bluuebunny/crossref_metadata_2025 huggingface dataset:
Inadvertent Doping through Supplement Use by Athletes: Assessment and Management of the Risk in Australia
Authors: Baylis Anna , Cameron-Smith David , Burke Louise M.
Published: August 2016

Many athletes report using a wide range of special sports foods and supplements. In the present study of 77 elite Australian swimmers, 99% of those surveyed reported the use of these special preparations, with 94% of swimmers reporting the use of non-food supplements. The most popular dietary supplements were vitamin or mineral supplements (used by 94% of the group), herbal preparations (61%), and creatine (31%). Eighty-seven percent of swimmers reported using a sports drink or other energy-providing sports food. In total, 207 different products were reported in this survey. Sports supplements, particularly supplements presented as pills or other non-food form, are poorly regulated in most countries, with little assurance of quality control. The risk of an inadvertent “positive doping test” through the use of sports supplements or sports foods is a small but real problem facing athletes who compete in events governed by anti-doping rules. The elite swimmers in this survey reported that information about the “doping safety” of supplements was important and should be funded by supplement manufacturers. Although it is challenging to provide such information, we suggest a model to provide an accredited testing program suitable for the Australian situation, with targeted athlete education about the “sports safety” of sports supplements and foods.
Short-Term β-Hydroxy-β-Methylbutyrate Supplementation Does Not Reduce Symptoms of Eccentric Muscle Damage
Authors: Paddon-Jones Douglas , Keech Andrew , Jenkins David
Published: August 2016

Purpose:

We examined the effects of short-term β-hydroxy-β-methylbutyrate (HMB) supplementation on symptoms of muscle damage following an acute bout of eccentric exercise.

Methods:

Non-resistance trained subjects were randomly assigned to a HMB supplement group (HMB, 40mg/kg body weight/day, n = 8) or placebo group (CON, n = 9). Supplementation commenced 6 days prior to a bout of 24 maximal isokinetic eccentric contractions of the elbow flexors and continued throughout post-testing. Muscle soreness, upper arm girth, and torque measures were assessed pre-exercise, 15 min post-exercise, and 1,2,3, 4,7, and 10 days post-exercise.

Results:

No pre-test differences between HMB and CON groups were identified, and both performed a similar amount of eccentric work during the main eccentric exercise bout (p > .05). HMB supplementation had no effect on swelling, muscle soreness, or torque following the damaging eccentric exercise bout (p > .05).

Conclusion:

Compared to a placebo condition, short-term supplementation with 40mg/kg body weight/day of HMB had no beneficial effect on a range of symptoms associated with eccentric muscle damage. If HMB can produce an ergogenic response, a longer pre-exercise supplementation period may be necessary.
Control of Muscle Protein Synthesis as a Result of Contractile Activity and Amino Acid Availability: Implications for Protein Requirements
Authors: Rennie Michael J.
Published: August 2016

The major anabolic influences on muscle are feeding and contractile activity. As a result of feeding, anabolism occurs chiefly by increases in protein synthesis with minor changes in protein breakdown. Insulin has a permissive role in increasing synthesis, but the availability of amino acids is crucial for net anabolism. We have investigated the role of amino acids in stimulating muscle protein synthesis, the synergy between exercise and amino acid availability, and some of the signaling elements involved. The results suggest that muscle is acutely sensitive to amino acids, that exercise probably increases the anabolic effects of amino acids by a separate pathway, and that for this reason it is unlikely that accustomed physical exercise increases protein requirements.
Energy Expenditure and Aging: Effects of Physical Activity
Authors: Starling Raymond D.
Published: August 2016

Aging is associated with a decline in daily energy expenditure that is disproportionately greater than the decline in daily energy intake. Collectively, these events can create a “positive” energy balance, secondary gains in central and total body fat, and a subsequently higher risk of morbidity and mortality. Participation in regular physical activity is a logical strategy to attenuate the decline in energy expenditure with aging, as physical activity can comprise between 10–50% of an older person’s daily energy expenditure. Understanding the influence of regular physical activity on energy expenditure with advancing age is clinically relevant, particularly since estimates predict that nearly 25% of the population will be ≥ 65 years of age by the year 2030. This brief review will focus on the current state of aging, energy expenditure, and physical activity literature. Topics to be addressed include: (a) measurement of physical activity in older adults; (b) aging and physical inactivity; and (c) influence of regular aerobic exercise on resting metabolic rate (RMR), thermic effect of food (TEF), and non-exercising physical activity.
Effects of Activity on Growth Factor Expression
Authors: Goldspink Geoffrey , Yang Shi Yu
Published: August 2016

For some time, it has been appreciated that muscle mass is regulated locally as well as systemically. We have cloned the cDNA of two isoforms of IGF-1, which are derived from the IGF-1 gene by alternate splicing. The expression of one of these was only detectable after mechanical stimulation. For this reason, this has been called mechano growth factor (MGF). The MGF is not glycosylated, is smaller, and has a shorter half-life in the unbound state than the systemic liver type IGF-1. As the result of a reading frame shift the MGF peptide also has a different C terminal sequence and thus has different binding protein/receptor affinities. Another splice variant (muscle L.IGF-I) is expressed in muscle during rest but is also upregulated by exercise. The latter is similar to the systemic liver type IGF-1. The evidence suggests that MGF has a high potency for inducing local protein synthesis and preventing apoptosis and therefore has an important role in local tissue repair and remodeling. Our physiological experiments show that stretch and particularly stretch combined with electrical stimulation, rather than stimulation alone are important in inducing MGF expression. The mechanotransduction mechanism is believed to involve the muscle cytoskeleton. During aging, the production of growth hormone and IGF-1 by the liver declines markedly. The discovery of MGF and muscle IGF-1 provides a link between physical activity and gene expression. This underlines the need for the elderly to remain active as the locally produced growth factors supplement the circulating IGF-1 levels.
Mechanisms of Muscle Insulin Resistance in Obese Individuals
Authors: Dohm G. Lynis
Published: August 2016

We previously reported that insulin resistance in skeletal muscle of obese individuals was associated with decreases in insulin signal transduction and tyrosine kinase activity of the insulin receptor. Herein is reviewed the recently published data supporting the hypothesis that protein kinase C (PKC) phosphorylates the insulin receptor on serine/threonine residues to decrease tyrosine kinase activity and cause insulin resistance. Treatment of insulin receptors from obese subjects with alkaline phosphatase restored tyrosine kinase activity, suggesting that the reduced activity was a result of hyperphosphorylation of the receptor. Incubating human muscle fiber strips with PKC inhibitors restored insulin action in muscle of obese patients, while activating PKC with a phorbol ester caused insulin resistance in muscle from lean control patients. The beta isoform of PKC was elevated in muscle of obese, insulin-resistant patients. These data are consistent with the hypothesis that elevated PKC activity may cause insulin resistance by phosphorylating the insulin receptor to decrease tyrosine kinase activity.
Regulation of Muscle Glucose Transport during Exercise
Authors: Richter Erik A. , Wojtaszewski Jørgen F.P. , Kristiansen Søren , Daugaard Jens R. , Nielsen Jakob N. , Derave Wim , Kiens Bente
Published: August 2016

In the present short review some factors affecting glucose utilization during exercise in skeletal muscle will be briefly described. Special focus will be put on the glucose transport step across the sarcolemma. Glucose transporters (GLUT4) are expressed at a surprisingly similar level in the different muscle fiber types in human skeletal muscle in contrast to findings in the rat. When working at the same absolute work load muscle glucose transport is decreased in trained compared with untrained muscle in part due to a decrease in GLUT4 translocation to the sarcolemma in trained muscle. However, when trained and untrained muscle are stressed severely by a workload taxing 100% of their peak oxygen uptake in a glycogen-depleted state, then glucose uptake is larger in trained than in untrained muscle and correlates with muscle GLUT4 content. Finally, the possible role of the AMP-activated protein kinase (AMPK) in regulating glucose uptake during exercise is discussed. It is indicated that at present no experiments definitively link activation of AMPK to activation of muscle glucose transport during exercise.
Effect of Aging on Glucose and Lipid Metabolism during Endurance Exercise
Authors: Mittendorfer Bettina , Klein Samuel
Published: August 2016

Endurance exercise increases the use of endogenous fuels to provide energy for working muscles. Elderly subjects oxidize more glucose and less fat during moderate intensity exercise. This shift in substrate use is presumably caused by age-related changes in skeletal muscle, including decreased skeletal muscle respiratory capacity, because adipose tissue lipolysis and plasma fatty acid availability are not rate limiting. Endurance training in elderly subjects increases muscle respiratory capacity, decreases glucose production and oxidation, and increases fat oxidation thereby correcting or compensating for the alterations in substrate oxidation associated with aging.
Plasma Triglyceride Metabolism in Humans and Rats during Aging and Physical Inactivity
Authors: Hamilton Marc T. , Areiqat Enas , Hamilton Deborah G. , Bey Lionel
Published: August 2016

Physical activity often declines with age because of a reduction in the spontaneous activities of daily living and because of less intense exercise. In controlled studies of young rats, it was shown that physical activities associated with walking and standing were especially important for maintaining a high level of lipoprotein lipase (LPL) activity in postural skeletal muscles (slowtwitch oxidative muscles). More intense contractions during run training were important for a high LPL activity in the fast-twitch glycolytic muscles. Aging also causes a fiber type–specific decrease of skeletal muscle LPL activity and LPL protein in weight-bearing skeletal muscles (and no aging effect in glycolytic muscles). Thus, contractile inactivity may be a significant factor causing sub-optimal triglyceride metabolism in skeletal muscles during both unloading in young animals and aging. Measurements of plasma LPL activity, plasma triglyceride (TG) clearance rates, postprandial hypertriglyceridemia after oral fat tolerance tests, and fasting TG levels were generally indicative of reduced plasma TG metabolism during middle or old age. In contrast, older endurance-trained individuals had a favorable blood lipid profile compared to age-matched or young controls, even when the controls were not overweight. Therefore, the poor TG metabolism that is frequently associated with aging may be caused by some of the same processes that lower skeletal muscle LPL activity of young sedentary individuals.
Effect of High and Low Rates of Fluid Intake on Post-exercise Rehydration
Authors: Kovacs Eva M.R. , Schmahl Regina M. , Senden Joan M.G. , Brouns Fred
Published: August 2016

The effect of a high (H) and a low (L) rate of post-exercise fluid consumption on plasma volume and fluid balance restoration was investigated. Eight well-trained cyclists were dehydrated at 3% of body weight (BW) by cycling at 28 °C. During the recovery period, they ingested a carbohydrate-electrolyte solution in a volume equivalent to 120% of BW loss. Randomly, they ingested 60%, 40%, and 20% in the 1 st, 2nd, and 3rd hours of the recovery period, respectively (H), or 24% · h−1 during 5 hours (L). BW loss was similar for both trials and resulted in a total drink intake of 2.6 ± 0.1 kg. Urine output in H exceeded significantly that of L in the 2nd and 3rd hours. This was reversed in the 5th and 6th hours. Plasma volume and fluid balance increased more rapidly in H compared to L. After 6 hours this difference disappeared. It is concluded that H results in a faster rate of plasma volume and fluid balance restoration compared to L, despite a temporary large urine output.
Effect of Flavor and Awareness of Kilojoule Content of Drinks on Preference and Fluid Balance in Team Sports
Authors: Minehan Michelle R. , Riley Malcolm D. , Burke Louise M.
Published: August 2016

A palatable flavor is known to enhance fluid intake during exercise; however, a fear of excessive kilojoule intake may deter female athletes from consuming a sports drink during training sessions. In order to examine this issue, we monitored fluid balance during 9 separate training sessions undertaken by junior elite female netball players (n = 9), female basketball players (n = 7), and male basketball players (n = 8). The beverages tested were water, a regular carbohydrate-electrolyte beverage (6.8% CHO, 18.7 mmol/L Na, 3.0 mmol/L K, 1130 kJ/L), and an identical tasting, low kilojoule electrolyte beverage (1% CHO, 18.7 mmol/L Na, 3.0 mmol/L K, 170 kJ/L). Each subject received each of the 3 drinks at 3 separate training sessions, in a randomized, balanced order. Subjects were aware of the beverage provided. Change in body mass over the training session was used to estimate body fluid change, while voluntary fluid intake was determined from the change in weight of drink bottles used in each session. The overall fluid balance on drinks classified as regular, low kilojoule, and water was -11.3 ml/h (95%CI -99.6 to 77.0), -29.5 ml/h (95%CI -101.4 to 42.5) and -156.4 ml/h (95%CI -215.1 to -97.6), respectively. The results indicate that, overall, better fluid balance was achieved using either of the flavored drinks compared to water. These data confirm that flavored drinks enhance fluid balance in a field situation, and suggest that the energy content of the drink is relatively unimportant in determining voluntary fluid intake.
Effects of Resistive Training and Chromium Picolinate on Body Composition and Skeletal Muscle Size in Older Women
Authors: Campbell Wayne W. , Joseph Lyndon J.O. , Anderson Richard A. , Davey Stephanie L. , Hinton Jeremy , Evans William J.
Published: August 2016

This study assessed the effect of resistive training (RT), with or without high-dose chromium picolinate (Cr-pic) supplementation, on body composition and skeletal muscle size of older women. Seventeen sedentary women, age range 54-71 years. BMI 28.8±2.4 kg/m2. were randomly assigned (double-blind) to groups (Cr-pic. n = 9; Placebo, n = 8) that consumed either 924 μg Cr/d as Cr-pic or a low-Cr placebo (<0.2 μg Cr/d) during a 12-week RT program (2 day/ week, 3 sets · exercise−1 · d1,80% of 1 repetition maximum). Urinary chromium excretion was 60-fold higher in the Cr-pic group, compared to the Placebo group (p < .001), during the intervention. Resistive training increased maximal strength of the muscle groups trained by 8 to 34% (p < .001), and these responses were not influenced by Cr-pic supplementation. Percent body fat and fat-free mass were unchanged with RT in these weight-stable women, independent of Cr-pic supplementation. Type I and type II muscle fiber areas of the m. vastus lateralis were not changed over time and were not influenced by Cr-pic supplementation. These data demonstrate that high-dose Cr-pic supplementation did not increase maximal strength above that of resistive training alone in older women. Further, these data show that, under these experimental conditions, whole body composition and skeletal muscle size were not significantly changed due to resistive training and were not influenced by supplemental chromium picolinate.
The Effect of a High Carbohydrate Meal on Endurance Running Capacity
Authors: Chryssanthopoulos Costas , Williams Clyde , Nowitz Andrea , Kotsiopoulou Christina , Vleck Veronica
Published: August 2016

This study examined the effects of a pre-exercise meal and a carbohydrate-electrolyte solution on endurance running capacity. Ten men performed 3 treadmill runs at 70% V̇O2max to exhaustion after consuming (a) a carbohydrate meal 3 h before exercise and a carbohydrate-electrolyte solution during exercise (M+C); or (b) the carbohydrate meal 3 h before exercise and water during exercise (M+W): or (c) a liquid placebo 3 h before exercise and water during exercise (P+W). Exercise time was longer in M+C (125.1 ±5.3 min; mean±SE) and M+W (111.9 ± 5.6 min) compared with P+W (102.9 ± 7.9 min;p< .01 and p < .05, respectively), and longer in M+C compared with M+W (p < .05). Serum insulin concentration at the start of exercise and carbohydrate oxidation rates during the first hour of exercise were higher, whereas plasma FFA concentrations throughout exercise were lower in M+W and M+C than in P+W (p < .01). A carbohydrate meal before exercise at 70% V̇O2max improved endurance running capacity; however, me combination of the meal and a carbohydrate-electrolyte solution during exercise further improved endurance running capacity.
Food and Fluid Intake and Disturbances in Gastrointestinal and Mental Function during an Ultramarathon
Authors: Glace Beth , Murphy Christine , McHugh Malachy
Published: August 2016

The purpose of this study was to document eating strategies employed by runners during a 160-km race, and to identify eating patterns that predispose the runner to disturbed mental or gastrointestinal functioning. We monitored intake in 19 volunteers during the 12 hours pre-race. Intake was determined by interview with runners approximately every 12 km throughout the race. The mean finish time was 24.3 hours, with 4 runners not completing the race. Body mass decreased during the race, 75.9 ± 2.3 kg to 74.4 ± 2.2 kg (p < .001). Runners ingested 2643 kcals during the 12 hours prerace (68% carbohydrate) and 3.8 L of fluid. During the race 6047 kcal, 18 L of fluid, and 12 g of sodium were consumed. Gastrointestinal distress (GI) was experienced by half of the participants, but was unrelated to food or fluid intake. Upper GI symptoms were more prevalent than lower and occurred mainly after 88 km. Runners with GI distress tended to complete fewer training miles (p = .10) and to do shorter training runs (p = .08). Half of the volunteers reported mental status changes (MSC), such as confusion or dizziness. Runners with MSC had greater intake of total calories, carbohydrate, and fluid (p < .05) than runners without MSC. They also completed shorter training runs (p = .03). Caloric and moisture intake for all runners far exceeded intakes described previously. Although intake did not match energy expenditure, it may represent the upper limit for absorption during exercise, and very high food and/or fluid intake appears to lead to perturbed mental status.
Effect of Acute and Short-Term Administration of Vanadyl Sulphate on Insulin Sensitivity in Healthy Active Humans
Authors: Jentjens Roy L.P.G. , Jeukendrup Asker E.
Published: August 2016

Vanadium compounds have been shown to have insulin-like properties in rats and non-insulin-dependent diabetic humans. The purpose of the present study was to examine whether the effects of acute and short-term administration of vanadyl sulphate (VS) on insulin sensitivity also exist in healthy active individuals. Five male and 2 female participants (age: 24.9 ± 1.5 years; height: 176.1 ± 2.9 cm; body mass: 70.1 ± 2.9 kg) underwent 3 oral glucose tolerance tests (OGTT). The first OGTT was performed to obtain a baseline index of insulin sensitivity (ISI). On the night preceding the second OGTT, participants ingested 100 mg of VS, and the acute effects of VS on ISI were examined. For the next 6 days, participants were instructed to ingest 50 mg of VS twice daily, and a final OGTT was performed on day 7 to determine the short-term effects of VS on ISI. No differences were found in fasting plasma glucose and insulin concentrations after VS administration. Furthermore, ISI after 1 day and 7 days of VS administration was not different compared with baseline ISI (4.8±0.1 vs. 4.7±0.1 vs. 4.7 ± 0.1, respectively). These results demonstrate that there are no acute and short-term effects of VS administration on insulin sensitivity in healthy humans.
Short-term Creatine Supplementation Improves Maximum Quadriceps Contraction in Women
Authors: Kambis Kenneth W. , Pizzedaz Sarah K.
Published: August 2016

Creatine monohydrate (CrH2O) supplementation has been demonstrated to increase skeletal muscle power output in men. However, its effect upon women is not as clearly defined. This study investigated the effect of oral creatine supplementation upon muscle function, thigh circumference, and body weight in women. Twenty-two consenting college-age women were assigned to 1 of 2 groups matched for dietary and exercise habits, phase of menstrual cycle, and fat-free mass (FFM). After familiarization with testing procedures, pretrial measures of muscle function (5 repetitions 60 deg · s−1 and 50 repetitions 180 deg · s−1) were conducted during maximal voluntary concentric contraction of the preferred quadriceps muscle using an isokinetic dynamometer. Subjects then ingested 0.5 g · kg−1 FFM of either CrH2O or placebo (one fourth dosage 4 times daily) in a double-blind design for 5 days. Resistance exercise was prohibited. After the ingestion phase was completed, all measures were repeated at the same time of day as during pretrials. Statistical analysis revealed time to peak torque in quadriceps extension decreased from pre-test values of 255 ± 11 ms (mean ± SEM) to post-test values of 223 ± 3 ms; average power in extension increased from 103 ± 7 W pre-test to 112 ± 7 W post-test; and, during flexion, average power increased from 59 ± 5 W pre-test to 65 ± 5 W post-test in the creatine group as compared to controls (p ≤ .05). FFM, percent body fat, mid-quadriceps circumference, skinfold thickness of the measured thigh, and total body weight did not change for both groups between trials. We conclude that CrH2O improves muscle performance in women without significant gains in muscle volume or body weight.
Creatine Supplementation: A Comparison of Loading and Maintenance Protocols on Creatine Uptake by Human Skeletal Muscle
Authors: Preen David , Dawson Brian , Goodman Carmel , Beilby John , Ching Simon
Published: August 2016

The purposes of this investigation were first to determine the impact of 3 different creatine (Cr) loading procedures on skeletal muscle total Cr (TCr) accumulation and, second, to evaluate the effectiveness of 2 maintenance regimes on retaining intramuscular TCr stores, in the 6 weeks following a 5-day Cr loading program (20 g · day−1). Eighteen physically active male subjects were divided into 3 equal groups and administered either: (a) Cr (4 X 5 g · day−1 X 5 days), (b) Glucose+Cr (1 g · kg−1 of body mass twice per day), or (c) Cr in conjunction with 60 min of daily muscular (repeated-sprint) exercise. Following the 5-day loading period, subjects were reassigned to 3 maintenance groups and ingested either 0 g · day−1, 2 g · day−1 or 5 g · day−1 of Cr for a period of 6 weeks. Muscle biopsy samples (vastus lateralis) were taken pre- and post-loading as well as post-maintenance and analyzed for skeletal muscle ATP, phosphocreatine (PCr), Cr, and TCr concentrations. Twenty-four hour urine samples were collected for each of the loading days and last 2 maintenance days, and used to determine whole body Cr retention. Post-loading TCr stores were significantly (p < .05) increased in all treatment conditions. The Glucose+Cr condition produced a greater elevation (p < .05) in TCr concentrations (25%) than the Cr Only (16%) or Exercise+Cr (18%) groups. Following the maintenance period, muscle TCr stores were still similar to post-loading values for both the 2 g · day−1 and 5 g · day−1 conditions. Intramuscular TCr values for the 0 g · day−1 condition were significantly lower than the other conditions after the 6-week period. Although not significantly different from pre-loading concentrations, muscle TCr for the 0 g · day−1 group had not fully returned to baseline levels at 6 weeks post-loading. The data suggests that Glucose+Cr (but with a much smaller glucose intake than currently accepted) is potentially the most effective means of elevating TCr accumulation in human skeletal muscle. Furthermore, after 5 days of Cr loading, elevated muscle TCr concentrations can be maintained by the ingestion of small daily Cr doses (2-5 g) for a period of 6 weeks and that TCr concentrations may take longer than currently accepted to return to baseline values after such a Cr loading regime.
One Hour Cycling Performance Is Not Affected by Ingested Fluid Volume
Authors: Backx Karianne , van Someren Ken A. , Palmer Garry S.
Published: August 2016

This study investigated the effect of differing fluid volumes consumed during exercise, on cycle time-trial (TT) performance conducted under thermoneutral conditions (20 °C, 70% RH). Ten minutes after consuming a bolus of 6 ml · kg−1 body mass (BM) of a 6.4% CHO solution and immediately following a warm-up, 8 male cyclists undertook a 1-h self-paced TT on 4 separate occasions. During a “familiarization” trial, subjects were given three 5-min periods (15– 20 min, 30–35 min, and 45–50 min) to consume fluid ad libitum. Thereafter subjects undertook, in random order, trials consuming high (HF), moderate (MF), or low fluid (LF) volumes, where 300, 150, and 40 ml of fluid were consumed at 15, 30, and 45 min of each trial, respectively, and total CHO intake was maintained at 57.6 g. During exercise, power output and heart rate were monitored continuously, whilst stomach fullness was rated every 10 min. Additionally, BM loss and BM loss corrected for fluid intake was calculated during each trial. At 40, 50, and 60 min differences in ratings of stomach fullness were found between trials (LF vs. HF and MF vs. HF). There were however no differences in performance or physiological variables (heart rate or BM loss) between trials. These results indicate that when a pre-exercise CHO bolus is consumed, there is no effect of subsequent consumption of different fluid volumes when trained cyclists undertake a 1-h performance task in a thermoneutral environment.
The Effect of Resistance Exercise on the Thermic Effect of Food
Authors: Denzer Charlene M. , Young John C.
Published: August 2016

Purpose:

The thermic effect of food (TEF) is the increment in energy expenditure above resting metabolic rate associated with the cost of absorption and processing of food for storage. Previous studies have shown that TEF is enhanced by aerobic endurance exercise of sufficient duration and intensity. The purpose of this study was to determine if a similar effect occurs with a single bout of resistance exercise (weightlifting).

Methods:

VO2 was measured in 9 healthy volunteers (3 males and 6 females) for 2 hours after ingestion of a 2760 kJ (660 kcal) carbohydrate meal with and without prior completion of a resistance training regimen (2 sets of 10 repetitions of 10 different exercises).

Results:

The meal caused an immediate and persistent thermic effect in both the control and the exercise trial. Mean oxygen consumption over baseline increased 20% in the control trial and 34% in the exercise trial. TEF calculated from VO2 and RER (total area under the response curve above baseline) was 73% greater in the exercise trial compared with the control trial (159 ± 18 vs. 92 ± 14 KJ/2 hrs, p < .02).

Conclusion:

These results indicate that TEF in response to a carbohydrate meal is enhanced following a single bout of resistance exercise.
Effects of Creatine on Body Composition and Strength Gains after 4 Weeks of Resistance Training in Previously Nonresistance-Trained Humans
Authors: Kilduff Liam P. , Pitsiladis Yannis P. , Tasker Louise , Attwood Jeff , Hyslop Paul , Dailly Andrew , Dickson Ian , Grant Stan
Published: August 2016

This study examined the effects of Cr supplementation on muscle strength in conjunction with resistance training in nonresistance-trained males utilizing strategies previously reported in the literature to help optimize muscle Cr uptake. Nineteen nonresistance-trained males underwent 4 weeks of resistance training (3 days · week−1) while assigned to Cr (20 g · d−1 Cr + 140 g · d−1 glucose) for 7 days (loading), followed by 5 g · d−1 Cr + 35 g · d−1 glucose for 21 days (maintenance; n = 9) or placebo (160 g · d−1 glucose [loading] followed by 40 g · d−1 [maintenance; n = 10]). In subjects classified as “responders” to Cr on the basis of body mass changes (n = 7), the magnitude of change in 180∞ · s−1 isokinetic (p = .029) and isometric (p = .036) force was greater compared to the placebo group. A positive correlation was found between changes in body mass and 180º · s−1 isokinetic (loading: r = 0.68, p = .04; maintenance: r = 0.70, p = .037) and isometric (loading: r = 0.82, p < .01) force. Estimated Cr uptake was also positively correlated with changes in 60º · s−1 (r = 0.90, p < .01) and 180º · s−1 (r = 0.68, p = .043) isokinetic force, and isometric force (r = 0.71, p = .033). These results indicate that Cr supplementation can increase muscle strength (allied with 4 weeks of strength training) but only in subjects whose estimated Cr uptake and body mass are significantly increased; the greater the Cr uptake and associated body mass changes, the greater the performance gains.
Antioxidant Diet Supplementation Influences Blood Iron Status in Endurance Athletes
Authors: Aguiló Antoni , Tauler Pere , Fuentespina Emilia , Villa Gerardo , Córdova Alfredo , Tur Josep A. , Pons Antoni
Published: August 2016

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.
Inadequate Carbohydrate Intake Following Prolonged Exercise Does Not Increase Muscle Soreness after 15 Minutes of Downhill Running
Authors: Nelson Matthew R. , Conlee Robert K. , Parcell Allen C.
Published: August 2016

In Delayed Onset Muscle Soreness (DOMS), muscles become sore 24 to 48 hours after eccentric and unaccustomed activity. Fiber stiffness, due to decreased muscle glycogen, may predispose muscle to greater damage during eccentric exercise. This study sought to determine if inadequate carbohydrate intake following a protocol to decrease muscle glycogen would increase DOMS after 15 min of downhill running. Thirty-three male subjects (age, 18–35 years) were randomized into 3 groups for testing over a 7-day period. The depletion (DEP) group (n = 12) underwent a glycogen depletion protocol prior to a 15-min downhill run designed to induce DOMS. The repletion (FED) group (n = 10) underwent a glycogen depletion protocol followed by a carbohydrate repletion protocol (>80% CHO) prior to downhill running. The third (ECC) group (n = 11) performed only the downhill running protocol. Subjective muscle soreness, isometric force production, relaxed knee angle, and thigh circumference were measured pretreatment and on days 1, 2, 3, 4, and 6 post treatment. Subjective muscle soreness for all groups increased from 0 cm pretreatment to 3.05 ± 0.72 cm (on a 10-cm scale) on day 1 post treatment (p < .05). All groups were significantly different from baseline measurements until day 4 post treatment. Each group experienced a decline in isometric force from 281 ± 45 N pre-to 253 ± 13 N on day 1 post treatment (p < .05). The decrease in isometric force persisted in all groups for 4 days post treatment. Increases in thigh circumference and relaxed knee angle elevations in all 3 groups were statistically different (p < .05) from pretreatment until day 4. No differences were noted between groups for any of the parameters examined. In the current study, 15 min of downhill running is sufficient to cause DOMS with the associated functional and morphological changes; however, inadequate carbohydrate intake after a glycogen depleting exercise does not appear to exacerbate DOMS and the associated symptoms.
Reliability and Validity of a Brief Questionnaire to Assess Calcium Intake in Female Collegiate Athletes
Authors: Ward Kenneth D. , Hunt Kami Mays , Berg Melanie Burstyne , Slawson Deborah A. , Vukadinovich Christopher M. , McClanahan Barbara S. , Clemens Linda H.
Published: August 2016

Calcium intake often is inadequate in female collegiate athletes, increasing the risk for training injuries and future osteoporosis. Thus, a brief and accurate assessment tool to quickly measure calcium intake in athletes is needed. We evaluated the reliability and validity, compared to 6 days of diet records (DRs), of the Rapid Assessment Method (RAM), a self-administered calcium checklist (14). Seventy-six female collegiate athletes (mean age = 18.8 yrs, range = 17–21; 97% Caucasian) were recruited from basketball, cross-country, field hockey, soccer, and volleyball teams. Athletes completed a RAM at the start of the training season to assess calcium intake during the past week. Two weeks later, a second RAM was completed to assess reliability, and athletes began 6 days of diet records (DRs) collection. At completion of DRs, athletes completed a final RAM, corresponding to the same time period as DRs, to assess agreement between the 2 instruments. The RAM demonstrated adequate testretest reliability over 2 weeks (n = 56; Intraclass correlation [ICC] = .54, p <.0001) and adequate agreement with DRs (n = 34; ICC = .41, p = .0067). Calcium intake was below recommended levels, and mean estimates did not differ significantly on the RAM (823±387 mg/d) and DRs (822±330 mg/d; p = .988). Adequacy of calcium intake from both DRs and the RAM was classified as “inadequate” (<1000 mg/d) and “adequate” (≥1000 mg/d). Agreement between the RAM and DRs for adequacy classification was fair (ICC = .30, p = .042), with the RAM identifying 84% of athletes judged to have inadequate calcium intake based on DRs. The RAM briefly and accurately estimates calcium intake in female collegiate athletes compared to DRs.
Cordyceps Sinensis (CordyMax Cs-4) Supplementation Does Not Improve Endurance Exercise Performance
Authors: Parcell Allen C. , Smith Jason M. , Schulthies Shane S. , Myrer J. William , Fellingham Gilbert
Published: August 2016

It is purported that supplementation with Cordyceps Sinensis (CordyMax Cs-4) will improve oxidative capacity and endurance performance. The intent of this investigation was to examine the effects of CordyMax Cs-4 supplementation on VO2peak, ventilatory threshold, and endurance performance in endurance-trained cyclists. Twenty-two male cyclists participated in 5 weeks of supplementation with CordyMax Cs-4 tablets (3 g/d). Training intensity was maintained by weekly documentation and reporting throughout the 5-week period. Subjects completed a VO2peak test and work-based time trial prior to and following the supplementation period. VO2peak was similar within and between placebo (PLA) and treatment (CS) groups prior to (59.9 ± 5.9 vs. 59.1 ± 5.4 ml/kg/min, respectively) and following (60.1 ± 5.5 vs. 57.1 ± 5.8 ml/kg/min, respectively) the supplementation period. Ventilatory threshold (VT) was measured at 72 ± 10% of VO2peak in P and T prior to supplementation and did not change in either group following the supplementation. PLA completed the time trial in 61.4 ± 2.4 min compared to 62.1 ± 4.0 min in T. Time trial measurements did not differ between groups, nor did they change in response to supplementation. It is concluded that 5 weeks of CordyMax Cs-4 supplementation has no effect on aerobic capacity or endurance exercise performance in endurance-trained male cyclists.
Acute Rhodiola Rosea Intake Can Improve Endurance Exercise Performance
Authors: De Bock Katrien , Eijnde Bert O. , Ramaekers Monique , Hespel Peter
Published: August 2016

Purpose:

The purpose of this study was to investigate the effect of acute and 4-week Rhodiola rosea intake on physical capacity, muscle strength, speed of limb movement, reaction time, and attention.

Methods:

PHASE I: A double blind placebo-controlled randomized study (n = 24) was performed, consisting of 2 sessions (2 days per session). Day 1: One hour after acute Rhodiola rosea intake (R, 200-mg Rhodiola rosea extract containing 3% rosavin + 1% salidroside plus 500 mg starch) or placebo (P, 700 mg starch) speed of limb movement (plate tapping test), aural and visual reaction time, and the ability to sustain attention (Fepsy Vigilance test) were assessed. Day 2: Following the same intake procedure as on day 1, maximal isometric knee-extension torque and endurance exercise capacity were tested. Following a 5-day washout period, the experimental procedure was repeated, with the treatment regimens being switched between groups (session 2). PHASE II: A double blind placebo-controlled study (n = 12) was performed. Subjects underwent sessions 3 and 4, identical to Phase I, separated by a 4-week R/P intake, during which subjects ingested 200 mg R/P per day.

Results:

PHASE I: Compared with P, acute R intake in Phase I increased 0 < -05) time to exhaustion from 16.8 ± 0.7 min to 17.2 ± 0.8 min. Accordingly, VO2peak (p < .05) and VCO2peak(p< .05) increased during R compared to P from 50.9 ± 1.8 ml • min-1 • kg−1 to 52.9 ± 2.7 ml • min-1 • kg"’ (VO2peak) and from 60.0 ± 2.3 ml • min-1 • kg-’ to 63.5 ± 2.7 ml • min-1 kg-1 (VCO2peak). Pulmonary ventilation (p = .07) tended to increase more during R than during P(P: 115.9±7.7L/min; R: 124.8 ± 7.7 L/min). All other parameters remained unchanged. PHASE II: Four-week R intake did not alter any of the variables measured.

Conclusion:

Acute Rhodiola rosea intake can improve endurance exercise capacity in young healthy volunteers. This response was not altered by prior daily 4-week Rhodiola intake.
Comparison of Water Turnover Rates in Young Swimmers in Training and Age-Matched Non-Training Individuals
Authors: Leiper John B. , Maughan Ron J.
Published: August 2016

Total body water (TBW) and water turnover rates (WTR) of 8 competitive swimmers (SW) and 6 age-matched non-training individuals (CON) were determined using deuterium oxide dilution and elimination. During the 7-day study, individuals in the SW group trained 9 times, swimming on average 42.4 km, while the CON group did no regular exercise. Water temperature in the swimming pool was between 26 and 29 °C during training sessions. Body mass at the beginning and end of the study period remained essentially the same in the SW (67.8 ± 6.3 kg) and CON (61.1 ± 8.5 kg) groups. Mean ± SD TBW of the SW (38.7 ± 5.6 L) was similar to that of the CON (37.5 ± 8:0 L). Mean WTR was faster in the SW (54 ± 18 ml · kg · day−1) than the CON (28 ± 21 ml · kg · day−1). Mean daily urine output was similar in the SW (14 ± 5 ml · kg · day−1) and CON (14 ± 3 ml · kg · day−1). Calculated non-renal daily water loss was faster in the SW (41 ± 21 ml · kg · day−1) than the CON (13 ± 20 ml · kg · day−1). This study demonstrates that WTR are faster in young swimmers who exercise strenuously in cool water than in non-training individuals and that the difference was due to the approximately 3-times greater non-renal water losses that the exercising group incurred. This suggests that exercise-induced increases in sweat rates are a major factor in water loss in swimmers training in cool water.
Resistive Training and Chromium Picolinate: Effects on Inositols and Liver and Kidney Functions in Older Adults
Authors: Campbell Wayne W. , Joseph Lyndon J.O. , Ostlund Richard E. , Anderson Richard A. , Farrell Peter A. , Evans William J.
Published: August 2016

This study assessed the effects of resistive training (RT) with or without chromium picolinate (Cr-pic) supplementation on the 24-h urinary excretions of myo-inositol, D-chiro-inositol, and pinitol, as well as clinical indices of kidney and liver functions. Thirty-two nondiabetic subjects, age 62 ± 4 y, performed RT twice weekly for 12 wk and consumed either 924 μg Cr/d as Cr-pic (n = 17) or a placebo (n = 15). Whole-body strength increased in all subjects by 20% and urinary chromium excretion increased 47-fold in the Cr-pic group. Urinary myo-inositol, D-chiro-inositol, and pinitol were not changed with RT or influenced by Cr-pic. Serum indices of kidney and liver functions were within clinically normal ranges at baseline and the end of the study. These results suggest that RT did not influence the urinary excretions of inositols. High dose Cr-pic did not influence the urinary excretion of inositols and the selected indices of kidney and liver functions in conjunction with RT
Daily Body Mass Variability and Stability in Active Men Undergoing Exercise-Heat Stress
Authors: Cheuvront Samuel N. , Carter Robert , Montain Scott J. , Sawka Michael N.
Published: August 2016

The purpose of this study was to quantify the variability and stability of 1st morning body mass (BM) fluctuations during daily exercise in the heat while following traditional fluid intake guidance. Data from 65 men were examined retrospectively. BM fluctuations were monitored over 4 to 15 consecutive days. Group daily variation in BM was 0.51 ± 0.20 kg. Group coefficient of variation was 0.66 ± 0.24%, normally distributed, and not related to either absolute BM (r = 0.04) or number of measurements (r = 0.34). Three days resulted in a similar variability estimate compared to 6 or 9 d, although precision was improved with 9 d. In conclusion, 3 consecutive BM measurements provide an accurate assessment of daily BM variability, which is less than 1% for active men when replacing 100% of sweat losses during exercise. The data also suggest that daily BM is a sufficiently stable physiological parameter for potential daily fluid balance monitoring.
Carbohydrate-Electrolyte Feedings and 1h Time Trial Cycling Performance
Authors: Desbrow Ben , Anderson Sally , Barrett Jennifer , Rao Elissa , Hargreaves Mark
Published: August 2016

The effects of a commercial sports drink on performance in high-intensity cycling was investigated. Nine well-trained subjects were asked to complete a set amount of work as fast as possible (time trial) following 24 h of dietary (subjects were provided with food, energy 57.4 ± 2.4 kcal/kg and carbohydrate 9.1 ± 0.4 g/kg) and exercise control. During exercise, subjects were provided with 14 mL/kg of either 6% carbohydrate-electrolyte (CHO-E) solution or carbohydrate-free placebo (P). Results showed that subjects’ performances did not greatly improve (time, 62:34 ± 6:44 min:sec (CHO-E) vs. 62:40 ± 5:35 min:sec (P); average power output, 283.0 ± 25.0 W (CHO-E) vs. 282.9 ± 29.3 W (P), P > 0.05) while consuming the sports drink. It was concluded that CHO-E consumption throughout a 1-h time trial, following a pre-exercise dietary regimen designed to optimize glucose availability, did not improve time or power output to a greater degree than P in well-trained cyclists.
Traditional and Nontraditional Supplement Use by Collegiate Female Varsity Athletes
Authors: Herbold Nancie H. , Visconti Bridget K. , Frates Susan , Bandini Linda
Published: August 2016

This study examined the traditional (single and multivitamin/mineral supplements) and nontraditional supplement (herbals, botanicals, and other biologic and nutrient supplements) use by female athletes. Frequency, reasons for use, and sources of supplement information were assessed with a self-report questionnaire. Participants were 162 collegiate female varsity athletes. More than half of all athletes used some type of supplement at least once a month (65.4%). Thirty-six percent (n = 58) of the sample used a multivitamin and mineral with iron. Twelve percent (n = 19) reported amino acid/protein supplement use and 17% (n = 29) used an herbal/botanical supplement. The most frequently cited reason for supplement use was “good health” (60.1%). A major source of information on supplements reported was family (53%). With the general rise in supplement use, nutrition education on the use of traditional and non-traditional supplements is warranted.
Food and Macronutrient Intake of Elite Kenyan Distance Runners
Authors: Onywera V.O. , Kiplamai F.K. , Tuitoek P.J. , Boit M.K. , Pitsiladis Y.P.
Published: August 2016

The food and macronutrient intake of elite Kenyan runners was compared to recommendations for endurance athletes. Estimated energy intake (EI: 2987 ± 293 kcal; mean ± standard deviation) was lower than energy expenditure (EE: 3605 ± 119 kcal; P < 0.001) and body mass (BM: 58.9 ± 2.7 kg vs. 58.3 ± 2.6 kg; P < 0.001) was reduced over the 7-d intense training period. Diet was high in carbohydrate (76.5%, 10.4 g/kg BM per day) and low in fat (13.4%). Protein intake (10.1%; 1.3 g/kg BM per day) matched recommendations for protein intake. Fluid intake was modest and mainly in the form of water (1113 ± 269 mL; 0.34 ± 0.16 mL/kcal) and tea (1243 ± 348 mL). Although the diet met most recommendations for endurance athletes for macronutrient intake, it remains to be determined if modifying energy balance and fluid intake will enhance the performance of elite Kenyan runners.