Aerobic training effects on glucose tolerance in prediabetic and normoglycemic humans.
ABSTRACT It is generally accepted that if prediabetic individuals adopt healthy lifestyle habits, the progression to type 2 diabetes mellitus can be prevented or delayed. However, the role of exercise training independent of other lifestyle factors has not been determined. Furthermore, patients with type 2 diabetes mellitus have been shown to experience greater training-induced changes in glucose and insulin metabolism compared with healthy subjects, but the adaptations of prediabetic individuals have not been adequately examined. We hypothesized that (i) prediabetic subjects would have greater endurance training-induced changes in plasma glucose and insulin responses to an oral glucose challenge compared with age- and body mass index-matched normoglycemic subjects and (ii) training would completely reverse the abnormal glucose metabolism of prediabetic subjects.
Plasma glucose and insulin responses to oral glucose tolerance tests (OGTTs) were examined in normoglycemic (n = 119) and prediabetic (n = 47) older men and women before and after a 6-month standardized endurance exercise training program.
Prediabetic subjects had greater glucose and insulin OGTT responses than normoglycemic subjects both before and after training (P < 0.05). Prediabetic subjects had greater training-induced changes in glucose and insulin areas under the glucose tolerance curve, as well as greater changes in glucose and insulin concentrations at several points of the OGTT. However, these changes did not eliminate the baseline differences in glucose tolerance between normoglycemic and prediabetic subjects. The between-group differences in changes in glucose and insulin variables were largely independent of changes in body weight or composition.
Our data indicate that prediabetes is associated with greater training-induced changes in glucose tolerance. However, 6 months of endurance training alone was not sufficient to completely reverse prediabetes.
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ABSTRACT: The aim of the present study was to determine which of the available glucose tolerance tests (oral (OGTT) vs. intravenous (IVGTT)) could more readily detect the insulin sensitizing effects of a bout of continuous exercise. Ten healthy moderately fit young men (VO2peak of 45.4 ± 1.8 mL·kg−1·min−1; age 27.5 ± 2.7 yr) underwent 4 OGTT and 4 IVGTT on different days following a standardized dinner and overnight fast. One test was performed immediately after 55 min of cycle-ergometer exercise at 60% VO2peak. Insulin sensitivity index was determined during a 50 min IVGTT according to Tura (CISI) and from a 120 min OGTT using the Matsuda composite index (MISI). After exercise, MISI improved 29 ± 10% without reaching statistical significance (p = 0.182) due to its low reproducibility (coefficient of variation 16 ± 3%; intra-class reliability 0.846). However, CISI significantly improved (50 ± 4%; p ISI compared with MISI suggests the preferential use of IVGTT to assess the effects of exercise on insulin sensitivity when using a glucose tolerance test.Applied Physiology Nutrition and Metabolism 07/2014; 39(7). · 2.23 Impact Factor
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ABSTRACT: This study described physiological and perceptual responses to Cardio tennis® for 'younger' and 'older' adult populations of both sex's for health-related outcomes. Thirty-one active participants, each with prior recreational tennis experience (∼2 years) (8 younger and 8 older males, and 7 younger and 8 older females) performed preliminary testing and a 50-min instructor-led Cardio tennis® session. Cardio tennis® is a conditioning-based tennis program comprised of warm-up movements, drill-based exercises (set movement and hitting games) and competitive play scenarios. Participants performed the 20-m shuttle run test to determine maximal heart rate (HR) during preliminary testing. Before, after and 30-min post Cardio tennis® session, HR, blood pressure (BP), Rate Pressure Product (RPP) and capillary blood lactate and glucose were determined. Further, HR and pedometer-derived step counts were measured throughout, while the session was filmed and coded for technical skill. Following the session, ratings of perceived exertion (RPE), enjoyment and challenge were obtained. HR, systolic BP and RPP were significantly increased by Cardio tennis® (p<0.05), though returned to pre-exercise levels 30-min after (p>0.05). HR and BP did not differ between groups pre- or 30-min post-exercise (p>0.05); however, were lower in younger males during and higher in younger females post-session (p<0.05). Lactate and glucose concentrations were increased in all groups (p<0.05), with lactate highest in male groups (p<0.05), without differences in glucose between groups (p>0.05). Stroke and step counts were not different between groups (p>0.05). RPE and perceived challenge were lowest in the younger male group compared to all other groups (p<0.05). Cardio tennis® presents as an effective stimulus to invoke sufficient cardiovascular and metabolic load to benefit health and fitness, though age-and sex-based responses should be considered in prescription.The Journal of Strength and Conditioning Research 05/2014; · 1.80 Impact Factor
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ABSTRACT: Background: High intensity training could be an effective way of improving health on individuals at high metabolic risk. Aim: To investigate the effects of a high intensity training intervention on metabolic-related markers in sedentary women at high metabolic risk. Material and Methods: Forty six sedentary women with a body mass index (BMI) over 25 kg/m² were assigned to four groups, according to their metabolic profile; hyperglycemia (H, n = 12), hyperglycemia/hypercholesterolemia (HH, n = 13), normoglycemia (N, n = 10) and normoglycemia/hypercholesterolemia (NH, n = 11). For 12 weeks and five days per week, subjects performed seven intervals of high intensity training (20 to 30 seconds) during a training session of 20 minutes. Anthropometric (body weight, body mass index (BMI), waist circumference) and metabolic variables (glucose, total cholesterol, LDL, HDL and TG) were measured at baseline, at 6 and 12 weeks of intervention. Results: BMI and waist circumference decreased significantly after 12 weeks of intervention. Similarly, glucose decreased significantly after 12 weeks of intervention in all groups. The reduction was of higher magnitude in those groups with hyperglycemia (H = -16%, HH = -22%, N = -7,5%, NH = -9,6%). However, lipid profile (TG, total cholesterol, LDL and HDL) improved significantly only in the hypercholesterolemic groups. Conclusions: Physical activity programs incorporating high intensity training can improve glucose and lipid profile in women with metabolic disorders. Moreover, this benefit is greatest in those individuals with highest metabolic burden.Revista medica de Chile 10/2013; 141(10):1293-9. · 0.37 Impact Factor