Person:
Núñez Sánchez, Francisco Javier

Profesor/a Titular de Universidad
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First Name
Francisco Javier
Last Name
Núñez Sánchez
Affiliation
Universidad Pablo de Olavide
Department
Deporte e Informática
Research Center
Area
Educación Física y Deportiva
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PAIDI Areas
PhD programs
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Now showing 1 - 6 of 6
  • Publication
    Eccentric-concentric Ratio: A Key Factor for Defining Strength Training in Soccer
    (Thieme Publishing, 2019-08-21) Núñez Sánchez, Francisco Javier; De Hoyo, Moisés; Muñoz López, Alejandro; Sañudo, Borja; Otero Esquina, Carlos; Sánchez, Hugo; Gonzalo Skok, Oliver
    The aims of this study were to analyse the effect of chronic strength training over concentric power (CON), eccentric power (ECC), ECC/CON ratio, and 20¿m linear sprint performance in elite young soccer players. Twenty young elite Spanish soccer players were assigned to an experimental group (CPG) which performed a front-step exercise using a conical pulley, 2¿3 sets of 6 repetitions each leg, during 9 weeks (CPG, n=10) in addition to its usual strength training, or to a control group (CG, n=10). The improvements in the ECC mean power (36%, ES=1.61), and ECC / CON ratio (17%, ES=1.77) were substantially greater in the CPG than in the CG while the CON mean power (16%, ES=0.83) was substantially greater in the CG than in the CPG. The sprinting time for 10¿m (2.8%, ES=0.78) and the 10¿m flying time between 10¿20¿m (1.72%, ES=0.41) were substantially enhanced in CPG and CG respectively. To be efficient when defining a functional strength training and performance increments using an inertial device, the mean power output need to be measured during the CON and ECC phases and an analysis of the ECC / CON ratio should be included.
  • Publication
    Relationships between Change of Direction, Sprint, Jump, and Squat Power Performance
    (MDPI, 2020-03-19) Suárez Moreno-Arrones, Luis Jesús; Gonzalo Skok, Oliver; Carrasquilla, Irene; Asian Clemente, José Antonio; Santalla Hernández, Alfredo; Lara López, Pilar; Núñez Sánchez, Francisco Javier
    The aim of the study was to investigate the relationships between countermovement jump (CMJ) height and inertial power in squat and sprint variables with change of direction (COD) performance. Fifty young healthy active males participated in the study. To determine these relationships, we carried out a 10-m linear sprint test (T 10 m), vertical jump tests (CMJ and CMJ Abalakov), an assessment of power relative to bodyweight in a flywheel squat (Pbw), and 10-m COD sprints with two different turn types (COD-90° and COD-180°). T10 m showed statistically large and moderate correlations with T10 m COD-180° (r = 0.55) and T10-m COD-90° (r = 0.41), respectively. Moderate to large correlations between jumping height, linear sprinting, and sprints with COD were found (r = -0.43 to r = -0.59), and there were unclear correlations between jumping height and the loss of speed caused by executing COD (DEC-COD). Pbw showed a large correlation with CMJ Abalakov and CMJ jump height (r = 0.65 and r = 0.57, respectively), and a moderate and large correlation with T 10 m, T 10 m COD-180°, and T10 m COD-90° (r = -0.33, r = -0.38, and r = -0.54, respectively). Despite the existence of substantial correlations between variables, straight linear sprinting, jumping performance, CODs and squat power were, for the most part, separate motor qualities (R2 from 14% to 34%), suggesting that all of them should be specifically assessed and trained.
  • Publication
    Validity of Field Methods to Estimate Fat-Free Mass Changes Throughout the Season in Elite Youth Soccer Players
    (Frontiers Media, 2020-02-12) Núñez Sánchez, Francisco Javier; Munguía Izquierdo, Diego; Suárez Moreno-Arrones, Luis Jesús
    The aim of this study was to determine the most effective anthropometric equations or bioelectrical impedance analysis (BIA) devices for quantifying the sensitivity to change in fat-free mass (FFM) in elite young soccer players, in comparison with measurements using dual-energy X-ray absorptiometry (DXA), between the pre- and mid-season. A total of 40 elite youth soccer players participated in this study. DXA values provided a criterion measure of FFM. Correlation coefficients, biases, limits of agreement, and differences were used as measures of sensitivity to change. All body density, skinfold, and anthropometric equations and BIA devices used to obtain FFM data showed positive and very large correlations (r from 0.70 to 0.89) with DXA. A significant increase in FFM was shown between time points using DXA, BIA, and all anthropometric equations (p < 0.01). The magnitudes of differences were small for DXA, BIA inbody and all anthropometric equations except those of Faulkner (1966), Durnin and Rahaman (1967), Brook (1971), and Sarría et al. (1998). Six anthropometric equations [Faulkner (1966), Durnin and Womersley (1974), Carter (1982), Slaughter et al. (1988), Reilly et al. (2009), and Munguia-Izquierdo et al. (2018)] and BIA Tanita showed no statistical differences compared to DXA, with a low bias. We concluded that the equations developed by Durnin and Womersley (1974), Carter (1982), Slaughter et al. (1988), Reilly et al. (2009), and Munguia-Izquierdo et al. (2018) showed the best sensitivity in assessing FFM changes between pre- and mid-season in elite youth soccer players.
  • Publication
    Lack of experience in the use the rotational inertia device is a limitation to mechanical squat performance
    (2021) Galiano, Carlos; Floria Martín, Pablo; Muñoz López, Alejandro; Núñez Sánchez, Francisco Javier
    It has been showed that previous experience in the use of rotational inertia devices (RIDs) enhances acute performance outcomes. The purpose of this study was to examine the differences in kinetic and kinematic profiles between athletes with and without experience in the use of different RIDs. Thirty-nine healthy men performed a half-squat incremental test on two different RIDs: a horizontal cylinder (YY) and a vertical cone-shaped axis (CP). The participants were grouped based on experience in the use of rotational inertia devices. Time, peak velocity, peak force, time to reach peak force, average force, impulse, and range of movement were analyzed to determine the differences between groups. Several biomechanical parameters differed between experts and non-experts using the same device with the same moments of inertia. Range of movement was higher in expert than in non-expert subjects only in YY devices. Experts achieved higher values using CP and YY devices in squat exercises than non-experts, except for eccentric peak force for YY. Previous experience in the use of RIDs will influence the results obtained in squat exercises.
  • Publication
    Field Methods to Estimate Fat-free Mass in International Soccer Players
    (Thieme Publishing, 2019-07-31) Núñez Sánchez, Francisco Javier; Munguía Izquierdo, Diego; Petri, Cristian; Suárez Moreno-Arrones, Luis Jesús
    Based on the high financial and logistical costs associated with the assessment of body composition with dual-energy X-ray absorptiometry (DXA), this study determined which field method has the best correlation with DXA data, and developed an equation to estimate fat-free mass (FFM) using the field anthropometric data in international soccer players. A total of 17 international soccer players participated in this study. DXA values provided a criterion measure of FFM. Correlation coefficients, biases, limits of agreement, and differences were used as validity measures, and regression analyses were used to develop the prediction equation. All field methods used to obtain FFM data showed positive correlations (r from 0.90¿0.96) with DXA. Only the equation developed by Deurenberg et al. [6] showed no differences from DXA with a low bias. The main strength of this study was providing a valid and accurate equation to estimate FFM specifically in international soccer players.
  • Publication
    Using Tensiomyography to Assess Changes in Knee Muscle Contraction Properties After Concentric and Eccentric Fatiguing Muscle Actions
    (Lippincott, Williams & Wilkins, 2020-03-11) Muñoz López, Alejandro; De Hoyo, Moisés; Núñez Sánchez, Francisco Javier; Sañudo, Borja
    Muñoz-López, A, De Hoyo, M, Nuñez, FJ, and Sañudo, B. Using tensiomyography to assess changes in knee muscle contraction properties after concentric and eccentric fatiguing muscle actions. J Strength Cond Res XX(X): 000¿000, 2020¿The purposes of this study were to analyze the effects of different types of muscle contraction (concentric and eccentric) on the passive muscular contraction properties of knee muscles and how muscle contraction can affect the muscles in different knee functions. In total, 23 active healthy men (age: 24.65 ± 1.95 years, height: 1.78 ± 0.05 m, mass: 75.33 ± 8.37 kg) participated in this study. Muscle soreness, muscle contractile properties assessed with tensiomyography (TMG) (vastus lateralis [VL] and biceps femoris [BF]), and isometric peak torque were tested before and immediately after 32 maximal repetitions of an isokinetic leg extension and flexion exercise at 180° per second. Muscle contractions were randomized to each subject's leg. From the TMG variables, only contraction velocity showed significant interactions in time × muscle × contraction (p = 0.046; partial ¿p2 = 0.19). A greater reduction was observed in the BF (¿29.03%) than in the VL (¿21.25%). There was a significant decrease in contraction velocity after concentric p < 0.001, d = 1.18) and eccentric (p = 0.007, d = 0.51) exercise for the BF, while for VL, a decrease was only observed after concentric exercise (p = 0.007, d = 0.66). The leg extension exercise showed reductions in the isokinetic peak torque (p < 0.001; partial ¿p2 = 0.83). Isometric peak torque (p < 0.001; partial ¿p2 = 0.80) and muscle soreness (p < 0.001; partial ¿p2 = 0.70) decreased after exercise. In conclusion, muscle mechanical properties were differently affected in relation to the muscle contraction and knee muscles involved, after a fatiguing leg extension isokinetic exercise. Isometric peak torque and muscle soreness were also reduced immediately after exercise. These results are particularly important to understand how TMG parameters are modified depending on the type of contraction.