1000 kcal consumed (1.0±0.4 mg and 0.9±0.2 mg, athletes and untrained, X±SD). While all subjects had normal EGRAC values, athletes tended to have slightly higher (p=0.09) values when compared to untrained females (1.06±0.06 vs 1.01±0.07). Total riboflavin excretion/24 hr was not different in athletes (98±51 mcg) versus untrained females (86±16 mcg) although riboflavin excretion/g creatinine was somewhat lower (p=0.1) in athletes (63±26 mcg/g) than in untrained females (82±28 mcg/g). Five athletes and five untrained subjects with the lowest riboflavin intakes were also compared. No significant differences were noted for EGRAC values or total urinary riboflavin excretion. However, athletes in the subgroup excreted significantly less (p<0.05) B2/g creatinine than did the untrained subgroup (50.8±15.5 and 81.3±16.7 mcg/g, respectively). Findings from the present study suggest that female athletes were able to maintain adequate riboflavin status from dietary intake alone.

Iron depletion without anemia is not associated with impaired selenium status in college-aged women.

Iron-deficiency anemia has been shown to alter body mineral concentrations and activities of iron- and non-iron-containing enzymes, especially those with antioxidant functions. These effects, however, have been less studied in nonanemic iron-depleted individuals. Thus, this study assessed indices of selenium status in 12 college-aged females with adequate iron stores and 15 college-aged females with low iron stores before and after iron therapy. Blood samples were drawn at baseline for both groups and following iron supplementation in the low-iron-stores group. Hematocrit, hemoglobin, and serum ferritin concentrations of the low-iron-stores group were significantly lower than those of the control group. The serum transferrin receptor-to-serum ferritin ratio in the low-iron-stores group was significantly greater than that of the control group. Serum selenium and glutathione peroxidase concentrations of the low-iron-stores group were not significantly different from those of the controls. Iron supplementation significantly increased hemoglobin, hematocrit, and serum ferritin concentrations and significantly decreased the serum transferrin receptor concentration and serum transferrin receptor:serum ferritin ratio in the low-iron-stores group posttreatment compared to pretreatment. Serum selenium and glutathione peroxidase concentrations did not differ significantly from pretreatment to posttreatment in the low-iron-stores group. Results of this study indicate that low iron stores without anemia are not associated with impaired selenium status in college-aged females.

Exercise and tissue ascorbic acid content in guinea pigs

Abstract The effects of treadmill exercise (20 m/min, five days/wk, one hr/day) on growth and tissue ascorbic acid (AA) concentrations were investigated in 40 young, male guinea pigs. Animals were fed ad libitium an AA-free diet which was supplemented with AA. AA was administered daily via gavage feeding. Animals were divided into two groups, exercise (E) and sedentary (S). Food consumption and body weight were recorded. After eight weeks, animals were sacrificed and blood taken via heart puncture. Liver, spleen, adrenals and kidneys were removed, weighed and frozen. Plasma and organ tissues were analyzed for AA. Results indicated that exercise had no significant effect on growth. Growth was within normal range. Exercised animals had significantly (p

The effects of supplemental vitamin B6 and exercise on the contractile properties of rat muscle

Abstract A 4-wk study was performed on 24 mature, male Sprague-Dawley rats divided into four equal and random groups in a 2×2 design. Animals received diets containing the minimum daily requirement (MDR) for vitamin B6 or diets containing 100MDR. Body weights and food intake were recorded. One MDR group and one 100MDR group were trained to climb a rotating drum treadmill for nine 10-sec bursts with no attached weights (wk 1), tailweights equal to 5% body weight (wk 2), 10% body weight (wk 3) and 15% body weight (wk 4). Upon completion of the training program, animals were anesthetized and the right leg gastrocnemius and plantaris muscles were isolated and electrically stimulated. Muscle contractile values were recorded. Animals were sacrificed and the left leg gastrocnemius and plantaris muscles removed. Muscle wet and dry weights were obtained. Results indicated that animals receiving 100MDR tended to eat less food and gain less weight than the MDR rats. Rats receiving 100MDR had significantly lower muscle wet and dry weights with the 100MDR/exercise group having the lowest muscle weights. Rats in the exercise groups had significantly greater muscle contractile values for most measurements. Rats in the 100MDR groups had somewhat decreased total muscle developed force values (p

Vitamin C and acute physiological responses to cigarette smoking

Abstract Ascorbic acid (AA) and sugar placeboes (S) were administered double-blind to 62 male and female subjects (18–24 yr). Groups received either a single dose of 400 mg or 1200 mg AA or S prior to testing. During testing, subjects were required to smoke two cigarettes within ten minutes. Before and after smoking values were obtained for resting heart rate (HR), systolic and diastolic blood pressure (BP), forced vital capacity, one-second forced expiratory volume and maximal flow rate. Smoking adversely affected all parameters measured. Four-hundred mg AA resulted in a significantly smaller increase in systolic BP following smoking. However, 1200 mg AA resulted in significantly larger increases in diastolic BP and HR. Effects of AA on HR and BP were more pronounced in females than in males. No differences in lung function were seen with AA supplementation. Results of the study suggest a dose-response effect of AA administration on HR and BP following smoking.