Research Outputs
Reliability and validity of different methods of estimating the one-repetition maximum during the free-weight prone bench pull exercise
This study examined the reliability and validity of three methods of estimating the one-repetition maximum (1RM) during the free-weight prone bench pull exercise. Twenty-six men (22 rowers and four weightlifters) performed an incremental loading test until reaching their 1RM, followed by a set of repetitions-to-failure. Eighteen participants were re-tested to conduct the reliability analysis. The 1RM was estimated through the lifts-to-failure equations proposed by Lombardi and O'Connor, general load-velocity (L-V) relationships proposed by Sánchez-Medina and Loturco and the individual L-V relationships modelled using four (multiple-point method) or only two loads (two-point method). The direct method provided the highest reliability (coefficient of variation [CV] = 2.45% and intraclass correlation coefficient [ICC] = 0.97), followed by the Lombardi's equation (CV = 3.44% and ICC = 0.94), and no meaningful differences were observed between the remaining methods (CV range = 4.95-6.89% and ICC range = 0.81-0.91). The lifts-to-failure equations overestimated the 1RM (3.43-4.08%), the general L-V relationship proposed by Sánchez-Medina underestimated the 1RM (-3.77%), and no significant differences were observed for the remaining prediction methods (-0.40-0.86%). The individual L-V relationship could be recommended as the most accurate method for predicting the 1RM during the free-weight prone bench pull exercise.
Características antropométricas y condición física funcional de adultos mayores chilenos insertos en la comunidad
Introducción: la antropometría y condición física funcional (CFF) son aspectos fundamentales para la conservación de la independencia funcional del adulto mayor (AM). Sin embargo, poco se ha investigado en AM chilenos. Objetivo: analizar características antropométricas y CFF de AM autovalentes. Métodos: participaron 116 sujetos del estudio. Se determinó la prevalencia de categorías de peso (índice de masa corporal [IMC]) y riesgo cardiometabólico (RCM) (perímetro de la cintura [PCIN], índice cintura-cadera [ICC] e índice cintura-talla [ICT]). Además, rendimiento físico "bajo la norma" y estándares de rendimiento (Batería Senior Fitness Test [SFT]). Se analizaron las diferencias antropométricas y de CFF en función del sexo y categorías etarias. Resultados: un 63,8% y 73,5% de hombres y mujeres respectivamente presentó exceso de peso. La mayor prevalencia de RCM se obtuvo mediante ICT y las pruebas con mayor prevalencia de bajo rendimiento fueron "Paso 2 minutos" (P2M) y "Juntar las manos detrás de la espalda" (JME). El estándar de rendimiento se alcanzó en un 29,7% y 17,3%, en hombres y mujeres respectivamente. Hombres presentaron mayor talla, ICC, fuerza y capacidad aeróbica. Mujeres presentaron mayor perímetro de cadera, IMC, ICT y flexibilidad. Estos resultados tienden a conservarse en los análisis de acuerdo a categorías etarias. Conclusiones: la muestra presentó una alta prevalencia de exceso de peso, RCM y bajo rendimiento físico, especialmente en mujeres. Debido a su bajo costo y complejidad, se plantea que la evaluación integral de parámetros antropométricos y de CFF debiese implementarse en programas de atención primaria orientados a la conservación de la funcionalidad del AM.
Assessment of the load-velocity profile in the free-weight prone bench pull exercise through different velocity variables and regression models
This aims of this study were (I) to determine the velocity variable and regression model which best fit the load-velocity relationship during the free-weight prone bench pull exercise, (II) to compare the reliability of the velocity attained at each percentage of the one-repetition maximum (1RM) between different velocity variables and regression models, and (III) to compare the within- and between-subject variability of the velocity attained at each %1RM. Eighteen men (14 rowers and four weightlifters) performed an incremental test during the free-weight prone bench pull exercise in two different sessions. General and individual load-velocity relationships were modelled through three velocity variables (mean velocity [MV], mean propulsive velocity [MPV] and peak velocity [PV]) and two regression models (linear and second-order polynomial). The main findings revealed that (I) the general (Pearson’s correlation coefficient [r] range = 0.964–0.973) and individual (median r = 0.986 for MV, 0.989 for MPV, and 0.984 for PV) load-velocity relationships were highly linear, (II) the reliability of the velocity attained at each %1RM did not meaningfully differ between the velocity variables (coefficient of variation [CV] range = 2.55–7.61% for MV, 2.84–7.72% for MPV and 3.50–6.03% for PV) neither between the regression models (CV range = 2.55–7.72% and 2.73–5.25% for the linear and polynomial regressions, respectively), and (III) the within-subject variability of the velocity attained at each %1RM was lower than the between-subject variability for the light-moderate loads. No meaningful differences between the within- and between-subject CVs were observed for the MV of the 1RM trial (6.02% vs. 6.60%; CV ratio = 1.10), while the within-subject CV was lower for PV (6.36% vs. 7.56%; CV ratio = 1.19). These results suggest that the individual load-MV relationship should be determined with a linear regression model to obtain the most accurate prescription of the relative load during the free-weight prone bench pull exercise.
Effect of muscle strength at different intensities on resting energy expenditure
Introduction: the regular practice of physical exercise is an important modulator of resting energy expenditure (REE), which depending on the intensity, duration, and type of exercise can increase the REE in an acute manner as well as long term. The effects of dynamic muscular strength exercises on the REE have been treated very little in literature. Objective: compare the effect of muscle strength exercise (MSE) at different intensities on the REE in young males. Methods: Intra-group design. Fourteen subjects aged 22,5±1,5 0,05) after the exercise at 40%RM. The REEpost 24h was maintained according to the REEpre when the intensity was 80%RM. Conclusion: The REEpost exercise is independent of the intensity of the exercise and only is maintained after 24 hours when the MSE is at a high intensity
The addition of very light loads into the routine testing of the bench press increases the reliability of the force–velocity relationship
Background: The aim of this study was to examine whether the addition of very light loads for modeling the force–velocity (F–V) relationship during the bench press (BP) exercise can confirm its experimental linearity as well as to increase the reliability and concurrent validity of the F–V relationship parameters (maximum force (F0), maximum velocity (V0), F–V slope, and maximum power (Pmax)). Method: The F–V relationship of 19 healthy men were determined using three different methods: (I) 6-loads free method: six loads performed during the traditional free-weight BP exercise (≈ 1–8–29–39–49–59 kg), (II) 4-loads free method: four loads performed during the traditional free-weight BP exercise (≈ 29–39–49–59 kg), and (III) 4-loads Smith method: four loads performed during the ballistic bench press throw exercise in a Smith machine (≈ 29–39–49–59 kg). Results: The linearity of the F–V relationship was very high and comparable for the three F–V methods (p = 0.204; median Pearson’s correlation coefficient (r) = 0.99). The three methods were ranked from the most to the least reliable as follows: 6-loads free (coefficient of variation (CV) range = 3.6–6.7%) > 4-loads Smith (CV range = 4.6–12.4%) > 4-loads free (CV range = 3.8–14.5%). The higher reliability of the 6-loads free method was especially pronounced for F–V slope (CVratio ≥ 1.85) and V0 (CVratio ≥ 1.49) parameters, while the lowest difference in reliability was observed for F0 (CVratio ≤ 1.27). The 6-loads free and 4-loads free methods showed a very high concurrent validity respect to the 4-loads Smith method for F0 and Pmax (r ≥ 0.89), a moderate validity for the F–V slope (r = 0.66–0.82), and a low validity for V0 (r ≤ 0.37). Discussion: The routine testing of the F–V relationship of upper-body muscles through the BP exercise should include trials with very light loading conditions to enhance the reliability of the F–V relationship.
Estudio comparado de la intensidad de entrenamiento sobre la máxima tasa de oxidación de grasas
Introducción: El ejercicio físico es un importante modulador de la máxima tasa de oxidación de grasas (MFO). Sin embargo, en la relación MFO-ejercicio, las zonas de transición metabólica en la prescripción del ejercicio no son consideradas. Objetivo: Conocer el efecto del entrenamiento en diferentes zonas de transición metabólica sobre la cinética de la MFO y su localización (Fatmax) en jóvenes varones activos. Método: 97 varones fueron distribuidos en 4 grupos homogéneos, 3 experimentales y un grupo control (GC). Cada grupo experimental participó en 8 semanas de entrenamiento administrado de forma continua a intensidad de umbral aeróbico o VT1 (CCVT1), interválica en umbral anaeróbico o VT2 (ITVT2), y en potencia aeróbica máxima o VO2max (ITVO2max). Antes y después del tratamiento los sujetos fueron testados en sendas pruebas con control de gases espirados para determinar el VO2max, VT1 y VT2, y la MFO (calorimetría indirecta) y Fatmax. Resultados: Los resultados muestran un incremento (entre 16,49 y 18,51%; p<0,01) en la MFO en los grupos experimentales. La Fatmax se redujo de media del 60,72±10,52 al 52,35±7,61 %VO2max (p<0,01) por efecto del entrenamiento. El grupo control no experimentó cambios de interés. El análisis intergrupo no presentó diferencias entre los grupos experimentales en ambas variables, sin embargo la comparación contra el GC, reflejó un mayor descenso de la Fatmax en CCVT1 (p<0,05). No se registraron cambios en el rendimiento, salvo un descenso del VO2max en el GC (p<0,05). Conclusión: 8 semanas de entrenamiento de diferente intensidad incrementan la MFO y reducen la Fatmax.