Custo energético em musculação: estudo da precisão da sua estimativa pela relação consumo de oxigénio / intensidade nos exercícios de extensão de pernas (leg extension), supino inclinado (inclined bench press), extensão de pernas na prensa (leg press) e flexão de antebraços (scott biceps curl)
Ficheiros
Data
2014-09-10
Título da revista
ISSN da revista
Título do Volume
Editora
Resumo
O presente estudo analisou uma metodologia de cálculo do custo energético (CE) em 4 exercícios de musculação. Foi desenhado para dar resposta às seguintes questões: i) qual o CE estimado pela relação consumo de oxigénio (VO2)/carga externa nos exercícios extensão de pernas (leg extension), supino inclinado (inclined bench press), extensão de pernas na prensa (leg press) e flexão de antebraços (scott biceps curl)? ii) qual a contri-buição aeróbia e anaeróbia para o esforço a 80% 1-RM nos 4 exercícios? iii) qual a pre-cisão de estimativa do CE e do défice de oxigénio acumulado (DOA) nos 4 exercícios? iv) existe relação entre a percepção subjectiva do esforço (PSE) e o CE nos 4 exercí-cios? v) a máxima lactatemia pós-esforço a 80% 1-RM reflete o DOA nos 4 exercícios? A amostra foi constituída por 31 indivíduos voluntários, do sexo masculino, com idades entre os 25 e os 35 anos, praticantes de musculação. Os sujeitos da amostra foram sub-metidos a testes de 1-RM para os 4 exercícios em estudo. Para cada exercício foram realizadas duas sessões com cargas de 12% a 30% de 1-RM com duração de 3 a 5 minu-tos e uma sessão com carga a 80% de 1-RM, com medição de lactato após esforço. Para além da medição do consumo de oxigénio, foi utilizada uma escala de percepção subjec-tiva de esforço (OMNI-RES) em todos os esforços. De acordo com os objectivos traça-dos, seguem as principais conclusões a que chegamos. O custo energético a baixas intensidades (até 30% 1-RM) variou entre 5 a 9 kcal/min nos exercícios de extensão de pernas, supino inclinado e extensão de pernas na prensa; no exercício de flexão de ante-braços foi menor (3 a 4 kcal/min). À carga de 80% 1-RM o CE atingiu 17 a 26 kcal/min e foi igualmente menor na flexão de antebraços (9 kcal/min). O erro relativo das regres-sões entre VO2/carga variou entre ≈ 7 e 20%, encontrando-se próximos dos referidos na literatura (Robergs et al., 2007 e Vianna, 2010), na sua maioria acima dos 10%. Como o erro foi maior quando se usou a potência mecânica como preditor do VO2, é preferível o uso da carga ou do trabalho mecânico para estudar exercícios de musculação. O erro da extrapolação linear do CE para a carga de 80% 1-RM variou entre ≈ 8 e 20%, valor que pode ser considerado desde aceitável (limite inferior) até dificilmente aceitável (limite superior). Em esforço de alta intensidade (80% 1-RM) a energia anaeróbia foi predomi-nante (entre 70 e 80% da energia total) com excepção do exercício de flexão de antebra-ços, em que predominou a energia aeróbia. O défice de oxigénio a 80% 1-RM variou entre 31 e 55 ml/kg/min nos exercícios extensão de pernas, supino inclinado e extensão de pernas na prensa, com um menor valor no exercício de flexão de antebraços com valor próximo de 10 ml/kg/min. O erro no défice de oxigénio acumulado foi elevado (acima de 20%) nos exercícios de extensão de pernas, supino inclinado e flexão de antebraços, sendo menor e aceitável no exercício de extensão de pernas na prensa (≈8,5%). O CE pode ser predito pela PSE à 5ª repetição em esforços exaustivos com baixa intensidade (até 30%) nos quatro exercícios aqui estudados, com erros de ≈ 6 a 8%. O somatório do equivalente energético do lactato no sangue com a energia aláctica assumida, não reflete o DOA.
The present study analyzed a method for the calculation of the energy cost (EC) in 4 resistance exercises. It was designed to address the following questions: i) what is the EC estimated by the oxygen uptake (VO2)/load relationship in the exercises of leg ex-tension, inclined bench press, leg press and scott biceps curl? ii) how much are the aer-obic and anaerobic contributions to the total energy release at 80% 1-RM in the 4 exer-cises? iii) how much is the precision of EC estimated by the accumulated oxygen deficit (AOD) in the 4 exercises? iv) is there a relationship between the rate of perceived exer-tion (RPE) and the EC in the 4 exercises? v) does the post-exercise peak blood lactate reflects the AOD in the 4 exercises? The sample included 31 male volunteers between 25 and 35 years of age and with previous experience in resistance training. All subjects underwent 1-RM testing in the 4 exercises. For each exercise the subjects performed 2 sessions including exhaustive sets with loads comprised between 12% and 30% and with a duration comprised 3 and 5 min and one session with one exhaustive set at 80% 1-RM, the latter with post-exercise blood lactate measurements. During every effort oxygen uptake was measured as well as the RPE with the OMNI-RES scale. The main conclusions of the study are as follows. The EC at low intensities (up to 30% 1-RM) varied between 5 and 9 kcal/min in the leg extension, inclined bench press and leg press, being lower in the biceps curl (3 to 4 kcal/min). At the 80% 1-RM load the EC attained 17 to 26 kcal/min and was also smaller in the biceps curl (9 kcal/min). The standard error of the regression ranged from ≈ 7 to 20%, lying close to those reported in the literature (Robergs et al., 2007 and Vianna, 2010), mostly above 10%. Since the error was larger when the mechanical power was included in the regression as inde-pendent variable, it is preferable to use the load or the mechanical work as predictors of VO2 when studying resistance exercises. The error of the linear extrapolation of the EC to the 80% 1-RM load ranged from ≈ 8 to 20%, values that may be considered accepta-ble (lower limit) or hardly acceptable (upper limit). At this high-intensity effort, anaero-bic energy release was predominant (70-80% of total energy release) with an exception of the biceps curl, where aerobic energy prevailed. The AOD at 80% 1-RM ranged from 31 to 55 ml/kg/min in the leg extension, inclined bench press and leg press, being lower in the biceps curl (near 10 ml/kg/min). The AOD imprecision was high (above 20%) in the leg extension, inclined bench press and in the biceps curl and it was smaller and acceptable in the leg press (≈ 8,5%). The EC at low intensity (up to 30%) can be pre-dicted by the RPE at the 5th repetition in the 4 exercises with errors of ≈ 6-8%. The sum of the blood lactate energy equivalent and the alactic energy assumptions did not match the AOD measurements in the current study.
The present study analyzed a method for the calculation of the energy cost (EC) in 4 resistance exercises. It was designed to address the following questions: i) what is the EC estimated by the oxygen uptake (VO2)/load relationship in the exercises of leg ex-tension, inclined bench press, leg press and scott biceps curl? ii) how much are the aer-obic and anaerobic contributions to the total energy release at 80% 1-RM in the 4 exer-cises? iii) how much is the precision of EC estimated by the accumulated oxygen deficit (AOD) in the 4 exercises? iv) is there a relationship between the rate of perceived exer-tion (RPE) and the EC in the 4 exercises? v) does the post-exercise peak blood lactate reflects the AOD in the 4 exercises? The sample included 31 male volunteers between 25 and 35 years of age and with previous experience in resistance training. All subjects underwent 1-RM testing in the 4 exercises. For each exercise the subjects performed 2 sessions including exhaustive sets with loads comprised between 12% and 30% and with a duration comprised 3 and 5 min and one session with one exhaustive set at 80% 1-RM, the latter with post-exercise blood lactate measurements. During every effort oxygen uptake was measured as well as the RPE with the OMNI-RES scale. The main conclusions of the study are as follows. The EC at low intensities (up to 30% 1-RM) varied between 5 and 9 kcal/min in the leg extension, inclined bench press and leg press, being lower in the biceps curl (3 to 4 kcal/min). At the 80% 1-RM load the EC attained 17 to 26 kcal/min and was also smaller in the biceps curl (9 kcal/min). The standard error of the regression ranged from ≈ 7 to 20%, lying close to those reported in the literature (Robergs et al., 2007 and Vianna, 2010), mostly above 10%. Since the error was larger when the mechanical power was included in the regression as inde-pendent variable, it is preferable to use the load or the mechanical work as predictors of VO2 when studying resistance exercises. The error of the linear extrapolation of the EC to the 80% 1-RM load ranged from ≈ 8 to 20%, values that may be considered accepta-ble (lower limit) or hardly acceptable (upper limit). At this high-intensity effort, anaero-bic energy release was predominant (70-80% of total energy release) with an exception of the biceps curl, where aerobic energy prevailed. The AOD at 80% 1-RM ranged from 31 to 55 ml/kg/min in the leg extension, inclined bench press and leg press, being lower in the biceps curl (near 10 ml/kg/min). The AOD imprecision was high (above 20%) in the leg extension, inclined bench press and in the biceps curl and it was smaller and acceptable in the leg press (≈ 8,5%). The EC at low intensity (up to 30%) can be pre-dicted by the RPE at the 5th repetition in the 4 exercises with errors of ≈ 6-8%. The sum of the blood lactate energy equivalent and the alactic energy assumptions did not match the AOD measurements in the current study.
Descrição
Tese de Doutoramento em Ciências do Desporto
Palavras-chave
Consumo de oxigénio , Custo energético , Erro padrão de regressão , Défice de oxigénio acumulado , Perceção subjetiva do esforço