Efficacy of high-intensity interval- or continuous aerobic-training on insulin resistance and muscle function in adults with metabolic syndrome: a clinical trial.

PURPOSE: We carried out a randomized, clinical trial in adults of both sexes with metabolic syndrome (MS) to assess the efficacy of high-intensity, low-volume interval training (HIIT) compared to moderate-intensity continuous training (MICT) on insulin resistance (IR), muscle mass, muscle activation, and serum musclin. METHODS: Fasting glycemia, insulinemia, and glycated haemoglobin were determined by conventional methods, IR by Homeostatic model assessment (HOMA), lean mass by Dual-Energy X-ray Absorptiometry, muscle activation through carnosine by Proton Magnetic Resonance Spectroscopy, and musclin by Enzyme-Linked ImmunoSorbent Assay before and after a supervised, three-times/week, 12-week treadmill programme. HIIT (n = 29) consisted of six intervals with one-minute, high-intensity phases at 90% of peak oxygen consumption (VO2peak). MICT (n = 31) trained at 60% of VO2peak for 30 min. RESULTS: Patients had a mean age of 50.8 ± 6.0 years, body mass index of 30.6 ± 4.0 kg/m2, and VO2peak of 29.0 ± 6.3 mL.kg-1.min-1. Compared to MICT, HIIT was not superior at reducing Ln HOMA-IR (adjusted mean difference: 0.083 [95%CI - 0.092 to 0.257]), carnosine or musclin or at increasing thigh lean mass. HIIT increased carnosine by 0.66 mmol/kg.ww (95% CI 0.08-1.24) after intervention. Both interventions reduced IR, body fat percentage and increased total lean mass/height2 and VO2peak. Musclin showed a non-significant reduction with a small effect size after both interventions. CONCLUSION: Compared to MICT, HIIT is not superior at reducing IR, carnosine or musclin or at increasing skeletal muscle mass in adults with MS. Both training types improved IR, muscle mass and body composition. NCT03087721, March 22nd, 2017. TRIAL REGISTRATION NUMBER: NCT03087721. Registered March 22nd, 2017.

Efficacy of high-intensity, low-volume interval training compared to continuous aerobic training on insulin resistance, skeletal muscle structure and function in adults with metabolic syndrome: study protocol for a randomized controlled clinical trial (Intraining-MET).

BACKGROUND: Evidence of the efficacy of high-intensity, low-volume interval training (HIIT-low volume) in treating insulin resistance (IR) in patients with metabolic disorders is contradictory. In addition, it is unknown whether this effect is mediated through muscle endocrine function, which in turn depends on muscle mass and fiber type composition. Our aims were to assess the efficacy of HIIT-low volume compared to continuous aerobic exercise (CAE) in treating IR in adults with metabolic syndrome (MS) and to establish whether musclin, apelin, muscle mass and muscle composition are mediators of the effect. METHODS: This is a controlled, randomized, clinical trial using the minimization method, with blinding of those who will evaluate the outcomes and two parallel groups for the purpose of showing superiority. Sixty patients with MS and IR with ages between 40 and 60 years will be included. A clinical evaluation will be carried out, along with laboratory tests to evaluate IR (homeostatic model assessment (HOMA)), muscle endocrine function (serum levels of musclin and apelin), thigh muscle mass (by dual energy x-ray absorptiometry (DXA) and thigh muscle composition (by carnosine measurement with proton magnetic resonance spectroscopy (1H-MRS)), before and after 12 weeks of a treadmill exercise program three times a week. Participants assigned to the intervention (n = 30) will receive HIIT-low volume in 22-min sessions that will include six intervals at a load of 90% of maximum oxygen consumption (VO2 max) for 1 min followed by 2 min at 50% of VO2 max. The control group (n = 30) will receive CAE at an intensity of 60% of VO2 max for 36 min. A theoretical model based on structural equations will be proposed to estimate the total, direct and indirect effects of training on IR and the proportion explained by the mediators. DISCUSSION: Compared with CAE, HIIT-low volume can be effective and efficient at improving physical capacity and decreasing cardiovascular risk factors, such as IR, in patients with metabolic disorders. Studies that evaluate mediating variables of the effect of HIIT-low volume on IR, such as endocrine function and skeletal muscle structure, are necessary to understand the role of skeletal muscle in the pathophysiology of MS and their regulation by exercise. TRIAL REGISTRATION: NCT03087721 . High-intensity Interval, Low Volume Training in Metabolic Syndrome (Intraining-MET). Registered on 22 March 2017, retrospectively registered.

Effects of energy drink major bioactive compounds on the performance of young adults in fitness and cognitive tests: a randomized controlled trial.

BACKGROUND: The consumption of beverages containing caffeine and taurine before exercising has been associated with increased physical and psychological performances and has been promoted to support the emotional state and provide vitality to consumers. However, there are contradictory results on these issues, it is not clear the effect of every major compound in relation to the whole effect of the beverages and there is a lack in knowledge about their degree of safety for consumption. METHODS: This study used a double-blind, placebo controlled, randomized, crossover design. Fourteen male volunteer soldiers from the Colombian army performed different tests to measure their cardiorespiratory fitness (VO2max and maximum heart rate), time to exhaustion, strength (isometric strength), power (vertical jump), concentration (Grid test) and memory (Digits test) after drinking 250 ml of one of the following beverages: one with 80 mg caffeine, one with 1000 mg taurine, one with 80 mg caffeine plus 1000 mg taurine, a commercial energy drink (Red Bull®) or a placebo drink. Subjects were caffeine-consumers that avoided caffeine during the day of evaluation. All beverages were matched in flavor and other organoleptic properties to the commercial one, were bottled in dark plastic bottles and were administered in identical conditions to the participants. Differences between treatments were assessed using repeated measures and analysis of variance. RESULTS: The mean ± SD values of VO2max, maximum heart rate, time to exhaustion, right handgrip strength, left handgrip strength, vertical jump, Grid test and Digits test were 61.3 ± 6.2 ml/kg.min, 196 ± 6.8 beats per min, 17 ± 1.2 min, 56.8 ± 6.6 kgf, 53.1 ± 5.9 kgf, 41.1 ± 3.8 cm, 19.9 ± 5.9 observed digits and 10.9 ± 3.1 remembered digits after drinking a placebo drink. Comparisons among the commercial drink, caffeine, taurine, caffeine plus taurine and placebo treatments did not show statistically differences in the results of the performed tests. No adverse effects were reported by the participants. CONCLUSION: The consumption of caffeine (80 mg) and taurine (1000 mg) or their combination does not increase the physical and cognitive ability in young adults during exercise.

Características funcionales de deportistas antioqueños de alto rendimiento

Se presentan los datos del consumo máximo de oxígeno (VO2max), de la capacidad física máxima de trabajo (PWCmax) y de la capacidad física máxima de trabajo a 170 pulsaciones por minuto (PWC170), de un grupo de deportistas de alto rendimiento, oriundos del departamento de Antioquia (Colombia). El estudio se realizó en 857 hombres competidores de atletismo de fondo, lucha olímpica, baloncesto, fútbol, microfútbol, ciclismo de pista, natación, patinaje y polo acuático. La valaración funcional se efectuó con un sistema espirométrico de circuito abierto y con un cicloergómetro de frenado electromagnético o una banda rodante motorizada, de acuerdo con las características y el gesto motor del deporte evaluado. De acuerdo con los resultados del presente estudio, en los deportes pedestres evaluados con una banda rodante, las determinaciones del VO2max, de la PWCmax y de la PWC170, son excelentes indicadores de la capacidad aeróbica, pero no lo son cuando para su determinación se emplea el cicloergómetro; quizás esto se deba a que la ejecución del trabajo en el cicloergómetro compromete masas musculares y gestos motores diferentes a los empleados comúnmente. Se propone la relación PWC170/PWCmax como un indicador de la eficiencia en la utilización de la capacidad aeróbica, útil para el diseño y control de los planes de entrenamiento en aquellos deportes en los cuales los procesos aeróbicos son determinantes para un adecuado desempeño.