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Hansen et al. Journal of the International Society of Sports Nutrition (2016) 13:9 DOI 10.1186/s12970-016-0120-4 RESEARCH ARTICLE Open Access Protein intake during training sessions has no effect on performance and recovery during a strenuous training camp for elite cyclists Mette Hansen1* , Jens Bangsbo2, Jørgen Jensen3, Matilde Krause-Jensen1, Bo Martin Bibby4,
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  RESEARCH ARTICLE Open Access Protein intake  during  training sessions hasno effect on performance and recoveryduring a strenuous training camp for elitecyclists Mette Hansen 1* , Jens Bangsbo 2 , Jørgen Jensen 3 , Matilde Krause-Jensen 1 , Bo Martin Bibby 4 , Ove Sollie 3 ,Ulrika Andersson Hall 5 and Klavs Madsen 1,5 Abstract Background:  Training camps for top-class endurance athletes place high physiological demands on the body.Focus on optimizing recovery between training sessions is necessary to minimize the risk of injuries and improveadaptations to the training stimuli. Carbohydrate supplementation during sessions is generally accepted as beingbeneficial to aid performance and recovery, whereas the effect of protein supplementation and timing is less wellunderstood. We studied the effects of protein ingestion during training sessions on performance and recovery of elite cyclists during a strenuous training camp. Methods:  In a randomized, double-blinded study, 18 elite cyclists consumed either a whey protein hydrolysate-carbohydrate beverage (PRO-CHO, 14 g protein/h and 69 g CHO/h) or an isocaloric carbohydrate beverage (CHO,84 g/h) during each training session for six days (25 – 29 h cycling in total). Diet and training were standardized andsupervised. The diet was energy balanced and contained 1.7 g protein/kg/day. A 10-s peak power test and a 5-minall-out performance test were conducted before and after the first training session and repeated at day 6 of thecamp. Blood and saliva samples were collected in the morning after overnight fasting during the week andanalyzed for biochemical markers of muscle damage, stress, and immune function. Results:  In both groups, 5-min all-out performance was reduced after the first training session and at day 6compared to before the first training session, with no difference between groups. Peak power in the sprint test didnot change significantly between tests or between groups. In addition, changes in markers for muscle damage,stress, and immune function were not significantly influenced by treatment. Conclusions:  Intake of protein combined with carbohydrate during cycling at a training camp for top cyclists didnot result in marked performance benefits compared to intake of carbohydrates when a recovery drink containingadequate protein and carbohydrate was ingested immediately after each training session in both groups. Thesefindings suggest that the addition of protein to a carbohydrate supplement consumed during exercise does notimprove recovery or performance in elite cyclists despite high demands of daily exhaustive sessions during a one-week training camp. Keywords:  Athletes, Muscle damage, Creatine kinase, Power, Endurance performance * Correspondence: kontakt@mettehansen.nu 1 Section of Sport Science, Department of Public Health, Aarhus University,Dalgas Avenue 4, 8000 Aarhus C, Denmark Full list of author information is available at the end of the article © 2016 Hansen et al.  Open Access  This article is distributed under the terms of the Creative Commons Attribution 4.0International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the srcinal author(s) and the source, provide a link tothe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/ ) applies to the data made available in this article, unless otherwise stated. Hansen  et al. Journal of the International Society of Sports Nutrition  (2016) 13:9 DOI 10.1186/s12970-016-0120-4  Background During periods of high-intensity training, nutrition is of outmost importance for top athletes in order to optimizetraining quality, muscular adaptations, and recovery between sessions. Similarly, endurance races over severaldays necessitate fast recovery. It is generally accepted thatingestion of carbohydrate is beneficial for performanceand recovery during high-intensity endurance sports[1, 2]. The effect of protein on endurance performance and recovery is less well understood. The majority of stud-ies on protein supplementation during exercise show noacute performance effect [3 – 6], but a few studies haveshown improved performance [7 – 10]. In most of thesestudies beverages were matched for carbohydrate contentrather than energy [7, 9, 10] and/or a suboptimal carbohy- drate beverage was used as a control [7 – 10], making itdifficult to differentiate between the effects of elevatedintake of protein or calories.The influence of protein supplementation during [11]or post-exercise [12 – 14] on recovery and subsequentperformance or endurance capacity has been investi-gated in several short-term (<24 h) studies, of whichsome report advantages [11, 12], whereas others report no effect [13 – 15] compared to intake of carbohydrate.Long-term effects (>24 h post-exercise) are less exam-ined and there is a lack of studies on elite athletes.Current results on well-trained athletes (max. oxygenuptake >60 ml O 2 /kg/min) are mixed. Some studiesshow no effect of ingesting protein-carbohydrate bever-ages compared to control (carbohydrate) during and/orafter exercise sessions on performance measured as timeto exhaustion (TTE) after two weeks intervention [16],repeat-sprint performance during six days intervention[17], or running performance during six days interven-tion [18]. Others show performance advantages of partialsubstitution of carbohydrate with protein in TTE duringtwo weeks intervention [19], time trials (TT) after oneweek intervention [20, 21], or repeat-sprint performance tests after 3 – 4 days intervention [22, 23]. Similarly, results from intervention trials are mixed in regard to effect of protein ingestion on attenuation of muscle damage. Acombined intake of protein and carbohydrate has, in somecases, shown attenuation of markers for muscle damage inwell-trained athletes [17 – 19, 21, 23, 24], whereas others report no difference [3, 20, 25]. The conditions vary con- siderably between studies and there is a great need forwell-controlled studies focusing specifically on the effectof protein on performance and recovery over a periodincluding daily strenuous exercise sessions.Optimization of performance and recovery is essentialat the top level where athletes often compete severaldays in succession. Elite athletes also have periods, typic-ally team training camps, where they add a substantialamount of extra training. Excessive training loads incombination with inadequate recovery can further leadto a state of overreaching or overtraining, characterizedby a long-term decrement in performance capacity aswell as a decline in immune function [26]. It is thereforeof specific interest to study nutritional strategies in orderto optimize recovery during training camps with exces-sive training loads. The present study was designed tore-examine the nutritional practice of the Danish na-tional team in race cycling (U23), which currently entailsconsumption of carbohydrate beverages during exerciseand recovery beverages containing both carbohydrateand protein post-exercise. The present study comparedthe effect of consuming a protein-supplemented carbo-hydrate beverage to an isocaloric carbohydrate beverageduring each session of an intense six-day training campfor Danish elite racing cyclists at Lanzarote. Under con-trolled conditions with cyclists, coaches, and scientistsall residing at the training campus for a full week, theaim was to determine whether ingestion of a beveragecontaining partial substitution of carbohydrates withprotein  during   exercise would have additional perform-ance and recovery effects beyond that of the proteinalready present in the recovery beverage. Both acute ef-fects of protein supplementation during the first sessionas well as accumulated effects over the six-day trainingcamp were examined. It was hypothesized that therecould be advantages of ingesting protein during exerciseover a training period since the training sessions wereextensive and lasted up to 6 h. Methods Design The study was designed as a double-blinded, random-ized, controlled intervention trial during a one-weektraining camp for elite racing cyclists (Fig. 1). The sub- jects were pre-tested before the camp and matched inpairs based on weight, maximal oxygen consumption(VO 2max ), a 5-min all-out performance, and traininghistory. Afterwards they were randomized to consumeeither a 1) carbohydrate beverage (CHO) or a 2)protein-carbohydrate beverage (PRO-CHO) during eachtraining session at the camp. Both groups consumed thesame recovery beverage after exercise, containing 18 gprotein (~0.25 g/kg) and 69 g carbohydrate (~1 g/kg).The athletes were further divided into a short distancegroup (~25 h/6 days) or a long distance group (29 h/6 days). The cyclists in CHO and PRO-CHO pairs werecycling the same distance.To evaluate the acute effect of the intervention, a testprotocol was performed in the morning at Day one(D1pre) and repeated after four (short distance group)or five (long distance group) hours of cycling (D1post).The test protocol was repeated at day six in the morning(D6pre). Breakfast and time points for testing at Day six Hansen  et al. Journal of the International Society of Sports Nutrition  (2016) 13:9 Page 2 of 11  were the same as at Day one of the intervention. Theprotocol consisted of a standardized warm-up prior to a10-s peak power test followed by a 3-min recovery period and a 5-min all-out performance test.Blood samples were collected before (morning sample)and immediately after the performance tests at Day 1and Day 6 as well as in the morning of day 3, 5, and 7,and analyzed for markers of muscle damage (creatinekinase (CK), lactate dehydrogenase (LDH), and myoglo-bin) and cortisol. Saliva samples were collected in themorning after overnight fasting at Day 1, 5, 6, 7, imme-diately after exercise, and 1 h after the training sessionon Day 6 to be analyzed for immunoglobulin A (IgA). Subjects Eighteen young, male racing cyclists (age 20±2 years)were recruited for the project. All subjects were part of,or candidates to, the Danish National Team in race cyc-ling (U23). The cyclists were block randomized to twogroups, which were similar with regards to age, weight,height, fat percentage measured by the sum of four skin-fold measurements [27], VO 2max , and performance in a5-min all-out bike test completed before the interventionperiod (Table 1). Ethics, consent, and permissions The study complied with the Declaration of Helsinkiand was approved by the local ethics committees (1-10-72-558-12). All subjects gave their informed consent toparticipate prior to the experiments. Beverages During the intervention period, each cyclist received onebottle (750 ml) containing the intervention beverage forevery hour of exercise performed. The PRO-CHO groupingested a beverage containing 0.2 g of protein/kg/h(Whey protein hydrolysate with a degree of hydrolysisbetween 23 – 29 %, Arla Foods Ingredients Group P/S,Viby, Denmark) and 1 g of CHO/kg/h (Maxim Energy Drink, Maxim International, Ishoej, Denmark). TheCHO group consumed an energy-matched carbohydratebeverage containing 1.2 g of CHO/kg/h (Maxim Energy Drink, Maxim International, Ishoej, Denmark). Thecarbohydrate content in both beverages consisted of maltodextrin and fructose in the ratio 2:1. We chose anisocaloric control beverage rather than a beveragematched for carbohydrate to isolate the effect of theaddition of protein rather than an extra amount of energy.Residual fluid left in used bottles was less than 300 mlin total per training day except for one subject in thePRO-CHO group who was not able to drink the totalbeverage volume on three of the six days (residual fluidremaining was 400 out of 4500 ml, 600 out of 3750 ml,and 1875 out of 3750 ml, respectively).Both groups consumed a recovery beverage immedi-ately after exercise each day containing 18 g of proteinand 69 g of carbohydrate corresponding to ~0.25 g pro-tein/kg and 1 g carbohydrate/kg (similar sources of pro-tein and carbohydrate as during cycling). Nothing elsewas ingested, except water, within the two hours beforeand the one hour after each training session each day.Neither the subjects nor the testing staff was informedabout the content of the beverages. Beverages were pre-pared by staff members not present during the trainingand performance testing. At D1, the recovery beveragewas ingested after the post-exercise testing (D1post).On Day 6, individual weight changes during the 6 htraining session were determined to check hydration sta-tus. The athletes were weighed immediately before andafter the training session in minimal clothing. The Fig. 1  Overall design of the test protocol. Before the training camp, the cyclists performed a VO 2max  test and were familiarized with the testprotocol before the block randomization procedure. During the intervention period at the training camp (Day 1 to Day 7), the test protocol wasrepeated at Day 1 after breakfast, Day 1 after the training session, and Day 6 after breakfast. In the morning at Day 1, 3, 5, 6, and 7, body weightwas measured, and blood samples were collected. Salivary samples were collected in the morning at Day 1, 5, 6, and 7, and 0 and 1 h afterexercise at Day 6 Table 1  Subject characteristics CHO PRO-CHOAge (years) 19± 2 20 ± 2Weight (kg) 71.8± 7.5 71.9± 4.2Height (m) 1.84± 0.06 1.82± 0.04Fat% 8.4 ± 2.3 10.0± 2.2VO2 max  (L O 2  /min) 5.2 ± 0.4 5.1 ± 0.3Fitness level (ml O 2  /min/kg) 72.5± 5.2 70.9± 4.1Watt max  (5-min Performance Test) 428 ± 32 426 ± 33 Values are mean±SD. Fat% measured by skinfold. VO 2max : maximal oxygenuptake. Watt max : Average Watt achieved in a 5-min Performance Test. Nosignificant differences were observed between groups (  p  > 0.05) in theshown parameters Hansen  et al. Journal of the International Society of Sports Nutrition  (2016) 13:9 Page 3 of 11  individual bottles were weighed before and after the 6 htraining session. On average the athletes were providedwith 4.33 L in total during the training session (0.72 L/h). One subject did not consume 0.35 L of the providedbeverages during the training session and two subjectsconsumed additional 0.50 and 0.75 L plain water.Weight data from these three subjects were adjusted inthe evaluation of the effect of 0.72 L/h on hydrationstatus (weight change). Training schedule and performance testing for thetraining camp The training regime was standardized and controlled by the National U23 coach in cycling. The subjects were di- vided in two groups depending on their training statusand history (long: 28.6 h/6 days and short 24.9 h/6 days).The cyclists in the matched pairs were within the sametraining groups and thereby an equal number of longand short distance subjects were represented in PRO-CHO and CHO respectively. The long distance groupbiked ~5, 5, 1, 6, 5, and 6 h during the 6 training days(plus standardized warm-up and tests) and the short dis-tance group biked 4, 4, 1, 4, 5, and 6 h (plus standardizedwarm-up and tests). The training program within both theshort and long distance group consisted of a mix of dis-tance training, interval training, mountain climbing, andan individual time trial. The total number of traininghours and training distance were identical in the twointervention groups since cyclists in the matched pairswere cycling together. Diet control To avoid any dietary bias, subjects followed a predeter-mined energy balanced diet plan throughout the week.Prior to the intervention week, each cyclist had an indi- vidual meeting with a dietitian where the importance of the diet control was emphasized. Furthermore, foodpreferences were noted and the subjects were asked if they were suffering from food allergies. Afterwards, anindividual diet plan was prepared based on the weight,training load, and preferences using the online softwaremadlogvita (http://www.madlogvita.dk). Total daily en-ergy expenditure (TEE) was estimated for each trainingday during the intervention and the diet plans variedbetween days, depending on training schedule. Totaldaily energy expenditure was estimated based on the fol-lowing equation: TEE (kJ/day)=RMR x PAL+EX, whereRMR is the estimated resting metabolic rate [28], PAL isestimated physical activity level in non-training hours,which was set at 1.5 corresponding to a sedentary life-style [28], and EX was the estimated energy used duringtraining sessions (number of training hours ×200 W ×3.6×(100/25)), assuming an exercise effectiveness of 25 % and an average power output of 200 W. The foodwas served as a buffet and the participants weighed allthe food items in accordance with their individual dietplan. A dietitian was available at the buffet each morningand evening. In addition, participants could always con-tact and meet with the dietitian if they had a questionabout their individual diet plans. The subjects were notallowed to consume dietary supplements, sports prod-ucts, or any food item apart from the items in their indi- vidual diet plans.The average distribution of macronutrients in the diet(excl. intervention beverages) was 8 g of carbohydrate/kg/day (~62 % of energy (E%)) and 1.7 g protein/kg/day.The 18 g protein in the recovery beverage ingested by both groups was included in the 1.7 g protein/kg/day,whereas the protein content in the intervention bever-ages ingested by PRO-CHO during cycling was inaddition to the controlled diet. Fat was supplemented tomeet each individual ’ s energy need (~22 – 24 E%). Thedaily intake of protein in CHO corresponded to proteinrecommendations for elite endurance athletes [29]. Theprotein intake in PRO-CHO, including the interventionbeverages, was 2.6 g/kg/day. Total daily carbohydrate in-take including beverages was 14.6 g/kg/day in CHO and13.6 g/kg/day in PRO-CHO. The energy content of thediet was adjusted (±125 kcal/day) to reestablish energy balance if morning weight had changed more than 1 kgbody weight and a bioimpedance measurement did notindicate that the weight change was due to change in hy-dration. Average energy intake was 24.4 MJ/day in long(29 h training) and 22.0 MJ/day in short (25 h training),including 8.4 MJ/day (long) and 7.2 MJ/day (short) fromintervention beverages. The food and nutrient compos-ition of the breakfast before the test protocol at D1 andD6 was the same to ensure standardization of thesubjects. Determination of VO 2max The subjects completed a VO 2max  test on a stationary bike ergometer (SRM) one or two weeks before thetraining camp. After a 15-min warm-up, subjects wereinstructed to work all-out for 5 min during which they were allowed to change load and cadence. VO 2  was con-tinuously measured through a mask connected to AMISsoftware (AMIS 2001, Innovision, Odense, Denmark).Every 30 s the average respiratory variables were regis-tered. Heart rate (HR) was continuously recorded usingPOLAR RS800 or RS800CX. Lactate was measured 1and 3 min after the test. To ensure that VO 2max  hadbeen obtained, two of the following four criteria had tobe met [30]: 1) VCO 2 /VO 2 >1.10, 2) HR was within ±5beats/min of maximal HR (HR max , based on earlier testresults), 3) Plateau in oxygen consumption, or 4) Accu-mulation of lactate (>8 mmol/L). Hansen  et al. Journal of the International Society of Sports Nutrition  (2016) 13:9 Page 4 of 11
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