International journal of sport nutrition and exercise metabolism (INT J SPORT NUTR EXE )

Publisher: International Society of Sport Nutrition, Human Kinetics


IJSNEM publishes original scientific investigations and scholarly reviews offering new insights into sport nutrition and exercise metabolism, as well as articles focusing on the application of the principles of biochemistry, physiology, and nutrition to sport and exercise. The journal also offers editorials, digests of related articles from other fields, research notes, and reviews of books, videos, and other media releases. IJSNEM is the official journal of the International Society of Sports Nutrition.

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    International Journal of Sport Nutrition and Exercise Metabolism website
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    International journal of sport nutrition and exercise metabolism, Sport nutrition and exercise metabolism., IJSNEM
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Human Kinetics

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Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: Nutritional supplements (NS) are defined as concentrated sources of nutrients and other substances that have a nutritional or physiological effect and that are used in high frequency among athletes. The study aimed to create a prediction profile for young elite athletes to identify those athletes who have a higher relative risk for using NS. The second objective was to examine the hypothesis that the consumption of NS paves a gateway for the use of illicit drugs and doping substances. A self-designed anonymous paper-and-pencil questionnaire was used to examine the prevalence of NS consumption, doping, and illicit drug use in elite athletes with a mean age of 17 years (SD=4 years). Logistic regression analysis was employed to assess whether NS consumption can be predicted by independent variables (e.g. biographical data, training characteristics, drug consumption behavior) to create the prediction profile for NS use. 55% and 5% of the athletes (n=536) responded positively to having used NS and illicit drugs, respectively. Nutritional supplement consumption was positively correlated with age (OR: 1.92; CI: 1.21-3.05), the desire to enhance performance in order to become an Olympic or World Champion (OR: 3.72; CI: 2.33-6.01), and being educated about NS (OR: 2.76; CI: 1.73-4.45). It was negatively correlated with training frequency (OR: 0.55; CI: 0.35-0.86) and the use of nicotine (OR: 0.29; CI: 0.1-0.74) but did not correlate with illicit drug use and alcohol consumption. The present results show that NS are used on a large scale in elite sports. The prediction profile presented in this article may help to identify those athletes who have a high risk for using NS in order to plan potential education and prevention models more individually.
    International journal of sport nutrition and exercise metabolism 06/2014;
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    ABSTRACT: The purpose of this study was to document the physiological changes that occur in a natural bodybuilder during prolonged contest preparation for a pro-qualifying contest. During the 26 week preparation, the athlete undertook a calorically restrictive diet with two days of elevated carbohydrate intake per week, increased cardiovascular (CV) training, and attempted to maintain resistance training load. The athlete was weighed twice a week and body composition was measured monthly by DXA. At baseline and every two weeks following CV structure and function was measured using a combination of ultrasound, applanation tonometry, and heart rate variability (HRV). Cardiorespiratory performance was measured by VO2peak at baseline, 13 weeks, and 26 weeks. Body weight (88.6 to 73.3 Kg, R2=.99) and percent body fat (17.5 to 7.4%) were reduced during preparation. CV measurements including blood pressure (128/61 to 113/54mmHg), brachial pulse wave velocity (7.9 to 5.8m/s), and measures of wave reflection all improved. Indexed cardiac output was reduced (2.5 to 1.8L/m2) primarily due to a reduction in resting heart rate (71 to 44bpm), and despite an increase in ejection faction (57.9 to 63.9%). Assessment of HRV found a shift in the ratio of low to high frequency (209.2 to 30.9%). Absolute VO2 was minimally reduced despite weight loss resulting in an increase in relative VO2 (41.9 to 47.7ml/Kg). In general, this prolonged contest preparation technique helped the athlete to improve body composition and resulted in positive CV changes, suggesting that this method of contest preparation appears to be effective in natural male bodybuilders.
    International journal of sport nutrition and exercise metabolism 06/2014;
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    ABSTRACT: The present study aimed to show the validity of a portable motion sensor, the SenseWear ArmbandTM (SWA), for the estimation of energy expenditure during pole walking. Twenty healthy adults (mean±SD: age 30.1±7.2 yr, body mass 66.1±10.6 kg, height 172.4±8.0 cm, BMI 22.1±2.4 kg·m-2) wore the armband during randomized pole walking activities at a constant speed (1.25 m·s- 1) and at seven grades (0%, ±5%, ±15% and ±25%). Estimates of total energy expenditure from the armband were compared to values derived from indirect calorimetry methodology (IC) using a 2- way mixed model ANOVA (Device x Slope), correlation analyses and Bland-Altman plots. Results revealed significant main effects for device, and slope (p<0.025) as well as a significant interaction (p<0.001). Significant differences between IC and SWA were observed for all conditions (p<0.05). SWA generally underestimate the EE values during uphill PW by 0.04 kcal·kg-1·min-1 (p<0.05). Whereas, a significant overestimation has been detected during flat and downhill PW by 0.01 and 0.03 kcal·kg-1·min-1 (p<0.05), respectively. The Bland-Altman plots revealed bias of the armband compared with the indirect calorimetry at any condition examined. The present data suggest that the armband is not accurate to correctly detect and estimate the energy expenditure during pole walking activities. Therefore, the observed over- and under-estimations warrants more work to improve the ability of SWA to accurately measure EE for these activities.
    International journal of sport nutrition and exercise metabolism 04/2014;
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    ABSTRACT: This study investigated whether combined ingestion and mouth rinsing with a carbohydrate solution could improve maximal sprint cycling performance. Twelve competitive male cyclists ingested 100 mL of one of the following solutions 20 min prior to exercise in a randomized double-blinded counterbalanced order; (a) 10% glucose solution, (b) 0.05% aspartame solution, (c) 9.0% maltodextrin solution, or (d) water as a control. Fifteen min after ingestion, repeated mouth rinsing was carried out with 11 × 15 mL bolus doses of the same solution at 30-s intervals. Each participant then performed a 45-s maximal sprint effort on a cycle ergometer. Peak power output was significantly higher in response to the glucose trial (1188 ± 166 W) compared with the water (1036 ± 177 W), aspartame (1088 ± 128 W) and maltodextrin (1024 ± 202W) trials by 14.7 ± 10.6, 9.2 ± 4.6 and 16.0 ± 6.0% respectively (p < 0.05). Mean power output during the sprint was significantly higher in the glucose trial compared with maltodextrin (p < 0.05) and also tended to be higher than the water trial (p = 0.075). Glucose and maltodextrin resulted in a similar increase in blood glucose, and the responses of blood lactate and pH to sprinting did not differ significantly between treatments (p > 0.05). These findings suggest that combining the ingestion of glucose with glucose mouth rinsing improves maximal sprint performance. This ergogenic effect is unlikely to be related to changes in blood glucose, sweetness or energy sensing mechanisms in the gastrointestinal tract.
    International journal of sport nutrition and exercise metabolism 03/2014;
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    ABSTRACT: Multiple day ultra-endurance challenges are increasing in popularity for recreational runners, but there is a paucity of evidence on which to base nutritional recommendations. This case study presents the nutritional status and body mass (BM) changes of a 66 year old, male experienced runner, during a 100-day, 3000 mile challenge (~30 mile・d–1). Daily energy expenditure and intake were estimated for a 24-hr period including a 30 mile run, using a Sensewear accelerometer and a food diary. These results were used by a registered dietitian to design a nutrition plan to provide energy and substrate availability for the run and to promote recovery for the following day. During the challenge, BM was recorded after the first void each day and nutritional intake was estimated using a 24-hr weighed food record, at the end of each week. At the start of the challenge BM was 81.0 kg: this fell to 73.0 kg by day 31, but remained stable until the completion of the challenge. Percentage body fat estimated using Bodpod fell from 20.9% to 16.0%, in contrast fat free mass (FFM) increased from 62.5 kg to 64.3 kg. This was despite a mean energy intake below the estimated expenditure, at 5427±1214 kcal (3426-6789 kcal). Mean daily carbohydrate and protein intake was 841±178 g and 172±47 g respectively. This equated to relative carbohydrate and protein intake of 11.2±2.6 (6.2-14.2 and 2.3±0.7 (1.3- 3.4 respectively. Mean carbohydrate intake was within the carbohydrate recommendations for activity >4.5 h (Burke, et al, 2001, Sports Med, 31(4), 267-299). In contrast mean protein intake was considerably higher than that recommended for endurance activities (Genton 2011, e-SPEN, 6, e77-e84). The observed increase in FFM likely reflects the positive energy balance achieved in weeks 6 to 13, since high protein intakes were apparent throughout and a negative energy balance was present only in the early weeks of the challenge.
    International journal of sport nutrition and exercise metabolism 02/2014; 24:S1.
  • International journal of sport nutrition and exercise metabolism 05/2013; In Press.
  • [Show abstract] [Hide abstract]
    ABSTRACT: To compare estimates of body density (Db) from air-displacement plethysmography (ADP) with measured and predicted thoracic-gas-volume (TGV) measurements and those from hydrodensitometry (HD) in children. Seventeen participants (13 male and 4 female; 10.1 ± 2.20 yr, 42.0 ± 15.03 kg, 145.6 ± 17.41 cm, 30.0 ± 8.66 kg/m²) were tested using ADP and HD, with ADP always preceding HD. Db estimates were compared between ADP with measured TGV, ADP with predicted TGV, and the reference measure, HD. Regression analyses were used to assess the accuracy of the ADP methods, and potential bias between the ADP procedures and HD were evaluated using Bland-Altman analyses. The cross-validation criteria described by Lohman for estimating Db relative to HD were used to interpret the results of the study. A significant difference was found between Db estimates from ADP with measured TGV (1.0453 ± 0.01934 g/cm³) and ADP with predicted TGV (1.0415 ± 0.01858 g/cm³); however, neither was significantly different from Db obtained by the reference HD procedure (1.0417 ± 0.02391 g/cm³). For both ADP procedures, regression analyses produced an r = .737-.738, r² = .543-.544, and SEE = 0.02 g/cm³, and the regression lines deviated significantly from the line of identity; however, no significant biases were indicated. Despite no significant mean differences between Db estimates from the ADP procedures and HD, more cross-validation research is needed before recommending the BOD POD for routine use with children in clinical and research settings.
    International journal of sport nutrition and exercise metabolism 06/2011; 21(3):240-7.
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    ABSTRACT: This study was conducted to assess the effects of exercise, diet, and their combination on metabolic syndrome (MS) risk factors including visceral fat mass (VFM), glucose intolerance, and dyslipidemia in OLETF rats. Thirty-two male rats were assigned to exercise (OLETF-Ex), dietary treatment (-DT), combination (-Ex&DT), or sedentary (-Sed) groups. Daily voluntary exercise using a rotary wheel was performed in OLETF-Ex. Each treatment was conducted from 21 to 31 wk of age. An oral glucose tolerance test was performed before and after the treatment period. Absolute levels of VFM, subcutaneous fat mass (SFM), and serum lipids including triglyceride, total cholesterol, and LDL-cholesterol (LDL-C) were measured after the treatment period. All therapeutic treatments resulted in significantly lower levels of body weight, VFM, SFM, and serum lipids than in sedentary control rats. All therapeutic treatments were also found to improve indices of oral glucose tolerance. Of the 3 therapeutic treatments, serum LDL-C levels were significantly lower in OLETF-Ex and OLETF-Ex&DT than in OLETF-Sed. The data demonstrate that all therapeutic approaches tested were effective in improving a number of MS-related parameters in OLETF rats. However, exercise-based therapeutic intervention may provide additional benefits for improving fat metabolism in MS patients.
    International journal of sport nutrition and exercise metabolism 06/2011; 21(3):222-32.
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    ABSTRACT: Simultaneous whole-body wash-down (WBW) and regional skin surface sweat collections were completed to compare regional patch and WBW sweat calcium (Ca), magnesium (Mg), copper (Cu), manganese (Mn), iron (Fe), and zinc (Zn) concentrations. Athletes (4 men, 4 women) cycled in a plastic open-air chamber for 90 min in the heat. Before exercise, the subjects and cycle ergometer (covered in plastic) were washed with deionized water. After the onset of sweating, sterile patches were attached to the forearm, back, chest, forehead, and thigh and removed on saturation. After exercise, the subjects and cycle ergometer were washed with 5 L of 15-mM ammonium sulfate solution to collect all sweat minerals and determine the volume of unevaporated sweat. Control trials were performed to measure mineral contamination in regional and WBW methods. Because background contamination in the collection system was high for WBW Mn, Fe, and Zn, method comparisons were not made for these minerals. After correction for minimal background contamination, WBW sweat [Ca], [Mg], and [Cu] were 44.6 ± 20.0, 9.8 ± 4.8, and 0.125 ± 0.069 mg/L, respectively, and 5-site regional (weighted for local sweat rate and body surface area) sweat [Ca], [Mg], and [Cu] were 59.0 ± 15.9, 14.5 ± 4.8, and 0.166 ± 0.031 mg/L, respectively. Five-site regional [Ca], [Mg], and [Cu] overestimated WBW by 32%, 48%, and 33%, respectively. No individual regional patch site or 5-site regional was significantly correlated with WBW sweat [Ca] (r = -.21, p = .65), [Mg] (r = .49, p = .33), or [Cu] (r = .17, p = .74). In conclusion, regional sweat [Ca], [Mg], and [Cu] are not accurate surrogates for or significantly correlated with WBW sweat composition.
    International journal of sport nutrition and exercise metabolism 06/2011; 21(3):233-9.
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    ABSTRACT: Nutrition education aims to enhance knowledge and improve dietary intake in athletes. Understanding athletes' nutrition knowledge and its influence on dietary intake will inform nutrition-education programs in this population. To systematically review the level of nutrition knowledge in athletes, benchmark this against nonathlete comparison groups, and determine the impact of nutrition knowledge on dietary intake. An extensive literature search from the earliest record to March 2010 using the terms nutrition knowledge or diet knowledge and athlete or sport was conducted. Included studies recruited able or physically disabled, male or female, competitive (recreational or elite) athletes over the age of 13 yr. Quantitative assessment of knowledge and, if available, diet intake was required. Because of variability in the assessment of nutrition knowledge and dietary intake, meta-analysis was not conducted. Twenty-nine studies (17 published before 2000) measuring nutrition knowledge (7 including a nonathlete comparison group) met inclusion criteria. Athletes' knowledge was equal to or better than that of nonathletes but lower than comparison groups including nutrition students. When found statistically significant, knowledge was greater in females than males. A weak (r < .44), positive association between knowledge and dietary intake was reported in 5 of 9 studies assessing this. Common flaws in articles included inadequate statistical reporting, instrument validation, and benchmarking. The nutrition knowledge of athletes and its impact on their dietary intake is equivocal. There is a need for high-quality, contemporary research using validated tools to measure nutrition knowledge and its impact on dietary intake.
    International journal of sport nutrition and exercise metabolism 06/2011; 21(3):248-61.
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    ABSTRACT: The purpose of this study was to examine the effect of high-intensity physical activity during training on the biochemical status of thiamin and riboflavin in athletes. Thiamin and riboflavin concentrations in whole blood of a group of 19 athletes (6 men and 13 women) were measured during a low-intensity preparatory period and compared with measurements taken during a high-intensity training period. Additional variables measured included anthropometric characteristics, estimated energy expenditure during swim training, distance covered, resting energy expenditure obtained by indirect calorimetry, estimated energy requirement per day, and dietary intake of energy, thiamin, and riboflavin estimated from 3-day food records. For both male and female subjects, no major changes were observed in anthropometric characteristics or dietary intake, but energy expenditure during swim training per day significantly increased in the intensive-training period (496 ± 0 kcal in the preparation period compared with 995 ± 96 kcal in the intensive-training period for male subjects [p < .001] and 361 ± 27 kcal vs. 819 ± 48 kcal, respectively, for female subjects [p < .001]). Blood thiamin concentration decreased significantly during the intensive-training period compared with the preparation period (41 ± 6 ng/ml decreased to 36 ± 3 ng/ml for male subjects [p = .048], and 38 ± 10 ng/ml decreased to 31 ± 5 ng/ml for female subjects [p = .004]); however, the concentration of riboflavin was unchanged. These results suggest that intense training affects thiamin concentration, but not riboflavin concentration, in the whole blood of college swimmers.
    International journal of sport nutrition and exercise metabolism 06/2011; 21(3):195-204.
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    ABSTRACT: Twelve adolescent athletes underwent, in a crossover-design study, 3 separate 90-min training sessions in the following conditions: no fluid ingestion allowed (NF), ad libitum ingestion of water (W), and ad libitum ingestion of a commercial 8% carbohydrate-electrolyte sports beverage (CSB). After each session athletes performed a set of basketball drills (2-point, 3-point, and free-throw shootout, suicide sprints, and defensive zigzags). Body weight (before and after sessions), rating of perceived exertion (RPE), urine color, and beverage acceptability were determined in each session. Athletes also completed a survey about their knowledge and behaviors regarding hydration and fluid replacement. The percentage of weight loss was significantly higher in NF (2.46% ± 0.87%) than in the other 2 conditions (W, 1.08% ± 0.67%, p = .006; CSB, 0.65% ± 0.62%, p = .001) but also higher in W than CSB (p = .012). RPE was higher in NF (16.8 ± 1.96) than in the W (14.2 ± 1.99, p = .004) and CSB (13.3 ± 2.06, p = .002) trials. Athletes' fluid intake was positively correlated with proper self-reported behaviors (r = .75, p = .005) and knowledge (r = .76, p = .004) about fluid and hydration. In conclusion, fluid restriction during exercise was associated with a greater level of dehydration and increased perceived exertion but had no impact on basketball performance compared with ad libitum drinking of water or a CSB. Athletes with more knowledge about hydration and better self-reported hydration behaviors ingested more fluids during training sessions.
    International journal of sport nutrition and exercise metabolism 06/2011; 21(3):214-21.
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    ABSTRACT: To examine the effect of yogurt supplementation pre- and postexercise on changes in body composition in overweight women engaged in a resistance-training program. Participants (age = 36.8 ± 4.8 yr) with a body-mass index of 29.1 ± 2.1 kg/m2 were randomized to yogurt supplement (YOG; n = 15) or isoenergetic sucrose beverage (CONT; n = 14) consumed before and after exercise for 16 wk. Participants were also instructed to reduce energy intake daily (-1,046 kJ) during the study. Body composition was assessed by dual-energy X-ray absorptiometry, waist circumference, and sagittal diameter. Strength was measured with 1-repetition maximum. Dietary recalls were obtained by a multipass approach using Nutrition Data System software. Insulin-like growth factor-1 and insulin-like growth-factor-binding protein-3 were measured with ELISA. Significant weight losses of 2.6 ± 4.5 kg (YOG) and 1.2 ± 2.5 kg (CONT) were observed. Total lean weight increased significantly over time in both YOG (0.8 ± 1.2 kg) and CONT (1.1 ± 0.9 kg). Significant reductions in total fat (YOG = 3.4 ± 4.1 kg vs. CONT = 2.3 ± 2.4 kg) were observed over time. Waist circumference, sagittal diameter, and trunk fat decreased significantly over time without group differences. Both groups significantly decreased energy intake while maintaining protein intake. Strength significantly increased over time in both groups. No changes over time or between groups were observed in hormone levels. These data suggest that yogurt supplementation offered no added benefit for increasing lean mass when combined with resistance training and modest energy restriction.
    International journal of sport nutrition and exercise metabolism 06/2011; 21(3):181-8.
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    ABSTRACT: The purpose of this study was to investigate the potential of bovine colostrum to attenuate postexercise decline in immune function. The authors evaluated the time course of a number of immune variables after short-term intense exercise in 9 male athletes after 10 d of supplementation with either colostrum or skim-milk powder. To increase the stress on the immune system subjects performed a glycogen-depletion trial the evening before the endurance trial (90 min at 50% Wmax). Blood samples were taken before the glycogen-depletion trial, before and after the endurance trial, and the next morning, ~22 hr after cessation of the exercise. Plasma cortisol levels increased over time, reaching the highest level directly after exercise, and were still elevated ~22 hr after exercise compared with baseline values (p < .001). Neutrophil cell count was increased after exercise and dropped below starting values 22 hr after exercise (time effect p < .001). Circulating immunoglobulins did not change over time. A significant time effect was seen for interleukin (IL)-6, IL-10, IL-1-receptor agonist, and C-reactive protein, with levels being higher directly after exercise (p < .05). Other cytokines (interferon-γ, IL-1a, IL-8, tumor necrosis factor-a) did not show a time effect. No differences were seen between colostrum and skim-milk powder in any of the investigated variables. Our results are consistent with the hypothesis that intense exercise affects several variables of the immune system. Colostrum did not alter any of the postexercise immune variables compared with skim-milk powder, suggesting no role for bovine colostrum supplementation in preventing postexercise immune suppression after short-term intense exercise.
    International journal of sport nutrition and exercise metabolism 04/2011; 21(2):135-45.
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    ABSTRACT: Maintenance of repeated-sprint performance is a goal during team-sport competition such as soccer. Quercetin has been shown to be an adenosine-receptor antagonist and may reduce oxidative stress via inhibition of the enzyme xanthine oxidase (XO). The purpose of the study was to determine the effect of quercetin consumption on performance of repeated sprints and, secondarily, the XO and inflammatory-marker response induced by repeated-sprint exercise. Fifteen recreationally active, young adult men completed 2 repeated-sprint tests (RST), 12 × 30-m maximal-effort sprints (S1-S12), each after 1 wk supplementation with a placebo, a 6% carbohydrate commercial sports drink, or that drink with 500 mg of quercetin-3-glucoside, consumed twice a day (1,000 mg/d). Blood samples were collected before supplementation (B0), at baseline before each RST (B1), immediately after RST (B2), and 1 hr after RST (B3). Mean sprint time increased progressively and was significantly higher by S9 for both treatments (5.9%); however, there were no significant differences between treatments. Percent fatigue decrement (%FD) for placebo (3.8% ± 2.3%) was significantly less than with quercetin (5.1% ± 2.7%). Changes in blood XO, IL-6, and uric acid from B1 to B2 were +47%, +77%, and +25%, respectively, with no difference by treatment. In conclusion, repeated-sprint performance was not improved by quercetin supplementation and was worse than with placebo when expressed as %FD. Quercetin did not attenuate indicators of XO activity or IL-6, a marker of the inflammatory response after sprint exercise.
    International journal of sport nutrition and exercise metabolism 04/2011; 21(2):91-6.

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