Cristian Martínez

Metabolic endotoxemia and saturated fat contribute to circulating NGAL concentrations in subjects with insulin resistance

Objective:Lipocalin-2 (neutrophil gelatinase-associated lipocalin, NGAL) is an innate immune system protein that has been linked to insulin resistance and obesity, but the mechanisms behind these associations are poorly known. We hypothesized that endotoxin (lipopolysaccharide, LPS) and fat intake were in the background of these associations.Design:We studied four cohorts: (1) a cross-sectional study in 194 subjects; (2) the changes in NGAL concentration induced by diet and weight loss in 36 obese women (with circadian rhythm in 8 of them); (3) the effects of acute fat intake on circulating NGAL concentration in 42 morbidly obese subjects; and (4) LPS-induced NGAL secretion ex vivo (whole blood and adipose tissue explants).Results:Serum NGAL concentration was significantly associated with fasting triglycerides and LPS-binding protein in patients with type 2 diabetes. In obese subjects, the intake of saturated fatty acids was the factor that best explained the variance of NGAL changes after weight loss (contributing independently to 14% of NGAL variance). In fact, weight loss significantly changed the circadian rhythm of NGAL. The acute increase in circulating NGAL after fat overload was significantly associated with fasting insulin (r=0.52, P<0.001), homeostasis model assessment of insulin resistance (HOMA-IR) (r=0.36, P=0.02) and post-load triglyceride concentrations (r=0.38, P=0.018). LPS-induced NGAL secretion from adipose tissue explants did not change significantly, but LPS led to a significant increase in NGAL concentration in the whole blood obtained from patients with type 2 diabetes.Conclusion:Metabolic endotoxemia and saturated fat might contribute to circulating NGAL concentration in patients with insulin resistance.

Effects of in-season low-volume high-intensity plyometric training on explosive actions and endurance of young soccer players.

Abstract Ramírez-Campillo, R, Meylan, C, Álvarez, C, Henríquez-Olguín, C, Martínez, C, Cañas-Jamett, R, Andrade, DC, and Izquierdo, M. Effects of in-season low-volume high-intensity plyometric training on explosive actions and endurance of young soccer players. J Strength Cond Res 28(5): 1335–1342, 2014—Integrating specific training methods to improve explosive actions and endurance in youth soccer is an essential part of players development. This study investigated the efficiency of short-term vertical plyometric training program within soccer practice to improve both explosive actions and endurance in young soccer players. Seventy-six players were recruited and assigned either to a training group (TG; n = 38; 13.2 ± 1.8 years) or a control group (CG; n = 38; 13.2 ± 1.8 years) group. All players trained twice per week, but the TG followed a 7-week plyometric program implemented within soccer practice, whereas the CG followed regular practice. Twenty-meter sprint time (20-m), Illinois agility test time, countermovement jump (CMJ) height, 20- (RSI20) and 40- (RSI40) cm drop jump reactive strength index, multiple 5 bounds distance (MB5), maximal kicking test for distance (MKD), and 2.4-km time trial were measured before and after the 7-week period. Plyometric training induced significant (p ⩽ 0.05) and small to moderate standardized effect (SE) improvement in the CMJ (4.3%; SE = 0.20), RSI20 (22%; SE = 0.57), RSI40 (16%; SE = 0.37), MB5 (4.1%; SE = 0.28), Illinois agility test time (−3.5%, SE = −0.26), MKD (14%; SE = 0.53), 2.4-km time trial (−1.9%; SE = −0.27) performances but had a trivial and nonsignificant effect on 20-m sprint time (−0.4%; SE = −0.03). No significant improvements were found in the CG. An integrated vertical plyometric program within the regular soccer practice can substitute soccer drills to improve most explosive actions and endurance, but horizontal exercises should also be included to enhance sprinting performance.

High-speed resistance training is more effective than low-speed resistance training to increase functional capacity and muscle performance in older women

OBJECTIVEnTo examine the effects of 12 weeks of high-speed resistance training (RT) versus low-speed RT on muscle strength [one repetition of maximum leg-press (1RMLP) and bench-press (1RMBP), plus dominant (HGd) and non-dominant maximum isometric handgrip], power [counter-movement jump (CMJ), ball throwing (BT) and 10-m walking sprint (S10)], functional performance [8-foot up-and-go test (UG) and sit-to-stand test (STS)], and perceived quality of life in older women.nnnMETHODSn45 older women were divided into a high-speed RT group [EG, n=15, age=66.3±3.7y], a low-speed RT group [SG, n=15, age=68.7±6.4y] and a control group [CG, n=15, age=66.7±4.9y]. The SG and EG were submitted to a similar 12-week RT program [3 sets of 8 reps at 40-75% of the one-repetition maximum (1<RM), CMJ and BT] using slow, controlled (3s) concentric muscle actions for the SG and using fast, explosive (<1s) concentric muscle actions for the EG (20% less work per exercise without CMJ and BT).nnnRESULTSnOver the 12-week training period, both RT groups showed small to large clinically significant improvements in the dependent variables; however, a significant difference was found between the EG and SG for the performance changes in BT, S10 and UG (20% vs. 11%, p<0.05; 14% vs. 9%, p<0.05; 18% vs. 10%, p<0.01; respectively). No significant changes were observed for the CG.nnnCONCLUSIONnBoth RT interventions are effective in improving functional capacity, muscle performance and quality of life in older women, although a high-speed RT program induces greater improvements in muscle power and functional capacity.

Effect of Vertical, Horizontal, and Combined Plyometric Training on Explosive, Balance, and Endurance Performance of Young Soccer Players

Abstract Ramírez-Campillo, R, Gallardo, F, Henriquez-Olguín, C, Meylan, CMP, Martínez, C, Álvarez, C, Caniuqueo, A, Cadore, EL, and Izquierdo, M. Effect of vertical, horizontal, and combined plyometric training on explosive, balance, and endurance performance of young soccer players. J Strength Cond Res 29(7): 1784–1795, 2015—The aim of this study was to compare the effects of 6 weeks of vertical, horizontal, or combined vertical and horizontal plyometric training on muscle explosive, endurance, and balance performance. Forty young soccer players aged between 10 and 14 years were randomly divided into control (CG; n = 10), vertical plyometric group (VG; n = 10), horizontal plyometric group (HG; n = 10), and combined vertical and horizontal plyometric group (VHG; n = 10). Players performance in the vertical and horizontal countermovement jump with arms, 5 multiple bounds test (MB5), 20-cm drop jump reactive strength index (RSI20), maximal kicking velocity (MKV), sprint, change of direction speed (CODS), Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1), and balance was measured. No significant or meaningful changes in the CG, apart from small change in the Yo-Yo IR1, were observed while all training programs resulted in meaningful changes in explosive, endurance, and balance performance. However, only VHG showed a statistically significant (p ⩽ 0.05) increase in all performance test and most meaningful training effect difference with the CG across tests. Although no significant differences in performance changes were observed between experimental groups, the VHG program was more effective compared with VG (i.e., jumps, MKV, sprint, CODS, and balance performance) and HG (i.e., sprint, CODS, and balance performance) to small effect. The study demonstrated that vertical, horizontal, and combined vertical and horizontal jumps induced meaningful improvement in explosive actions, balance, and intermittent endurance capacity. However, combining vertical and horizontal drills seems more advantageous to induce greater performance improvements.

Effects of plyometric training on endurance and explosive strength performance in competitive middle- and long-distance runners.

Abstract Ramírez-Campillo, R, Álvarez, C, Henríquez-Olguín, C, Baez, EB, Martínez, C, Andrade, DC, and Izquierdo, M. Effects of plyometric training on endurance and explosive strength performance in competitive middle- and long-distance runners. J Strength Cond Res 28(1): 97–104, 2014—The purpose of this study was to examine the effect of a short-term plyometric training program on explosive strength and endurance performance in highly competitive middle- and long-distance runners. Athletes were randomly assigned to a control group (CG, n = 18, 12 men) and an explosive strength training group (TG, n = 18, 10 men). Drop jump (DJ) from 20 (DJ20) and 40 cm (DJ40), countermovement jump with arms (CMJA), 20-m sprint time, and 2.4-km endurance run time test were carried out before and after 6 weeks of explosive strength training. Also, the combined standardized performance (CSP) in the endurance and explosive strength test was analyzed. After intervention, the CG did not show any significant change in performance, whereas the TG showed a significant reduction in 2.4-km endurance run time (−3.9%) and 20-m sprint time (−2.3%) and an increase in CMJA (+8.9%), DJ20 (+12.7%), and DJ40 (16.7%) explosive performance. Strength training group also exhibited a significant increase in CSP, although the CG showed significant reduction. We conclude that properly programmed concurrent explosive strength and endurance training could be advantageous for middle- and long-distance runners in their competitive performance, especially in events characterized by sprinting actions with small time differences at the end of the race.

Effect of Unilateral, Bilateral, and Combined Plyometric Training on Explosive and Endurance Performance of Young Soccer Players

Abstract Ramírez-Campillo, R, Burgos, CH, Henríquez-Olguín, C, Andrade, DC, Martínez, C, Álvarez, C, Castro-Sepúlveda, M, Marques, MC, and Izquierdo, M. Effect of unilateral, bilateral, and combined plyometric training on explosive and endurance performance of young soccer players. J Strength Cond Res 29(5): 1317–1328, 2015—The aim of the study was to compare the effects of bilateral, unilateral, or combined bilateral and unilateral plyometric training (PT) on muscle power output, endurance, and balance performance adaptations in young soccer players. Four groups of young soccer players (age 11.4 ± 2.2 years) were divided into control group (CG; n = 14), bilateral group (BG; n = 12), unilateral group (UG; n = 16), and bilateral + unilateral group (B + UG; n = 12). Players were measured in unilateral and bilateral countermovement jump with arms, 5 multiple bounds test, 20-cm drop jump reactive strength index, maximal kicking velocity, sprint and agility test time, endurance, and balance performance. The PT was applied during 6 weeks, 2 sessions per week, for a total of 2,160 jumps. After intervention, all PT groups showed a statistically significant (p ⩽ 0.05) change in all performance measures, with no statistically significant differences between treatments. Among the 21 performance measures, the B + UG showed a significantly (p ⩽ 0.05) higher performance change in 13 of them vs. the CG, whereas the UG and BG showed only 6 and 3, respectively. The current study showed that bilateral, unilateral, and combined bilateral and unilateral PT ensured significant improvement in several muscular power and endurance performance measures in young soccer players. However, the combination of unilateral and bilateral drills seems more advantageous to induce superior performance improvements.

The Effects of Interday Rest on Adaptation to 6 Weeks of Plyometric Training in Young Soccer Players

Abstract Ramírez-Campillo, R, Meylan, CMP, Álvarez-Lepín, C, Henriquez-Olguín, C, Martinez, C, Andrade, DC, Castro-Sepúlveda, M, Burgos, C, Baez, EI, and Izquierdo, M. The effects of interday rest on adaptation to 6 weeks of plyometric training in young soccer players. J Strength Cond Res 29(4): 972–979, 2015—The purpose of this study was to determine the effects of short-term plyometric training interposed with 24 or 48 hours of rest between training sessions on explosive and endurance adaptations in young soccer players. A total of 166 players, between 10 and 17 years of age, were randomly divided into 3 groups: a control group (CG; n = 55) and 2 plyometric training groups with 24 hours (PT24; n = 54) and 48 hours (PT48; n = 57) of rest between training sessions. Before and after intervention, players were measured in squat jump, countermovement jump, 20 (RSI20) cm drop jump reactive strength index, broad long jump, 20-m sprint time, 10 × 5-m agility time, 20-m multistage shuttle run test, and sit-and-reach test. The plyometric training program was applied during 6 weeks, 2 sessions per week, with a load from 140 to 260 jumps per session, replacing some soccer-specific drills. After intervention, the CG did not show significant performance changes. PT24 and PT48 groups showed a small-to-moderate significant improvement in all performance tests (p < 0.001), with no differences between treatments. Although it has been recommended that plyometric drills should not be conducted on consecutive days, the study shows that plyometric training applied twice weekly on consecutive or nonconsecutive days results in similar explosive and endurance adaptations in young male soccer players.The purpose of this study was to determine the effects of short-term plyometric training interposed with 24 or 48 hours of rest between training sessions on explosive and endurance adaptations in young soccer players. A total of 166 players, between 10 and 17 years of age, were randomly divided into 3 groups: a control group (CG; n = 55) and 2 plyometric training groups with 24 hours (PT24; n = 54) and 48 hours (PT48; n = 57) of rest between training sessions. Before and after intervention, players were measured in squat jump, countermovement jump, 20 (RSI20) cm drop jump reactive strength index, broad long jump, 20-m sprint time, 10 × 5-m agility time, 20-m multistage shuttle run test, and sit-and-reach test. The plyometric training program was applied during 6 weeks, 2 sessions per week, with a load from 140 to 260 jumps per session, replacing some soccer-specific drills. After intervention, the CG did not show significant performance changes. PT24 and PT48 groups showed a small-to-moderate significant improvement in all performance tests (p < 0.001), with no differences between treatments. Although it has been recommended that plyometric drills should not be conducted on consecutive days, the study shows that plyometric training applied twice weekly on consecutive or nonconsecutive days results in similar explosive and endurance adaptations in young male soccer players.

Análisis del IMC y Somatotipo en una Muestra de Adolescentes con Sobrepeso y Obesidad en Temuco-Chile

El sobrepeso y la obesidad en Chile se han convertido en una epidemia que sobrepasa todos los sectores sociales. Los factores mas importantes han sido el cambio del estilo de vida, economicos, sedentansmo, geneticos, entre otros. El proposito de este estudio fue analizar el indice de msa corporal (IMC) y somatotipo en una muestra de adolescentes con sobrepeso y obesidad de la ciudad de Temuco-Chile. Evaluamos 50 sujetos de ambos sexos (19 hombres 31 mujeres) de 14 a 16 anos de edad, de colegios municipalizados de la ciudad de Temuco, IX Region, Chile. Los sujetos fueron evaluados en sus propios colegios. Para obtener el somatotipo utilizamos el metodo antropometrico de Heath & Carter, efectuandose la clasificacion del IMC de acuerdo a las normas de la OMS. Las mujeres resultaron ser mas endomorficas que los hombres, siendo esta diferencia estadisticamente significativa. Los componentes mesomorfico y ectomorfico no presentaron diferencias estadisticamente significativas segun el sexo. El IMC mostro un valor de 27. La muestra presento un predominio del componente endomesomorfico para hombres y mujeres pero, ademas, en ambos hay predominio de este componente. Estos resultados demostraron la existencia de una gran cantidad de tejido adiposo en los adolescentes, con el consecuente aumento de peso y obesidad. Esto ultimo, producto de la falta de actividad fisica, cambios de los habitos alimenticios y diversos factores adicionales tales como padres obesos y aspectos geneticos.

Effect of Progressive Volume-Based Overload During Plyometric Training on Explosive and Endurance Performance in Young Soccer Players.

Abstract Ramírez-Campillo, R, Henríquez-Olguín, C, Burgos, C, Andrade, DC, Zapata, D, Martínez, C, Álvarez, C, Baez, EI, Castro-Sepúlveda, M, Peñailillo, L, and Izquierdo, M. Effect of progressive volume-based overload during plyometric training on explosive and endurance performance in young soccer players. J Strength Cond Res 29(7): 1884–1893, 2015—The purpose of the study was to compare the effects of progressive volume-based overload with constant volume-based overload on muscle explosive and endurance performance adaptations during a biweekly short-term (i.e., 6 weeks) plyometric training intervention in young soccer players. Three groups of young soccer players (age 13.0 ± 2.3 years) were divided into: control (CG; n = 8) and plyometric training with (PPT; n = 8) and without (NPPT; n = 8) a progressive increase in volume (i.e., 16 jumps per leg per week, with an initial volume of 80 jumps per leg each session). Bilateral and unilateral horizontal and vertical countermovement jump with arms (CMJA), 20-cm drop jump reactive strength index (RSI20), maximal kicking velocity (MKV), 10-m sprint, change of direction speed (CODS), and Yo-Yo intermittent recovery level 1 test (Yo-Yo IR1) were measured. Although both experimental groups significantly increased CMJA, RSI20, CODS, and endurance performance, only PPT showed a significant improvement in MKV and 10-m sprint time. In addition, only PPT showed a significantly higher performance improvement in jumping, MKV, and Yo-Yo IR1 compared with CG. Also, PPT showed higher meaningful improvement compared with NPPT in all (except 1) jump performance measures. Furthermore, although PPT involved a higher total volume compared with NPPT, training efficiency (i.e., percentage change in performance/total jump volume) was similar between groups. Our results show that PPT and NPPT ensured significant improvement in muscle explosive and endurance performance measures. However, a progressive increase in plyometric training volume seems more advantageous to induce soccer-specific performance improvements.

Intersession and intrasession reliability and validity of the my jump app for measuring different jump actions in trained male and female athletes

Abstract Gallardo-Fuentes, F, Gallardo-Fuentes, J, Ramírez-Campillo, R, Balsalobre-Fernández, C, Martínez, C, Caniuqueo, A, Cañas, R, Banzer, W, Loturco, I, Nakamura, FY, and Izquierdo, M. Intersession and intrasession reliability and validity of the My Jump app for measuring different jump actions in trained male and female athletes. J Strength Cond Res 30(7): 2049–2056, 2016—The purpose of this study was to analyze the concurrent validity and reliability of the iPhone app named My Jump for measuring jump height in 40-cm drop jumps (DJs), countermovement jumps (CMJs), and squat jumps (SJs). To do this, 21 male and female athletes (age, 22.1 ± 3.6 years) completed 5 maximal DJs, CMJs, and SJs on 2 separate days, which were evaluated using a contact platform and the app My Jump, developed to calculate jump height from flight time using the high-speed video recording facility on the iPhone. A total of 630 jumps were compared using the intraclass correlation coefficient (ICC), Bland-Altman plots, Pearsons product moment correlation coefficient (r), Cronbachs alpha (&agr;), and coefficient of variation (CV). There was almost perfect agreement between the measurement instruments for all jump height values (ICC = 0.97–0.99), with no differences between the instruments (p > 0.05; mean difference of 0.2 cm). Almost perfect correlation was observed between the measurement instruments for SJs, CMJs, and DJs (r = 0.96–0.99). My Jump showed very good within-subject reliability (&agr; = 0.94–0.99; CV = 3.8–7.6) and interday reliability (r = 0.86–0.95) for SJs, CMJs, and DJs in all subjects. Therefore, the iPhone app named My Jump provides reliable intersession and intrasession data, as well as valid measurements for maximal jump height during fast (i.e., DJs) and slow (i.e., CMJs) stretch-shortening cycle muscle actions, and during concentric-only explosive muscle actions (i.e., SJs), in both male and female athletes in comparison with a professional contact platform.