Energy expenditure and dietary intake during high-volume and low-volume training periods among male endurance athletes

The primary purpose of this study was to examine dietary intake in endurance-trained athletes during a week of high-volume and a week of low-volume training while measuring exercise energy expenditure (EEE), resting metabolic rate (RMR), and nonexercise activity thermogenesis (NEAT). In addition, compliance with current American College of Sports Medicine/American Dietetic Association nutrition and performance recommendations for macronutrients was evaluated. Energy expenditure and dietary intake were measured in 15 male endurance athletes during 2 nonconsecutive weeks resembling a high-volume and a low-volume training period. Anthropometric measurements were taken and percentage body fat was determined at the beginning and end of each week of training. Total daily energy expenditure (TDEE) was calculated by summing RMR, NEAT, and EEE. Dietary intake was assessed with an online food-frequency questionnaire completed at the end of each week of data collection. Despite significant differences between TDEE and energy intake, no difference in body composition between the beginning and end of either week of training was observed, suggesting underreporting of caloric intake. Further, no changes in total caloric intake or macronutrient intake occurred even though TDEE increased significantly during the high-volume training. Reported carbohydrate intake (4.5?g·kg(-1)) and fiber intake (25?g·day(-1)) were below recommendations, whereas fat intake (1.3?g·kg(-1)) was slightly above recommendations. In summary, no short-term dietary adjustments occurred in response to differences in training regimen. Because these athletes were generally consuming a Western diet, they may have required some support to achieve desirable intakes for health and performance.     

Iron status in female endurance athletes and in non-athletes

Iron status was studied in 126 female endurance athletes and 52 control subjects, all aged 16-20 years. The study aimed at identifying factors responsible for iron deficiency. Twenty-six percent of athletes and 50% of controls had latent iron-deficiency without anemia symptoms. A too low intake of iron (especially heme iron: 0.3 mg daily), and of nutrients influencing iron metabolism, were identified as main causes of iron deficiency in control subjects. In athletes, whose iron intake was sufficient (14.6 mg), the principal cause of iron deficiency were blood losses due to menstruation. High level of physical activity, expressed as training volume and experience, did not adversely affect iron stores, as these were higher than in control subjects and the incidence of iron deficiency was much lower than in the control group. It was concluded that an increased intake of iron and of dietary factors involved in iron metabolism prevented possible exercise-induced losses of iron in young athletes.     

Nutritional and plasmatic antioxidant vitamins status of ultra endurance athletes

OBJECTIVE: The "Marathon des Sables" (MDS) is a competition known to induce oxidative stress. Antioxidant vitamins prevent exercise-induced oxidative damages. The purpose of this study was to evaluate daily intake and plasma level of the main antioxidant vitamins (alpha-tocopherol, vitamin C, beta-carotene and retinol) in 19 male athletes who participated in this competition. METHODS: Data collected before the beginning of the competition included daily dietary intake using a 7-day food record and plasma biochemical measurements (alpha-tocopherol, vitamin C, beta-carotene and retinol). RESULTS: First, total energy intake was obviously lower than the energetic intake usually observed in well-trained endurance athletes. Second, antioxidant vitamins intake was also insufficient. Indeed, the intake was lower than the French Dietary Reference Intakes (DRI) for this population in 18 subjects for vitamin E and 6 subjects for vitamin C, beta-carotene and Retinol Equivalent. As a significant relationship was found between total energy intake and the intake of vitamin E (r = 0.73; p < 0.001) and vitamin C (r = 0.78; p < 0.001), the low total energy intake contributed partially to the insufficient antioxidant vitamins intake. The dietary questionnaire analysis also revealed a low intake of vegetable oils, fruits and vegetables. However, plasma concentrations of these antioxidant vitamins were similar to the literature data observed in athletes. CONCLUSION: This study evidenced obvious insufficient energy intake in ultra endurance athletes associated with a low antioxidant vitamin intake.     

Caffeine as a lipolytic food component increases endurance performance in rats and athletes

Caffeine is one of the famous ergogenic aids in the athletic field. Caffeine has been known to stimulate lipolysis that spares stored glycogen utilization during moderate intensity exercise. Therefore, we investigated the effects of caffeine ingestion on exercise performance in rats and athletes. Rats were administered the caffeine (6 mg/kg) 1 h prior to the exercise then were run on a treadmill at a speed of 20 m/min. They were decapitated at 0 min, 30 min, 60 min of exercise, and exhausted time point. Human subjects ingested the caffeine (5 mg/kg) 1 h prior to the exercise. They exercised on a cycle ergometer at 60% of their VO2max for 45 min, and then the exercise intensity was increased to 80% of their VO2max until exhaustion. Blood and breathing gas samples were collected and calculated every 10 min during exercise. Respiratory exchange ratio of the caffeine trial was significantly lower than that of the placebo trial in the athletes' study (p<0.05). Blood free fatty acid (FFA) levels in studies of both rats and athletes were increased by caffeine ingestion during exercise (p<0.05). Blood lactate levels were also increased during exercise in both rats and athletes (p<0.05). Increased FFA and glycerol concentrations reduced glycogen utilization during exercise compared with placebo group in rats. In addition, endurance time to exhaustion was significantly increased by the caffeine ingestion in both rats and athletes (p<0.05). These results suggest that the caffeine ingestion enhanced endurance performance resulting from spare stored glycogen with increasing lipolysis from adipose tissues and fat oxidation during exercise both in rats and in athletes.     

Relationships between vitamin and mineral supplement use, dietary intake, and dietary adequacy among adolescents

OBJECTIVE: To examine patterns of supplement use among US adolescents and the relationship between supplement use and dietary intake and adequacy. DESIGN: Adolescents self-reported 2 days of food intake using the 24-hour recall method and supplement use during a personal interview conducted as part of the 1994 Continuing Survey of Food Intakes of Individuals (CSFII). SUBJECTS: A national sample of 423 adolescents included in the 1994 CSFII survey. STATISTICAL ANALYSIS: chi 2 analysis was used to determine which demographic factors were significantly related to patterns of supplement use. Weighted percentages of adolescents by category of supplement use for selected vitamins and minerals (calcium; iron; zinc; folic acid; and vitamins A, B-6, C, and E) are presented. Relationships between dietary intake of macronutrients and vitamins and minerals among adolescents and supplement use were determined using a least-squares model of general linear regression. RESULTS: Approximately one-third of adolescents reported using supplements, with 15.6% of youth using them on a daily basis. The majority of supplement users reported taking multivitamins (N = 95; 65.5%) whereas only one-third of supplement users reported taking individual vitamins or minerals. Supplement use was found to vary by gender, household size, and US region of residence. Adolescents who reported using supplements had higher mean dietary intakes of most micronutrients and lower intakes of total and saturated fat than those who did not use supplements. More than one-third of adolescents had dietary intakes of vitamins A and E, calcium, and zinc that were < 75% of the US Recommended Dietary Allowance. APPLICATIONS/CONCLUSIONS: The majority of US adolescents do not use vitamin or mineral supplements. Interestingly, adolescents who do use supplements, even on an infrequent basis, consume diets that are more nutrient-dense than those who do not use supplements. Dietary intakes of several micronutrients were inadequate among all adolescents in this study, regardless of supplement use status. There is a need to develop and implement programs aimed at improving the dietary intakes of US adolescents.     

Prospective study of dietary fat and risk of cataract extraction among US women

The authors examined prospectively the association between dietary fat intake and cataract extraction in adult women from the Nurses' Health Study. A total of 71,083 women were followed prospectively for up to 16 years between 1984 and 2000. Dietary fat was assessed by repeated food frequency questionnaires. Incident cases of cataract extraction were determined by a biennial questionnaire. The multivariate-adjusted relative risk for the highest compared with the lowest quintile of total fat intake was 1.10 (95% confidence interval (CI): 0.99, 1.22; p(trend) = 0.01). Women in the highest quintile of long-chain omega-3 fatty acid had a 12% lower risk of cataract extraction compared with those in the lowest quintile (relative risk = 0.88, 95% CI: 0.79, 0.98; p(trend) = 0.02). Total fish intake was inversely associated with cataract (for intake of > or = 3/week vs. <1/month: relative risk = 0.89, 95% CI: 0.81, 0.98; p(trend) = 0.01). The authors' findings suggest that higher intake of long-chain omega-3 fatty acid (eicosapentaenoic acid and docosahexaenoic acid) and consumption of fish may modestly reduce the risk of cataract.     

Factors related to dietary status of limited resource farm families: a case study.

A case study approach was used to study 10 limited resource farm families to identify factors relative to the farm family situation that are associated with adequate or inadequate food habits. Dietary measures were developed and adequacy of diets was analyzed in relation to gender, women's off- or on-farm employment, predominant farm activities, and cohesiveness. Traditional families, with two adults present and the women employed on the farm, had the most adequate diets and higher cohesiveness ratings. Families in transition, with women employed off the farm or headed by widowed women farmers, had the poorest diets nutritionally and tended to have lower cohesiveness ratings. The presence of a food source raised or grown for income purposes did not guarantee the use of the food for family consumption.     

Vitamin and mineral supplementation: effect on the running performance of trained athletes

There is limited scientific justification for the widespread use of vitamin and mineral supplements by athletes. We used a 9-mo, placebo-controlled crossover study design to determine whether a multivitamin and mineral supplement influenced the athletic performance of 30 competitive male athletes. At 0, 3, 6, and 9 mo the runners performed a progressive treadmill test to volitional exhaustion for measurement of maximal oxygen consumption, peak running speed, blood lactate turnpoint, and peak postexercise blood lactate level. Running time in a 15 km time trial was also measured. None of these variables was influenced by 3 mo of active supplementation. We conclude that 3 mo of multivitamin and mineral supplementation was without any measurable ergogenic effect.     

Influence of type and amount of dietary lipid on plasma lipid concentrations in endurance athletes

Changes in plasma total cholesterol, triglyceride, and lipoprotein concentrations were assessed in three male endurance cyclists who consumed isoenergetic diets for 28-day periods in which carbohydrate, polyunsaturated fat, or saturated fat contributed about 50% of the daily energy intake. Dietary cholesterol was similar among the diets. Maximal aerobic capacity was maintained at 62 ml O2/(kg X min). Body weights were held within 3% of admission levels. The polyunsaturated fat diet significantly (p less than 0.05) reduced mean fasting plasma total cholesterol in comparison to the saturated fat and carbohydrate diets (160 versus 254 and 243 mg/dl, respectively). Similarly, the polyunsaturated fat diet depressed (p less than 0.05) mean plasma triglycerides relative to the saturated fat and carbohydrate diets (37 versus 62 and 79 mg/dl, respectively). No significant dietary effects were seen on high-density lipoprotein cholesterol. The observed changes in plasma total cholesterol were not significantly different than the values predicted by the Keys' equation, delta CHL = 1.35(2 delta S-delta P) + 1.5 delta Z. We conclude that under controlled conditions in which physical activity is constant l) dietary lipid differences influence fasting serum lipid and lipoprotein concentrations among men with high energy expenditures, and 2) the Keys' equation gives useful predictions of changes in plasma total cholesterol among vigorous men consuming different types and amounts of dietary lipid.     

Vitamin and mineral status: effects on physical performance

Public health recommendations encourage the selection of a balanced diet and increasing physical activity to foster health and well-being. Whereas the adverse effects of restricted intakes of protein, fat, and carbohydrate on physical performance are well known, there is limited information about the impact of low intakes of vitamins and minerals on the exercise capacity and performance of humans. Physically active people generally consume amounts of vitamins and minerals consistent with the recommendations for the general public. However, when intakes are less than recommendations, some noticeable functional impairments occur. Acute or short-term marginal deficiencies, identified by blood biochemical measures of vitamin B status, had no impacts on performance measures. Severe deprivation of folate and vitamin B12 result in anemia and reduce endurance work performance. Evidence of vitamin A and E deficiencies in athletic individuals is lacking apparently because body storage is appreciable. In contrast to vitamins, marginal mineral deficiencies impair performance. Iron deficiency, with or without anemia, impairs muscle function and limits work capacity. Magnesium deprivation increases oxygen requirements to complete submaximal exercise and reduces endurance performance. Use of vitamin and mineral supplements does not improve measures of performance in people consuming adequate diets. Young girls and individuals participating in activities with weight classifications or aesthetic components are prone to nutrient deficiencies because they restrict food intake and specific micronutrient-rich foods. This information will be useful to professionals who counsel physically active people and scientific groups who make dietary recommendations to improve health and optimize genetic potential.     

Nutritional concerns of female athletes: a case study.

Some of the nutritional concerns of female athletes are highlighted in this case study of a 20-year-old woman who wants to lose 16% of her body weight to qualify for the position of coxswain on a national crew team. These concerns include adequacy of vitamin, mineral, protein, and carbohydrate intake as well as amenorrhea and pathogenic eating behaviors.     

Drink-flavor change's lack of effect on endurance cycling performance in trained athletes

This study investigated whether a change in beverage flavor during endurance cycling improves subsequent performance. Eight trained male athletes (age 24.3 +/- 3.9 y, weight 74.7 +/- 6.0 kg, peak O(2) uptake [VO(2peak)] 65.4 +/- 5.4 mL x kg(-1) x min(-1); mean +/- SD) undertook 3 trials, with training and diet being controlled. Trials consisted of 120 min of steady-state (SS) cycling at approximately 70% VO(2peak), immediately followed by a 7-kJ/kg time trial (TT). During exercise subjects were provided with fluids every 20 min. After 80 min of SS cycling subjects either continued drinking the same-flavor sports drink or changed to an alternate flavor-either an alternate-flavor sports drink (AFSD) or cola. All beverages were carbohydrate and volume matched. Changing drink flavor caused no significant change in TT time (sports drink 27:16 +/- 03:12, AFSD 27:06 +/- 03:16, cola 27:03 +/- 02:42; min:s). The various flavors produced no treatment effects on heart rate, blood glucose, or rating of perceived exertion throughout the SS exercise protocol. The influence of other taste variables such as palatability, bitterness, or timing of flavor change on endurance-exercise performance requires more rigorous investigation.     

An alternative dietary strategy to make weight while improving mood, decreasing body fat, and not dehydrating: a case study of a professional jockey

Professional jockeys are unique among weight-making athletes, as they are often required to make weight daily and, in many cases, all year-round. Common methods employed by jockeys include dehydration, severe calorie restriction, and sporadic eating, all of which have adverse health effects. In contrast, this article outlines a structured diet and exercise plan, employed by a 22-yr-old professional National Hunt jockey in an attempt to reduce weight from 70.3 to 62.6 kg, that does not rely on any of the aforementioned techniques. Before the intervention, the client's typical daily energy intake was 8.2 MJ (42% carbohydrate [CHO], 36% fat, 22% protein) consumed in 2 meals only. During the 9-wk intervention, daily energy intake was approximately equivalent to resting metabolic rate, which the athlete consumed as 6 meals per day (7.6 MJ, 46% CHO, 19% fat, 36% protein). This change in frequency and composition of energy intake combined with structured exercise resulted in a total body-mass loss of 8 kg, corresponding to reductions in body fat from 14.5% to 9%. No form of intentional dehydration occurred throughout this period, and mean urine osmolality was 285 mOsm/kg (SD 115 mOsm/kg). In addition, positive changes in mood scores (BRUMS scale) also occurred. The client was now able to ride light for the first time in his career without dehydrating, thereby challenging the cultural practices inherent in the sport.     

Effects of dietary fibers on mineral status of chicks

We investigated the effects of replacing dietary starch with dietary fibers of various types and particle sizes on utilization of bivalent cations by chicks. Inclusion of polyethylene powder, alfalfa cell walls, corn bran, oat bran and wheat bran into diets resulted in lower serum and tibia Zn levels. However, addition of pectin, cellulose and a xylose:gum arabic (50:50) mixture did not affect tissue Zn levels, whereas addition of 4% lignin increased serum Zn level from 2.50 to 3.44 micrograms/ml. Ingestion of fibers with particle sizes less than 300 micrometers resulted in higher serum Zn levels compared with those of particle sizes greater than 300 micrometers. Incorporation of 4 and 8% pectin decreased (P less than 0.05) serum and tibia Mg levels. When brans were fed, kidney Mg levels were lower due to fiber additions. Inclusion of lignin, the xylose:gum arabic mixture and alfalfa cell walls resulted in lower liver Cu levels; polyethylene and solka floc had no effect on liver Cu status. Fiber did not affect tissue Ca or Fe status. Each mineral influenced by fiber type, level or particle size appeared to be affected through different mechanisms.     

Mental health status and dietary intake among California adults: a population-based survey

California Health Interview Survey (2005–2015) data were used to examine the association between dietary intake frequencies and mental health – Kessler-6 scores categorised as no/low (NLPD), moderate (MPD) or serious psychological distress (SPD). The 245,891 surveys represented 27.7 million adults annually, with 13.2% having MPD and 3.7% SPD. Survey-adjusted regression adjusting for gender, age, race, education, poverty, marital status, BMI, geography and year found MPD and SPD associated with lower consumption of fruits (adjusted odds ratio 0.79 and 0.65, respectively), vegetables (AOR 0.81 and 0.68), and increased consumption of French fries (AOR 1.24, 1.30), fast food (AOR 1.32, 1.27), soda (AOR 1.23, 1.26) and variance-adjusted daily teaspoons of sugar (coefficients 3.05, 4.21), all p-values less than 0.001. In this large population-based sample, moderate and SPD were independently associated with unhealthy diet. Targeted public health interventions could focus on young adults and those with less than 12 years of education.     

Impact of iron depletion without anemia on performance in trained endurance athletes at the beginning of a training season: a study of female collegiate rowers

The objective of this study was to determine the impact of iron depletion without anemia on performance in a sample of female collegiate rowers at the beginning of a training season (August 2008, January 2009, and September 2009). One hundred sixty-five female collegiate rowers from 5 colleges and universities in central New York State participated in a screening of iron status. Blood hemoglobin (Hgb), serum ferritin (sFer), and soluble transferrin receptor were measured to determine prevalence of iron depletion and anemia. Rowers' habitual moderate and vigorous physical activity, as well as their best time to complete a 2-km simulated race during the previous 3 months, were self-reported. Sixteen rowers (10%) were identified as anemic (Hgb <12.0 g/dl). Using a sFer cutoff of <20.0 μg/L, 30% (n = 44) of the nonanemic rowers were identified as iron depleted without anemia and reported 2-km times ~21 s slower (p < .004) than rowers with normal iron status. Given the high prevalence of iron depletion reported in this and other studies, screening for low iron stores at the start of a training program in female athletes involved in an endurance sport may be clinically useful. In this study, iron-depleted rowers (sFer <20-25 μg/L) reported a decrease in performance time compared with those with normal iron stores.     

Smoking status: effects on the dietary intake, physical activity, and body fat of adult men

This investigation evaluated the relationship between smoking status and body fatness, dietary intake, and physical activity in adults. Subjects were 210 males who were either regular cigarette smokers (n = 35) or nonsmokers (n = 175). Estimated body fat and waist-to-hip (girth) measurements were carefully obtained. Additionally, a sensitive assessment of long-term dietary intake and a multifactorial approach to the assessment of physical activity were made. Results indicated that smokers had lower estimated body fat as calculated by multiple skinfold thickness assessments. In contrast, smokers reported the same total energy intakes as nonsmokers and their levels of physical activity were significantly lower than those of nonsmokers. The differences in intake and expenditure in smokers and the role of metabolism as a possible determinant of the body fat differences in smokers vs nonsmokers are discussed.