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Effects of carbohydrate supplementation on aerobic exercise performance during acute high altitude exposure and after 22 days of acclimatization and energy deficit.
Bradbury, KE, Berryman, CE, Wilson, MA, Luippold, AJ, Kenefick, RW, Young, AJ, Pasiakos, SM
Journal of the International Society of Sports Nutrition. 2020;(1):4
Abstract
BACKGROUND The ergogenic effects of supplemental carbohydrate on aerobic exercise performance at high altitude (HA) may be modulated by acclimatization status. Longitudinal evaluation of potential performance benefits of carbohydrate supplementation in the same volunteers before and after acclimatization to HA have not been reported. PURPOSE This study examined how consuming carbohydrate affected 2-mile time trial performance in lowlanders at HA (4300 m) before and after acclimatization. METHODS Fourteen unacclimatized men performed 80 min of metabolically-matched (~ 1.7 L/min) treadmill walking at sea level (SL), after ~ 5 h of acute HA exposure, and after 22 days of HA acclimatization and concomitant 40% energy deficit (chronic HA). Before, and every 20 min during walking, participants consumed either carbohydrate (CHO, n = 8; 65.25 g fructose + 79.75 g glucose, 1.8 g carbohydrate/min) or flavor-matched placebo (PLA, n = 6) beverages. A self-paced 2-mile treadmill time trial was performed immediately after completing the 80-min walk. RESULTS There were no differences (P > 0.05) in time trial duration between CHO and PLA at SL, acute HA, or chronic HA. Time trial duration was longer (P < 0.05) at acute HA (mean ± SD; 27.3 ± 6.3 min) compared to chronic HA (23.6 ± 4.5 min) and SL (17.6 ± 3.6 min); however, time trial duration at chronic HA was still longer than SL (P < 0.05). CONCLUSION These data suggest that carbohydrate supplementation does not enhance aerobic exercise performance in lowlanders acutely exposed or acclimatized to HA. TRIAL REGISTRATION NCT, NCT02731066, Registered March 292,016.
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Effects of a commercially available branched-chain amino acid-alanine-carbohydrate-based sports supplement on perceived exertion and performance in high intensity endurance cycling tests.
Gervasi, M, Sisti, D, Amatori, S, Donati Zeppa, S, Annibalini, G, Piccoli, G, Vallorani, L, Benelli, P, Rocchi, MBL, Barbieri, E, et al
Journal of the International Society of Sports Nutrition. 2020;(1):6
Abstract
BACKGROUND Sports nutritional supplements containing branched-chain amino acids (BCAA) have been widely reported to improve psychological and biological aspects connected to central fatigue and performance in endurance exercise, although the topic is still open to debate. The aim of the present study was to determine whether the intake of a commercially available BCAA-based supplement, taken according to the manufacturer's recommendations, could affect the rating of perceived exertion (RPE) and performance indexes at the beginning (1d) and end of a 9-week (9w) scheduled high intensity interval training program, with an experimental approach integrating the determination of psychometric, performance, metabolic and blood biochemical parameters. METHODS This was a randomized double-blind placebo-controlled study. Thirty-two untrained, healthy young adults (20 males and 12 female) were enrolled. A high-intensity endurance cycling (HIEC) test was used to induce fatigue in the participants: HIEC consisted in ten 90 s sprints interspersed by ten 3 min recovery phases and followed by a final step time to exhaustion was used. In parallel with RPE, haematological values (creatine kinase, alanine, BCAA, tryptophan, ammonia and glucose levels), and performance indexes (maximal oxygen consumption - VO2max, power associated with lactate thresholds - WLT1, WLT2 and time to exhaustion - TTE) were assessed. All subject took the supplement (13.2 g of carbohydrates; 3.2 g of BCAA and 1.6 g of L-alanine per dose) or placebo before each test and training session. Dietary habits and training load were monitored during the entire training period. RESULTS The administration of the supplement (SU) at 1d reduced RPE by 9% during the recovery phase, as compared to the placebo (PL); at 9w the RPE scores were reduced by 13 and 21% during the sprint and recovery phase, respectively; at 9w, prolonged supplement intake also improved TTE and TRIMP. SU intake invariably promoted a rapid increase (within 1 h) of BCAA serum blood levels and prevented the post-HIEC tryptophan: BCAA ratio increase found in the PL group, at both 1d and 9w. There was no difference in dietary habits between groups and those habits did not change over time; no difference in glycemia was found between SU and PL. VO2max, WLT1 and WLT2 values improved over time, but were unaffected by supplement intake. CONCLUSIONS On the whole, these results suggest that i) the intake of the BCAA-based commercially available supplement used in this study reduces RPE as a likely consequence of an improvement in the serum tryptophan: BCAA ratio; ii) over time, reduced RPE allows subjects to sustain higher workloads, leading to increased TRIMP and TTE.
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Titrating a modified ketogenic diet for patients with McArdle disease: A pilot study.
Løkken, N, Hansen, KK, Storgaard, JH, Ørngreen, MC, Quinlivan, R, Vissing, J
Journal of inherited metabolic disease. 2020;(4):778-786
Abstract
Glycogen storage disease type V (GSDV) is a rare inborn error of carbohydrate metabolism. Patients present with exercise intolerance due to blocked glycogen breakdown in skeletal muscle. Introducing alternative fuel substrates, such as ketone bodies (KBs), could potentially alleviate muscle symptoms. This pilot study investigates which of three different modified ketogenic diet regimes is optimal for GSDV-patients to follow in a future large-scale study. Participants were randomised to follow one of three diet regimes for 3 weeks (#1: 65%/15%/20%; #2: 75%/15%/10%, or #3: 80%/15%/5%, fat/protein/carbohydrate). The primary outcome was exercise tolerance assessed by heart rate (HR) changes during constant load cycling. Secondary outcomes included levels of ketosis, and changes in perceived exertion and indirect calorimetry measures during exercise. Ten GSDV-patients were included. Eight completed the study. The other two were excluded. Diet #3 showed the highest average KB level (1.1 mmol/L) vs #2 (0.5 mmol/L) and #1 (0.3 mmol/L). Five patients reported subjective symptom relief, all of whom were on diets #2 and #3. All diet regimes seemed to improve fatty acid oxidation rates and exercise capacity as indicated by a small decrease in HR and perceived exertion. The results of this open-label pilot study show that diets #2 and #3 induce ketosis and improve symptoms and exercise capacity in GSDV-patients. Diet #2 had the highest acceptability score and was superior or equal to diet #3 in all other parameters, except level of ketosis. Based on this, we suggest testing diet #2 in a large-scale, placebo-controlled study in GSDV.
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Effect of Oral Carbohydrate Intake During Labor on the Rate of Instrumental Vaginal Delivery: A Multicenter, Randomized Controlled Trial.
Simonet, T, Gakuba, C, Desmeulles, I, Corouge, J, Beucher, G, Morello, R, Gérard, JL, Ducloy-Bouthors, AS, Dreyfus, M, Hanouz, JL
Anesthesia and analgesia. 2020;(6):1670-1677
Abstract
BACKGROUND Carbohydrate intake during physical exercise improves muscle performance and decreases fatigue. We hypothesized that carbohydrate intake during labor, which is a period of significant physical activity, can decrease the instrumental vaginal delivery rate. METHODS In a multicenter, prospective, randomized, controlled trial, healthy adult pregnant women presenting with spontaneous labor were assigned to a "Carbohydrate" group (advised to drink 200 mL of apple or grape juice without pulp every 3 hours) or a "Fasting" group (water only). The primary outcome was the instrumental vaginal delivery rate. Secondary outcomes included duration of labor, rate of cesarean delivery, evaluation of maternal hunger, thirst, stress, fatigue, and overall feeling during labor by numeric rating scale (0 worst rating to 10 best rating), rate of vomiting, and hospital length of stay. Statistical analysis was performed on an intention-to-treat basis. The primary outcome was tested with the "Fasting" group as the reference group. The P values for secondary outcomes were adjusted for multiple comparisons. The differences between groups are reported with 99% confidence interval (CI). RESULTS A total of 3984 women were analyzed (2014 in the Carbohydrate group and 1970 in the Fasting group). There was no difference in the rate of instrumental delivery between the Carbohydrate (21.0%) and the Fasting (22.4%) groups (difference, -1.4%; 99% CI, -4.9 to 2.2). No differences were found between the Carbohydrate and the Fasting groups for the duration of labor (difference, -7 minutes; 99% CI, -25 to 11), the rate of cesarean delivery (difference, -0.3%; 99% CI, -2.4 to 3.0), the rate of vomiting (difference, 2.8%; 99% CI, 0.2-5.7), the degree of self-reported fatigue (difference, 1; 99% CI, 0-2), self-reported hunger (difference, 0; 99% CI, -1 to 1), thirst (difference, 0; 99% CI, -1 to 1), stress (difference, 0; 99% CI, -1 to 1), overall feeling (difference, 0; 99% CI, 0-0), and the length of hospitalization (difference, 0; 99% CI, -1 to 0). CONCLUSIONS Carbohydrate intake during labor did not modify the rate of instrumental vaginal delivery.
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Nutritional adequacy of very low- and high-carbohydrate, low saturated fat diets in adults with type 2 diabetes: A secondary analysis of a 2-year randomised controlled trial.
Tay, J, Thompson, CH, Luscombe-Marsh, ND, Noakes, M, Buckley, JD, Wittert, GA, Brinkworth, GD
Diabetes research and clinical practice. 2020;:108501
Abstract
BACKGROUND Growing evidence supports use of very low-carbohydrate (LC) diets for glycaemic control in type 2 diabetes. However, limited data on the micronutrient adequacy of LC diets exist. OBJECTIVE This study compared the long-term effects of a very low-carbohydrate, high unsaturated/low saturated fat (LC) diet to a high-carbohydrate, low-fat (HC) diet on micronutrient biomarkers in adults with obesity and type 2 diabetes. METHODS 115 adults with type 2 diabetes (mean[SD]; BMI:34.6[4.3]kg/m2, age:58[7]yrs, HbA1c:7.3[1.1]%, 56[12]mmol/mol) were randomized to one of two planned, nutritionally-replete, energy-matched, hypocaloric diets (500-1000 kcal/day deficit): (1) LC:14% energy carbohydrate, 28%protein, 58%fat[<10% saturated fat]) or (2) HC:53%carbohydrate, 17%protein, 30%fat [<10%saturated fat]) for 2 years. Nutritional biomarkers- folate, β-carotene, vitamin B12, D, E, copper, zinc, selenium, calcium, magnesium, sodium, potassium, iron, ferritin, transferrin and transferrin saturation were measured in fasting blood at baseline, 24, 52 and 104 weeks. RESULTS 61 participants completed the study with similar dropouts in each group (P = 0.40). For all biomarkers assessed, there were no differential response between groups overtime (P ≥ 0.17 time × diet interaction). Mean vitamin and mineral levels remained within normal (laboratory-specific) reference ranges without any reported cases of clinical deficiencies. CONCLUSION In free-living individuals with type 2 diabetes, nutrition biomarkers within normal ranges at baseline did not change significantly after 2 years on a prescribed LC or HC diet. These results demonstrate the feasibility of delivering a nutritionally replete LC diet and the importance of considering nutritional factors in planning LC diets that have strong public health relevance to the dietary management of type 2 diabetes. TRIAL REGISTRATION http://www.anzctr.org.au/, ANZCTR No. ACTRN12612000369820.
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Exercising with low muscle glycogen content increases fat oxidation and decreases endogenous, but not exogenous carbohydrate oxidation.
Margolis, LM, Wilson, MA, Whitney, CC, Carrigan, CT, Murphy, NE, Hatch, AM, Montain, SJ, Pasiakos, SM
Metabolism: clinical and experimental. 2019;:1-8
Abstract
BACKGROUND Initiating aerobic exercise with low muscle glycogen content promotes greater fat and less endogenous carbohydrate oxidation during exercise. However, the extent exogenous carbohydrate oxidation increases when exercise is initiated with low muscle glycogen is unclear. PURPOSE Determine the effects of muscle glycogen content at the onset of exercise on whole-body and muscle substrate metabolism. METHODS Using a randomized, crossover design, 12 men (mean ± SD, age: 21 ± 4 y; body mass: 83 ± 11 kg; VO2peak: 44 ± 3 mL/kg/min) completed 2 cycle ergometry glycogen depletion trials separated by 7-d, followed by a 24-h refeeding to elicit low (LOW; 1.5 g/kg carbohydrate, 3.0 g/kg fat) or adequate (AD; 6.0 g/kg carbohydrate, 1.0 g/kg fat) glycogen stores. Participants then performed 80 min of steady-state cycle ergometry (64 ± 3% VO2peak) while consuming a carbohydrate drink (95 g glucose +51 g fructose; 1.8 g/min). Substrate oxidation (g/min) was determined by indirect calorimetry and 13C. Muscle glycogen (mmol/kg dry weight), pyruvate dehydrogenase (PDH) activity, and gene expression were assessed in muscle. RESULTS Initiating steady-state exercise with LOW (217 ± 103) or AD (396 ± 70; P < 0.05) muscle glycogen did not alter exogenous carbohydrate oxidation (LOW: 0.84 ± 0.14, AD: 0.87 ± 0.16; P > 0.05) during exercise. Endogenous carbohydrate oxidation was lower and fat oxidation was higher in LOW (0.75 ± 0.29 and 0.55 ± 0.10) than AD (1.17 ± 0.29 and 0.38 ± 0.13; all P < 0.05). Before and after exercise PDH activity was lower (P < 0.05) and transcriptional regulation of fat metabolism (FAT, FABP, CPT1a, HADHA) was higher (P < 0.05) in LOW than AD. CONCLUSION Initiating exercise with low muscle glycogen does not impair exogenous carbohydrate oxidative capacity, rather, to compensate for lower endogenous carbohydrate oxidation acute adaptations lead to increased whole-body and skeletal muscle fat oxidation.
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A randomized controlled trial of preoperative carbohydrate drinks on postoperative walking capacity in elective colorectal surgery.
Wongyingsinn, M, Luangchan, S, Tungsongsawat, S, Trakarnsanga, A, Lohsiriwat, V
Asia Pacific journal of clinical nutrition. 2019;(4):727-733
Abstract
BACKGROUND AND OBJECTIVES Routine overnight fasting may increase the risk of postoperative complications and delay postoperative recovery. Oral carbohydrate drinks have been shown to reduce glucose utilization and postoperative negative nitrogen balance while preserving muscle mass and strength. This randomized controlled trial aimed to examine whether preoperative oral carbohydrate drinks can enhance postoperative physical recovery in patients undergoing major colorectal surgery. METHODS AND STUDY DESIGN Seventy patients were randomly assigned to receive either a 12.5% oral carbohydrate drink or pure water. Patients in both groups received 800- mL of one of the drinks on the evening before surgery, and another 400-mL drink on the morning of the operative day. The primary outcomes were the distances covered in 2-minute-walk tests at 24, 48 and 72-hours and 6- minute walk tests at 7-10 days postoperatively. The secondary outcomes were the postoperative serum insulin and glucose concentrations, nitrogen balance, duration of hospital stay, and the patient satisfaction scores. RESULTS There were no significant differences in the characteristics of the two patients-groups. The postoperative 2-minute and 6-minute walk test distances, serum insulin and glucose concentrations of both groups were not statistically different. Patients receiving carbohydrate drink had more positive nitrogen balance than the control group. The duration of hospital stay and patient satisfaction scores were similar for both-groups. CONCLUSIONS There were no statistically significant differences in the postoperative walking capacities of patients receiving a carbohydrate drink or pure water; only the nitrogen balance on postoperative day 3 was higher for patients receiving the carbohydrate drink.
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The Effect of Preoperative Oral Carbohydrate on Breastfeeding After Cesarean Section: A Double-Blind, Randomized Controlled Clinical Trial.
Fard, RK, Tabassi, Z, Qorbani, M, Hosseini, S
Journal of dietary supplements. 2018;(4):445-451
Abstract
Delay in the initiation of breastfeeding is one of the problems of cesarean section. Its causes are insulin resistance, pain, anxiety, stress, thirst, hunger, and so on. Preoperative oral carbohydrate (OCH) reduces postoperative insulin resistance and improves postoperative recovery. The present study was conducted to evaluate the effect of preoperative oral carbohydrate on breastfeeding after cesarean section. In this double-blind randomized clinical trial, 91 pregnant women who underwent elective cesarean section were randomly assigned to preoperative OCH (Nutricia Preop; n = 45) or control group (water flavored with lemon; n = 46). The patients ingested 800 ml + 400 ml of liquid before the surgery. The time to first breastfeeding after surgery (min), the duration of breastfeeding (min), and breastfeeding frequency were measured using a questionnaire for up to 36 h after the surgery. Time to first breastfeeding after surgery was significantly shorter in the OCH group than in the control group (27.47 ± 11.51 vs. 51.96 ± 20.20 min, p< .001). The mean frequency of breastfeeding (6.14 ± 0.55 vs. 4.82 ± 0.46, p < .001) was significantly higher and the mean duration of breastfeeding (116.48 ± 19.68 vs. 82.13 ± 12.40 min, p < .001) was significantly longer in the OCH group compared with the control group in the first 36 h after the surgery. Preoperative oral carbohydrate improves breastfeeding after surgery (time to first breastfeeding, breastfeeding frequency, and breastfeeding duration). Further clinical trials and precise measurement tools are needed to assess breastfeeding to confirm these effects. The study was registered at http://www.IRCT.ir (IRCT2016072629082N1).
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Effect of Dietary Carbohydrate Type on Serum Cardiometabolic Risk Indicators and Adipose Tissue Inflammatory Markers.
Meng, H, Matthan, NR, Fried, SK, Berciano, S, Walker, ME, Galluccio, JM, Lichtenstein, AH
The Journal of clinical endocrinology and metabolism. 2018;(9):3430-3438
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Abstract
CONTEXT AND OBJECTIVE Direct comparisons between types of dietary carbohydrate in terms of cardiometabolic risk indicators are limited. This study was designed to compare the effects of an isocaloric exchange of simple, refined, and unrefined carbohydrates on serum cardiometabolic risk indicators, adipose tissue inflammatory markers, and peripheral blood mononuclear cell (PBMC) fractional cholesterol efflux. DESIGN, PARTICIPANTS, AND MEASURES Participants [postmenopausal women and men (N = 11), 65 ± 8 years, body mass index 29.8 ± 3.2 kg/m2, low-density lipoprotein (LDL) cholesterol ≥2.6 mmol/L] were provided with diets (60% energy from total carbohydrate, 15% from protein, 25% from fat) for 4.5 weeks in a randomized crossover design, with 2-week washout periods. The variable component was an isocaloric exchange of simple, refined, or unrefined carbohydrate-containing foods. Serum lipoprotein, glucose, insulin, and inflammatory marker concentrations were measured. Abdominal subcutaneous adipose tissue was aspirated to assess macrophage and inflammatory marker gene expression and ex vivo cytokine secretion, and PBMCs were isolated to assess ex vivo fractional cholesterol efflux. RESULTS Fasting serum LDL and non-high-density lipoprotein (HDL) cholesterol concentrations were higher after the refined compared with simple or unrefined carbohydrate-enriched diets (P < 0.01). Other serum measures, ex vivo fractional cholesterol efflux and adipose tissue gene expression and ex vivo cytokine secretion, were similar between diets. CONCLUSIONS Diets enriched in refined compared with simple or unrefined carbohydrate resulted in higher fasting serum LDL and non-HDL cholesterol concentrations but had little effect on other cardiometabolic risk indicators. This small study raises the intriguing possibility that refined carbohydrate may have unique adverse effects on cardiometabolic risk indicators distinct from simple and unrefined carbohydrate.
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Effects of protein-carbohydrate supplementation on immunity and resistance training outcomes: a double-blind, randomized, controlled clinical trial.
Naclerio, F, Larumbe-Zabala, E, Ashrafi, N, Seijo, M, Nielsen, B, Allgrove, J, Earnest, CP
European journal of applied physiology. 2017;(2):267-277
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Abstract
PURPOSE To examine the impact of ingesting hydrolyzed beef protein, whey protein, and carbohydrate on resistance training outcomes, body composition, muscle thickness, blood indices of health and salivary human neutrophil peptides (HNP1-3), as reference of humoral immunity followed an 8-week resistance training program in college athletes. METHODS Twenty-seven recreationally physically active males and females (n = 9 per treatment) were randomly assigned to one of the three groups: hydrolyzed beef protein, whey protein, or non-protein isoenergetic carbohydrate. Treatment consisted of ingesting 20 g of supplement, mixed with orange juice, once a day immediately post-workout or before breakfast on non-training days. Measurements were performed pre- and post-intervention on total load (kg) lifted at the first and last workout, body composition (via plethysmography) vastus medialis thickness (mm) (via ultrasonography), and blood indices of health. Salivary HNP1-3 were determined before and after performing the first and last workout. RESULTS Salivary concentration and secretion rates of the HNP1-3 decreased in the beef condition only from pre-first-workout (1.90 ± 0.83 μg/mL; 2.95 ± 2.83 μg/min, respectively) to pre-last-workout (0.92 ± 0.63 μg/mL, p = 0.025, d = 1.03; 0.76 ± 0.74 μg/min, p = 0.049, d = 0.95), and post-last-workout (0.95 ± 0.60 μg/mL, p = 0.032, d = 1.00; 0.59 ± 0.52 μg/min, p = 0.027, d = 1.02). No other significant differences between groups were observed. CONCLUSIONS Supplementation with a carbohydrate-protein beverage may support resistance training outcomes in a comparable way as the ingestion of only carbohydrate. Furthermore, the ingestion of 20 g of hydrolyzed beef protein resulted in a decreased level and secretion rates of the HNP1-3 from baseline with no negative effect on blood indices of health.