to euhydration ( Mitchell et al., 1994 ; Robertson, 1974 ). Hence, there is considerable scientific interest in understanding factors that enhance fluid retention and assist with rehydration after exercise. When consumed without food and matched for volume, nutrient-dense beverages (e.g., milk and
Liam Sayer, Nidia Rodriguez-Sanchez, Paola Rodriguez-Giustiniani, Christopher Irwin, Danielle McCartney, Gregory R. Cox, Stuart D.R. Galloway and Ben Desbrow
Jason R. Karp, Jeanne D. Johnston, Sandra Tecklenburg, Timothy D. Mickleborough, Alyce D. Fly and Joel M. Stager
Nine male, endurance-trained cyclists performed an interval workout followed by 4 h of recovery, and a subsequent endurance trial to exhaustion at 70% VO2max, on three separate days. Immediately following the first exercise bout and 2 h of recovery, subjects drank isovolumic amounts of chocolate milk, fluid replacement drink (FR), or carbohydrate replacement drink (CR), in a single-blind, randomized design. Carbohydrate content was equivalent for chocolate milk and CR. Time to exhaustion (TTE), average heart rate (HR), rating of perceived exertion (RPE), and total work (WT) for the endurance exercise were compared between trials. TTE and WT were significantly greater for chocolate milk and FR trials compared to CR trial. The results of this study suggest that chocolate milk is an effective recovery aid between two exhausting exercise bouts.
Ricardo J.S. Costa, Vera Camões-Costa, Rhiannon M.J. Snipe, David Dixon, Isabella Russo and Zoya Huschtscha
nutrition application. Considering that the nutritional composition of dairy milk meets the criteria for the general recovery nutrition guidelines and recommendation ( Thomas et al., 2016 ), it is not surprising that the consumption of dairy milk after exercise supports muscle glycogen resynthesis, muscle
Sharon L. Miller, Carl M. Maresh, Lawrence E. Armstrong, Cara B. Ebbeling, Shannon Lennon and Nancy R. Rodriguez
The interaction of substrates and hormones in response to ingestion of intact proteins during endurance exercise is unknown. This study characterized substrate and hormone responses to supplementation during endurance exercise. Nine male runners participated in 3 trials in which a non-fat (MILK), carbohydrate (CHO), or placebo (PLA) drink was consumed during a 2-hour treadmill >· run at 65% V̇O2max. Circulating levels of insulin, glucagon, epinephrine, norepi-nephrine, growth hormone, testosterone, and cortisol were measured. Plasma substrates included glucose, lactate, free fatty acids, and select amino acids. Except for insulin and cortisol, hormones increased with exercise. While post-exercise insulin concentrations declined similarly in all 3 trials, the glucagon increase was greatest following MILK consumption. CHO blunted the post-exercise increase in growth hormone compared to levels in MILK. Free fatty acids and plasma amino acids also were responsive to nutritional supplementation with both CHO and MILK attenuating the rise in free fatty acids compared to the increase observed in PLA. Correspondingly, respiratory exchange ratio increased during CHO. Essential amino acids increased significantly only after MILK and were either unchanged or decreased in CHO. PLA was characterized by a decrease in branched-chain amino acid concentrations. Modest nutritional supplementation in this study altered the endocrine response as well as substrate availability and utilization following and during an endurance run, respectively.
Kate Lambourne, Richard Washburn, Jaehoon Lee, Jessica L. Betts, David Thomas, Bryan Smith, Cheryl Gibson, Debra Kay Sullivan and Joseph Donnelly
Fluid milk consumed in conjunction with resistance training (RT) provides additional protein and calcium, which may enhance the effect of RT on body composition. However, the literature on this topic is inconsistent with limited data in adolescents. Therefore, we examined the effects of a supervised RT program (6 mo, 3 d/wk, 7 exercises, 40–85% 1-repetition maximum) with daily milk supplementation (24 oz/day, one 16-oz dose immediately post-RT) on weight, fat mass (FM), and fat-free mass (FFM) assessed via dual-energy X-ray absorptiometry (baseline, 3 mo, 6 mo) in a sample of middle-school students who were randomly assigned to 1 of 3 supplement groups: milk, isocaloric carbohydrate (100% fruit juice), or water (control). Thirty-nine boys and 69 girls (mean age = 13.6 yr, mean BMI percentile = 85th) completed the study: milk n = 36, juice n = 34, water n = 38. The results showed no significant differences between groups for change in body weight (milk = 3.4 ± 3.7 kg, juice = 4.2 ± 3.1 kg, water = 2.3 ± 2.9 kg), FM (milk = 1.1 ± 2.8 kg, juice = 1.6 ± 2.5 kg, water = 0.4 ± 3.6 kg), or FFM (milk = 2.2 ± 1.9 kg, juice = 2.7 ± 1.9 kg, water = 1.7 ± 2.9 kg) over 6 mo. FFM accounted for a high proportion of the increased weight (milk = 62%, juice = 64%, water = 74%). These results from a sample of predominantly overweight adolescents do not support the hypothesis that RT with milk supplementation enhances changes in body composition compared with RT alone.
Janet R. Wojcik, Janet Walberg-Rankin, Lucille L. Smith and F.C. Gwazdauskas
This study examined effects of carbohydrate (CHO), milk-based carbohydrate-protein (CHO-PRO), or placebo (P) beverages on glycogen resynthesis, muscle damage, inflammation, and muscle function following eccentric resistance exercise. Untrained males performed a cycling exercise to reduce muscle glycogen 12 hours prior to performance of 100 eccentric quadriceps contractions at 120% of 1-RM (day 1) and drank CHO (n = 8), CHO-PRO (n = 9; 5 kcal/kg), or P (n = 9) immediately and 2 hours post-exercise. At 3 hours post-eccentric exercise, serum insulin was four times higher for CHO-PRO and CHO than P (p < .05). Serum creatine kinase (CK) increased for all groups in the 6 hours post-eccentric exercise (p < .01), with the increase tending to be lowest for CHO-PRO (p < .08) during this period. Glycogen was low post-exercise (33 ± 3.7 mmol/kg ww), increased 225% at 24 hours, and tripled by 72 hours, with no group differences. The eccentric exercise increased muscle protein breakdown as indicated by urinary 3-methylhistidine and increased IL-6 with no effect of beverage. Quadriceps isokinetic peak torque was depressed similarly for all groups by 24% 24 hours post-exercise and remained 21 % lower at 72 hours (p < .01). In summary, there were no influences of any post-exercise beverage on muscle glycogen replacement, inflammation, or muscle function.
Adam U. Upshaw, Tiffany S. Wong, Arash Bandegan and Peter W.R. Lemon
Postexercise chocolate milk ingestion has been shown to enhance both glycogen resynthesis and subsequent exercise performance. To assess whether nondairy chocolate beverage ingestion post–glycogen-lowering exercise can enhance 20-km cycling time trial performance 4 hr later, eight healthy trained male cyclists (21.8 ± 2.3y, VO2max = 61.2 ± 1.4 ml·kg-1·min-1; M ± SD) completed a series of intense cycling intervals designed to lower muscle glycogen (Jentjens & Jeukendrup, 2003) followed by 4 hr of recovery and a subsequent 20-km cycling time trial. During the first 2 hr of recovery, participants ingested chocolate dairy milk (DAIRYCHOC), chocolate soy beverage (SOYCHOC), chocolate hemp beverage (HEMPCHOC), low-fat dairy milk (MILK), or a low-energy artificially sweetened, flavored beverage (PLACEBO) at 30-min intervals in a double-blind, counterbalanced repeated-measures design. All drinks, except the PLACEBO (247 kJ) were isoenergetic (2,107 kJ), and all chocolate-flavored drinks provided 1-g CHO·kg body mass-1·h-1. Fluid intake across treatments was equalized (2,262 ± 148 ml) by ingesting appropriate quantities of water based on drink intake. The CHO:PRO ratio was 4:1, 1.5:1, 4:1, and 6:1 for DAIRYCHOC, MILK, SOYCHOC, and HEMPCHOC, respectively. One-way analysis of variance with repeated measures showed time trial performance (DAIRYCHOC = 34.58 ± 2.5 min, SOYCHOC = 34.83 ± 2.2 min, HEMPCHOC = 34.88 ± 1.1 min, MILK = 34.47 ± 1.7 min) was enhanced similarly vs PLACEBO (37.85 ± 2.1) for all treatments (p = .019) These data suggest that postexercise macronutrient and total energy intake are more important for same-day 20-km cycling time trial performance after glycogen-lowering exercise than protein type or protein-to-carbohydrate ratio.
Brenton J. Baguley, Jessica Zilujko, Michael D. Leveritt, Ben Desbrow and Christopher Irwin
The aim of this study was to compare the effect of ad libitum intake of a milk-based liquid meal supplement against a carbohydrate-electrolyte sports drink following exercise induced fluid loss. Seven male participants (age 22.3 ± 3.4 years, height 179.3 ± 7.9 cm, body mass 74.3 ± 7.3 kg; mean ± SD) completed 4 separate trials and lost 1.89 ± 0.44% body mass through moderate intensity exercise in the laboratory. After exercise, participants consumed ad libitum over 2 h a milk-based liquid meal supplement (Sustagen Sport) on two of the trials (S1, S2) or a carbohydrate-electrolyte sports drink (Powerade) on two of the trials (P1, P2), with an additional 1 hr observational period. Measures of body mass, urine output, gastrointestinal tolerance and palatability were collected throughout the recovery period. Participants consumed significantly more Powerade than Sustagen Sport over the 2 h rehydration period (P1 = 2225 ± 888 ml, P2 = 2602 ± 1119 mL, S1 = 1375 ± 711 mL, S2 = 1447 ± 857 ml). Total urine output on both Sustagen trails was significantly lower than the second Powerade trial (P2 = 1447 ± 656 ml, S1 = 153 ± 62 ml, S2 = 182 ± 118 mL; p < .05) and trended toward being lower compared with the first Powerade trial (P1 = 1057 ± 699 ml vs. S1, p = .067 and vs. S2, p = .061). No significant differences in net fluid balance were observed between any of the drinks at the conclusion of each trial (P1 = −0.50 ±0. 46 kg, P2 = −0.40 ± 0.35 kg, S1 = −0.61 ± 0.74 kg, S2 = −0.45 ± 0.58 kg). Gastrointestinal tolerance and beverage palatability measures indicated Powerade to be preferred as a rehydration beverage. Ad libitum milk-based liquid meal supplement results in similar net fluid balance as a carbohydrate-electrolyte sports drink after exercise induced fluid loss.
Flatwater kayaking requires upper-body muscle strength and a lean body composition. This case study describes a nutrition intervention with a 19-year-old male elite sprint kayaker to increase muscle mass and improve recovery posttraining. Before the intervention, average daily energy intake was 13.6 ± 2.5 MJ (M ± SD; protein, 1.8 g/kg; carbohydrate, 3.6 g/kg), and the athlete was unable to eat sufficient food to meet the energy demands of training. During the 18-month intervention period, the athlete’s daily energy intake increased to 22.1 ± 3.8 MJ (protein, 3.2 g/kg; carbohydrate, 7.7 g/kg) by including milk-based drinks pre- and posttraining and before bed and an additional carbohydrate-based snack midmorning. This simple dietary intervention, along with a structured strength and conditioning program, resulted in an increase of 10 kg body mass with minimal change in body fat percentage. Adequate vitamin D status was maintained without the need for supplementation during the intervention period. In addition, the athlete reported the milk-based drinks and carbohydrate snacks were easy to consume, and no adverse side effects were experienced. This was the first time the athlete was able to maintain weight during intensive phases of the training cycle.
Daniel P. Joaquim, Claudia R. Juzwiak and Ciro Winckler
juice, milk, and fruits (three types). Lunch and dinner: vegetables (five types: two raw leaves, two raw vegetables, and one cooked or steamed vegetable), meat dishes (two options), side dishes (white and brown rice, beans, cooked pasta, or tubers), and dessert (two types of sweets and two types of