Flavored Water Placebo Research Articles

Influence of exercise on plasma ammonia and urea after ingestion beverages of carbohydrate electrolyte

Ingestion of beverages with carbohydrate electrolyte during exercise can delay fatigue. Fatigue caused by the decreasing of glycogen deposit source and indefensible reproduced ATP result in the improvement of IMP and ammonia during fatigue. The aim of this research was to observe the alteration of plasma ammonia and urea before, during and after exercise, after ingestion beverages of carbohydrate - electrolyte. Ten male subjects (age 18-30 years) were subjected to there cycle ergometer at 60% of VO2max with a pedal speed of 60 rpm until there is fatigued. The subject was given a drink of carbohydrate-electrolyte at a concentration of 6%, 12% and a flavored water placebo (P) to consume the volume of 3 ml/kg BW every 20 minutes. Blood samples were taken at rest and every 20 minutes until fatigue for analyzing plasma ammonia and urea. Mean exercise until fatigue show that no difference for three beverages. However, plasma ammonia and urea were significantly increase compared before and after exercise (p<0.001). Results of plasma ammonia before exercise for beverages CHO 12% (HC) (31.86±1.93μml/l vs 86.50±5.13μml/l), for CHO 6% (MC) (33.08±1.43μml/l vs 90.68±3.41μml/l), for no carbohydrate (P) (33.64±1.93μml/l vs 93.12 ± 2.91μml/l). Whereas plasma urea before exercise for beverages CHO 12% (4.75±0.12mmol/l vs 5.44±0.10mmol/l), for CHO 6% (4.88±0.20mmol/l vs 5.22± 0.10mmol/l), for Placebo (4.88±0.20mmol/l vs 5.54±0.24mmol/l). Conclusions that increase of plasma ammonia of during fatigue, can become the criteria for determining intensity exercise until fatigue results are better than plasma lactate.

Effect of Preexercise Ingestion of Modified Amylomaize Starch on Glycemic Response While Cycling.

Amylomaize-7 is classified as a resistant corn starch and is 68% digestible. When modified by partial hydrolysis in ethanol and hydrochloric acid its digestibility is 92%, yet retains its low glycemic and insulinemic properties. The purpose of this study was to characterize the metabolic response when modified amylomaize-7 or dextrose is consumed in the hour before exercise, and to compare the effect on performance of a brief high-intensity cycling trial. Ten male, trained cyclists were given 1g/kg body mass of dextrose (DEX) or modified amylomaize-7 (AMY-7) or a flavored water placebo (PL) 45min prior to exercise on a cycle ergometer. A 15-min ride at 60%Wmax was immediately followed by a self-paced time trial (TT) equivalent to 15min at 80%Wmax. When cyclists consumed DEX, mean serum glucose concentration increased by 3.3 ± 2.1mmol/L before exercise, compared to stable serum glucose observed for AMY-7 or PL. Glucose concentrations returned to baseline by pre-TT in all treatments. However, the mean post-TT glucose concentration of the DEX group was significantly lower than baseline, AMY-7, or PL. Serum insulin concentration increased nine-fold from baseline to preexercise in the DEX trial, whereas PL or AMY-7 remained unchanged. Time required to complete the performance trial was not significantly different between DEX, AMY-7 or PL. Preexercise ingestion of modified amylomaize-7 compared to dextrose resulted in a more stable serum glucose concentration, but did not offer a performance advantage in this high-intensity cycling trial.

Combined Interval Training and Post-exercise Nutrition in Type 2 Diabetes: A Randomized Control Trial

Background: High-intensity interval training (HIIT) can improve several aspects of cardiometabolic health. Previous studies have suggested that adaptations to exercise training can be augmented with post-exercise milk or protein consumption, but whether this nutritional strategy can impact the cardiometabolic adaptations to HIIT in type 2 diabetes is unknown.Objective: To determine if the addition of a post-exercise milk or protein beverage to a high-intensity interval training (HIIT) intervention improves cardiometabolic health in individuals with type 2 diabetes.Design: In a proof-of-concept, double-blind clinical trial 53 adults with uncomplicated type 2 diabetes were randomized to one of three nutritional beverages (500 mL skim-milk, macronutrient control, or flavored water placebo) consumed after exercise (3 days/week) during a 12 week low-volume HIIT intervention. HIIT involved 10 X 1-min high-intensity intervals separated by 1-min low-intensity recovery periods. Two sessions per week were cardio-based (at ~90% of heart rate max) and one session involved resistance-based exercises (at RPE of 5–6; CR-10 scale) in the same interval pattern. Continuous glucose monitoring (CGM), glycosylated hemoglobin (HbA1c), body composition (dual-energy X-ray absorptiometry), cardiorespiratory fitness (), blood pressure, and endothelial function (%FMD) were measured before and after the intervention.Results: There were significant main effects of time (all p < 0.05) but no difference between groups (Interaction: all p > 0.71) for CGM 24-h mean glucose (−0.5 ± 1.1 mmol/L), HbA1c (−0.2 ± 0.4%), percent body fat (−0.8 ± 1.6%), and lean mass (+1.1 ± 2.8 kg). Similarly, (+2.5 ± 1.6 mL/kg/min) and %FMD (+1.4 ± 1.9%) were increased, and mean arterial blood pressure reduced (−6 ± 7 mmHg), after 12 weeks of HIIT (all p < 0.01) with no difference between beverage groups (Interaction: all p > 0.11).Conclusion: High-intensity interval training is a potent stimulus for improving several important metabolic and cardiovascular risk factors in type 2 diabetes. The benefits of HIIT are not augmented by the addition of post-exercise protein.

Randomized Controlled-Trial of Milk and High-Intensity Interval Training on Metabolic Health in Type 2 Diabetes

Milk consumption post-exercise may provide additional lean mass gains and body fat loss. Such favorable body composition changes could promote further improvements in glycemic control and quality of life (QoL) in exercising older adults with type 2 diabetes (T2D). PURPOSE: To determine if the addition of post-exercise low-fat milk to high-intensity interval training (HIIT) improves metabolic health more than HIIT and isolated milk-protein, or HIIT alone. METHODS: In a proof-of-concept, randomized double-blind controlled trial, 47 adults with physician-diagnosed T2D (58 ± 10 y, A1c: 7.1 ± 0.8%, BMI: 35 ± 7 kg/m2) were randomly assigned to one of three nutritional beverages (500 mL skim-milk, milk-protein isolate or flavored water placebo) after HIIT exercise (2x cardio- and 1x resistance-based / wk) for 12 weeks. Body composition (dual-energy X-ray absorptiometry), glycemic control (hemoglobin A1c, continuous glucose monitoring) and QoL (SF-36) were measured before and after the intervention. Inferential analyses for clinical chances were performed using the spreadsheet at www.newstats.org. RESULTS: There were main effects of time but no group X time interactions. All results are therefore presented as main effects of time with groups collapsed, with probability of change being clinically beneficial shown for select variables. Body mass was unchanged (-0.8 ± 3.2 kg, p=0.13), however, lean mass (+1.3 ± 2.9 kg, p<0.01, likely beneficial) and percent body fat (-0.85 ± 1.6%, p<0.01, possibly beneficial) were improved in all groups. Hemoglobin A1c (-0.2 ± 1.6 %, p<0.01, most likely trivial), 24-h mean glucose (-0.4 ± 1.2 mmol/L, p=0.04) and glycemic variability (MAGE: -1.1 ± 2.9, p=0.02) were reduced. QOL also increased (95%CI: +5.3-17%, most likely beneficial) after HIIT. CONCLUSION: The consumption of milk or protein after HIIT does not result in additional benefits for metabolic health compared to HIIT alone. In line with current evidence, HIIT is a potent stimulus for improving several aspects of metabolic health in patients with type 2 diabetes.

The Effects Of Different Sodium And Carbohydrate Concentration And pH On The Intestinal Fluid Absorption In Humans

To be an effective fluid replacement beverage during activity, a beverage must provide enough energy to sustain performance and yet be absorbed rapidly in the small intestine. Although the effect of carbohydrate (CHO) on fluid absorption is well-established, the interactive impact of sodium and CHO concentrations and the effect of pH on fluid absorption are still not clear. PURPOSE: To determine the effects of different levels of sodium content at two different CHO concentrations on water absorption. Secondarily, we compared the effect of pH on water flux. METHODS: Seven male subjects were perfused with six beverages (60 min per beverage) at a rate of 15 ml/min in a randomized order using the triple lumen perfusion technique. Water absorption from each solution was calculated based on changes of polyethylene glycol (PEG) concentration in the intestinal samples. Test beverages included water (W, pH = 7), a flavored water placebo (WP, pH = 3), a 3% CHO (sucrose and dextrose) solution with either 18 mEq sodium (LCLS) or 72 mEq sodium (LCHS), and a 6% CHO (sucrose and dextrose) solution with either 18 mEq sodium (HCLS) or 72 mEq sodium (HCHS). Beverage osmolality ranged from 0 to 381 mOsm/kg. A two-factor repeated measures ANOVA was used to determine the significance in water flux (a=0.05). RESULTS: CHO concentration ranging from 0 up to 6% did not significantly affect mean water flux (-19.7 ± 3.6, -16.3 ± 2.6, and -14.0 ± 0.9 ml·cm-1·h-1 for W, LCLS, and HCLS, respectively) over the 60 minutes of perfusion. Likewise, the sodium content at either CHO concentration did not affect water flux (-12.2 ± 1.2 and -10.7 ± 1.0 ml·cm-1·h-1 for LCHS and HCHS, respectively). Finally, there was no significant difference in water flux based on pH (W: -19.7 ± 3.6 ml·cm-1·h-1 vs. WP: -14.0 ± 2.7 ml·cm-1·h-1). CONCLUSIONS: Increasing the sodium content to 72 mEq in either a 3% or a 6% CHO solution did not facilitate the rate of intestinal fluid absorption. In addition, a decrease of beverage pH from 7 to 3 did not appear to significantly influence intestinal absorption of fluid.

Core Temperature and Metabolic Responses After Carbohydrate Intake During Exercise at 30°C

Carbohydrate ingestion has recently been associated with elevated core temperature during exercise in the heat when testing for ergogenic effects. Whether the association holds when metabolic rate is controlled is unclear. Such an effect would have undesirable consequences for the safety of the athlete. To examine whether ingesting fluids containing carbohydrate contributed to an accelerated rise in core temperature and greater overall body heat production during 1 hour of exercise at 30 degrees C when the effort was maintained at steady state. Crossover design (repeated measures) in randomized order of treatments of drinking fluids with carbohydrate and electrolytes (CHO) or flavored-water placebo with electrolytes (PLA). The beverages were identical except for the carbohydrate content: CHO = 93.7 +/- 11.2 g, PLA = 0 g. Research laboratory. Nine physically fit, endurance-trained adult males. Using rectal temperature sensors, we measured core temperature during 30 minutes of rest and 60 minutes of exercise at 65% of maximal oxygen uptake (Vo(2) max) in the heat (30.6 degrees C, 51.8% relative humidity). Participants drank equal volumes (1.6 L) of 2 beverages in aliquots 30 minutes before and every 15 minutes during exercise. Volumes were fixed to approximate sweat rates and minimize dehydration. Rectal temperature and metabolic response (Vo(2), heart rate). Peak temperature, rate of temperature increase, and metabolic responses did not differ between beverage treatments. Initial hydration status, sweat rate, and fluid replacement were also not different between trials, as planned. Ingestion of carbohydrate in fluid volumes that minimized dehydration during 1 hour of steady-state exercise at 30 degrees C did not elicit an increase in metabolic rate or core temperature.

Effects Of Caffeinated Sports Drinks On Physical/Mental Function During Team Sports Exercise

The ergogenic effects of caffeine ingestion (240–840 mg) on exercise performance is well established, albeit in some cases with negative side effects. However, recent evidence shows that much smaller doses can have beneficial effect on endurance performance as well as on mental function. Less is known about the possible synergistic effects of low dose of caffeine (CAF) and carbohydrate (CHO) feedings, especially as related to team sports performance. PURPOSE: To determine the effects of low dose (100 mg) CAF ingestion along with typically recommended CHO on physical and mental function during intermittent high intensity exercise that mimics the demands of competitive team sports. METHODS: Physically active male (N=6) and female (N=4) low to moderate caffeine users participated in this study. Experimental trials consisted of four ∼22-minute quarters (QTR) of shuttle running. Physical and mental function tests were administered throughout the experimental trial including (20-m sprint, vertical jump, gross motor skill test, force sensation, rating of perceived exertion, profile of mood states and psychomotor vigilance test).On four separate occasions, subjects received 20-oz of flavored water placebo (PLA), CHO, PLA+CAF and CHO+CAF prior to exercise. During exercise, subjects ingest PLA, CHO, PLA and CHO respectively (3.5 ml·kg-1). RESULTS: No difference was found in 20-m sprint time, vertical jump and gross motor skills performance between any treatments. However, both caffeine treatments (PLA+CAF and CHO+CAF) significantly improved psychomotor vigilance and reduced force sensation at HALFTIME (p<0.05). CHO+CAF also improved self-reported perception of fatigue, vigor and overall mood compared to PLA+CAF (p<0.05). Systolic blood pressure was increased with CHO+CAF compare to other three treatments. However, no difference was found in heart rate, core body temperature, plasma volume change, or hydration status between any treatments. CONCLUSION: The data suggest that ingestion of a low dose of caffeine prior to exercise did not add to the expected benefits of CHO feedings alone on physical tasks. However, all of the mental function tasks were significantly enhanced with the combination of CHO plus CAF, with little or no adverse side effects. Funded by Gatorade Sports Science Institute.

Two Percent Dehydration Impairs and Six Percent Carbohydrate Drink Improves Boys Basketball Skills

To determine the effects of exercise heat-induced two percent dehydration (DEH) and euhydration (EUH) with a six percent carbohydrate-electrolyte solution (CES) compared with placebo EUH (P EUH) on basketball skills in skilled young players. Fifteen 12- to 15-yr-old boys underwent three separate 2-h exercise heat exposures (double blind, random order): 2% DEH by limiting fluid intake during exercise in the heat and basketball skill drills, EUH (no net weight change) with a 6% CES, and EUH with a flavored water placebo (P EUH). After recovery, subjects performed an orchestrated sequence of continuous basketball drills designed to simulate a game (12-min quarters + a 10-min halftime). Performance measures and component drills inherent to basketball included various individual and combined shooting percentages (3-point, 15-foot, free-throw shots), sprint (suicides, court widths), lateral movement (zigzags, lane slides), and defensive drill (combining lateral and front-to-back movement) times. Compared with P EUH (53 +/- 11%), combined shooting percentage was impaired by 2% DEH (45 +/- 9%; P = 0.002) and improved by CES intake (60 +/- 8%; P = 0.003). Total sprint times showed a similar effect (83 +/- 10 vs 78 +/- 9 vs 76 +/- 9 s; DEH vs P EUH vs CES; P < 0.001 and P = 0.04, respectively). Total lateral movement times were impaired by 2% DEH (73 +/- 8 vs 68 +/- 8 s; P = 0.001). CES improved total defensive drill times compared with 2% DEH (77 +/- 10 vs 82 +/- 10; P = 0.006). Deterioration in basketball skill performance accompanies two percent dehydration in skilled 12- to 15-yr-old basketball players. Additionally, EUH with a 6% CES significantly improves shooting performance and on-court sprinting over EUH with water.

Youth Basketball Performance is Impaired by 2% Dehydration and Improved by Ingesting 6% Carbohydrate Solution

Dehydration (DEH) by 2% has been suggested to impair athletic performance during short duration high-intensity intermittent activity in adults, and fully replacing fluid loss with a 6% carbohydrate-electrolyte solution (CES) has been shown to improve performance over euhydration (EUH) with water. Few studies have investigated the impact of DEH and/or CES ingestion on sport-specific performance in children. PURPOSE: To determine the effect of 2% DEH and CES EUH compared to placebo EUH on basketball performance in highly-skilled young players. METHODS: After consuming a low-carbohydrate standardized breakfast, 15 12–15-year old boy basketball players completed 2 hours of 15-minute exercise bouts at 50% VO2max, with 5 minute rest periods between bouts at 30°C, 20% rh. Each subject completed 3 double-blinded trials in random order: 1) 2% DEH by limiting fluid intake, 2) euhydration with a 6% CES and 3) euhydration with a flavored water placebo (P). After an hour recovery, subjects performed an orchestrated sequence of continuous basketball drills designed to simulate a game with four 12-minute quarters and a 10-minute halftime rest. The drink treatment was continued to maintain the imposed level of DEH or EUH. Performance measures included: combined shooting percentage (three-point, 15-foot, and free throw shots) and combined times for sprints (suicides and court widths), lateral movement (zig-zag and lane slides), and defensive (combining lateral and front-to-back movement) drills. RESULTS: Compared to the P trial (53 ± 3%) combined shooting percentage was impaired by 2% DEH (45 ± 2%; p<0.002) and improved by CES intake (60 ± 2%; p<0.003). Total sprint times showed the same pattern (41 ± 1 vs. 39 ± 1 vs. 38 ± 1 s; DEH vs. P vs. CES; p<0.001 and P=0.05 respectively). Lateral movement total times were impaired by 2% DEH compared to both EUH trials (37 ± 1 vs. 34 ± 1 s each; DEH vs. P and G; p<0.0002). Neither DEH nor CES had a significant effect on defensive drill times. CONCLUSION: Deterioration in basketball skill performance accompanies 2% dehydration. EUH with a 6% CES significantly improved shooting performance and on-court sprinting over EUH with water alone. This degree of improvement is important in a sport where subtle changes in performance could be the deciding factor in winning or losing a basketball game. Supported by the National Basketball Association and the Gatorade Sports Science Institute

Effects of Carbohydrate and Branch-Chain Amino Acid Ingestion on Intermittent, High Intensity Running 720

Research is beginning to accumulate regarding a possible ergogenic effect of carbohydrate feedings on intermittent high intensity exercise of relatively short duration (= 60 min). Branched chain amino acid (BCAA) supplementation has also been suggested to delay fatigue during prolonged exercise but the effect has not been tested in other exercise situations. Therefore, the purpose of this study was to examine the effects of carbohydrate and BCAA ingestion before and during shuttle running to fatigue. Eight subjects performed three exercise trials consisting of 5 × 15 min sessions of shuttle running (intervals of walking, sprinting, and running at 55% & 95% VO2max) followed by intermittent running (at 55% & 95% VO2max) to fatigue. Trials were completed in a double-blind counterbalanced fashion. Treatments included: flavored water placebo (P), carbohydrate 1h before (5ml/kg; 18%), immediately before and during exercise(2 ml/kg; 6%) (CHO), and carbohydrate+BCAA (7g at 1h and immediately before exercise). Results show that subjects ran longer when fed either CHO or CHO+BCAA as compared to P (CHO 9.65±2.07, CHO+BCAA 9.00±2.26, P 6.36±1.63 min; mean±SE; p<0.05). CHO & CHO+BCAA had higher glucose and lower FFA concentrations that P (p<0.05). These results indicate that drinking carbohydrate solutions 1h before and during exercise improves running capacity during exercise that imitates various sports, and that the addition of BCAA does not further enhance this effect.

Acceptability and Effect of Carbohydrate-Electrolyte Solutions on Electrolyte Homeostasis during Field Training

Two lemon-lime flavored 2.5% carbohydrate-electrolyte solutions (CE1 supplemented with Na+, K+, and Mg+; and CE2 supplemented with NA+) were compared to plain water (water) and lemon-lime flavored water placebo (placebo) to evaluate their acceptability and consumption during 8 days of field training in hot weather. Acceptability ratings and consumption of CE2 and the flavored water placebo were similar and greater, respectively, than those for CE1. Average Na+ and K+ intakes, and serum electrolytes levels, were not affected during the 8-day trial. If food intake is adequate, consumption of carbohydrate-electrolyte solutions is apparently unnecessary to maintain electrolyte homeostasis.

Incidence of Hypohydration When Consuming Carbohydrate-Electrolyte Solutions during Field Training

Carbohydrate-electrolyte solutions (CE1, CE2) were evaluated for their ability to reduce the incidence of hypohydration during field training in hot weather (max Tamb = 88 degrees-100 degrees F). Hydration status was monitored twice daily in Army reservists who consumed ad libitum CE1, or CE2, or water, or a flavored water placebo. The water group had the highest percentage incidence of urine specific gravity greater than or equal to 1.030 (22%), whereas CE2 and flavored water placebo groups had the lowest (6% and 8%, respectively). Average total fluid intake was greatest in CE2 and lowest in CE1. CE2 and flavored water placebo were more effective than CE1 and water in reducing the overall incidence of hypohydration during this field exercise.

RPE, blood glucose, and carbohydrate oxidation during exercise

This study examined the effects of glucose ingestion on differentiated and undifferentiated ratings of perceived exertion (RPE) during prolonged cycling exercise. On two occasions, seven trained males cycled for 180 min on a Monark cycle ergometer at 70% peak VO2 (VO2peak). Subjects consumed an 8% glucose/electrolyte drink (G) or a flavored water placebo (P) every 15 min throughout exercise. Measurement of RPE, ventilation (VE), oxygen uptake (VO2), respiration rate (RR), respiratory exchange ratio (RER), heart rate (HR), and venous blood sample collection preceded ingestion of the drink. Subjects were homogenous with respect to height, weight, and VO2peak. RPE for the legs and overall body were significantly attenuated (P less than 0.05) during the last 45 min of exercise. Plasma glucose and insulin were higher (P less than 0.05) in G than in P at virtually all time points. CHO oxidation and work rate were maintained throughout exercise in G but not during the last 30 min of exercise in P (P less than 0.05). Percent changes in plasma volume, plasma lactate, HR, VE, RR, and RPE for the chest were not different between conditions (P greater than 0.05). The data suggest that ingestion of carbohydrate beverages during endurance cycling can maintain plasma glucose and CHO oxidation during the latter stages of prolonged exercise. As a result, it appears that a relationship exists between attenuation of ratings of perceived exertion (especially in the legs), blood glucose, and CHO oxidation late in prolonged exercise. The mechanism for this probably involves the increased availability of blood-borne glucose to serve as substrate for brain and/or muscle energy metabolism during a time when endogenous stores of carbohydrate are low.

Carbohydrate-electrolyte replacement during a simulated triathlon in the heat

Effects of a 7% carbohydrate-electrolyte drink (CE) or a flavored water placebo (P) on physiological function and performance were compared during a simulated triathlon (ST) in the heat. Ten trained male triathletes performed two STs, consisting of 1.5 km swimming, 40 km cycling, and 10 km running in an environmentally controlled area at self-selected race pace. Subjects consumed 2 ml.kg-1 (130-174 ml) of CE or P following the swim, at 8.0-km intervals during cycling, and at 3.2-km intervals during running. Sweat rate, rectal and mean skin temperatures, perceived exertion, heart rate, plasma osmolality, percent change in plasma volume, total protein, Na+, K+, and lactate were similar during the ST under both drink conditions, but RER and plasma glucose were higher (P less than 0.05) with CE. During the last 4 km of running, VO2 was significantly higher with CE. Mean run time and total ST time were faster with CE (by 1.4 and 1.2 min) although not significantly different (P less than 0.06 and P less than 0.10) from P. Subjects reported no significant difference in nausea, fullness, or stomach upset with CE compared to P. General physiological responses were similar for each drink during 2 h of multi-modal exercise in the heat; however, blood glucose, carbohydrate utilization, and exercise intensity at the end of a ST may be increased with CE fluid replacement.