bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy and Nutrient Status of Amenorrheic Athletes Participating in a Diet and Exercise Training Intervention Program
Authors: Kopp-Woodroffe Sheila A. , Manore Melinda M. , Dueck Christine A. , Skinner James S. , Matt Kathleen S.
Published: August 2016

Chronic energy deficit is one of the strongest factors contributing to exercise-induced menstrual dysfunction. In such cases, macro- and micronutrient intakes may also be low. This study presents the results of a diet and exercise training intervention program, designed to reverse athletic amenorrhea, on improving energy balance and nutritional status in 4 amenorrheic athletes. The 20-week program provided a daily sport nutrition supplement and 1 day of rest/week. The intervention improved self-reported energy intake (El) and balance in all participants. The program increased protein intakes for the 3 athletes with a protein deficit to within the recommended levels for active individuals. Micronutrient intakes increased, as did serum concentrations of vitamin B12, folate, zinc, iron, and ferritin. These results indicate that some amenorrheic athletes have poor nutritional status due to restricted Els and poor food selections. A sport nutrition supplement may improve energy balance and nutritional status in active amenorrheic women.
The Effects of Zinc Depletion on Peak Force and Total Work of Knee and Shoulder Extensor and Flexor Muscles
Authors: Van Loan Marta D. , Sutherland Barbara , Lowe Nicola M. , Turnlund Judith R. , King Janet C.
Published: August 2016

In this study we tested the effect of zinc (Zn) on muscle function in humans. After receiving 12 mg Zn/day for 17 days. 8 male subjects received 0.3 mg Zn/day tor either 33 or 41 days. Subjects were divided into two groups for repletion. Group A subjects received overnight infusions of 66 mg Zn on Days 1 and 10 and then were fed 12 mg Zn/day for another 16 days. Group B subjects were fed 12 mg Zn/day for 3 weeks. Peak force and total work capacity of the knee and shoulder extensor and flexor muscle groups were assessed using an isokinetic dynamometer at baseline, at two points during depletion, and at repletion. Plasma Zn declined significantly during depletion and remained below baseline levels after repletion. The peak force of the muscle groups tesied was not affected by acute Zn depletion: however, total work capacity for the knee extensor muscles and shoulder extensor and flexor muscles declined significantly. The data suggest that acute Zn depletion alters the total work capacity of skeletal muscle.
Effects of In-Season (5 Weeks) Creatine and Pyruvate Supplementation on Anaerobic Performance and Body Composition in American Football Players
Authors: Stone Michael H. , Sanborn Kimberly , Smith Lucille L. , O'Bryant Harold S. , Hoke Tommy , Utter Alan C. , Johnson Robert L. , Boros Rhonda , Hruby Joseph , Pierce Kyle C. , Stone Margaret E. , Garner Brindley
Published: August 2016

The purpose of this investigation was to study the efficacy of two dietary supplements on measures of body mass, body composition, and performance in 42 American football players. Group CM (n = 9) received creatine monohy-drate, Group P (n = 11) received calcium pyruvate. Group COM (n = 11) received a combination of calcium pyruvate (60%) and creatine (40%), and Group PL received a placebo. Tests were performed before (Tl) and after (T2) the 5-week supplementation period, during which the subjects continued their normal training schedules. Compared to P and PL. CM and COM showed significantly greater increases for body mass, lean body mass, 1 repetition maximum (RM) bench press, combined 1 RM squat and bench press, and static vertical jump (SVJ) power output. Peak rate of force development for SVJ was significantly greater for CM compared to P and PL. Creatine and the combination supplement enhanced training adaptations associated with body mass/composition, maximum strength, and SVJ; however, pyruvate supplementation alone was ineffective.
Magnesium, Zinc, and Copper Status in Women Involved in Different Sports
Authors: Nuviala Ramón J. , Lapieza María G. , Bernal Enrique
Published: August 2016

The dietary intake, serum levels, and urinary excretion of magnesium, zinc, and copper were studied in 78 women involved in different sports (karate, handball, basketball, and running) and in 65 sedentary women. Seven-day, weighed-food dietary reports revealed that no group of female athletes reached the minimal intake recommended for magnesium (280 mg/day) and zinc (12 mg/day), although their values were superior to those offne control group. The estimated safe and adequate minimal intake of copper (1.5 mg/day) was amply surpassed by the basketball players and runners but was not reached by the handball players. Serum levels and urinary excretion of magnesium, zinc, and copper did not seem related either to their intake or to the type of physical activity performed. The influence of other factors such as nutritional status, bioavailability, intestinal absorption mechanisms, and muscle-level modifications might explain the differences between the different groups of female athletes.
Acute Carbohydrate Consumption Does Not Influence Resistance Exercise Performance during Energy Restriction
Authors: Dalton Renee A. , Walberg Rankin Janet , Sebolt Don , Gwazdauskas Frank
Published: August 2016

The effect of acute carbohydrate consumption on performance and metabolism of resistance-trained males was determined. Twenty-two subjects, assigned to either carbohydrate (C, n = 8), placebo (P, n - 8), or control (N, n = 6), performed standardized workouts every other day for a week prior to testing and throughout the testing period. Three of these workouts (Tl, T2, and T3) were the performance test in that the last bouts of leg extension and bench press were done to failure at 80% of 10 repetition maximum. A carbohydrate or placebo beverage was consumed 30 min prior to T3. Blood samples were drawn before and after T2 and T3. There was no effect of carbohydrate or energy restriction on number of repetitions done during the leg extension performance test. Carbohydrate intake prior to a resistance exercise bout done in negative energy balance state did not affect performance or evidence of muscle damage.
Ginseng Treatment Improves Psychomotor Performance at Rest and During Graded Exercise in Young Athletes
Authors: Ziemba Andrzej W. , Chmura Jan , Kaciuba-Uscilko Hanna , Nazar Krystyna , Wisnik Piotr , Gawronski Wojciech
Published: August 2016

This study was designed to determine the effect of ginseng treatment on multiple choice reaction time (RT) during exercise. Fifteen soccer players (age 19.07 ± 0.62 yrs) were placed in a double-blind manner into one of two groups: ginseng (n = 7), receiving 350 mg of ginseng daily for 6 weeks, or placebo (n = 8), receiving a placebo daily for 6 weeks. Before and after the treatment all the subjects performed an incremental bicycle ergometer exercise with intensity increasing 50 W every 3 min until volitional exhaustion. RT was measured before exercise, and then in the last 2 min of each exercise load. Maximal oxygen uptake (VO2max) and lactate threshold (LAT) were also determined from the exercise test. Ginseng treatment was found to shorten RT at rest and during exercise, shifting the exercise load associated with the shortest RT toward higher exercise loads. Neither ginseng nor placebo influenced VO2 max and LAT. In conclusion, ginseng extract does improve psychomotor performance during exercise without affecting exercise capacity.
Resting Metabolic Rate and Thermogenic Effect of Glucose in Trained and Untrained Girls Age 11-15 Years
Authors: Burkhard-Jagodzinska Krystyna , Nazar Krystyna , Ladyga Maria , Starczewska-Czapowska Janina , Borkowski Lech
Published: August 2016

Twelve girls who trained in rowing were examined twice a year for 4 years. Their initial age was 11.7 ± (SD) 0.2 yrs. Control groups consisted of 13 girls age 11.5±0.3 yrs and 18 girls age 14.4±0.3 yrs examined simultaneously with trained girls in the first and last year of the study, respectively. The examination involved basic anthropometry, estimation of sexual maturation (Tanner scale), 2-day food records, measurements of resting metabolic rate, energy expenditure following glucose ingestion (50 g), and determinations of blood glucose and plasma insulin concentrations prior to and 2 hrs after glucose load. Body mass, height, and fat content were slightly greater in trained girls. None of the subjects reported disturbances in menstrual function, and the age of menarche was similar for all. Both trained and untrained girls reported similar daily energy intake closer to the lower limit or slightly below the estimates of energy requirements for adolescents. Resting metabolic rate calculated per kg of total body mass or lean body mass was lower in trained girls, while the thermogenic effect of glucose was greater. Plasma insulin concentrations measured 2 hrs after glucose ingestion were lower in trained girls. The results suggest that in circumpubertal girls, increased physical activity leads to energy conservation at rest in postabsorptive state and a tendency toward enhancement of food-induced thermogenesis.
The Effect of Glycemic Index on Plasma Glucose and Lactate Levels during Incremental Exercise
Authors: Stannard Stephen R. , Thompson Martin W. , Miller Janette C. Brand
Published: August 2016

Consumption of low glycemic index (GI) foods before submaximal endurance exercise may be beneficial to performance. To test whether this may also be true for high intensity exercise. 10 trained cyclists began an incremental exercise test to exhaustion 65 min after consuming equal carbohydrate portions of glucose (HGI), pasta (LGI), and a noncarbohydrate control (PL). Time to fatigue did not differ significantly (p = 0.05) between treatments. Plasma glucose concentration was significantly lower after LGI vs. HGI from 15 to 45 min of rest postprandial. During exercise, plasma glucose concentration was significantly lower after HGI vs. LGI from 200 W until exhaustion. Plasma lactate concentration following HGI was significantly higher than PL from 30 min of rest postprandial through to the end of the 200-W workload. Plasma lactate concentration following LGI was significantly lower than after HGI from 45 min of rest postprandial through to the end of the 100-W workload. At higher exercise intensities, there was no significant difference in plasma lactate levels between treatments. These findings suggest that a high GI carbohydrate meal (1 g/kg body wt) 65 min prior to exercise decreases plasma glucose and increases plasma lactate levels compared to a low GI meal, but not enough to be detrimental to incremental exercise performance.
Eating Pattern and Nutritional Status of International Elite Flatwater Paddlers
Authors: García-Rovés Pablo M. , Fernández Serafina , Rodríguez Manuel , Pérez-Landaluce Javier , Patterson Angeles M.
Published: August 2016

The aim of this study is to accurately describe the eating pattern and nutritional status of international elite flatwater paddlers during 1 week of a high volume training camp. Ten male and 5 female international elite flatwater paddlers were recruited to take part in this study. These athletes were all members of the Spanish National Team. To assess the intake of energy, macronutrients, and micronutrients, we used the weighed food intake method carried out by an observer. Biochemical and hematological profiles were also obtained. Average daily energy intake in male and female flatwater paddlers was 21.5 ± 2.3 and 16.5 ± 1.7 MJ, respectively. Furthermore, the male athletes showed average carbohydrate and protein intakes of 7.5 ±0.8 and 2.2 ±0.3 g ·kg·1 body weight - day ’, respectively. Similar intakes were found in female paddlers. carbohydrate 7.3 ± 1.1 and protein 2.0±0.3g·kg·1 body weight·day·1. Daily relative contribution to energy from fat was higher than recommended for sports practitioners or sedentary people (< 30 % of daily energy) in both genders (39.1 ± 2.1 and 40.2± 2.9% for men and women, respectively). Nevertheless, this diet with a high fat content (rich in monounsaturated fatty acids) did not seem to influence the paddlers’ blood lipid profile that presented low values for total cholesterol and tryglicerides and high values for high-density lipoprotein cholesterol (HDL-cholesterol). Flatwater paddlers’ micronutrient intake was higher than Recommended Dietary Allowances/Dietary Reference Intake (RDA/DRIs), except for folate that is close to DRI values. Further studies are required in order to understand whether this level of fat intake could impair highly trained athletes’ performance and health.
Carbohydrate Supplementation Attenuates Muscle Glycogen Loss during Acute Bouts of Resistance Exercise
Authors: Haff G. Gregory , Koch Alexander J. , Potteiger Jeffrey A. , Kuphal Karen E. , Magee Lawrence M. , Green Samuel B. , Jakicic John J.
Published: August 2016

The effects of carbohydrate (CHO) supplementation on muscle glycogen and resistance exercise performance were examined with eight highly resistance trained males (mean ± SEM, age: 24.3 ± 1.1 years, height: 171.9±2.0 cm, body mass: 85.7 ± 3.5 kg; experience 9.9 ± 2.0 years). Subjects participated in a randomized, double blind protocol with testing sessions separated by 7 days. Testing consisted of an initial isokinetic leg exercise before and after an isotonic resistance exercise (IRT) session consisting of 3 leg exercises lasting ~39 min. Subjects consumed a CHO (1.0 g CHO ·kg body mass−1) or placebo treatment (PLC), prior to and every 10-min (0.5 g CHO ·kg body mass−1) during the IRT. Muscle tissue was obtained from the m vastus lateralis after a supine rest (REST) immediately after the initial isokinetic test (POST-ISO) and immediately after the IRT (POST-IRT). The CHO treatment elicited significantly less muscle glycogen degradation from the POST-ISO to POST-IRT (126.9 ± 6.5 to 109.7 ± 7.1 mmol·kg wet weight−1) compared to PLC (121.4±8.1 to 88.3±6.0 mmol·kg wet weight−1). There were no differences in isokinetic performance between the treatments. The results of this investigation indicate that the consumption of a CHO beverage can attenuate the decrease in muscle glycogen associated with isotonic resistance exercise but does not enhance the performance of isokinetic leg exercise.
Effect of Iron Supplementation on Thyroid Hormone Levels and Resting Metabolic Rate in Two College Female Athletes: A Case Study
Authors: Rosenzweig Penny Harris , Volpe Stella L.
Published: August 2016

Iron plays an important role in thyroid hormone metabolism; thus, iron deficiency anemia may lead to alterations in resting metabolic rate (RMR). Based on this premise, two iron-deficient-anemic female athletes, 18 (A 1) and 21 (A2) years of age, were supplemented with 23 mg/day of elemental iron to assess its effects on iron and thyroid hormone status and RMR at 0, 8, and 16 weeks. Anemia was clinically corrected in both subjects (hemoglobin: Al = 11.0 to 13.0 to 12.6 g/dL and A2 = 11.5 to 13.9 to 12.6 g/dL, 0 to 8 to 16 weeks, respectively). Serum ferritin (SF) concentration also improved in both subjects (Al: 5.0 to 11.0 to 15.0 ng/dL and A2: 5.0 to 16.0 to 20.0 ng/dL; 0 to 8 to 16 weeks, respectively); however, 16 weeks of iron supplementation did not fully replete iron stores. A2 increased dietary iron and ascorbic acid intakes from 8 to 16 weeks, possibly accounting for her higher SF concentrations. RMR and total thyroxine changed over time: Al increased while A2 decreased in these variables. Although clinical correction of iron deficiency anemia occurred after 16 weeks of low-level iron supplementation, RMR and thyroid hormone metabolism were oppositely affected in the two subjects.
Blood Glucose Responses to Carbohydrate Feeding Prior to Exercise in the Heat: Effects of Hypohydration and Rehydration
Authors: Echegaray Marcos , Armstrong Lawrence E. , Maresh Carl M. , Riebe Deborah , Kenefick Robert W. , Castellani John W. , Kavouras Stavros , Casa Douglas
Published: August 2016

This study assessed the plasma glucose (PG) and hormonal responses to carbohydrate ingestion, prior to exercise in the heat, in a hypohydrated state versus partial rehydration with intravenous solutions. On separate days, 8 subjects (21.0 ± 1.8 years; 57.3 ± 3.7 ml · kg−1 · min−1) exercised at 50% V̇O2maxin a 33 °C environment until a 4% body weight loss was achieved. Following this, subjects were rehydrated (25 ml · kg−1) with either: 0.45% IV saline (45IV), 0.9% IV saline (9IV), or no fluid (NF). Subjects then ingested 1 g · kg−1 of carbohydrate and underwent an exercise test (treadmill walking, 50% V̇O2max, 36 °C) for up to 90 min. Compared to pre-exercise level (294 mg · dl−1), PG increased significantly (>124 mg · dl−1) at 15 min of the exercise test in all trials and remained significantly elevated for 75 min in NF, 30 min more than in the 2 rehydration trials. Although serum Insulin increased significantly at 15 min of exercise in the 45IV trial (7.2 ± 1.2 vs. 23.7 ± 4.7 μIU · ml−1) no significant differences between trials were observed. Peak plasma norepinephrine was significantly higher in NF (640 ± 66 pg · ml−1) compared to the 45IV and 9IV trials (472 ± 55 and 474 ± 52 pg · ml−1, respectively). In conclusion, ingestion of a small solid carbohydrate load prior to exercise in the 4% hypohydration level resulted in prolonged high PG concentration compared to partial IV rehydration.
Resistance Training Affects Iron Status in Older Men and Women
Authors: Murray-Kolb Laura E. , Beard John L. , Joseph Lyndon J. , Davey Stephanie L. , Evans William J. , Campbell Wayne W.
Published: August 2016

Objective:

To examine the effects of resistance training on hematological and selected indices of iron status in 17 women aged 54–71 years and 18 men aged 56–69 years.

Design:

Tests and evaluations were done before and after all subjects participated in a resistance training program twice weekly for 12 weeks.

Results:

The resistance training was effective as evidenced by increases in skeletal muscle strength of 20 ± 9% and 23 ± 13% for the men and women, respectively. Hematological parameters and serum iron concentrations were within normal clinical ranges and were unchanged by resistance training for both the men and the women. Total iron binding capacity (TIBC) and transferrin saturation were also unaffected by resistance training in the women but were significantly affected in the men. The men showed a decreased TIBC (p < .0001) and an increased transferrin saturation (p = .050). Serum ferritin concentrations decreased significantly in the women (p = .041) but were unchanged in the men. Transferrin receptor concentrations were unaffected by resistance training in the women but increased significantly in the men (p = .030).

Conclusions:

With resistance training, iron status of older men and women changes in a sex specific way.
Nutritional Status of U.S. Elite Female Heptathletes during Training
Authors: Mullins Veronica A. , Houtkooper Linda B. , Howell Wanda H. , Going Scott B. , Brown C. Harmon
Published: August 2016

This study describes the body composition, dietary nutrient intake, dietary practices, and biochemical indices of iron status of elite female American heptathletes during training. Four-day diet records and dietary practice questionnaires were obtained from 19 female heptathletes (26 ± 3 years) during the training season. Anthropometric measurements and fasting blood samples were obtained at the lowest phase of the training cycle. These athletes had a low body fat (13.8 ± 2.7%) and high fat-free mass to height ratios (33.0 ± 2.0 kg/m). Average nutrient intakes were > 67% of the reference intakes for all nutrients except vitamin E. Most dietary nutrient densities were higher than NHANES III nutrient densities for women 20–29 years old. More than 50% of the athletes took vitamin supplements and monitored their hydration status. Fifteen of the 17 athletes reported a normal menstrual cycle. Markers of biochemical iron status were all within the normal range. On average, these athletes were lean with high levels of fat free mass, adequate nutrient intakes, and normal biochemical indices of iron status. However, individual data reveals considerable variability within this group.
β-Hydroxy-β-Methylbutyrate (HMB) Supplementation Does Not Affect Changes in Strength or Body Composition during Resistance Training in Trained Men
Authors: Slater Gary , Jenkins David , Logan Peter , Lee Hamilton , Vukovich Matthew , Rathmacher John A. , Hahn Allan G.
Published: August 2016

This investigation evaluated the effects of oral β-Hydroxy-β-Methylbutyrate (HMB) supplementation on training responses in resistance-trained male athletes who were randomly administered HMB in standard encapsulation (SH), HMB in time release capsule (TRH), or placebo (P) in a double-blind fashion. Subjects ingested 3 g · day−1 of HMB or placebo for 6 weeks. Tests were conducted pre-supplementation and following 3 and 6 weeks of supplementation. The testing battery assessed body mass, body composition (using dual energy x-ray absorptiometry), and 3-repetition maximum isoinertial strength, plus biochemical parameters, including markers of muscle damage and muscle protein turnover. While the training and dietary intervention of the investigation resulted in significant strength gains (p < .001) and an increase in total lean mass (p = .01), HMB administration had no influence on these variables. Likewise, biochemical markers of muscle protein turnover and muscle damage were also unaffected by HMB supplementation. The data indicate that 6 weeks of HMB supplementation in either SH or TRH form does not influence changes in strength and body composition in response to resistance training in strength-trained athletes.
Pathophysiology of Body Composition and Metabolic Abnormalities in HIV-Infection: Therapeutic Implications
Authors: Hellerstein Marc K.
Published: August 2016

Changes in body composition and metabolism have been a central feature of HIV infection from the outset—initially, as the wasting syndrome and, more recently, as metabolic and body fat redistribution syndromes associated with antiretroviral (ARV) therapy. Here, advances in physiologic and biochemical understanding of these conditions are reviewed. First, the pathophysiology of wasting in HIV-1 infection is discussed, focusing on the failure of nutrients to increase lean tissue (“anabolic block”) and the role of hypogonadism. Results of anabolic interventions, including recombinant growth hormone, testosterone, and progressive resistance exercise, are presented. Next, ARV-associated disorders are reviewed, including lipoatrophy and an hypothesized “mitochondrial toxicity.” The possibility of establishing pathogenesis in vivo in humans, by direct measurement of mitochondrial DNA synthesis and adipocyte proliferation, is discussed. In summary, important advances have occurred toward the goal of explaining body composition and metabolic abnormalities associated with HIV disease.
Muscle Protein Metabolism and the Sarcopenia of Aging
Authors: Short Kevin R. , Nair K. Sreekumaran
Published: August 2016

Loss of muscle mass, strength, and oxidative capacity accompanies normal aging in humans. The mechanisms responsible for these changes remain to be clearly defined. Muscle protein mass and function depend on protein turnover. Synthesis rate of the major muscle contractile protein, myosin heavy chain (MHC), and transcript levels of fast MHC isoforms decrease in association with strength reductions, while mitochondrial protein synthesis rate declines in parallel with activities of mitochondrial enzymes and maximal oxidative capacity (V̇O2max). Resistance exercise training increases the synthesis rate of MHC and transcript levels of the slow MHC isoform in older humans, along with increasing muscle strength. The relationship between the synthesis of muscle proteins, and muscle size and function, with aging and exercise training are discussed in this review.
Protein Metabolism and Age: Influence of Insulin and Resistance Exercise
Authors: Farrell Peter A.
Published: August 2016

Skeletal muscle proteins are constantly being synthesized and degraded, and the net balance between synthesis and degradation determines the resultant muscle mass. Biochemical pathways that control protein synthesis are complex, and the following must be considered: gene transcription, mRNA splicing, and transport to the cytoplasm; specific amino acyl-tRNA, messenger (mRNA), ribosomal (rRNA) availability; amino acid availability within the cell; the hormonal milieu; rates of mRNA translation; packaging in vesicles for some types of proteins; and post-translational processing such as glycation and phosphorylation/dephosphorylation. Each of these processes is responsive to the need for greater or lesser production of new proteins, and many states such as sepsis, uncontrolled diabetes, prolonged bed-rest, aging, chronic alcohol treatment, and starvation cause marked reductions in rates of skeletal muscle protein synthesis. In contrast, acute and chronic resistance exercise cause elevations in rates of muscle protein synthesis above rates found in nondiseased rested organisms, which are normally fed. Resistance exercise may be unique in this capacity. This chapter focuses on studies that have used exercise to elucidate mechanisms that explain elevations in rates of protein synthesis. Very few studies have investigated the effects of aging on these mechanisms; however, the literature that is available is reviewed.
Physiology of Aging
Authors: Masoro Edward J.
Published: August 2016

Although physiological deterioration occurs with advancing adult age, the interpretation of cross-sectional and longitudinal studies of age-changes in physiological processes are often complicated by confounders unrelated to aging. Age-associated disease is a major cause of physiological deterioration. To avoid this factor, only subjects free of discernible disease are used in many studies of what is referred to as “normal” aging. However, it is important to recognize that age-associated disease is not only a common occurrence but also an integral part of aging. Increasingly, gene-environment interactions are recognized as playing a major role in age-associated physiological deterioration, and there is great individual variation in both the rate of aging and the occurrence of age-associated physiological deterioration.
Adaptive Potentials of Skeletal Muscle in Young and Aging Rats
Authors: Pette Dirk , Škorjanc Dejan
Published: August 2016

We compared responses of the fast extensor digitorum longus (EDL) and tibialis anterior (TA) muscles in young (15-week) and aging (101-week) male Brown Norwegian rats to 50 days of chronic low-frequency stimulation (CLFS, 10 Hz, 10 hours/day). After 50 days of CLFS, the EDL muscles of the young (22-week) and aging (108-week) rats displayed similar increases in type IIA fibers, relative concentration of myosin heavy chain MHCIIa, elevations in mitochondrial citrate synthase and 3-hydroxyacyl-CoA dehydrogenase activities, and similar decreases in glycolytic enzyme activities (glyceraldehydephosphate dehydrogenase, lactate dehydrogenase). TA muscle in young rats contained a few cytochrome c oxidase negative (COX−) type I fibers. Their number was ~2-fold elevated by CLFS. Conversely, aging muscle, which contained a slightly higher amount of COX− fibers than young TA muscle, responded to CLFS with a significant decrease in COX− fibers. The appearance of small COX-positive type I fibers in stimulated aging muscle indicated that regenerating type I fibers “diluted” the COX-deficient fiber population.
Mineral Metabolism in Male Cyclists during High-Intensity Endurance Training
Authors: Dressendorfer Rudolph H. , Petersen Stewart R. , Lovshin Shona E. Moss , Keen Carl L.
Published: August 2016

This study examined the effects of intense endurance training on basal plasma and 24-hour urinary calcium (Ca), magnesium (Mg), iron (Fe), zinc (Zn), and copper (Cu) levels in 9 male competitive cyclists. The supervised training program followed a baseline period and included a volume phase (6 weeks, averaging 87% of maximal heart rate [HRmax]), an interval phase (18 days, 100% of HRmax), and a 10-day unloading taper. The primary training outcome measure was 20-km time-trial cycling performance. Subjects ate unrestricted diets and maintained their weight. Compared to baseline, performance improved significantly (p < .05), while mineral metabolism was not significantly different after the volume phase. However, after the interval phase, renal Ca excretion increased (p < .05) and plasma Ca fell slightly below the clinical norm. As compared to the interval phase, urinary Ca decreased (p < .05), plasma Ca increased (p < .05), and performance further improved (p < .05) after the taper. Whereas Mg, Fe, Zn, and Cu metabolism remained unchanged throughout the study, greater renal Ca excretion was associated with very high intensity interval training.
Nutritional Intake of French Soccer Players at the Clairefontaine Training Center
Authors: Leblanc J.Ch. , Gall F. Le , Grandjean V. , Verger Ph.
Published: August 2016

Young, French male athletes undergoing intensive elite sports training at the National Training Centre in Clairefontaine served as the subjects (N = 180; age range: 13 to 16 years) in a 3-year dietary survey aimed at characterizing their nutritional intake in terms of energy, macronutrients, calcium, and iron. Each year, the subjects were grouped by level into 3 promotions so that 9 groups could be studied. Dietary intake data were collected each year for each subject in the 9 groups, using a 5-day food record. The results showed that their total energy intake (TEI) was insufficient for athletes (ranging from 2352 ± 454 to 3395 ± 396 kcal/d as opposed to the recommended range of between 3819 and 5185 kcal/d). Furthermore, their diet was unbalanced, with too great an emphasis upon fatty foods (29.1 ± 2.8 to 34.1 ± 3.1% TEI vs. the 20% recommended), to the detriment of carbohydrates (48.5 ± 4.3 to 56.6 ± 3.1% TEI vs. the 55 to 60% recommended). The calcium intake was too low in 5 of the 9 groups while, in contrast, the iron intake was satisfactory in all groups. Furthermore, during this 3-year period at the Clairefontaine Centre, the subjects significantly (p < .05) improved their calcium and iron intakes (1021 ± 197 and 12 ± 2 mg/d in 1996, 1299 ± 155 and 16 ± 2 mg/d in 1997, and 1252 ± 184 and 17 ± 2 mg/d in 1998). This rise in micronutrient intakes may have been due to a physiological adaptation to growth or to the positive effects of courses on nutrition given during their stay at the Centre.
The Effect of Bovine Colostrum Supplementation on Exercise Performance in Elite Field Hockey Players
Authors: Hofman Zandrie , Smeets Rolf , Verlaan George , Lugt Richard v.d. , Verstappen Peter A.
Published: August 2016

In a double-blind, randomized, placebo-controlled study, we investigated the effect of 8 weeks of supplementation with bovine colostrum (Intact™) on body composition and exercise performance (5 × 10-m sprint, vertical jump, shuttle-run test, and suicide test). Seventeen female and 18 male elite field hockey players, including players from the Dutch national team, received either 60 g of colostrum or whey protein daily. The 5 × 10-m sprint test performance improved significantly (p = .023) more in the colostrum group [0.64±0.09 s (mean ± SEM)] compared to the whey group (0.33±0.09 s). The vertical jump performance improved more in the colostrum group (2.1 ± 0.73 cm) compared to the whey group (0.32 ± 0.82 cm). However, this was not statistically significant (p = .119). There were also no significant differences in changes in body composition and endurance tests between the 2 groups. It is concluded that in elite field hockey players, colostrum supplementation improves sprint performance better than whey. However, there were no differences with regard to body composition or endurance performance.
Effect of Aspartate and Asparagine Supplementation on Fatigue Determinants in Intense Exercise
Authors: Marquezi Marcelo Luis , Roschel Hamilton Augusto , Costa André dos Santos , Sawada Letícia Aiko , Lancha Jr. Antonio Herbert
Published: August 2016

Purpose: This study evaluated the effect of aspartate (ASP) and asparagine (ASG) supplementation on fatigue determinants in Wistar rats exercised to exhaustion by swimming. Methods: The animals were tested for anaerobic threshold (AT) determination and then supplemented with 350 mM ASP + 400 mM ASG · day−1 (AA group, n = 16) or 2 ml · day−1 of distillated water (PLC group, n = 16) for 7 days. On the 7th day of supplementation, the animals were divided into 4 new groups and killed at rest (RAA, n = 8; RPLC, n = 8), or immediately after the swimming exercise to exhaustion (EAA, n = 8; EPLC, n = 8). Results: No significant differences were observed between amino acids and placebo rest groups for muscle and liver glycogen, blood glucose, lactate, ala-nine, and glutamine concentrations. However, in the exhaustion groups, the EAA group showed higher exercise time (68.37+ 25.42 X 41.12 + 13.82 min, p < .05) and lower blood lactate concentration (8.57 ± 1.92 X 11.28 + 2.61 mmol · L−1, p < .05) than the EPLC group. Moreover, the ASP+ASG supplementation decreased the rate of glycogen degradation of gastrocnemius (1.00 + 0.51 X 3.43 ± 0.99 μg · 100 mg of tissue sample−1 · min−1), extensor digitorius longus (5.70 ± 2.35 X 8.11 ± 3.97 μg · 100 mg of tissue sample−1 min−1) and liver (0.51 ± 0.34 X 3.37 ± 2.31 μg · 100 mg of tissue sample−1 min−1) for EAA. Conclusion: These results suggest that ASP+ASG supplementation may increase the contribution of oxidative metabolism in energy production and delay fatigue during exercise performed above the AT.
Effect of Creatine Supplementation on Aerobic Performance and Anaerobic Capacity in Elite Rowers in the Course of Endurance Training
Authors: Chwalbiñska-Moneta Jolanta
Published: August 2016

The effect of oral creatine supplementation on aerobic and anaerobic performance was investigated in 16 elite male rowers during 7-day endurance training. Before and after the daily ingestion of 20 g creatine monohydrate for 5 days (Cr-Group, n = 8) or placebo (Pl-Group, n = 8), subjects performed two exercise tests on a rowing ergometer: (a) incremental exercise consisting of 3-min stage durations and increased by 50 W until volitional exhaustion; (b) an all-out anaerobic exercise performed against a constant load of 7 W/kg. Heart rate and blood lactate concentrations were determined during exercise and recovery. Maximal power output did not significantly differ after the treatment in either group. The mean individual lactate threshold rose significantly after Cr treatment from 314.3 ± 5.0 W to 335.6 ± 7.1 W (p < .01), as compared with 305.0 ± 6.9 W and 308.9 ± 5.9 W (ns), before and after placebo ingestion, respectively. During the anaerobic test, the athletes supplemented with creatine were able to continue rowing longer (mean increase, 12.1 ± 4.5 s; p < .01) than Pl-Group (2.4 ± 8.2 s; ns). No significant differences were found between groups in blood LA after the all-out exercise. The results indicate that in elite rowers, creatine supplementation improves endurance (expressed by the individual lactate threshold) and anaerobic performance, independent of the effect of intensive endurance training.
Food for Trans-Atlantic Rowers: A Menu Planning Model and Case Study
Authors: Clark Nancy , Coleman Cato , Figure Kerri , Mailhot Tom , Zeigler John
Published: August 2016

Every 4 years, rowers from around the world compete in a 50- to 60-day transAtlantic rowing challenge. These ultra-distance rowers require a diet that provides adequate calories, protein, vitamins, minerals, and fluids so they can perform well day after day, minimize fatigue, and stay healthy. Yet, the rowers are confronted with menu planning challenges. The food needs to be lightweight, compact, sturdy, non-spoiling in tropical temperatures, calorie dense, easy to prepare, quick to cook, and good tasting. Financial concerns commonly add another menu planning challenge. The purpose of this case study is to summarize the rowers’ food experiences and to provide guidance for sports nutrition professionals who work with ultra-endurance athletes embarking on a physical challenge with similar food requirements. The article provides food and nutrition recommendations as well as practical considerations for ultra-distance athletes. We describe an 8,000 calorie per day menu planning model that uses food exchanges based on familiar, tasty, and reasonably priced supermarket foods that provide the required nutrients and help contain financial costs.
The Nutritional and Anthropometric Status of Gaelic Football Players
Authors: Reeves Sue , Collins Kieran
Published: August 2016

The aim of this study was to investigate the dietary intakes and anthropometric profiles of county and club Gaelic football players and compare them to soccer players and control subjects. Seven-day dietary records were analyzed and anthropometric measurements were taken midway through the Gaelic football competitive season. The county group with a mean height of 1.82 ± 0.04 m were significantly taller (p < .05) and had less body fat than any other group. The county and club teams consumed 151 ± 11 and 150 ± 16 kJ · kg−1 · day−1, respectively, with 52.2 ± 5% and 49.5 ± 9% of their energy intakes as carbohydrate. This compares to 173 ± 11 kJ · kg−1 · day−1 for the soccer players and 159 ± 8 kJ · kg−1 · day−1 for the controls, with 57 ± 4% and 44.9 ± 5% of their energy from carbohydrate. The nature of Gaelic football demands a balanced diet, rich in energy and carbohydrate and with adequate calcium is consumed; the subjects needed to increase these dietary components in order to meet the energetic demands of competition and training. Additional nutritional counseling was provided on an individual basis.
Dietary Composition Influences Short-term Endurance Training–Induced Adaptations of Substrate Partitioning during Exercise
Authors: Jacobs Kevin A. , Paul David R. , Geor Ray J. , Hinchcliff Kenneth W. , Sherman W. Michael
Published: August 2016

The purpose of the current study was to examine the influence of dietary composition on short-term endurance training–induced adaptations of substrate partitioning and time trial exercise performance. Eight untrained males cycled for 90 min at ~54% aerobic capacity while being infused with [6,62H]glucose before and after two 10-d experimental phases separated by a 2-week washout period. Time trial performance was measured after the 90-min exercise trials before and after the 2nd experimental phase. During the first 10-d phase, subjects were randomly assigned to consume either a high carbohydrate or high fat diet while remaining inactive (CHO or FAT). During the second 10-d phase, subjects consumed the opposite diet, and both groups performed identical daily supervised endurance training (CHO+T or FAT+T). CHO and CHO+T did not affect exercise metabolism. FAT reduced glucose flux at the end of exercise, while FAT+T substantially increased whole body lipid oxidation during exercise and reduced glucose flux at the end of exercise. Despite these differences in adaptation of substrate use, training resulted in similar improvements in time trial performance for both groups. We conclude that (a) 10-d high fat diets result in substantial increases in whole body lipid oxidation during exercise when combined with daily aerobic training, and (b) diet does not affect short-term training-induced improvements in high-intensity time trial performance.
Effect of Active versus Passive Recovery on Metabolism and Performance during Subsequent Exercise
Authors: McAinch Andrew J. , Febbraio Mark A. , Parkin Joann M. , Zhao Shuang , Tangalakis Kathy , Stojanovska Lilian , Carey Michael F.
Published: August 2016

This study tested the hypothesis that active recovery between bouts of intense aerobic exercise would lead to better maintenance of exercise performance in the second bout of exercise. Seven trained men on 2 separate occasions (VO2peak = 58.3 ± 9.4 ml · kg–1 · min–1) performed as much work as possible during two 20-min cycling exercise bouts, separated by a 15-min recovery period. During passive recovery (PR), subjects rested supine, while during active recovery (AR) subjects continued to cycle at 40% VO2peak. Muscle biopsies and blood samples were obtained. Neither muscle glycogen or lactate was different when comparing AR with PR at any point. In contrast, plasma lactate concentration was higher (p < .05) in PR versus AR during the recovery period, such that subjects commenced the second bout of intense exercise with a lower (p < .05) plasma lactate concentration in AR (4.4 ± 0.7 vs. 7.7 ± 1.4 mmol · L–1 following AR and PR, respectively). Work performed in Bout 2 was less than that performed in Bout 1 in both trials (p < .01), with no difference in work performed between trials. These data do not support the benefit of AR when compared to PR in the maintenance of subsequent intense aerobic exercise performance.
Effect of Endurance Training and Fasting on Renal Gluconeogenic Enzymes in the Rat
Authors: Sumida Ken D. , Garrett Jeff H. , Mcjilton William T. , Hevener Andrea L. , Donovan Casey M.
Published: August 2016

The purpose of this study was to examine the effects of chronic exercise training (running 30 m/min, 10% grade, 90 min/d for 8–10 weeks) on specific renal enzyme activities involved with the gluconeogenic pathway in the fed and 24-hr fasted state in rats. A portion of the kidney (containing the cortex and medulla) was homogenized from which cytosolic (c) and mitochondrial (m) fractions were separated. Maximal gluconeogenic enzyme activities were assessed for: phosphoenolpyruvate carboxykinase (cPEPCK), fructose 1,6-bisphosphatase (cFBP), pyruvate carboxylase (mPC), aspartate aminotrans-ferase (cAspAT), alanine aminotransferase (cAlaAT), and lactate dehydroge-nase (cLDH). In the fed state, there was no significant difference between groups in any of the enzymes examined (nmoles/min × mg protei n–1): cPEPCK (25.8 ± 1.7), cFBP(106.8 ± 7.1), mPC (20.7 ± 1.8), cAspAT( 1047.1 ±38.6), cAlaAT (52.3 ±4.3), and cLDH(1728.6± 163.2). After the 24-hr fast, there was a significant increase in cPEPCK (52.4 ± 2.9 and 52.0 ± 2.1) and mPC (44.6 ± 4.3 and 47.6 ± 4.9), control and trained, respectively. These results suggest that the maximal enzyme activities for cPEPCK and mPC can be augmented as a result of fasting that was independent of the training status.
Zinc and Copper Biochemical Indices of Antioxidant Status in Elite Athletes of Different Modalities
Authors: Koury Josely C. , de Oliveira Astrogildo V. , Portella Emílson S. , de Oliveira Cyntia F. , Lopes Gustavo C. , Donangelo Carmen M.
Published: August 2016

The purpose of this study was lo compare zinc and copper biochemical indices of antioxidant status and their relationship in elite athletes of different modalities: aerobic with high-impact (triathletes, n = 10 and long-distance runners, n = 12), anaerobic with high-impact (short-distance runners, n = 9), and anaerobic with low-impact (short-distance swimmers, n = 13). The influence of recent dietary intake and body composition was also evaluated. A venous blood sample was drawn 16-20 hr after competition for the following measurements: packed-cell volume and hemoglobin in blood; copper and zinc in plasma and erythrocytes; ceruloplasmin in plasma; superoxide dismutase activity and metal-lothionein in erythrocyles; and erythrocyte osmotic fragility. Zinc and copper intakes were not different in the athlete groups and did not affect the biochemical indices measured. Athletes of the long-distance high-impact aerobic modalities had higher indices of antioxidant protection (erythrocyte zinc, superoxide dismutase activity, and metallothionein) than those of the short-distance low-impact modalities, suggesting that there is adaptation of the antioxidant capacity to the specific training. Significant correlations were observed in all athletes between erythrocyte zinc, superoxide dismutase activity, and metallothionein consistent with the importance of an adequate zinc status in the response of antioxidant mechanisms to intense exercise.
The Effects of Creatine Supplementation on Cardiovascular, Metabolic, and Thermoregulatory Responses during Exercise in the Heat in Endurance-Trained Humans
Authors: Kilduff L.P. , Georgiades E. , James N. , Minnion R.H. , Mitchell M. , Kingsmore D. , Hadjicharalambous M. , Pitsiladis Y.P.
Published: August 2016

The effects of creatine (Cr) supplementation on cardiovascular, metabolic, and thermoregulatory responses, and on the capacity of trained humans to perform prolonged exercise in the heat was examined. Endurance-trained males (n = 21) performed 2 constant-load exercise tests to exhaustion at 63 ± 5 % VO2max in the heat (ambient temperature: 30.3 ± 0.5 °C) before and after 7 d of Cr (20 g · d–1 ’ Cr + 140 g • d–1 glucose polymer) or placebo. Cr increased intraccl-lular water and reduced thermoregulatory and cardiovascular responses (e.g., heart rate, rectal temperature, sweat rate) but did not significantly increase time to exhaustion (47.0 ± 4.7 min vs. 49.7 ± 7.5 min, P = 0.095). Time to exhaustion was increased significantly in subjects whose estimated intramuscular Cr levels were substantially increased (“responders”: 47.3 ± 4.9 min vs. 51.7 ± 7.4 min, P = 0.031). Cr-induced hyperhydration can result in a more efficient thermoregulatory response during prolonged exercise in the heat.
Effects of an Alleged Myostatin-Binding Supplement and Heavy Resistance Training on Serum Myostatin, Muscle Strength and Mass, and Body Composition
Authors: Willoughby Darryn S.
Published: August 2016

This study examined 12 wk of resistance training and cystoseim canariensis supplementation on serum levels of myostatin and follistatin-like related gene (FLRG) and muscle strength and body composition. Twenty-two untrained males were randomly assigned to a placebo (PLC) or myostatin binder (MYO) group in a double-blind fashion. Blood was obtained before and after 6 and 12 wk of training. PLC and MYO trained thrice weekly using 3 sets of 6 to 8 repetitions at 85% to 90% 1 repetition maximum. MYO ingested 1200 mg/d of cystoseim canariensis. Data were analyzed with 2-way ANOVA. After training, total body mass, fat-free mass, muscle strength, thigh volume/mass, and serum myostatin and FLRG increased for both groups (P < 0.05); however, there were no differences between groups (P > 0.05). Twelve wk of heavy resistance training and 1200 mg/d of cystoseim canariensis supplementation appears ineffective at inhibiting serum myostatin and increasing muscle strength and mass or decreasing fat mass.
Effects of Microhydrin® Supplementation on Endurance Performance and Metabolism in Well-Trained Cyclists
Authors: Glazier Lee R. , Stellingwerff Trent , Spriet Lawrence L.
Published: August 2016

This study investigated whether the supplement Microhydrin® (MH) contains silica hydride bonds (Si-H) and if Microhydrin supplementation increased performance or altered metabolism compared to placebo (PL) during prolonged endurance cycling. Seven endurance-trained male cyclists consumed 9.6 g of MH or PL over 48 h in a randomized, double-blind, crossover design. Subjects cycled at ~ 70% of their VO2peak, coupled with five 2-min bursts at 85% VO2peak to simulate hill climbs over 2 h. Subjects then completed a time trial, which required them to complete 7 kJ/kg body mass as quickly as possible. Infrared spectrometry analysis showed a complete absence of Si-H bonds in MH. There was no difference in time trial performance between the 2 trials (PL: 2257 ± 120 s vs. MH: 2345 ± 152 s). Measured oxygen uptake, respiratory exchange ratio, carbohydrate (MH: 2.99 ± 0.13 g/min; PL: 2.83 ± 0.17 g/min avg. over 2 h) and fat (MH: 0.341 ± 0.06 g/min; PL: 0.361 ± 0.07 g/min) oxidation rates and all blood parameters (lactate, glucose, and free fatty acids) were all unaffected by MH supplementation. The volume of expired CO2 and ventilation were significantly greater with MH supplementation (P ≤ 0.05). The results indicate that oral Microhydrin supplementation does not enhance cycling time trial performance or alter metabolism during prolonged submaximal exercise in endurance-trained cyclists.