ORIGINAL ARTICLE

Correlation between the protein and carbohydrate supplement and anthropometric and strength variables in individuals submitted to a resistance training program

Correlación entre la suplementación de proteínas e hidratos de carbono con las variables antropométricas y de fuerza en individuos sometidos a un programa de entrenamiento con pesos

Patrícia Veiga de Oliveira^I; Luciana Baptista^II; Fernando Moreira^II; Antônio Herbert Lancha Junior^I

^ISchool of Physical Education and Sports of the São Paulo University – São Paulo/SP
^IINove de Julho Hospital – São Paulo/SP

Correspondence to

ABSTRACT

The majority of individuals following regular resistance exercise trainings have a major esthetic concern that may be summarized through the increase in the strength and muscular mass under the training associated to the supplement. The purpose of this paper was to verify if the intake of a high protein diet (4 g.kg^-1.d^-1) associated to the training causes a higher increase in the muscular mass and strength compared to the normo protein dietetic pattern.
METHODOLOGY: Sixteen volunteers were divided in two groups according to the supplement pattern: a total of 4 g.kg^-1.d^-1 protein (HP), and carbohydrate (NP) intake following the caloric quantity of the protein supplement (225 g.d^-1). Both groups were submitted to the resistance training protocol to the biceps and triceps muscles three times a week for 8 weeks. It was analyzed the strength, the muscular mass, the muscular cross section area, the cortisol and the insulin.
RESULTS: The HP group presented higher protein intake, and the NP group presented higher carbohydrate intake. Both groups also presented a difference in the cortisol values. The NP group presented a positive correlation between the higher carbohydrate intake (%) and the increase in the muscle area, and also between the strength to the overhead triceps, and the increase in the muscular mass and the higher carbohydrate intake.
CONCLUSION: It is suggested that the correlation between the carbohydrate intake and the increase in the muscular area and strength to the overhead triceps found in the NP group is related to the favorable metabolic situation to the protein synthesis.

Keywords: Protein supplement. Muscular mass. Muscular cross section area. Strength.

RESUMEN

La gran mayoría de los individuos que se adhieren a los programas regulares de ejercicios con pesos tienen gran preocupación estética que se resume al aumento de la fuerza y masa muscular con empleo del entrenamiento asociado a la suplementación. El objetivo de este trabajo era verificar la ingestión de una dieta hiperprotéica (4g.kg^-1.d^-1), unido al entrenamiento que provoca un aumento más grande de la masa muscular y fuerza cuando se lo compara al modelo normoprotéico dietético.
METODOLOGIA: Dieciséis voluntarios divididos en dos grupos según el suplementación: con proteína (HP), recibiendo 4g.kg^-1.d^-1, y con hidratos de carbono (NP), en la cantidad calórica de suplementación proteica (225g.d¹). Los dos grupos se sometieron al entrenamiento con pesos para los músculos bíceps y tríceps, 3 veces por semana durante 8 semanas. La fuerza, la masa muscular, el área de sección transverso muscular, se analizaron así como el cortisol y la insulina.
RESULTADOS: El grupo HP presentó el consumo de la proteína más grande y el grupo NP, de hidratos de carbono. Los grupos también presentaron diferencia en los valores del cortisol. El grupo NP presentó la correlación positiva entre el aumento más grande en la ingestión de hidratos de carbono (%) y el área de aumento M, y también entre la fuerza para el ejercicio del tríceps (TFR2) y el aumento de la masa muscular y la ingestión más grande de hidratos de carbono.
CONCLUSIÓN: Este estudio hace pensar en que la correlación entre la ingestión de hidratos de carbono y el aumento del área muscular y de la fuerza para el ejercicio tríceps por el grupo NP está relacionada con la situación metabólica favorable para la síntesis protéica.

Palabras-clave: Suplementación protéica. Masa muscular. Área de sección. Transverso muscular. Fuerza.

INTRODUCTION

The benefits of practicing regular exercises have been provedby many researchers⁽¹⁾. As to the specific case of theresistance training, scientific evidences confirm that anadequate training program induces several benefits, such as:improvement in the insulin response to the glycosis overload, inthe insulin sensitivity, and a lower chance to developcardiovascular diseases, among others⁽²⁾.Nevertheless, the majority of young adults following regularresistance exercise programs have esthetic concerns that can besummarized by an increase in the strength and muscular mass whichare not necessarily restricted to the benefic physiologicallimits to the health. For this, it is yearly launched in themarket several diets and protein supplements aiming to have asynergistic action on the muscular mass gain by means of theresistance training.

Justification

Taking into account the indiscriminate way that individualsuse to follow their diets and supplements through an undeterminedtime^(3,4) without any prove that such strategies willhave such synergistic action on the muscular mass and strengthincrease, this paper seeks to verify if the protein supplementassociated to the practice of the resistance activity is reallyeffective in increasing the muscular mass compared to individualsreceiving the same isocaloric supplement as carbohydrate.

Purpose

To verify if the effects of a hyperprotein diet (4g.kg^-1.d^-1) associated to a high intensityresistance exercise program causes a major increase in themuscular mass and strength compared to the normo-protein dieteticpattern in carbohydrate-supplemented individuals in the samecaloric amount than the group receiving protein.

METHODOLOGY

The project started with sixteen individuals and finished withtwelve individuals. All volunteers were students from the Schoolof Physical Education of the São Paulo Military Police ina semi-internship regimen, performing four meals at the school(breakfast, snack, lunch and snack) in order to allow an easyfood control. Every volunteer was also performing the samephysical activities pertinent to the school program.

The project was approved by the Ethics Committee from theInstitute of Biomedical Sciences, and every volunteer signed aFree Clarified Consent term.

Analysis of the diet

The nutritional assessment was performed with the fulfillmentof the 3-day food inquiring (2 working days and 1 weekend day)every 15 days along the whole interventional period (8 weeks).The Virtual Nutri software (version 2.5) was used to the foodintake calculation.

Supplement

All individuals were randomly divided in two groups: half ofthe group (n = 8) received a protein supplement (HP), and theother half received a carbohydrate supplement (NP). The amount ofthe supplemented protein was calculated from the protein intakeanalysis attained by means of the food records. Each individualreceived a protein supplement equivalent to 4g.kg^-1.d^-1 added to the proteins ingestedin the diet. The protein supplements used were milkvanilla-flavored serum protein (70%) and powdered slim milk(30%). The carbohydrate used was the maltodextrin. The amount ofcarbohydrate supplemented (225 g.d^-1) was calculatedby the caloric equivalence supplied by the protein supplement,and it was adjusted after four weeks.

The supplements were previously tested and homogenized withwater, in order to be flavored through the addition of quitesimilar aromatizing and sweetening agents, dyes, and powder milkin order to gain flavor, color and smell aiming to make difficultthe identification of the sampling to the volunteers. Every bagcontaining the supplements was identified through numbers (1 to16). All individuals were instructed to homogenize thesupplements with 1,000 ml water and to consume in four portionsalong the day (in the morning, in the lunch, in the afternoon andat night).

1-MR Test and prescription of the activity

Prior to the test, every individual performed a stretching andwarm up: 10 repetitions for every exercise (7 kg bar). All ofthem performed an average of four tries to attain the maximalload of every exercise (the load was estimated through the BorgScale⁽⁵⁾. The training consisted of four exercises:arm curl (AC), preacher curl (PC), overhead triceps (OT) andlying down triceps extention (LDTE) performed in five series witheight repetitions, three times a week (1 day interval betweentrainings). The intervals consisted in 3 minutes between series,and five minutes between exercises.

One week before the beginning of the intervention process,every individual was familiarized to every movement with a 80%load, when it was performed every necessary correction in themovements and posture. The intervention period had a eight weekendurance. Every volunteer had a record to the frequencycontrolling, and they were instructed to not be absent to none ofthe training sessions (in an amount of 24 sessions). Whenever itwould be necessary to be absent for more than one trainingsession, they would be excluded from the project. After fourweeks, every load was readjusted (1-MR test). All the trainingsessions were supervised.

Assessment of the body composition

Cutaneous folds and circumference: a Harpenden compass wasused to measure the cutaneous folds, as well as a tape measure tothe circumferences. The cutaneous folds assessed were: triceps,biceps, subscapular, suprailiac, supraspinal, abdomen, thigh, andleg. The measurement of the circumferences were performed using atape measure in the thorax, waist, hips, relaxed and contractedbiceps, forearm, thigh, and leg. The measurements were performedthree consecutive times each, and the value used was the averageof the three measures. Every measurement was performed using thesame device and it was made by the same researcher. The protocolused to calculate the density was the Durnin andWomwersley⁽⁶⁾, and to calculate the percentage of fat(pre-intervention = % fat1, and post-intervention = % fat 2) andthe muscular mass (pre-intervention = Mm1, and post-intervention= Mm2) it was used the Siri equation⁽⁷⁾. Everyvolunteer was weighted in an electronic scale, and the height wasmeasured in a board stadiometer.

Strength test (isokinetic)

Every volunteer performed a stretching and warm up of theupper limbs. The warm up was composed by three series of fifteenrepetitions with thera band, an elastic stripe fastened in afixed unit in which the participants performed their flexion andextension movements of the both arms' elbows. The strength testin the isokinetic stadiometer was performed in a CYBEX NORMdevice, having the athlete in supine position with his upper limbstabilized trying to reproduce the extension and flexionmovements of the elbow. Five repetitions (60%/sec.) wereperformed, adapted from Neu⁽⁶⁾. The torque peak (TP)was analyzed to the right and left flexor and extensormuscles.

Cortisol and insulin analysis

It was collected 10 ml of the anticubital vein blood from allindividuals after a 12 hours starvation period 8am. The blood wascentrifuged and frozen (–10ºC) to the later cortisoland insulin analysis. The serum cortisol and insulin wereanalyzed through the radio-immuno-assay technique (Coat-A-CountCortisol kit and insulin kit).

Computed tomography

The image acquisitions were accomplished in a SIEMENS – SOMATION PLUS 4 device, at the Center of Computerized Tomography of the Nove de Julho Hospital, and every analysis was accomplished using the software of the own device. The protocol used to the image acquisition was adapted from MacDougal⁽⁹⁾. Before entering into the room, individuals had their dominant arm marked at the higher circumference spot of the flexed biceps. Next, a tape measure was placed in the distance between the acromion and olecranon bones, and the reference spot was recorded in the tape measure where the pen mark was previously done. That procedure was followed in order to mark the exact cut spot where it would be attained the tomographic images in the two moments, pre- and post-intervention. The images were accomplished having the volunteers in supine position with their arms relaxed aside their bodies, having the palm of their hands up. It was attained two tomographic images through 10 mm with axial cuts at the preciously marked reference spot. The first image attained was used to adjust the field of sight of the biceps muscle, and it was despised and not analyzed. The second image attained was analyzed assisted by the mouse of the device, drawing the circumference of the arm muscles, and applying the value of the muscular density between 30 and 100 hounsfield units (HU) to calculate the area of the muscle in the 10 mm width predefined by Goodpaster et al. (1997). The values of the muscular area in the pre- and post-intervention (M1 and M2 areas, respectively) were compared.

The timetable of every test performed is presented on table 1.

Statistical analysis

A descriptive analysis was performed presenting the mean andthe standard deviations. In order to verify if the sampling had anormal distribution, the Kolmogorov-Smirnov test was performed.To verify if there was any difference between the assessedvariables between the HP and NP groups, the t-Student test forindependent samplings was used, and to check the differencewithin each group between the first and second measurements, thepaired t-Student test was used. To assess the correlation betweenvariables, it was used the R. Pearson linear correlationcoefficient. The significance level adopted was p < 0.05. Thesoftware used was the SPSS version 10.0.

RESULTS

The descriptive data of that population is found on tables 2, 3, and 4. The strength data are presented on table 5.

Figure 1 represents the cortisol variation comparing both groups.

The correlations are represented on table 6. The NP group presented a significant correlation between the increased carbohydrate intake % and the increase in the muscular area (M2 area), r = 0.9; p = 0.001, figure 2. There was no significant correlation to them in the HP group (r = 0.13; p = 0.8). Related to the strength, the NP group presented a positive correlation between the increase in the strength to the overhead triceps (OT) and the increase in the muscular mass (Mm2), r = 0.8; p = 0.01. The HP group did not present a significant correlation between the same variables (r = 0.01; p = 0.8).

The NP group also presented a positive correlation between theincrease in the carbohydrate intake (C2%) and the increase in thestrength to the overhead triceps (OT) exercise, r = 0.85; p =0.04, it was observed no significant correlation between bothvariables in the HP group (r = 0.4; p = 0.3).

There was a positive correlation between the increase in themuscular mass (Mm2) and the increase in the M2 area (r = 0.9; p =0.02) in the NP group; the HP group did not present a significantcorrelation between both variables (0.73; p = 0.09).

DISCUSSION

It was verified that the HP group presented a 32.1% intake (4g.kg^-1.d^-1) of protein, and 37.4%carbohydrate, and the NP group had a 14% intake of protein (1.8g.kg^-1.d^-1), and 63% carbohydrate.According to Lemon⁽¹⁰⁾, 0.89g.kg^-1.d^-1 of protein are required to keepa positive nitrogenous balance in sedentary individuals, but forendurance athletes and individuals practicing resistanceexercises, such positive balance occurs with a 1.2-1.5g.kg^-1.d^-1 intake, respectively.

Results attained in the paired t-test show that the supplementand the physical activity were effective within each group inpromoting the increase in the mass, in the muscular cross sectionarea and the strength increase after the eight week period.

Tarnopolsky⁽¹¹⁾ verified that whenever the proteinintake in the diet increases from 0.86 to 1.4g.kg^-1.d^-1, the protein synthesis increasesin men submitted to the resistance training, but when the intakeis higher than 2.4 g.kg^-1.d^-1, nosignificant difference was found. Nevertheless, the authors didnot use the carbohydrate supplement in order to allow somecomparison. It was found no significant differences as to theanthropometric data to the strength variables and to the insulinanalysis.

It is important to point out that the collection was performedafter a 12 hour of starvation period, and so, it did notrepresent the acute effect which is provoked right after atraining session same as it is done by other authors.

In this paper, it was verified significant differences in thecortisol concentrations, the NP group presented a –18.1%decrease, and the HP group a 33.6% increase.Thyfault⁽¹²⁾ verified the acute effect with liquidcarbohydrate supplement (1 g.kg^-1.d^-1)before and after the activity) or the placebo supplementassociated to the resistance exercise (2-day training). It wasanalyzed the cortisol, insulin, ammonia, and glycosisconcentrations, and it was verified an increase in the insulinconcentrations after the exercise and one and a half hour afterthe activity ended. There was no significant difference to otherhormones upon the comparison ob both groups.

According to the correlation analysis, it is believed that thestrength increase to the seated triceps extension is directlyassociated to the increase in the muscular mass and thecarbohydrate intake in the HP group. By means of the analysis, itwas shown that the NP group presented a higher increase in themuscular cross section area compared to the HP group.

Rozenek⁽¹³⁾ submitted two groups to the resistancetraining (four series of eight repetitions at 70% 1-MR, 10exercises for eight weeks) and supplement. A group received 356 gof glycosis and 1.7 g.kg^-1.d^-1 of protein(placebo group) in an amount equivalent to a surplus of 2,020kcal per day. There was no significant difference between bothgroups. The authors raised the hypothesis that there must be anoptimization limit of the consumed protein, and when such limitis surpassed, probably there are no benefits as to the strengthand muscular mass gain.

Despite it was not performed certain dosages which couldverify the accuracy of this fact, it is believed that the highprotein concentration (4 g.kg^-1.d^-1) shouldprovoke an unbalance in the Krebs cycle to the energeticproduction due to the lack of the carbohydrate substrate, thusincreasing the ketonic bodies concentrations, an increase in thecortisol concentrations compromising the protein synthesis. Onthe other hand, it was verified a decrease in the cortisolconcentrations in the NP group followed by a positive correlationbetween the carbohydrate intake and the increase in the muscularcross section area, suggesting that the carbohydrate supplement(225 g.d^-1) associated to the 1.8g.kg^-1.d^-1 protein intake and to theresistance training is favorable to the increase in the proteinsynthesis. It is believed that the positive correlation betweenthe anthropometric variables and only the carbohydrate intake isa consequence of the increase in the insulin concentrations afterthe consumption, resulting in a decrease in the chronic cortisolconcentrations, promoting a better environment for anabolism.

CONCLUSION

The NP group presented a positive correlation between thecarbohydrate intake and the increase in the muscular mass andstrength to the seated triceps extension. According to theresults presented in this study, carbohydrate supplementedindividuals (225 g.d^-1) associated to the proteinintake of 1.8 g.kg^-1.d^-1 when submitted tothe resistance training presented a higher increase in themuscular mass compared to individuals submitted to the samesupplemented training with 4 g.kg^-1.d^-1. Itwill be required further studies in order to clarify the role ofthe protein and the carbohydrate in the promotion of the proteinsynthesis in resistance exercise practitioners. It is not knownfor sure the mechanism involving the high protein supplement inthe muscular and strength gain process.

All the authors declared there is not any potentialconflict of interests regarding this article.

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04531-000 – São Paulo, SP – Brazil
E-mail: pativeoli@hotmail.com

Received in 18/2/05.
Final version received in 25/9/05.
Approved in 27/9/05.