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Mitchell M. Kanter

Free radicals have been implicated in the development of diverse diseases such as cancer, diabetes, and cataracts, and recent epidemic-logical data suggest an inverse relationship between antioxidant intake and cardiovascular disease risk. Data also suggest that antioxidants may delay aging, Research has indicated that free radical production and subsequent lipid peroxidation are normal sequelae to the rise in oxygen consumption with exercise. Consequently, antioxidant supplementation may detoxify the peroxides produced during exercise and diminish muscle damage and soreness. Vitamin E, beta carotene, and vitamin C have shown promise as protective antioxidants. Other ingestible products with antioxidant properties include selenium and coenzyme Q10. The role (if any) that free radicals play in the development of exercise-induced tissue damage, or the protective role that antioxidants may play, remains to be elucidated. Current methods used to assess exercise-induced lipid peroxidation are not extremely specific or sensitive; research that utilizes more sophisticated methodologies should help to answer many questions regarding dietary antioxidants.

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Robert R. Jenkins

Elemental and gaseous oxygen presents a conundrum in that it is simultaneously essential for and potentially destructive to human life. Traditionally the ability to consume large volumes of oxygen has been assumed to be totally beneficial to the organism. In the past 10 years it has become clear that oxygen radicals are generated even during normal resting metabolism Nevertheless, such radicals are usually of no appreciable threat since a wide array of protective biochemical systems exist. However, under certain circumstances aerobic exercise may increase free radical production to a level that overwhelms those defenses. A broad array of nutrients such as vitamin C, vitamin E, p-carotene, and so forth are known to suppress such radical events. This paper reviews the status of our knowledge relative to the potential benefits of nutritional modification in augmenting the organism's normal defense against harmful radical chemistry.

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Laura J. Morrison, Frances Gizis and Barbara Shorter

Supplement use was surveyed in a convenience sample of persons who exercised regularly at a Long Island, NY gym. Participants, age at least 18 y, completed anonymous questionnaires. A majority (84.7%) took supplements. Many consumed multivitamin/minerals (MVM; 45%), protein shakes/bars (PRO; 42.3%), vitamin C (34.7%), and vitamin E (VE; 23.4%) at least 5 times per wk. Other dietary supplements were used less frequently or by fewer participants. Ephedra was consumed by 28% at least once per wk. Choices and reasons for dietary supplement use varied with age of the participant. More of the oldest consumed MVM or VE, while those 45 y or younger chose PRO. Those younger than 30 consumed creatine more frequently. The oldest participants took supplements to prevent future illness, while others took supplements to build muscle. The reason for committing to an exercise program influenced supplement use. Bodybuilders more frequently consumed PRO, creatine, and ephedra compared to those exercising for health reasons.

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Mitchell M. Kanter and Melvin H. Williams

Three nutritional products that have very different mechanisms of action are antioxidant vitamins, carnitine, and choline. Antioxidant vitamins do not appear to have a direct effect on physical performance in well-fed people but have been touted for their ability to detoxify potentially damaging free radicals produced during exercise. Carnitine purportedly enhances lipid oxidation, increases VO2max, and decreases plasma lactate accumulation during exercise. However, studies of carnitine do not generally support its use for ergogenic purposes. Choline supplements have been advocated as a means of preventing the decline in acetylcholine production purported to occur during exercise; this decline may reduce the transmission of contraction-generating impulses across the skeletal muscle, an effect that could impair one’s ability to perform muscular work. However, there are no definitive studies in humans that justify choline supplementation. Much of the scientific data regarding the aforementioned nutrients are equivocal and contradictory. Their potential efficacy for improving physical performance remains largely theoretical.

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Yuki Kokubo, Yuri Yokoyama, Kumiko Kisara, Yoshiko Ohira, Ayaka Sunami, Takahiro Yoshizaki, Yuki Tada, Sakuko Ishizaki, Azumi Hida and Yukari Kawano

This cross-sectional study explored the prevalence of iron deficiency (ID) and associations between dietary factors and incidence of ID in female rhythmic gymnasts during preseason periods. Participants were 60 elite collegiate rhythmic gymnasts (18.1 ± 0.3 years [M ± SD]) who were recruited every August over the course of 8 years. Participants were divided into 2 groups according to the presence or absence of ID. Presence of ID was defined either by ferritin less than 12 µg/L or percentage of transferrin saturation less than 16%. Anthropometric and hematologic data, as well as dietary intake, which was estimated via a semiquantitative food frequency questionnaire, were compared. ID was noted in 48.3% of participants. No significant group-dependent differences were observed in physical characteristics, red blood cell counts, hemoglobin, hematocrit, haptoglobin, or erythropoietin concentrations. The ID group had a significantly lower total iron-binding capacity; serum-free iron; percentage of transferrin saturation; ferritin; and intake of protein, fat, zinc, vitamin B2, vitamin B6, beans, and eggs but not iron or vitamin C. The recommended dietary allowance for intake of protein, iron, zinc, and various vitamins was not met by 30%, 90%, 70%, and 22%–87% of all participants, respectively. Multiple logistic analysis showed that protein intake was significantly associated with the incidence of ID (odds ratio = 0.814, 95% confidence interval [0.669, 0.990], p = .039). Participants in the preseason’s weight-loss periods showed a tendency toward insufficient nutrient intake and were at a high risk for ID, particularly because of lower protein intake.

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Kimberly M. White, Stephanie J. Bauer, Kristopher K. Hartz and Monika Baldridge

Introduction:

Resistance training is an effective method to decrease body fat (BF) and increase fat-free mass (FFM) and fat oxidation (FO). Dairy foods containing calcium and vitamin D might enhance these benefits. This study investigated the combined effects of habitual yogurt consumption and resistance training on body composition and metabolism.

Methods:

Untrained women (N = 35) participated in an 8-wk resistance-training program. The yogurt group (Y) consumed 3 servings of yogurt containing vitamin D per day, and the control groups maintained their baseline lowdairy-calcium diet. Postexercise, Y consumed 1 of the 3 servings/d fat-free yogurt, the protein group consumed an isocaloric product without calcium or vitamin D, and the carbohydrate group consumed an isocaloric product without protein. Strength, body composition, fasted resting metabolic rate (RMR) and FO, and serum 25-hydroxyvitamin D were measured before and after training.

Results:

Calories (kcal · kg−1 · d−1) and protein (g · kg−1 · d−1) significantly increased from baseline for Y. FFM increased (main effect p = .002) and %BF decreased (main effect .02) for all groups with training, but Group × Time interactions were not observed. RMR and FO did not change with training for any group.

Conclusion:

Habitual consumption of yogurt during resistance training did not augment changes in body composition compared with a low-dairy diet. Y decreased %BF as a result of training, however, even with increased calorie consumption.

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Richard D. Lewis and Christopher M. Modlesky

Calcium and vitamin D can significantly impact bone mineral and fracture risk in women. Unfortunately, calcium intakes in women are low and many elderly have poor vitamin D status. Supplementation with calcium (~1000 mg) can reduce bone loss in premenopausal and late postmenopausal women, especially at sites that have a high cortical bone composition. Vitamin D supplementation slows bone loss and reduces fracture rates in late postmenopausal women. While an excess of nutrients such as sodium and protein potentially affect bone mineral through increased calcium excretion, phytoestrogens in soy foods may attenuate bone loss ihrough eslrogenlike activity. Weight-bearing physical activity may reduce the risk of osteoporosis in women by augmenting bone mineral during the early aduli years and reducing the loss of bone following menopause. High-load activities, such as resistance training, appear to provide the best stimulus for enhancing bone mineral; however, repetitive activities, such as walking, may have a positive impact on bone mineral when performed at higher intensities. Irrespective of changes in bone mineral, physical activities that improve muscular strength, endurance, and balance may reduce fracture risk by reducing the risk of falling. The combined effect of physical activity and calcium supplementation on bone mineral needs further investigation.

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Antoni Aguiló, Pere Tauler, Emilia Fuentespina, Gerardo Villa, Alfredo Córdova, Josep A. Tur and Antoni Pons

Objective:

The aim of this work was to check the effects of antioxidant supplementation (vitamins E and C, and β-carotene) on the basal iron status of athletes prior to and following their training and competition season (3 months).

Design:

Eighteen amateur trained male athletes were randomly distributed in 2 groups: placebo (lactose) and antioxidant supplemented (vitamin E, 500 mg/d; vitamin C, 1 g/d; and β-carotene, 30 mg/d). The study was double blind. Hematological parameters, dietary intake, physical activity intensity, antioxidant status (GSH/GSSG ratio), and basal iron status (serum iron, transferrin, ferritin, and iron saturation index) were determined before and after the intervention trials.

Results:

Exercise decreased antioxidant defenses in the placebo group but not in the antioxidant-supplemented group. No changes were found in the number of erythrocytes, hematocrit, or hemoglobin concentration, or in values of serum iron parameters, after taking the antioxidant cocktail for 3 months, in spite of the exercise completed. The placebo group showed a high oxidative stress index, and decreases in serum iron (24%) and iron saturation index (28%), which can neither be attributed to aspects of the athletes’ usual diet, nor to hemoconcentration.

Conclusions:

Antioxidant supplementation prevents the decrease of serum iron and the iron saturation index, and a link between iron metabolism and oxidative stress may also be suggested.

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Donna Beshgetoor and Jeanne F. Nichols

This study compared the dietary intakes of supplementing (SA) and non-supplementing athletes (NSA). Twenty-five female master athletes (mean age = 50.4 yr) participated in the study (SA = 16, NSA = 9). Four-day diet records were analyzed using Nutritionist V. Statistical significance (p < .005) was determined by independent t tests. No significant differences were observed in intakes of kilocalories (SA = 2079 ± 628 kcals, NSA = 2001 ± 435 kcals), protein (SA = 104 ± 75 g, NSA = 84 ± 35 g), fat (SA = 65 ± 39 g, NSA = 61 ± 22 g), or carbohydrates (SA = 269 ± 112 g, NSA = 277 ± 43 g). Mean intakes exceeded Dietary Reference Intake (DRI) guidelines for all micro-nutrients except calcium and vitamin E (NSA = 79% and 87% of DRI, respectively). SA had significantly greater total intakes than NSA for calcium (p = .0001), magnesium (p = .004), vitamin C (p = .003), and vitamin E (p = .001). Results suggest that female master athletes may rely on dietary supplements rather than nutrient-dense food choices to provide daily nutritional needs.

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Jay L. Tuttle, Jeffrey A. Potteiger, Blanche W. Evans and John C. Ozmun

This study examined the effects of aspartate supplementation (ASP) on plasma ammonia concentrations ([NH4+]) during and after a resistance training workout (RTW). Twelve male weight trainers were randomly administered ASP or vitamin C in a crossover, double blind protocol, each trial separated by 1 wk. ASP and vitamin C were given over a 2-hr period beginning 5 hr prior to the RTW. The RTW consisted of bench, incline, shoulder, and triceps presses, and biceps curls at 70% of one repetition maximum (1-RM). After the RTW a bench press test (BPT) to failure at 65% of 1-RM was used to assess performance. [NH4+] was determined preexercise, 20 and 40 min midworkout, immediately postexercise, and 15 min postexercise. Treatment-by-time ANOVAs, paired t tests, and contrast comparisons were used to identify mean differences. No significant differences were observed between treatments for [NH4+] or BPT. [NH4+] increased significantly from Pre to immediately postexercise for both the ASP and vitamin C trials. Acute ASP supplementation does not reduce [NH4+] during and after a high intensity RTW in weight trained subjects.