Aerobic interval training (AIT) improves the health of metabolic syndrome patients (MetS) more than moderate intensity continuous training. However, AIT has not been shown to reverse all metabolic ...syndrome risk factors, possibly due to the limited duration of the training programs. Thus, we assessed the effects of 6 months of AIT on cardio‐metabolic health and muscle metabolism in middle‐aged MetS. Eleven MetS (54.5±0.7 years old) underwent 6 months of 3 days a week supervised AIT program on a cycle ergometer. Cardio‐metabolic health was assessed, and muscle biopsies were collected from the vastus lateralis prior and at the end of the program. Body fat mass (−3.8%), waist circumference (−1.8%), systolic (−10.1%), and diastolic (−9.3%) blood pressure were reduced, whereas maximal fat oxidation rate and VO2peak were significantly increased (38.9% and 8.0%, respectively; all P<.05). The remaining components of cardio‐metabolic health measured (body weight, blood cholesterol, triglycerides, and glucose) were not changed after the intervention, and likewise, insulin sensitivity (CSi) remained unchanged. Total AMPK (23.4%), GLUT4 (20.5%), endothelial lipase (33.3%) protein expression, and citrate synthase activity (26.0%) increased with training (P<.05). Six months of AIT in MetS raises capacity for fat oxidation during exercise and increases VO2peak in combination with skeletal muscle improvements in mitochondrial enzyme activity. Muscle proteins involved in glucose, fat metabolism, and energy cell balance improved, although this was not reflected by parallel improvements in insulin sensitivity or blood lipid profile.
We studied if salt and water ingestion alleviates the physiological strain caused by dehydrating exercise in the heat. Ten trained male cyclists (
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: 60 ± 7 mL/kg/min) completed three ...randomized trials in a hot‐dry environment (33 °C, 30% rh, 2.5 m/s airflow). Ninety minutes before the exercise, participants ingested 10 mL of water/kg body mass either alone (CON trial) or with salt to result in concentrations of 82 or 164 mM Na+ (ModNa+ or HighNa+ trial, respectively). Then, participants cycled at 63% of
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for 120 min immediately followed by a time‐trial. After 120 min of exercise, the reduction in plasma volume was lessened with ModNa+ and HighNa+ trials (−11.9 ± 2.1 and −9.8 ± 4.2%) in comparison with CON (−16.4 ± 3.2%; P < 0.05). However, heat accumulation or dissipation (forearm skin blood flow and sweat rate) were not improved by salt ingestion. In contrast, both salt trials maintained cardiac output (∼1.3 ± 1.4 L/min; P < 0.05) and stroke volume (∼10 ± 11 mL/beat; P < 0.05) above CON after 120 min of exercise. Furthermore, the salt trials equally improved time‐trial performance by 7.4% above CON (∼289 ± 42 vs 269 ± 50 W, respectively; P < 0.05). Our data suggest that pre‐exercise ingestion of salt plus water maintains higher plasma volume during dehydrating exercise in the heat without thermoregulatory effects. However, it maintains cardiovascular function and improves cycling performance.
Our purpose in this study was to investigate efficient and sustainable combinations of exercise and diet-induced weight loss (DIET), in order to combat obesity in metabolic syndrome (MetS) patients. ...We examined the impact of aerobic interval training (AIT), followed by or concurrent to a DIET on MetS components. 36 MetS patients (54±9 years old; 33±4 BMI; 27 males and 9 females) underwent 16 weeks of AIT followed by another 16 weeks without exercise from the fall of 2013 to the spring of 2014. Participants were randomized to AIT without DIET (E CON, n=12), AIT followed by DIET (E-then-D, n=12) or AIT concurrent with DIET (E+D, n=12) groups. Body weight decreased below E CON similarly in the E-then-D and E+D groups (~5%). Training improved blood pressure and cardiorespiratory fitness (VO2peak) in all groups with no additional effect of concurrent weight loss. However, E+D improved insulin sensitivity (HOMA) and lowered plasma triglycerides and blood cholesterol below E CON and E-then-D (all P<0.05). Weight loss in E-then-D in the 16 weeks without exercise lowered HOMA to the E+D levels and maintained blood pressure at trained levels. Our data suggest that a new lifestyle combination consisting of aerobic interval training followed by weight loss diet is similar, or even more effective on improving metabolic syndrome factors than concurrent exercise plus diet.
This study analyzed the effects of pseudoephedrine (PSE) provided at different time of day on neuromuscular performance, side effects, and violation of the current doping cut‐off threshold World ...Anti‐Doping Agency (WADA). Nine resistance‐trained males carried out bench press and full squat exercises against four incremental loads (25%, 50%, 75%, and 90% one repetition maximum 1RM), in a randomized, double‐blind, cross‐over design. Participants ingested either 180 mg of PSE (supra‐therapeutic dose) or placebo in the morning (7:00 h; AMPLAC and AMPSE) and in the afternoon (17:00 h; PMPLAC and PMPSE). PSE enhanced muscle contraction velocity against 25% and 50% 1RM loads, only when it was ingested in the mornings, and only in the full squat exercise (4.4–8.7%; P < 0.05). PSE ingestion raised urine and plasma PSE concentrations (P < 0.05) regardless of time of day; however, cathine only increased in the urine samples. PSE ingestion resulted in positive tests occurring in 11% of samples, and it rose some adverse side effects such us tachycardia and heart palpitations. Ingestion of a single dose of 180 mg of PSE results in enhanced lower body muscle contraction velocity against low and moderate loads only in the mornings. These mild performance improvements are accompanied by undesirable side effects and an 11% risk of surpassing the doping threshold.
This study investigated which exercise mode (continuous or sprint interval) is more effective for improving insulin sensitivity. Ten young, healthy men underwent a non-exercise trial (CON) and 3 ...exercise trials in a cross-over, randomized design that included 1 sprint interval exercise trial (SIE; 4 all-out 30-s sprints) and 2 continuous exercise trials at 46% VO2peak (CELOW) and 77% VO2peak (CEHIGH). Insulin sensitivity was assessed using intravenous glucose tolerance test (IVGTT) 30 min, 24 h and 48 h post-exercise. Energy expenditure was measured during exercise. Glycogen in vastus lateralis was measured once in a resting condition (CON) and immediately post-exercise in all trials. Plasma lipids were measured before each IVGTT. Only after CEHIGH did muscle glycogen concentration fall below CON (P<0.01). All exercise treatments improved insulin sensitivity compared with CON, and this effect persisted for 48-h. However, 30-min post-exercise, insulin sensitivity was higher in SIE than in CELOW and CEHIGH (11.5±4.6, 8.6±5.4, and 8.1±2.9 respectively; P<0.05). Insulin sensitivity did not correlate with energy expenditure, glycogen content, or plasma fatty acids concentration (P>0.05). After a single exercise bout, SIE acutely improves insulin sensitivity above continuous exercise. The higher post-exercise hyperinsulinemia and the inhibition of lipolysis could be behind the marked insulin sensitivity improvement after SIE.
We determined if dehydration alone or in combination with hyperthermia accelerates muscle glycogen use during intense exercise. Seven endurance‐trained cyclists (VO2max = 54.4 ± 1.05 mL/kg/min) ...dehydrated 4.6% of body mass (BM) during exercise in the heat (150 min at 33 ± 1 °C, 25 ± 2% humidity). During recovery (4 h), subjects remained dehydrated (HYPO trial) or recovered all fluid losses (REH trials). Finally, subjects exercised intensely (75% VO2max) for 40 min in a neutral (25 ± 1 °C; HYPO and REH trials) or in a hot environment (36 ± 1 °C; REHHOT). Before the final exercise bout vastus lateralis glycogen concentration was similar in all three trials (434 ± 57 mmol/kg of dry muscle (dm)) but muscle water content was lower in the HYPO (357 ± 14 mL/100 g dm) than in REH trials (389 ± 25 and 386 ± 25 mL/100 g dm; P < 0.05). After 40 min of intense exercise, intestinal temperature was similar between the HYPO and REHHOT trials (39.2 ± 0.5 and 39.2 ± 0.4 °C, respectively) and glycogen use was similar (172 ± 86 and 185 ± 97 mmol/kg dm, respectively) despite large differences in muscle water content. In contrast, during REH, intestinal temperature (38.5 ± 0.4 °C) and glycogen use (117 ± 52 mmol/kg dm) were significantly lower than during HYPO and REHHOT. Our data suggest that hyperthermia stimulates glycogen use during intense exercise while muscle water deficit has a minor role.
We studied if dehydrating exercise would reduce muscle water (H2Omuscle) and affect muscle electrolyte concentrations. Vastus lateralis muscle biopsies were collected prior, immediately after, and 1 ...and 4 h after prolonged dehydrating exercise (150 min at 33 ± 1 °C, 25% ± 2% humidity) on nine endurance‐trained cyclists (VO2max = 54.4 ± 1.05 mL/kg/min). Plasma volume (PV) changes and fluid shifts between compartments (Cl− method) were measured. Exercise dehydrated subjects 4.7% ± 0.3% of body mass by losing 2.75 ± 0.15 L of water and reducing PV 18.4% ± 1% below pre‐exercise values (P < 0.05). Right after exercise H2Omuscle remained at pre‐exercise values (i.e., 398 ± 6 mL/100 g dw muscle−1) but declined 13% ± 2% (342 ± 12 mL/100 g dw muscle−1; P < 0.05) after 1 h of supine rest. At that time, PV recovered toward pre‐exercise levels. The Cl− method corroborated the shift of fluid between extracellular and intracellular compartments. After 4 h of recovery, PV returned to pre‐exercise values; however, H2Omuscle remained reduced at the same level. Muscle Na+ and K+ increased (P < 0.05) in response to the H2Omuscle reductions. Our findings suggest that active skeletal muscle does not show a net loss of H2O during prolonged dehydrating exercise. However, during the first hour of recovery H2Omuscle decreases seemly to restore PV and thus cardiovascular stability.
Aim: Higher-elevation areas on islands and continental mountains tend to be separated by longer distances, predicting higher endemism at higher elevations; our study is the first to test the ...generality of the predicted pattern. We also compare it empirically with contrasting expectations from hypotheses invoking higher speciation with area, temperature and species richness. Location: Thirty-two insular and 18 continental elevational gradients from around the world. Methods: We compiled entire floras with elevation-specific occurrence information, and calculated the proportion of native species that are endemic ('percent endemism') in 100-m bands, for each of the 50 elevational gradients. Using generalized linear models, we tested the relationships between percent endemism and elevation, isolation, temperature, area and species richness. Results: Percent endemism consistently increased monotonically with elevation, globally. This was independent of richness—elevation relationships, which had varying shapes but decreased with elevation at high elevations. The endemism—elevation relationships were consistent with isolation-related predictions, but inconsistent with hypotheses related to area, richness and temperature. Main conclusions: Higher per-species speciation rates caused by increasing isolation with elevation are the most plausible and parsimonious explanation for the globally consistent pattern of higher endemism at higher elevations that we identify. We suggest that topography-driven isolation increases speciation rates in mountainous areas, across all elevations and increasingly towards the equator. If so, it represents a mechanism that may contribute to generating latitudinal diversity gradients in a way that is consistent with both present-day and palaeontological evidence.
Abstract Background and aims Exercise training can improve health of patients with metabolic syndrome (MetS). However, which MetS factors are most responsive to exercise training remains unclear. We ...studied the time-course of changes in MetS factors in response to training and detraining. Methods and results Forty eight MetS patients (52 ± 8.8 yrs old; 33 ± 4 BMI) underwent 4 months (3 days/week) of supervised aerobic interval training (AIT) program. After 1 month of training, there were progressive increases in high density lipoprotein cholesterol (HDL-c) and reductions in waist circumference and blood pressure (12 ± 3, −3.9 ± 0.4, and −12 ± 1%, respectively after 4 months; all P < 0.05). However, fasting plasma concentration of triglycerides and glucose were not reduced by training. Insulin sensitivity (HOMA), cardiorespiratory fitness (VO2 peak) and exercise maximal fat oxidation (FOMAx ) also progressively improved with training (−17 ± 5; 21 ± 2 and 31 ± 8%, respectively, after 4 months; all P < 0.05). Vastus lateralis samples from seven subjects revealed that mitochondrial O2 flux was markedly increased with training (71 ± 11%) due to increased mitochondrial content. After 1 month of detraining, the training-induced improvements in waist circumference and blood pressure were maintained. HDL-c and VO2 peak returned to the values found after 1–2 months of training while HOMA and FOMAx returned to pre-training values. Conclusions The health related variables most responsive to aerobic interval training in MetS patients are waist circumference, blood pressure and the muscle and systemic adaptations to consume oxygen and fat. However, the latter reverse with detraining while blood pressure and waist circumference are persistent to one month of detraining.
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