What if gastrointestinal complications in endurance athletes were gut injuries in response to a high consumption of ultra-processed foods? Please take care of your bugs if you want to improve endurance performance: a narrative review.

To improve performance and recovery faster, athletes are advised to eat more often than usual and consume higher doses of simple carbohydrates, during and after exercise. Sports energetic supplements contain food additives, such as artificial sweeteners, emulsifiers, acidity regulators, preservatives, and salts, which could be harmful to the gut microbiota and impair the intestinal barrier function. The intestinal barrier plays a critical function in bidirectionally regulation of the selective transfer of nutrients, water, and electrolytes, while preventing at the same time, the entrance of harmful substances (selective permeability). The gut microbiota helps to the host to regulate intestinal homeostasis through metabolic, protective, and immune functions. Globally, the gut health is essential to maintain systemic homeostasis in athletes, and to ensure proper digestion, metabolization, and substrate absorption. Gastrointestinal complaints are an important cause of underperformance and dropout during endurance events. These complications are directly related to the loss of gut equilibrium, mainly linked to microbiota dysbiosis and leaky gut. In summary, athletes must be cautious with the elevated intake of ultra-processed foods and specifically those contained on sports nutrition supplements. This review points out the specific nutritional interventions that should be implemented and/or discontinued depending on individual gut functionality.

Possible relationship between the gut leaky syndrome and musculoskeletal injuries: the important role of gut microbiota as indirect modulator.

This article aims to examine the evidence on the relationship between gut microbiota (GM), leaky gut syndrome and musculoskeletal injuries. Musculoskeletal injuries can significantly impair athletic performance, overall health, and quality of life. Emerging evidence suggests that the state of the gut microbiota and the functional intestinal permeability may contribute to injury recovery. Since 2007, a growing field of research has supported the idea that GM exerts an essential role maintaining intestinal homeostasis and organic and systemic health. Leaky gut syndrome is an acquired condition where the intestinal permeability is impaired, and different bacteria and/or toxins enter in the bloodstream, thereby promoting systemic endotoxemia and chronic low-grade inflammation. This systemic condition could indirectly contribute to increased local musculoskeletal inflammation and chronificate injuries and pain, thereby reducing recovery-time and limiting sport performance. Different strategies, including a healthy diet and the intake of pre/probiotics, may contribute to improving and/or restoring gut health, thereby modulating both systemically as local inflammation and pain. Here, we sought to identify critical factors and potential strategies that could positively improve gut microbiota and intestinal health, and reduce the risk of musculoskeletal injuries and its recovery-time and pain. In conclusion, recent evidences indicate that improving gut health has indirect consequences on the musculoskeletal tissue homeostasis and recovery through the direct modulation of systemic inflammation, the immune response and the nociceptive pain.

Acute Effects of Different Overspeed Loads with Motorized Towing System in Young Athletes: A Pilot Study.

Overspeed is a training method used to improve running speed, although its effects are not supported by consensual scientific evidence. The overspeed stimulus can be boosted by several methods, including motorized towing devices. Our objectives were to analyze the acute effects of three overspeed loads in young athletes and to select optimal loads for training periods. Eight young athletes (16.73 ± 1.69 years) performed one unassisted sprint and three assisted sprints, and kinematic and biomechanical data were compared. Significant increases (p < 0.05) in step velocity and step length were found with 2, 4, and 5.25 kg in maximum running speed, flight time and horizontal distance from the first contact to the vertical projection of the center of mass with 4 and 5.25 kg. Significant time decreases were found in 5 m flying sprint and contact time with 4 and 5.25 kg, and no significant changes were observed in step rate. The individually recommended loads would be between 3.47 ± 0.68% and 6.94 ± 1.35% body weight. Even having limitations, we can understand this work and its results as a pilot study to replicate the methodology and the use of new devices to more broadly investigate the effects of overspeed.

Osgood-Schlatter Disease: Appearance, Diagnosis and Treatment: A Narrative Review.

Osgood-Schlatter disease is the most common osteochondritis of the lower limb in sport-practicing children and adolescents. Its manifestation usually coincides with the appearance of the secondary ossification center of the tibia and is linked to the practice of sports with an explosive component. In the present study, a review of the factors related to its appearance, diagnosis and treatment was carried out. Its appearance seems to be multifactorial and related to multiple morphological, functional, mechanical and environmental factors. Given all the above, risk factor reduction and prevention seem the most logical strategies to effectively prevent the appearance of the condition. In addition, it is essential to create prevention programs that can be objectively assessed and would allow to stop the progress of the pathology, particularly in those sports where high forces are generated on the insertion zone of the patellar tendon at sensitive ages. More studies are needed to clarify which type of treatment is the most appropriate-specific exercises or the usual care treatment.

Acute effects of overspeed stimuli with towing system on athletic sprint performance: A systematic review with meta-analysis.

Overspeed-based training is widely used to improve athletes' maximum running speed and towing systems are one of the most frequently employed methods for this purpose. However, the effectiveness of this modality has not been thoroughly determined. This review analyzes the acute effects of overspeed conditions with towing systems in sprinters. The articles were searched, analysed and selected following the PRISMA methodology in the PubMed, SPORTDiscus and Google Scholar databases. Sixteen studies were included, with a total sample of 240 men and 56 women (14 to 31y; 1.73 to 1.82 m; 66.2 to 77.0 kg). The main acute responses found were: 1) an increase in maximum running speed (ES = 1.54, large), stride length (ES = 0.92, moderate), flight time (ES = 0.28, small) and stride rate (ES = 0.12, trivial); and, 2) a decrease in contact time (ES = 0.57, small). However, analysis of the reported ground reaction forces and electromyography data did not provide enough consistent evidence to conclusively determine whether the changes are due to a greater muscular response of the athlete or the effect of the towing system. Future research should focus on studying the mechanisms responsible for the observed acute effects.

Putative Role of MCT1 rs1049434 Polymorphism in High-Intensity Endurance Performance: Concept and Basis to Understand Possible Individualization Stimulus.

Monocarboxylate transporters (MCTs) have been proposed as important mediators of the exchange between lactate (La-) producer and La- recipient (consumer) cells. Previous studies have suggested that the MCT1 A1470T genotype could be related to different physical performance phenotypes. This study followed the guidelines for Strengthening the Reporting of Genetic Association Studies (STREGA) and aimed to evaluate the distribution of the MCT1 polymorphism rs1049434 in endurance-trained athletes compared to the untrained population. Moreover, this study explored the potential influence of the polymorphism alleles phenotypes on high-intensity exercise performance. In a cross-sectional study fashion, a total of 85 triathletes from northern Spain were genotyped for MCT1 rs1049434 and compared to a control group of 107 healthy male participants (1000 Genomes Research Study for Iberian Populations in Spain). All athletes performed a 30 s Wingate all-out test (WAnT) on a cycle ergometer. Peak and mean power (absolute and relative) were measured. After verification of the Hardy-Weinberg equilibrium, the findings indicated that the MCT1 TT genotype was overrepresented in triathletes in comparison to the genotypic frequency of the general Spanish population. No significant associations were found between any MCT1 genotype and peak or mean power performance in the WAnT. Further studies are required to understand the relationship among MCT1 A1470T polymorphism, endurance-trained athletes, and high-intensity performance.

The GALNTL6 Gene rs558129 Polymorphism Is Associated With Power Performance.

Díaz, J, Álvarez Herms, J, Castañeda, A, Larruskain, J, Ramírez de la Piscina, X, Borisov, OV, Semenova, EA, Kostryukova, ES, Kulemin, NA, Andryushchenko, ON, Larin, AK, Andryushchenko, LB, Generozov, EV, Ahmetov, II, and Odriozola, A. The GALNTL6 gene rs558129 polymorphism is associated with power performance. J Strength Cond Res 34(11): 3031-3036, 2020-The largest genome-wide association study to date in sports genomics showed that endurance athletes were 1.23 times more likely to possess the C allele of the single nucleotide polymorphism rs558129 of N-acetylgalactosaminyltransferase-like 6 gene (GALNTL6), compared with controls. Nevertheless, no further study has investigated GALNTL6 gene in relation to physical performance. Considering that previous research has shown that the same polymorphism can be associated with both endurance and power phenotypes (ACTN3, ACE, and PPARA), we investigated the association between GALNTL6 rs558129 polymorphism and power performance. According to this objective we conducted 2 global studies regarding 2 different communities of athletes in Spain and Russia. The first study involved 85 Caucasian physically active men from the north of Spain to perform a Wingate anaerobic test (WAnT). In the second study we compared allelic frequencies between 173 Russian power athletes (49 strength and 124 speed-strength athletes), 169 endurance athletes, and 201 controls. We found that physically active men with the T allele of GALNTL6 rs558129 had 5.03-6.97% higher power values compared with those with the CC genotype (p < 0.05). Consistent with these findings, we have shown that the T allele was over-represented in power athletes (37.0%) compared with endurance athletes (29.3%; OR = 1.4, p = 0.032) and controls (28.6%; OR = 1.5, p = 0.015). Furthermore, the highest frequency of the T allele was observed in strength athletes (43.9%; odds ratio [OR] = 1.9, p = 0.0067 compared with endurance athletes; OR = 2.0, p = 0.0036 compared with controls). In conclusion, our data suggest that the GALNTL6 rs558129 T allele can be favorable for anaerobic performance and strength athletes. In addition, we propose a new possible functional role of GALNTL6 rs558129, gut microbiome regarding short-chain fatty acid regulation and their anti-inflammatory and resynthesis functions. Nevertheless, further studies are required to understand the mechanisms involved.

Effects of a Single Power Strength Training Session on Heart Rate Variability When Performed at Different Simulated Altitudes.

Álvarez-Herms, Jesús, Sonia Julià-Sánchez, Hannes Gatterer, Francisco Corbi, Gines Viscor, and Martin Burtscher. Effects of a single power strength training session on heart rate variability when performed at different simulated altitudes. High Alt Med Biol. 21:292-296, 2020. Background: This study assessed heart rate variability (HRV) after a single power strength training session performed at different hypoxic levels. Materials and Methods: Eight physically active subjects (31.1 ± 4.3 years; 177.6 ± 3.0 cm; 70.1 ± 5.2 kg) performed 6 bouts of 15-second continuous maximal jump exercises interspersed by 3 minutes of rest at different altitude levels (total volume of each session: 20 minutes). The normoxic hypoxia levels were FiO2 low altitude: 20.9%; moderate altitude: 16.5%; and high altitude: 13.5%. Results: Average power output during the jumps was similar for all conditions (≅3150 W). Twenty-four hours before (PRE) and 24 hours after (POST) each training session, HRV parameters (R-R, square root of the mean of the sum of differences between intervals [RMSSD], pNN50, and very low frequency, low frequency, and high frequency) were determined without resulting in significant statistical differences, neither from PRE to POST nor between conditions (p > 0.05). Conclusions: This study showed a negligible perturbation of HRV parameters 24 hours after a single power strength session up to a hypoxic level equivalent to 4000 m. Further studies are needed to determine the hypoxia-dependent threshold and intensities of training loads affecting HRV.

Dental occlusion and body balance: A question of environmental constraints?

BACKGROUND: In the past few years, growing interest was given to the relationship between the dental occlusion and the body balance. While most research focused on this relationship at static conditions, it is evident that the contribution of the sensory information for balance control is different depending on the environmental constraints. RESEARCH QUESTION: The aim of the present paper was to elucidate whether the stomatognathic system (SS) contributes differently on body balance regulation according to the presence of external disturbances. METHODS: Literature regarding the different sources involved in the proprioceptive information to the SS was reviewed. The influence of dental occlusion on balance control at different external environments was then explored. RESULTS: The main findings are: (a) a plausible evidence between the masticatory and cervical muscles can be described; (b) a reciprocal connection between the trigeminal and vestibular nuclei supports the influence of the SS on body balance; (c) traditionally, research involving the relationship between the SS and balance control has focused on strictly controlled situations, thus, ignoring the sensory reweighting which occurs depending on the external disturbances; and (d) the afferences of dental occlusion for balance control seem strengthened when more difficult conditions are present. CONCLUSION: Results of the present review suggest that afferent signals from dental occlusion effectively contribute to balance control when more external perturbations are present, that is unstable support surface, fatigue and tasks being performed. However, more studies are needed to elucidate the mechanisms by which dental occlusion may influence balance control focusing on different external environments.

The Influence of Dental Occlusion on Dynamic Balance and Muscular Tone.

Excellent postural control is essential to improve the physical performance of athletes. Stability of the body during motor tasks depends on different physiological systems. The influence of dental occlusion on body balance has been widely investigated in the past few years. It has been suggested that this relationship is strengthened by disturbing environments for balance control (i.e., unstable platform, fatigue, development tasks.). Moreover, dental occlusion may influence the muscle tone of both masticatory and postural muscles, which are involved in the preservation of balance. Therefore, we attempted to determine whether (i) there are differences in dynamic balance assessed by the modified star excursion balance test between opposed dental occlusion conditions (dental contact: intercuspal position/no dental contact: cotton rolls mandibular position) and (ii) dental occlusion influences the biomechanical and viscoelastic properties of the masticatory and postural muscles assessed with MyotonPRO®. Thirty physically active subjects were recruited for the study. The main findings were the following: (i) the Star Excursion Balance Test composite score was significantly higher for measurements made in cotton rolls mandibular position (p < 0.001) and also in subjects showing a correct occlusion (p = 0.04), and (ii) the biomechanic and viscolelastic properties of selected muscles showed different trend according to the presence of malocclusal traits. It is concluded that dental occlusion conditioned both dynamic stability and the biomechanic and viscoelastic properties of the analyzed muscles.

Putative Role of Respiratory Muscle Training to Improve Endurance Performance in Hypoxia: A Review.

Respiratory/inspiratory muscle training (RMT/IMT) has been proposed to improve the endurance performance of athletes in normoxia. In recent years, due to the increased use of hypoxic training method among athletes, the RMT applicability has also been tested as a method to minimize adverse effects since hyperventilation may cause respiratory muscle fatigue during prolonged exercise in hypoxia. We performed a review in order to determine factors potentially affecting the change in endurance performance in hypoxia after RMT in healthy subjects. A comprehensive search was done in the electronic databases MEDLINE and Google Scholar including keywords: "RMT/IMT," and/or "endurance performance," and/or "altitude" and/or "hypoxia." Seven appropriate studies were found until April 2018. Analysis of the studies showed that two RMT methods were used in the protocols: respiratory muscle endurance (RME) (isocapnic hyperpnea: commonly 10-30', 3-5 d/week) in three of the seven studies, and respiratory muscle strength (RMS) (Powerbreathe device: commonly 2 × 30 reps at 50% MIP (maximal inspiratory pressure), 5-7 d/week) in the remaining four studies. The duration of the protocols ranged from 4 to 8 weeks, and it was found in synthesis that during exercise in hypoxia, RMT promoted (1) reduced respiratory muscle fatigue, (2) delayed respiratory muscle metaboreflex activation, (3) better maintenance of SaO2 and blood flow to locomotor muscles. In general, no increases of maximal oxygen uptake (VO2max) were described. Ventilatory function improvements (maximal inspiratory pressure) achieved by using RMT fostered the capacity to adapt to hypoxia and minimized the impact of respiratory stress during the acclimatization stage in comparison with placebo/sham. In conclusion, RMT was found to elicit general positive effects mainly on respiratory efficiency and breathing patterns, lower dyspneic perceptions and improved physical performance in conditions of hypoxia. Thus, this method is recommended to be used as a pre-exposure tool for strengthening respiratory muscles and minimizing the adverse effects caused by hypoxia related hyperventilation. Future studies will assess these effects in elite athletes.

The influence of dental occlusion on the body balance in unstable platform increases after high intensity exercise.

Existing evidence suggests that body balance ability is associated with dental occlusion. The purpose of this study was to determine whether: (i) there are differences in balance between opposed dental occlusion (intercuspal position, ICP; cotton rolls, CR) for two extreme levels of stability and (ii) the influence of dental occlusion on the balance control gets stronger under fatigue conditions. To this aim, various measures for assessing postural control in ten physically active subjects were obtained prior to and following a maximal lower limbs exercise consisting in six sets of fifteen seconds stretch-shortening cycle jumping. Balance control at stable and unstable condition was evaluated on an unstable platform Balance System SD for both dental occlusion conditions at random order. Metabolic and psychological measurements ensured the high intensity of the exercise. At unstable level, balance control was significantly improved in the CR condition, for both rest (p=0.03) and fatigue (p<0.001). Whereas at stable level, the influence of dental occlusion only reached significance in fatigue condition (p=0.04). It could be concluded that the sensory information linked to the dental occlusion for the balance control comes strongly into effect when more difficult conditions for the balance control are present (i.e., unstable conditions, fatigue).

Dental Occlusion Influences the Standing Balance on an Unstable Platform.

Contradictory results are still reported on the influence of dental occlusion on the balance control. We attempted to determine whether there are differences in balance between opposed dental occlusion (Intercuspal position (ICP)/"Cotton rolls" mandibular position [CR]) for two extreme levels of stability (stable/ unstable). Twenty-five subjects were monitored under both dental occlusion and level of stability conditions using an unstable platform Balance System SD. The resulting stability index suggests that body balance is significantly better when dental occlusion is set in CR (p < .001) in unstable but not in stable conditions. Occlusal traits significantly influencing postural control were Angle Class (p < .001), crowding (p = .006), midline deviation (p < .001), crossbite (p < .001), anterior open bite (p = .05), and overjet (p = .01). It could be concluded that the sensory information linked to the dental occlusion for the balance control comes strongly into effect in unstable conditions.

Differing levels of acute hypoxia do not influence maximal anaerobic power capacity.

OBJECTIVE: The purpose of this study was to determine the effects of different inspired oxygen fractions (Fio2) on average and peak power capacity during consecutive jumps to assess the effectiveness of a hypoxic explosive-strength program. METHODS: Eight physically active subjects (aged 33.62 ± 4.07 years; height, 1.77 ± 0.05 m; weight, 74.38 ± 6.86 kg) completed a Bosco jump test, consisting of a series of 15-second "all-out" jumps with 3 minutes of recovery, performed in a normoxia condition (N [Fio2 = 21%]) and in two hypoxic conditions: moderate hypoxia (MH [Fio2 16.5% o2]) and high hypoxia (HH [13.5% o2]). A force platform provided the average and the maximal power output (W) generated during consecutive jumps. Measurements were also taken of lactate, creatine kinase, arterial oxygen saturation, and perceived exertion using the Borg fatigue scale. RESULTS: The average power outputs throughout the entire sets were similar between N (3187 ± 46) and MH (3184 ± 15; P > .05), but slightly greater with HH (3285 ± 43) compared with N (P < .05). Values for lactate during N (7.5 ± 3.0), MH (7.7 ± 4.0), and HH (7.9 ± 3.0; P > .05), and for creatine kinase (values before, 69.8 ± 15; and 24 hours after in N [79.4 ± 15.60], MH [85.2 ± 26.7], and HH [84.3 ± 47.2]; P > .05) were similar for all conditions. Only during exercise in hypoxia were moderate and severe hypoxemia induced as the sets increased and Fio2 was lower (P < .05). At the same time, the perceived exertion reported by subjects was substantially higher at HH (8.9 ± 1.1) than at N (7.1 ± 1.9; P < .05). CONCLUSIONS: Jumping power output was not negatively affected by mild or high hypoxia in comparison with normoxia during an anaerobic workout despite having higher hypoxemia and a greater perception of exertion.

Efecto del ejercicio anaeróbico láctico sobre el pH salival / The effect of anaerobic lactic acid-producing exercise on salivary pH

Introducción: Valores bajos del pH salival están fuertemente relacionados con un mayor riesgo de caries dental. El objetivo del presente estudio fue valorar los cambios en los valores del pH salival tras la realización de ejercicio anaeróbico máximo, su posible relación con el valor de lactato sanguíneo, y el análisis del estado de la cavidad bucal en atletas de disciplinas de carácter anaeróbico. Material y métodos: Estudio de naturaleza experimental, con la participación de 6 sujetos (3 hombres, 3 mujeres; edad 21,67 ± 5,32 años; peso 61 ± 7,18 kg; altura 1,70 ± 0,05 m), atletas de nivel alto, no de élite. Los sujetos realizaron 2 sesiones (S1, S2) de ejercicio anaeróbico láctico con los mismos criterios (máximo número de series de 300 m en pista al 90% de la intensidad máxima individual). Se tomaron muestras de saliva total, no estimulada, en 3 momentos: a) justo antes del ejercicio; b) inmediatamente después de cada serie, y c transcurridos 30 min después del ejercicio, para la medición del pH salival. También se tomaron muestras de lactato sanguíneo inmediatamente después de cada serie. Resultados: La variación del pH salival basal respecto al pH de la última serie es estadísticamente significativa en ambas sesiones (S1: p = 0,028; S2: p = 0,044). Conclusiones: Los datos obtenidos sugieren una respuesta alcalinizante de las glándulas salivales durante la realización de ejercicio anaeróbico láctico. Sería interesante estudiar las modificaciones cualitativas en la composición de la saliva durante la realización de ejercicio anaeróbico y la prolongación del efecto de dichas modificaciones en el tiempo (AU)

Introduction: A low salivary pH is strongly associated with the incidence of dental caries. The aim of this study was to determine if high intensity anaerobic exercise could affect the salivary pH response, and to determine if there is correlation between salivary pH and blood lactate values. Additionally, we also aim to determine the state of oral health in anaerobic events athletes. Material and methods: Six healthy and physically active subjects, high-level athletes (3 men and 3 women; age 21.67 ± 5.32 years; weight 61 ± 7.18 kg; height 1.70 ± 0.05 m) performed a clinical trial consisting of two sessions of anaerobic lactic acid-producing exercise. Each session consisted of running the maximum number of sets of 300 meters at 90% of the individual maximal intensity. Non-stimulated whole saliva samples were collected from all subjects at three different times: (I) before the exercise; (II) immediately after each 300 m set, and (III) 30 minutes after the exercise. Blood lactate was measured after each 300 m set to assess the anaerobic character of the test. Results: Salivary pH increased significantly after the exercise in both sessions of the study (S1: P = 0.028; S2: P = 0.044). Conclusion: Our results suggest that performing anaerobic lactic acid-producing exercise has an effect on saliva alkalinization. More research is needed to assess the qualitative modifications in saliva due to performing anaerobic exercise and their effect on dental health (AU)

Potenciales aplicaciones del entrenamiento de hipoxia en el fútbol / Potential applications of hypoxia in football training

En el fútbol profesional entrenar en hipoxia no es una práctica extendida, aunque las posibles mejoras en el rendimiento físico obtenidas a través de su uso podrían ser relevantes en la preparación y recuperación física. El carácter de esfuerzo intermitente que define el fútbol requiere que el jugador se recupere lo más rápido posible entre esfuerzos de alta y baja intensidad. En un estudio previo realizado por este grupo de investigación se constató una mejora significativa de la frecuencia cardíaca de recuperación desde esfuerzo máximo después de realizar un protocolo de entrenamiento de fuerza resistencia en hipoxia intermitente. Del mismo modo, los beneficios fisiológicos de la exposición y entrenamiento en hipoxia podrían aumentar el rendimiento individual de los jugadores de fútbol. Este estudio pretende revisar los estudios publicados sobre el tema y el uso y las posibles aplicaciones del entrenamiento en hipoxia para el rendimiento físico en el fútbol (AU)

The use of hypoxia in professional football training is not widely used although improvements in physical performance obtained with hypoxia could be relevant for the fitness and physical recovery. Football is defined as an intermittent effort sport and requires that players recover as quickly as possible between great efforts. In a study previously carried out by this research group a significant improvement was found in heart rate recovery from maximal exercise after performing strength resistance training in intermittent hypoxia. Similarly, the physiological benefits of exposure and training in hypoxia may increase the individual performance of soccer players. The main aim of this review is analyze the literature on the use and possible applications of hypoxia training for physical performance in football (AU)

Valoración de la Frecuencia Cardíaca de Recuperación después de un programa de entrenamiento de fuerza-resistencia en hipoxia / Changes in heart rate recovery index after a programme of strength/endurance training in hypoxia

Objetivo: Doce sujetos jóvenes físicamente activos se dividieron en dos grupos equilibrados para entrenar en hipoxia (HYP) y normoxia (NOR). Material y métodos: Los sujetos fueron asignados a cada grupo en base a los resultados en una prueba previa de salto en contramovimiento de sesenta segundos (CMJ60). Ambos grupos realizaron durante 4 semanas un entrenamiento idéntico de fuerza (volumen, intensidad, carácter y condiciones de esfuerzo) en las extremidades inferiores (squat, half-squat y saltos). Resultados: Ambos grupos mejoraron en todos los casos. Se analizó la evolución temporal de la frecuencia cardiaca durante la prueba CMJ60 y el posterior período de recuperación de tres minutos. El grupo HYP (n=5) refleja una mejoría del índice de recuperación de la frecuencia cardiaca en comparación con el grupo NOR (prueba t de Student) después de 2 (p=0,03) y 3 (p=0,05) minutos de finalizar el test de saltos. Conclusiones: Concluimos que un protocolo de entrenamiento de fuerza resistencia (12 sesiones en 4 semanas) de las extremidades inferiores en altitud simulada podría mejorar el índice de recuperación de la frecuencia cardiaca en comparación con el mismo entrenamiento realizado a nivel del mar(AU)

Objective: To determine whether twelve sessions of resistance training on lower limbs at simulated altitude (2500m) were efficient to elicit an improvement in heart rate recovery index in the first 3min of recovery after a maximal jump test. Materials and methods: Twelve young physically active subjects were divided in two balanced groups for training in hypoxia (HYP) and normal oxygen (NOR). The subjects were assigned to each group based on previous test results in the 60s counter-movement jump test (CMJ60). Results: Both groups performed identical strength training (volume, intensity, character and effort conditions) on the lower limbs (squats, half-squats and jumps) for 4 weeks. Both groups improved the measured parameters in all cases. We analyzed the time course of heart rate during the CMJ60 test and the subsequent 3min recovery period. HYP group (n=5) improved the heart rate recovery index as compared to NOR group (Student's t-test) at minute 2 (P=0.03) and minute 3 (P=0.05). Conclusions: We conclude that a protocol of resistance training on lower limbs (12 sessions in 4 weeks) at a simulated altitude could improve heart rate recovery index compared to the same training performed at sea level(AU)