Dr. Ulloa-Diaz, David

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.

The regular practice of physical activity contributes to weight control and improves maximal oxygen uptake (VO2max), socialization and quality of life. Aim: To determine the effect of moderate-to-vigorous physical activity on body composition and VO2max in a group of overweight school-age males. Material and Methods: We studied fifty-five overweight males aged 15.6 ± 0.7 years. Participants were divided in two groups (experimental and control groups). The intervention in the experimental group was the practice of small-sided games during 60 minutes, two days per week and during 11 weeks. At baseline and the end of the intervention, body composition was measured using bioimpedance and VO2max was calculated using the Course Navette test. Results: A 7% reduction in the percentage of body fat and a 9% increase in VO2max were observed in the experimental group (p < 0.01). No changes were recorded in the control group. Conclusions: Eleven weeks of small-sided exercises performed twice per week increased VO2max and reduced fat mass in overweight adolescents.

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.

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.

Aim. To determine the absolute and relative reliability of functional trunk tests, using a functional electromechanical dynamometer to evaluate the isokinetic strength of trunk flexors and to determine the most reliable assessment condition, in order to compare the absolute and relative reliability of mean force and peak force of trunk flexors and to determine which isokinetic condition of evaluation is best related to the maximum isometric. Methods. Test-retest of thirty-seven physically active male student volunteers who performed the different protocols, isometric contraction and the combination of three velocities (V1 = 015 m s−1, V2 = 0.30 m s−1, V3 = 0.45 m s−1) and two range of movement (R1 = 25% cm ; R2 = 50% cm) protocols. Results. All protocols to evaluate trunk flexors showed an absolute reliability provided a stable repeatability for isometric and dynamic protocols with a coefficient of variation (CV) being below 10% and a high or very high relative reliability (0.69 < intraclass correlation coefficient [ICC] > 0.86). The more reliable strength manifestation (CV = 6.82%) to evaluate the concentric contraction of trunk flexors was mean force, with 0.15 m s−1 and short range of movement (V1R1) condition. The most reliable strength manifestation to evaluate the eccentric contraction of trunk flexors was peak force, with 0.15 m s−1 and a large range of movement (V1R2; CV = 5.07%), and the most reliable way to evaluate isometric trunk flexors was by peak force (CV = 7.72%). The mean force of eccentric trunk flexor strength with 0.45 m s−1 and short range of movement (V3R1) condition (r = 0.73) was best related to the maximum isometric contraction. Conclusion. Functional electromechanical dynamometry is a reliable evaluation system for assessment of trunk flexor strength.

Background: There is no conclusive evidence about the association between physical fitness (PF) and health related quality of life (HRQOL) in older adults. Aim: To seek for an association between PF and HRQOL in non-disabled community-dwelling Chilean older adults. Material and Methods: One hundred and sixteen subjects participated in the study. PF was assessed using the Senior Fitness Test (SFT) and hand grip strength (HGS). HRQOL was assessed using eight dimensions provided by the SF-12v2 questionnaire. Binary multivariate logistic regression models were carried out considering the potential influence of confounder variables. Results: Non-adjusted models, indicated that subjects with better performance in arm curl test (ACT) were more likely to score higher on vitality dimension (OR > 1) and those with higher HGS were more likely to score higher on physical functioning, bodily pain, vitality and mental health (OR > 1). The adjusted models consistently showed that ACT and HGS predicted a favorable perception of vitality and mental health dimensions respectively (OR > 1). Conclusions: HGS and ACT have a predictive value for certain dimensions of HRQOL.

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