El término influencer se define como la nueva versión del líder de opinión que convive en el entorno online y tiene la capacidad de influir en un determinado colectivo para modificar sus opiniones, beneficiándose del enorme potencial que tienen las redes sociales. Son muchos los estudios en redes sociales los que afirman que la mayoría de los usuarios siguen a los influencers para tomar decisiones de compra o inspirarse. Con objeto de identificar algunos antecedentes y consecuencias claves del liderazgo de opinión en el contexto de Instagram y comparar el nivel de engagement que alcanzan los influencers con respecto al tipo de publicaciones (generales o patrocinadas), se diseña una metodología de análisis de contenido comparado de indicadores cuantitativos y cualitativos. Por último, los resultados de este artículo indican que las publicaciones patrocinadas de los líderes de opinión provocan un nivel de engagement menor que el alcanzado por las publicaciones generales.

Riscart-López, J, Rendeiro-Pinho, G, Mil-Homens, P, Costa, RS-d, Loturco, I, Pareja-Blanco, F, and León-Prados, JA. Effects of Four different velocity-based training programming models on strength gains and physical performance. J Strength Cond Res 35(3): 596–603, 2021—The aim of this study was to compare the effects of 4 velocity-based training (VBT) programming models (linear programming [LP], undulating programming [UP], reverse programming [RP], and constant programming [CP]) on the physical performance of moderately strength-trained men. Forty-three young (age: 22.9 ± 4.8 years; body mass [BM]: 71.7 ± 7.6; full squat [SQ] relative strength 1.32 ± 0.29) subjects were randomly assigned to LP (gradually increase training intensity and decrease volume), UP (volume and intensity increase or decrease repeatedly), RP (gradually increases volume and decrease intensity), and CP (maintains constant volume and intensity) groups and followed an 8-week VBT intervention using the SQ exercise and monitoring movement velocity for every repetition. All groups trained with similar relative average intensity (67.5% 1 repetition maximum [1RM]), magnitude of velocity loss within the set (20%), number of sets (3), and interset recoveries (4 minutes) throughout the training program. Pre-training and post-training measurements included predicted SQ (1RM), average velocity attained for all loads common to pre-tests and post-tests (AV), average velocity for those loads that were moved faster (AV > 1) and slower (AV < 1) than 1 m·s⁻¹ at pre-tests, countermovement jump height (CMJ), and 20-m sprint time (T20). No significant group × time interactions were observed for any of the variables analyzed. All groups obtained similar increases (shown in effect size values) in 1RM strength (LP: 0.88; UP: 0.54; RP: 0.62; CP: 0.51), velocity-load-related variables (LP: 0.74–4.15; UP: 0.46–5.04; RP: 0.36–3.71; CP: 0.74–3.23), CMJ height (LP: 0.35; UP: 0.53; RP: 0.49; CP: 0.34), and sprint performance (LP: 0.34; UP: 0.35; RP: 0.32; CP: 0.30). These results suggest that different VBT programming models induced similar physical performance gains in moderately strength-trained subjects.

Introduction: Physical match actions are simulated through modified games. Pitch size and set configuration seems to influence the physical responses during small-sided games. Objective: The aim of the present study is to analyze the effects of pitch size and set configuration during small-sided games. Methodology: Fourteen young male field soccer players performed three small-sided games, involving 7 vs. 7 + 2 goalkeepers: 3 x 8 min with 5 min of rest between sets on a 68 x 40 m pitch (194 m2); same pitch area but 6 x 4 min with 2 min of rest (194 m2); and 6 x 4 min with 2 min of rest on a 40 x 34 m pitch (97 m2). Vertical jump, kick velocity and sprint were assessed to examine the residual fatigue before and after each small-sided game. Results: Larger pitch sizes showed significantly higher physical demands. Shorter bouts demanded greater distances at high intensity than longer bouts. A significant SSG x time interaction was observed for 10-m sprint time (P = 0.04), where a greater impairment was observed after completing 6 x 4 min (194 m2). Discussion: Higher external loads have been observed during games on larger pitches. A 4 min bout was provided as the optimal physical training stimulus. Conclusions: Larger pitch sizes and shorter bout durations are higher-demand games than smaller pitch sizes and longer bouts. Sprint performance is impaired after completing every small-sided game, especially acceleration capacity after completing modified games involving larger pitch areas and shorter bout durations.

Purpose: To examine the effects of 4 programming models (linear [LP], undulating [UP], reverse [RP], and constant [CP]) on physical performance. Methods: Forty-eight moderately strength-trained men were randomly assigned to LP, UP, RP, and CP groups according to their 1-repetition maximum (1RM) in the full-squat exercise (SQ) and followed an 8-week training intervention using the SQ and monitoring movement velocity for every repetition. All groups trained with similar mean relative intensity (65% 1RM), number of repetitions (240), sets (3), and interset recovery (4 min) throughout the training program. Pretraining and posttraining measurements included, in the SQ, 1RM load, the average velocity attained for all absolute loads common to pretests and posttests (AV), and the average velocity for loads that were moved faster (AV > 1) and slower (AV < 1) than 1 m·s⁻¹ at pretraining tests. Moreover, countermovement jump height and 20-m running sprint time were measured. Results: A significant time effect was found for all variables analyzed (P < .05), except for 20-m running sprint time. Significant group × time interactions were observed for 1RM, AV > 1, and AV (P < .05). After training, all groups attained significant strength gains on 1RM, AV, AV > 1, and AV < 1 (P < .001–.01). LP and RP groups improved their countermovement jump height (P < .01), but no significant changes were observed for UP and CP. No significant improvements were achieved in 20-m running sprint time for any groups. Conclusions: These different programming models are all suitable for improving physical performance. LP and RP induce similar or greater gains in physical performance than UP and CP.

Background: Great physical requirements are necessary to maintain the entire body in a streamlined and aerodynamic position during downhill skiing. Balance control has an important role in alpine skiing and depends on muscle endurance and strength. The central processing of proprioception and the force capacity of muscle are altered by fatigue. The objective of this study was to assess the effects of fatigue and visual input on balance control in alpine skiing. Methods: Eleven male professional skiers participated in the study. Balance control with eyes open and eyes closed was assessed before and after performing a maximal effort specific alpine ski test. Variables: the total travel distance (TTD) (mm), radial area (RA) (mm²), ratio between TTD and RA (TTD/RA) (1/mm), mean center of pressure (COP) velocity (total length of the COP path per unit time) (mm/s), the mean mediolateral (ML) COP oscillation velocity (Lat_Vel) (mm/s), the mean anteroposterior (AP) COP oscillation velocity (AP_Vel) (mm/s), mean ML (MLD) (mm) and mean AP (APD) (mm) displacements of the COP and the distance from the ordinate origin (mean X and mean Y) (theoretical point where the COP should be) to the point at which the COP is located, and heart rate were measured. Results: The results showed differences in the variables related to postural control and balance before and after the stress test (p = 0.002–0.037). However, no differences were found when the results obtained with open and closed eyes were compared. Conclusions: The results showed that performance in alpine skiing could be negatively affected by fatigue. However, the dynamic parameters are not decreased by visual input during muscle fatigue.

(1) Background: The range of loads is defined as the difference between the highest and the lowest relative load (i.e., %1RM) used throughout a resistance training program. However, the optimal range of loads has not been studied yet. Thus, the aim of this study was to compare the effects of different ranges of load (from 50 to 85% 1RM (R_50–85), from 55 to 75% 1RM (R_55–75), and from 60 to 70% 1RM (R_60–70) on physical performance using velocity-based resistance training (VBT). (2) Methods: Thirty-eight men (mean ± standard deviation; age: 23.3 ± 3.6 years, body mass: 76.5 ± 8.3 kg, and height: 1.77 ± 0.04 m) were randomly assigned to R_50–85, R_55–75 and R_60–70 groups and followed an 8-week VBT intervention using the full squat (SQ) exercise. All groups trained with similar mean relative intensity (65% 1RM) and total volume (240 repetitions). Pre- and post-training measurements included the following: in the SQ exercise, 1RM load, the average velocity attained for all absolute loads common to pre-tests and post-tests (AV), and the average velocity for those loads that were moved faster (AV > 1) and slower (AV < 1) than 1 m·s⁻¹ at Pre-training tests. Moreover, countermovement jump (CMJ) height and 10 m (T10), 20 m (T20), and 10–20 m (T10–20) running sprint times were measured. (3) Results: Significant group x time interactions were observed in AV (p ≤ 0.01), where R_50–85 obtained significantly greater gains than R_60–70 (p ≤ 0.05). All groups attained significant increases in 1RM, AV, AV > 1, AV < 1, and CMJ (p ≤ 0.001–0.005). Significant improvements were observed in running sprint for R_60–70 in T10–20 and R_60–70 in T20 and T10–20 (p ≤ 0.05), but not for R_50–85. (4) Conclusions: Different ranges of loads induce distinct strength adaptions. Greater ranges of loads resulted in greater strength gains in the entire load-velocity spectrum. However, in high-velocity actions, such as sprinting, significant enhancements were observed only for smaller ranges of loads. Coaches and strength and conditioning professionals could use a range of loads according to the time-related criterion (i.e., proximity or number of future competitions), enabling better adaptation and increasing physical performance at a specific time.