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Summary Abdominal adiposity and low cardiorespiratory fitness are assosicated with insulin resistance in people with impaired glucose tolerance and type 2 diabetes. However, little is known about which factor precedes insulin resistance in people with impaired glucose tolerance and type 2 diabetes, and which is the stronger predictor of insulin resistance in non-diabetic people. The purpose of this study was to examine the relationship between insulin resistance and cardiorespiratory fitness, visceral fat, and subcutaneous fat in nondiabetic people. Subjects included 87 men and 77 women aged 30-72 y (mean Ϯ SD, 51.3 Ϯ 12.3 y). Cardiorespiratory fitness was assessed by measuring the maximal oxygen uptake (V · O 2max ) in a progressive continuous test to exhaustion on a cycle ergometer. The visceral and subcutaneous fat areas were measured by magnetic resonance imaging. The homeostasis model assessment of insulin resistance (HOMA-R) was calculated from the fasting concentrations of glucose and insulin. Stepwise multiple linear regression analysis revealed that visceral and subcutaneous fat were significant correlates of HOMA-R, explaining 24% and 6% of the variance, respectively, whereas sex, age, and V · O 2max were not significant independent determinants. Abdominal fat deposition rather than cardiorespiratory fitness is a significant predictor of insulin resistance in non-diabetic people; visceral fat is the most important factor.

We examined whether cardiorespiratory fitness (maximal oxygen uptake, V O 2 max) and muscular strength (grip strength) are associated with individual and clustered metabolic risk factors independently of abdominal adiposity in Japanese men (nϭ110) and women (nϭ110) aged 20-69 years. Blood pressure, triglycerides (TG), HDL cholesterol, and fasting plasma glucose (FPG) were assessed and metabolic risk score was calculated, which is the sum of the z scores for each individual risk factor. Waist circumference was measured and the area of visceral fat was assessed by MRI. Multiple linear regression analysis revealed that V O 2 max was inversely associated with TG in men ( pϽ0.05) and grip strength was negatively associated with FPG and metabolic risk score in women ( pϽ0.001 and pϽ0.05, respectively), independently of waist circumference. Adjusting for visceral fat instead of waist circumference, similar results were obtained in women (pϽ0.01 and pϽ0.05, respectively), but the association between V O 2 max and TG in men was attenuated to nonsignificant. This cross-sectional study demonstrates that muscular strength is inversely associated with plasma glucose levels and clustered metabolic risk factors independently of abdominal adiposity in Japanese women, but not in men.

The present study elucidated the effects of habitual rowing exercise on arterial stiffness and plasma levels of the vasoconstrictor endothelin-1 and the vasodilator nitric oxide (NO) in older men. Eleven rowers (68.0 ± 1.6 years) and 11 sedentary control older men (64.9 ± 1.1 years) were studied. Peak oxygen uptake (36.0 ± 1.7 vs. 27.7 ±1.9 ml · kg(-1) · min(-1)), leg press power (1346 ± 99 vs. 1077 ± 68 W), and HDL-cholesterol (75 ± 5 vs. 58 ±3 mg · ml(-1)) were higher and triglyceride (78 ± 9 vs. 120 ± 14 mg · ml(-1)) was lower in rowers than in control participants (all P < 0.05). Arterial stiffness indices (carotid β-stiffness and cardio-ankle vascular index) and plasma endothelin-1 and NOx (nitrite + nitrate) levels did not differ between the two groups. These results suggest that habitual rowing exercise in older men is associated with high muscle power and aerobic capacity, and favourable blood lipid profile without affecting arterial stiffness or plasma levels of endotheline-1 and NO.

SummaryWe investigated the effects of two carbohydrate-based sports drinks on fluid intake and immunoendocrine responses to cycling. Six well-trained male cyclists completed trials on three separate days that involved cycling at 60% V · O2peak for 90 min in hot conditions (28.161.5˚C and 52.663.1% relative humidity). During each trial, the subjects consumed ad libitum (1) an isotonic sports drink (osmolality 317 mOsm/kg), (2) . Blood glucose concentration was significantly higher at the end of the isotonic and hypotonic drink trials compared with the water trial. Neutrophil count and the plasma concentrations of catecholamines, interleukin 6 (IL-6), myeloperoxidase, calprotectin and myoglobin increased significantly during all three trials. IL-6 and calprotectin were significantly lower following the hypotonic drink trial compared with the water trial. In conclusion, hypotonic sports drinks are appealing for athletes to drink during exercise, and may help to offset fluid losses and attenuate some inflammatory responses to exercise.

BackgroundSex hormones are known to regulate some responses during exercise. Evaluation of the differences in exercise response with regard to menstrual cycle will help understand the menstrual cycle phase specific adaptations to exercise and athletic performance.MethodsWe investigated the effects of menstrual cycle phase and carbohydrate (CHO) ingestion on immune response during endurance exercise at 30°C. Six healthy women completed 4 trials comprising 90 min of cycling at 50% peak aerobic power ()trueV˙O2normalpeak and a high intensity time trial performance test (POST). They ingested a placebo- or CHO-containing beverage during the trials, which were performed during both the follicular and luteal phases of the menstrual cycle. In all trials, thermoregulatory, cardiorespiratory, and immune responses were measured during exercise and after POST.ResultsAlthough the thermoregulatory responses differed between the menstrual cycle phases, the cardiorespiratory responses were not different. After placebo ingestion, leukocyte concentration (cells/μL) at POST (15.9 × 103) in the luteal phase was significantly higher than that in the follicular phase (12.9 × 103). The rise in leukocyte concentration was attenuated upon CHO ingestion, and the difference between menstrual cycle phases disappeared. A significant positive correlation was found between leukocyte concentration and serum free fatty acid concentrations. Interleukin-6, calprotectin, and myeloperoxidase concentrations significantly increased at POST in all trials, but no significant differences were observed between menstrual cycle phase or beverage type. Concentrations of other cytokines did not change during exercise in any of the 4 trials. Menstrual cycle phase and beverage type had no significant effect on the POST outcome. Thus, differences in leukocyte mobilization between menstrual cycle phases could result from the effect of sex hormones on substrate utilization.ConclusionsThe menstrual cycle affected circulating leukocyte concentrations during endurance exercise with POST when a placebo was ingested. Therefore, we recommend ingesting CHO beverages to attenuate immune disturbances, especially in the luteal phase, even though they are unlikely to enhance test performance.

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SummaryThis study examined the effects of maintaining euhydration by ingesting fluids with or without carbohydrate on subjective responses of untrained men during prolonged exercise in a hot environment. Six healthy untrained subjects completed 90 min of cycling exercises at 55% maximal oxygen consumption (V O 2 max ) in a hot environment (temperature: 28˚C, humidity: 50%) under three different experimental conditions. During the first trial, subjects did not ingest fluids during exercise (dehydration (DH) trial). In the second and third trials, subjects received mineral water (MW) and hypotonic fluid containing carbohydrate (HF), respectively, in amounts equaling their weight loss in the DH trial. At the end of exercise, the overall rating of perceived exertion (RPE-O) was lower in the MW and HF trials than in the DH trial (14.3 Ϯ 1.0 and 13.7 Ϯ 0.6 vs 17.7 Ϯ 1.0, p Ͻ 0.05, respectively). RPEcardiovascular and RPE-legs were lower at the end of exercise in the HF trial compared with the DH trial. V O 2 , heart rate (HR), and rectal temperature increased during exercise in the three trials. At the end of exercise, the drift in V O 2 was lower in the MW and HF trials than in the DH trial (304 Ϯ 41 and 339 Ϯ 40 vs 458 Ϯ 33 mL, p Ͻ 0.05, respectively). HR at the end of exercise in the HF trial was lower than in the DH trial (158 Ϯ 5 vs 173 Ϯ 7 bpm, p Ͻ 0.05). These results suggest that maintaining euhydration during prolonged exercise in untrained men could attenuate RPE-O and that hypotonic electrolyte-carbohydrate solution could attenuate RPE-legs during exercise. Key Words maintaining euhydration, perceived exertion, prolonged exercise, heat exposure Dehydration, hyperthermia and muscle glycogen depletion are the major determinant factors that induce the reduction of performance during prolonged exercise. Fluid ingestion, especially in a hot environment, attenuates hyperthermia and cardiovascular drift ( 1-4 ), and carbohydrate ingestion reduces the rating of perceived exertion (RPE) during prolonged exercise in endurance-trained subjects ( 5-10 ). However, there is no available data about the physiological and subjective benefits of maintaining body water by ingesting fluid with or without carbohydrate supplementation during prolonged submaximal exercise in untrained healthy subjects.Maintaining euhydration by fluid ingestion attenuates cardiovascular strain induced by both hyperthermia and dehydration during prolonged submaximal exercise in the heat ( 2-4 ). Gonzalez-Alonso et al. suggested that despite a marked cardiovascular drift at the 120 min of exercise, corresponding to ~60% maximal oxygen consumption (V O 2 max ) in a dehydration trial, the increase in V O 2 for exercising and nonexercising muscle of the whole body was similar to a euhydration trial ( 2 ). Additionally, it has been demonstrated that during prolonged exercise an increase in carbohydrate availability by carbohydrate supplementation attenuated RPE ( 8 , 9 , 11 ) while fluid ingestion did not attenuate the RPE ( 4 , 12 ). However, these stu...