Open Access
Effects of plyometric training and creatine supplementation on maximal-intensity exercise and endurance in female soccer players
(Elsevier, 2016) Ramírez Campillo, Rodrigo; González Jurado, José Antonio; Martínez Salazar, Cristian; Alonso Martínez, Alicia; Izquierdo Redín, Mikel; Ciencias de la Salud; Osasun Zientziak
Objectives: To investigate the effects of a six-week plyometric training and creatine supplementation intervention on maximal-intensity and endurance performance in female soccer players during in-season training. Design: Randomized, double-blind, placebo-controlled trial. Methods: Young (age 22.9 ± 2.5 y) female players with similar training load and competitive background were assigned to a plyometric training group receiving placebo (PLACEBO, n = 10), a plyometric training group receiving creatine supplementation (CREATINE, n = 10) or a control group receiving placebo without following a plyometric program (CONTROL, n = 10). Athletes were evaluated for jumping, maximal and repeated sprinting, endurance and change-of-direction speed performance before and after six weeks of training. Results: After intervention the CONTROL group did not change, whereas both plyometric training groups improved jumps (ES = 0.25–0.49), sprint (ES = 0.35–0.41), repeated sprinting (ES = 0.48–0.55), endurance (ES = 0.32–0.34) and change-of-direction speed performance (ES = 0.46–0.55). However, the CREATINE group improved more in the jumps and repeated sprinting performance tests than the CONTROL and the PLACEBO groups. Conclusions: Adaptations to plyometric training may be enhanced with creatine supplementation.
Open Access
Construct validity and test-retest reliability of the International Fitness Scale (IFIS) in Colombian children and adolescents aged 9-17.9 years: the FUPRECOL study
(PeerJ, 2017) Ramírez Vélez, Robinson; Cruz Salazar, Sandra Milena; Martínez, Myriam; Lusa Cadore, Eduardo; Alonso Martínez, Alicia; Correa Bautista, Jorge Enrique; Izquierdo Redín, Mikel; Ortega, Francisco B.; García Hermoso, Antonio; Ciencias de la Salud; Osasun Zientziak
Background: there is a lack of instruments and studies written in Spanish evaluating physical fitness, impeding the determination of the current status of this important health indicator in the Latin population, especially in Colombia. The aim of the study was two-fold: to examine the validity of the International Fitness Scale (IFIS) with a population-based sample of schoolchildren from Bogota, Colombia and to examine the reliability of the IFIS with children and adolescents from Engativa, Colombia. Methods: the sample comprised 1,873 Colombian youths (54.5% girls) aged 9–17.9 years. We measured their adiposity markers (waist-to-height ratio, skinfold thickness, percentage of body fat and body mass index), blood pressure, lipids profile, fasting glucose, and physical fitness level (self-reported and measured). A validated cardiometabolic risk index score was also used. An age- and sex-matched subsample of 229 schoolchildren who were not originally included in the sample completed the IFIS twice for reliability purposes. Results: our data suggest that both measured and self-reported overall physical fitness levels were inversely associated with percentage of body fat indicators and the cardiometabolic risk index score. Overall, schoolchildren who self-reported “good” or “very good” fitness had better measured fitness levels than those who reported “very poor/poor” fitness (all p < 0.001). The test-retest reliability of the IFIS items was also good, with an average weighted kappa of 0.811. Discussion: our findings suggest that self-reported fitness, as assessed by the IFIS, is a valid, reliable, and health-related measure. Furthermore, it can be a good alternative for future use in large studies with Latin schoolchildren from Colombia.
Open Access
Normative reference values for the 20 m shuttle-run test in a population-based sample of school-aged youth in Bogota, Colombia: the FUPRECOL study
(Wiley, 2017) Ramírez Vélez, Robinson; Palacios López, Adalberto; Prieto Benavides, Daniel Humberto; Correa Bautista, Jorge Enrique; Izquierdo Redín, Mikel; Alonso Martínez, Alicia; Ciencias de la Salud; Osasun Zientziak
Objectives: Our aim was to determine the normative reference values of cardiorespiratory fitness (CRF) and to establish the proportion of subjects with low CRF suggestive of future cardio‐metabolic risk. Methods: A total of 7244 children and adolescents attending public schools in Bogota, Colombia (55.7% girls; age range of 9–17.9 years) participated in this study. We expressed CRF performance as the nearest stage (minute) completed and the estimated peak oxygen consumption (V˙O2peak). Smoothed percentile curves were calculated. In addition, we present the prevalence of low CRF after applying a correction factor to account for the impact of Bogota's altitude (2625 m over sea level) on CRF assessment, and we calculated the number of participants who fell below health‐related FITNESSGRAM cut‐points for low CRF. Results: Shuttles and V˙O2peak were higher in boys than in girls in all age groups. In boys, there were higher levels of performance with increasing age, with most gains between the ages of 13 and 17. The proportion of subjects with a low CRF, suggestive of future cardio‐metabolic risk (health risk FITNESSGRAM category) was 31.5% (28.2% for boys and 34.1% for girls; X2 P = .001). After applying a 1.11 altitude correction factor, the overall prevalence of low CRF was 11.5% (9.6% for boys and 13.1% for girls; X2 P = .001).
Open Access
Cardiorespiratory fitness cut-points are related to body adiposity parameters in Latin American adolescents
(MDPI, 2019) Prieto Benavides, Daniel Humberto; García Hermoso, Antonio; Izquierdo Redín, Mikel; Alonso Martínez, Alicia; Agostinis-Sobrinho, César; Correa Bautista, Jorge Enrique; Ramírez Vélez, Robinson; Ciencias de la Salud; Osasun Zientziak
Background and Objectives: A deficiency exists in the criterion-referenced cut-points for field-based cardiorespiratory fitness (CRF) in Latin American youths. The aims of the present study were two-fold: (1) To identify the ability of CRF estimated by the 20-m shuttle-run test (20mSRT) to differentiate between 'healthy' and 'unhealthy' phenotypes (by adiposity) in adolescents; (2) to assess the association between obesity and relative peak oxygen uptake (VO2peak) in a large and diverse sample of Latin American youths. In total, 72,505 adolescents aged between 13 and 15 years were recruited from Chile and Colombia (47.5% girls). Materials and Methods: The waist circumference (WC) and waist-to-height ratio (WHtR) were used to identify body adiposity markers. CRF was measured using the 20mSRT (VO2peak). Receiver operating characteristic curves and logistic regression were used to determine the discriminatory ability of CRF to predict body adiposity parameters. Results: For boys and girls, VO2peak showed a significant predictive capacity to detect body fat (area under the curve [AUC] > 0.62). The sensitivity of VO2peak was medium (>63%) for all age- and sex-specific cut-points, with optimal cut-points in 13- to 15-year olds for obesity identified as 43.77 mL·kg-1·min-1 and 38.53 mL·kg-1·min-1 in boys and girls, respectively. Conclusions: According to these cut-points, adolescents with low CRF were more likely to be obese either by WC or WHtR. The CRF cut-points can be used as quantitative markers for a healthier body in Latin American adolescents.
Open Access
Feasibility and reliability of physical fitness tests among Colombian preschool children
(MDPI, 2019) Amado Pacheco, Julio César; Prieto Benavides, Daniel Humberto; Correa Bautista, Jorge Enrique; García Hermoso, Antonio; Agostinis-Sobrinho, César; Alonso Martínez, Alicia; Izquierdo Redín, Mikel; Ramírez Vélez, Robinson; Ciencias de la Salud; Osasun Zientziak
The aim of the study was to assess the feasibility and reliability of physical fitness field tests used in the 'Fuprecol kids' study among Colombian preschool children aged 3-5 years. A total of 90 preschoolers aged 3-5 years participated in the study. Weight, height, waist circumference, cardiorespiratory fitness (CRF), musculoskeletal fitness (handgrip strength and standing broad jump), speed-agility (4 × 10 m shuttle run), and flexibility (sit and reach test) components were tested twice (two weeks apart). The feasibility of the tests (preschoolers able to complete the test) ranged from 96% in the CRF test to 100% in the musculoskeletal fitness, speed-agility, and flexibility tests. Overall, the %TEMs were 0.625% for the weight, 0.378% for the height, 1.035% for the body mass index, and 0.547 % for the waist circumference. In addition, all tests were substantial reliable, for CRF (in stages and laps, concordance correlation coefficient = 0.944 and 0.941, respectively) in both sexes and flexibility (concordance correlation coefficient = 0.949) in girls. There were no significant differences in fitness test-retest mean differences in the boys (P gt; 0.05), except in CRF (laps P = 0.017). In girls, there were differences in CRF (stages (P = 0.017) and laps (P= 0.013)), and flexibility (P = 0.002) variables. The results from this study indicate that the 'Fuprecol kids' battery of tests, administered by physical education teachers, was reliable and feasible for measuring components of physical fitness in preschoolers in a school setting in Colombia.
Open Access
High muscular fitness has a powerful protective cardiometabolic effect in adults: influence of weight status
(BioMed Central, 2016) Ramírez Vélez, Robinson; Correa Bautista, Jorge Enrique; Lobelo, Felipe; Izquierdo Redín, Mikel; Alonso Martínez, Alicia; Rodríguez Rodríguez, Fernando; Cristi Montero, Carlos; Ciencias de la Salud; Osasun Zientziak
Background: Low levels of muscular fitness (MF) are recognized as an important marker of nutritional status and a predictor of metabolic complications, cardiovascular disease and death, however, the relationship between MF, body mass index (BMI) and the subsequent cardiometabolic protective effects has been less studied among Latin American populations. This study identified an association between MF and the cardiometabolic risk score index (CMRSI) and the lipid-metabolic cardiovascular risk index (LMCRI) in a wide sample of university students grouped according to their BMI. Methods: Six thousand ninety five healthy males (29.6 ± 11.7 year-old) participated in the study. Absolute strength was measured using a T.K.K. analogue dynamometer (handgrip), and the participant’s strength was then calculated relative to their body mass (MF/BM). The LMCRI was derived from the levels of triglycerides, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), and glucose levels in a blood sample. The CMRSI was calculated by summing the standardized residuals (z-score) for waist circumference, total cholesterol, LDL-c, triglycerides, HDL-c, and median blood pressure. Subjects were divided into six subgroups according to BMI (normal vs. overweight/obese) and MF/BM tertiles (unfit, average, fit). Results: The group of participants with low and moderate levels of MF/BM showed higher CMRSI values independent of BMI (P < 0.001). The group with normal BMI and high MF/BM had the highest levels of cardiometabolic protection. All overweight/obese BMI groups had significantly higher LMCRI values independent of the level of MF/BM (P < 0.001). Conclusions: Participants with high MF/BM showed reduced cardiometabolic risk, which increased significantly when they were within normal parameters.
Open Access
Schoolbag weight carriage in Portuguese children and adolescents: a cross-sectional study comparing possible influencing factors
(BMC, 2019) Barbosa, João; Marqués, Mário C.; Izquierdo Redín, Mikel; Neiva, Henrique P.; Barbosa, Tiago M.; Ramírez Vélez, Robinson; Alonso Martínez, Alicia; García Hermoso, Antonio; Aguado Jiménez, Roberto; Marinho, Daniel; Ciencias de la Salud; Osasun Zientziak
Background Schoolbags and the consequences of carrying them, particularly those associated with overload, are often studied as a health concern. Modifications in gait and posture were reported when children carried loads that corresponded to more than 10% of their body weight (BW). The aims of this study were to verify the load that is carried by Portuguese students and how it is influenced by factors such as school grade, school schedule, lunch site, physical education, sex and body mass index (BMI). Acquiring a more specific knowledge of the Portuguese context and understanding the influence of these factors may allow us to generate proposals to control them in ways that benefit students.MethodsThe load carried by students in the 5th grade (10.60.4years) and 9th grade (14.70.6years) were weighed with a luggage scale on all days of the week, resulting in 680 evaluations. Data related to the school day were also collected, such as the student's lunch site, how he or she got to school and his or her school schedule for that day. Individual height and weight were also assessed. Results The 5th grade students carried greater loads than the 9th grade students, resulting in a substantial difference relative to their BW. The school loads of the 5th grade students were mostly greater than 10% of their BWs. Girls tended to carry heavier loads than boys, and overweight students also tended to carry heavier loads. Students who could eat lunch at home carried less weight, and on physical education days, the total load carried increased, but the backpacks of the 5th grade students were lighter.Conclusions The results of the current study describe excessive schoolbag weight among Portuguese students and expound on some of the factors that influence it, which can help researchers and professionals design a solution to decrease children's schoolbag loads.
Open Access
Cardiorespiratory fitness normative values in Latin-american adolescents: role of fatness parameters
(MDPI, 2019) Ramírez Vélez, Robinson; García Hermoso, Antonio; Alonso Martínez, Alicia; Agostinis-Sobrinho, César; Correa Bautista, Jorge Enrique; Triana Reina, Héctor Reynaldo; Izquierdo Redín, Mikel; Ciencias de la Salud; Osasun Zientziak
The aim of this study was to provide percentile values for a cardiorespiratory fitness (CRF) field test for Latin-American adolescents (34,461 girls and 38,044 boys) aged 13 to 15 years. The role of fatness parameters on the CRF level across age groups was also examined, with a focus on non-obese (healthy) and obese groups. CRF was assessed using the 20-meter shuttle run test protocol. Anthropometric parameters were measured using body mass index z-score (body mass index (BMI) z-score), BMI, waist circumference (WC), and waist-to-height ratio (WHtR). Participants were categorized according to the BMI z-score, WC, and WHtR international cut-off points as healthy and obese. Age-and sex-specific reference tables for the 3rd, 10th, 25th, 50th, 75th, 90th, and 97th centile scores were calculated using Cole’s lambda, mu, and sigma method. The prevalence of obesity according to the BMI z-score, WC, and WHtR was 9.6%, 11.2%, and 15.0%, respectively. Across all age and sex groups, a negative association was found between relative peak oxygen uptake (VO2 peak) and BMI, WC, and WHtR. In boys and girls there were higher levels of performance across all age groups, with most apparent gains between the ages of 13 and 14 years old. Overall, participants categorized in the healthy group had shown to have significantly higher VO2 peak than their obese counterparts (p < 0.001; Cohen’s d> 1.0). In conclusion, our study provides age-and sex-specific reference values for CRF (VO2 peak, mL·kg−1·min−1 ). The anthropometric parameters were inversely associated with CRF in all ages in both sexes. The obese group had worse CRF than their healthy counterparts independent of anthropometric parameters used to determine obesity.
Open Access
Effects of backpacks on ground reaction forces in children of different ages when walking, running, and jumping
(MDPI, 2019) Barbosa, João; Marqués, Mário C.; Neiva, Henrique P.; Esteves, Dulce; Alonso Martínez, Alicia; Izquierdo Redín, Mikel; Ramírez Campillo, Rodrigo; Álvarez, Cristian; Marinho, Daniel; Ciencias de la Salud; Osasun Zientziak
Backpacks for transporting school loads are heavily utilized by children, and their mechanical advantages have been allowing children to transport heavy loads. These heavy loads may increase ground reaction forces (GRFs), which can have a negative effect on joints and bone health. The aim of this study was to investigate the effect of backpacks on the GRFs generated by children during walking, running, and jumping. Twenty-one children from the fifth (G-5, n = 9) and ninth (G-9, n = 12) grades walked, ran, and jumped over a force plate. When walking, the G-5 had GRF increments in the first (17.3%; p < 0.001) and second (15.4%; p < 0.001) peak magnitude, and in the total integral of the vertical force (20%; p < 0.001), compared to the control condition (i.e., no backpack), and the G-9 had increments of 10.4%, 9%, and 9% (p < 0.001), respectively. The G-9 did not prolong their total stance time (p > 0.05), unlike the G-5 (p = 0.001). When running, total stance time increased 15% (p < 0.001) and 8.5% (p < 0.001) proportionally to the relative load carried, in the G-5 and G-9, respectively. Peak GRF did not increase in any group when running or landing from a jump over an obstacle. It was found that GRF was affected by the backpack load when walking and running. However, when landing from a jump with the backpack, schoolchildren smoothed the landing by prolonging the reception time and thus avoiding GRF peak magnitudes.
Open Access
Inter-individual variability in responses to 7 weeks of plyometric jump training in male youth soccer players
(Frontiers Media, 2018) Ramírez Campillo, Rodrigo; Álvarez, Cristian; Gentil, Paulo; Alonso Martínez, Alicia; Izquierdo Redín, Mikel; Ciencias de la Salud; Osasun Zientziak
The purpose of this study was to compare the inter-individual variability in the effects of plyometric jump training (PJT) on measures of physical fitness (sprint time, change of direction speed, countermovement jump, 20- and 40-cm drop jump reactive strength index, multiple five bounds distance, maximal kicking distance, and 2.4-km time trial) in youth soccer players who completed a PJT program versus players who completed soccer training only. In a single-blinded study, participants aged between 10 and 16 years were randomly divided into a PJT group (n = 38) and a control group (n = 38). The experimental group participated in a PJT program twice weekly for 7 weeks, whereas the control group continued with their regular soccer training sessions. Between-group differences were examined using a Mann–Whitney U test. Nonresponders where defined as individuals who failed to demonstrate any beneficial change that was greater than two times the typical error of measurement from zero. The results indicated that the mean group improvement for all physical fitness measures was greater (p < 0.05) in the PJT group (Δ = 0.4 to 23.3%; ES = 0.04 to 0.58) than in the control group (Δ = 0.1 to 3.8%; ES = 0.02 to 0.35). In addition, a significantly greater (p < 0.05) number of responders across all dependent variables was observed in the PJT group (from 4 up to 33 responders) than in the control group (from 0 up to 9 responders). In conclusion, compared to soccer training only, PJT induced greater physical fitness improvements in youth soccer players, with a greater number of responders for all the physical fitness tests related to jumping, speed, change of direction speed, endurance, and kicking technical ability.