Alpine Skiing as Winter-Time High-Intensity Training.

Introduction: To counteract the winter activity deficit, we set out to analyze cardiorespiratory and metabolic responses of two high-intensity training (HIT) protocols during alpine skiing (AS), cross-country skiing (XCS), and indoor cycling (IC) and the effects of sex, age, and fitness level in this comparison.

Methods: Nineteen healthy subjects (two age and fitness groups, both sexes) performed AS, XCS, and IC with measurements of oxygen uptake (V˙O2), energy expenditure (EE), HR, lactate, blood glucose and rate of perceived exertion, determined during 4 min of continuous HIT (HITc: 90% HRmax for XCS and IC or short turn skiing during AS) or 10-min intermittent HIT [HITint: 5 × 1 min high intensity (>90% HRmax or short turn skiing), 1 min active recovery].

Results: During all three exercise modes and irrespective of HIT protocols, sex, age, and fitness, participants were able to reach exercise intensities >90% HRmax and >84% V˙O2max.

A Comparison between Alpine Skiing, Cross-Country Skiing and Indoor Cycling on Cardiorespiratory and Metabolic Response.

Since physical inactivity especially prevails during winter months, we set out to identify outdoor alternatives to indoor cycling (IC) by comparing the metabolic and cardiorespiratory responses during alpine skiing (AS), cross-country skiing (XCS) and IC and analyse the effects of sex, age and fitness level in this comparison. Twenty one healthy subjects performed alpine skiing (AS), cross-country skiing (XCS), and IC. Oxygen uptake (VO2), total energy expenditure (EE), heart rate (HR), lactate, blood glucose and rate of perceived exertion (RPE) were determined during three 4-min stages of low, moderate and high intensity.

Repeated high intensity bouts with long recovery: are bicarbonate or carbohydrate supplements an option?

The effects of varying recovery modes and the influence of preexercise sodium bicarbonate and carbohydrate ingestion on repeated high intensity performance, acid-base response, and recovery were analyzed in 12 well-trained males. They completed three repeated high intensity running bouts to exhaustion with intervening recovery periods of 25 min under the following conditions: sodium bicarbonate, active recovery (BIC); carbohydrate ingestion, active recovery (CHO); placebo ingestion, active recovery (ACTIVE); placebo ingestion, passive recovery (PASSIVE). Blood lactate (BLa), blood gases, heart rate, and time to exhaustion were collected.

Effects of daily mechanical horseback riding on insulin sensitivity and resting metabolism in middle-aged type 2 diabetes mellitus patients.

The present study was conducted to investigate the effect of daily passive exercise using a horseback riding machine (Joba) on insulin sensitivity and resting metabolism in middle-aged, diabetic patients. Participants were 24 type 2 diabetes mellitus patients aged 59 +/- 8 years (mean +/- SD; range from 43 to 75 years of age). Patients were randomly divided into control (normal lifestyle) and Joba exercise groups.

Decreased enzyme activity and contents of hepatic branched-chain alpha-keto acid dehydrogenase complex subunits in a rat model for type 2 diabetes mellitus.

The mitochondrial branched-chain alpha-keto acid dehydrogenase complex (BCKDC) is responsible for the committed step in branched-chain amino acid catabolism. In the present study, we examined BCKDC regulation in Otsuka Long-Evans Tokushima Fatty (OLETF) rats both before (8 weeks of age) and after (25 weeks of age) the onset of type 2 diabetes mellitus. Long-Evans Tokushima Otsuka (LETO) rats were used as controls.

Development of new passive exercise equipment inducing contraction of functional muscles around knee joint without pain.

A new type of 'Passive Exercise Equipment' has been developed, which can induce muscular contraction of the functional muscles around knee joint. Not only user s who are not eager to exercise but also patients with both type 2 diabetes and knee joint osteoarthritis can perform exercise just by following our equipment's motion while sitting on it. In order to reduce knee joint pain, the equipment has three types of original functions.

Voluntary running improves in vivo insulin resistance in high-salt diet fed rats.

It is well known that exercise training, including voluntary running (VR), improves insulin resistance. However, the effect of VR on insulin resistance induced by high salt intake is unclear. The aim of this study was to determine whether VR would improve the glucose utilization in normal male Sprague-Dawley rats fed a high-salt diet (HSD) on 2-week early prevention and 1-week midway intervention protocols.

Clinical aspects of physical exercise for diabetes/metabolic syndrome.

Evidence-based medicine (EBM) has come to be regarded as essential in all fields of medical sciences and practical medicine. In the field of diabetes and exercise, among the epidemiological studies of physical exercise, recent mega-trials such as the Diabetes Prevention Program (DPP) in the U.S.

Increased expression of hepatic pyruvate dehydrogenase kinases 2 and 4 in young and middle-aged Otsuka Long-Evans Tokushima Fatty rats: induction by elevated levels of free fatty acids.

The activity of the pyruvate dehydrogenase complex (PDC) is regulated by covalent modification of its E1 component, which is catalyzed by specific pyruvate dehydrogenase kinases (PDKs) and phosphatases. In the liver, PDK2 and PDK4 are the most abundant PDK isoforms, which are responsible for inactivation of PDC when glucose availability is scarce in the body. In the present study, regulatory mechanisms of hepatic PDC were examined before and after the onset of type 2 diabetes mellitus in Otsuka Long-Evans Tokushima Fatty (OLETF) rats, using Long-Evans Tokushima Otsuka (LETO) rats as controls.

Attenuated response of the serum triglyceride concentration to ingestion of a chocolate containing polydextrose and lactitol in place of sugar.

We examined the effects of ingesting a non-sugar chocolate containing polydextrose and lactitol in place of sucrose and lactose on the concentrations of plasma glucose and serum insulin and triglyceride in humans. A regular chocolate was used as the control. A crossover study was employed, and the subjects each ingested 46 g of the control or non-sugar chocolate in the experiments.

Mechanical horseback riding improves insulin sensitivity in elder diabetic patients.

The present study was undertaken to analyze the acute and chronic effects of exercise on insulin sensitivity in elder diabetic patients using a horseback riding therapeutic equipment (Joba). The acute effects of exercise were examined by means of a single session of Joba riding that lasted for 30 min. The average glucose infusion rates (GIR) before and during exercise were regarded as an index of the insulin action in peripheral tissues by the euglycemic clamp.

Gosha-jinki-gan (a Herbal Complex) Corrects Abnormal Insulin Signaling.

Previous studies have shown that the traditional herbal complex Gosha-jinki-gan (GJG) improves diabetic neuropathy and insulin resistance. The present study was undertaken to elucidate the molecular mechanisms related with the long-term effects of GJG administration on insulin action in vivo and the early steps of insulin signaling in skeletal muscle in streptozotocin (STZ) diabetes. Rats were randomized into five subgroups: (1) saline treated control, (2) GJG treated control, (3) 2-unit insulin + saline treated diabetic, (4) saline + GJG treated diabetic and (5) 2-unit insulin + GJG treated diabetic groups.

Regulation of branched-chain amino acid metabolism and pharmacological effects of branched-chain amino acids.

Significant evidence of the pharmacological and physiological effects of branched-chain amino acids (BCAA) has accumulated, attracting the interest of not only clinicians but also basic medical researchers. We summarize here the characteristic features of BCAA catabolism, focusing on the initial two enzymes in the pathway, branched-chain aminotransferase and branched-chain alpha-keto acid dehydrogenase complex. In addition, we describe a unique characteristic of the valine catabolic pathway.

Estrogen controls branched-chain amino acid catabolism in female rats.

A diurnal rhythm occurs in the activity state of branched-chain alpha-keto acid dehydrogenase complex (BCKDC) in female but not male rats. We attempted to determine the role played by ovarian hormones in this difference in enzyme regulation. A series of experiments examined the effects of the 4-d estrous cycle, ovariectomy, and replacement of female sex steroids on the catabolism of BCAAs.

Downregulation of the skeletal muscle pyruvate dehydrogenase complex in the Otsuka Long-Evans Tokushima Fatty rat both before and after the onset of diabetes mellitus.

The pyruvate dehydrogenase complex (PDC) catalyzes the irreversible oxidative decarboxylation of pyruvate in mitochondria. The PDC activity is regulated by a phosphorylation/dephosphorylation cycle catalyzed by specific kinases (PDK) and phosphatases (PDP). In this study, the regulatory mechanisms of PDC were examined in skeletal muscle of the spontaneously diabetic Otsuka Long-Evans Tokushima Fatty (OLETF) rat before and after the onset of diabetes.

Exercise promotes BCAA catabolism: effects of BCAA supplementation on skeletal muscle during exercise.

Branched-chain amino acids (BCAAs) are essential amino acids that can be oxidized in skeletal muscle. It is known that BCAA oxidation is promoted by exercise. The mechanism responsible for this phenomenon is attributed to activation of the branched-chain alpha-keto acid dehydrogenase (BCKDH) complex, which catalyzes the second-step reaction of the BCAA catabolic pathway and is the rate-limiting enzyme in the pathway.

Effects of liver failure on branched-chain alpha-keto acid dehydrogenase complex in rat liver and muscle: comparison between acute and chronic liver failure.

Background/aims: Branched-chain alpha-keto acid dehydrogenase (BCKDH) complex catalyses the committed step in the branched-chain amino acid (BCAA) catabolic pathway. In many cases of liver failure, the serum BCAAs/aromatic amino acids ratio (Fisher's ratio) decreases, and BCAAs have been administered to patients with liver failure to correct this ratio. We conducted an animal study to examine whether the effects on hepatic BCKDH complex differ between acute liver failure (ALF) and chronic liver failure (CLF).

Effects of liver failure on the enzymes in the branched-chain amino acid catabolic pathway.

Branched-chain alpha-keto acid dehydrogenase (BCKDH) complex catalyzes the committed step of the catabolism of branched-chain amino acids (BCAA). The liver cirrhosis chemically induced in rats raised the activity of hepatic BCKDH complex and decreased plasma BCAA and branched-chain alpha-keto acid concentrations, suggesting that the BCAA requirement is increased in liver cirrhosis. Since the effects of liver cirrhosis on the BCKDH complex in human liver are different from those in rat liver, further studies are needed to clarify the differences between rats and humans.

Cinnamon extract (traditional herb) potentiates in vivo insulin-regulated glucose utilization via enhancing insulin signaling in rats.

Cinnamon has been shown to potentiate the insulin effect through upregulation of the glucose uptake in cultured adipocytes. In the present study, we evaluated the effect of the cinnamon extract on the insulin action in awaked rats by the euglycemic clamp and further analyzed possible changes in insulin signaling occurred in skeletal muscle. The rats were divided into saline and cinnamon extract (30 and 300 mg/kg BW-doses: C30 and C300) oral administration groups.

Physical exercise improves glucose metabolism in lifestyle-related diseases.

The beneficial effects of physical exercise on the decreased insulin sensitivity caused by detrimental lifestyle were reviewed based on experimental evidences. In epidemiological studies, disease prevention has been considered at three levels: primary (avoiding the occurrence of disease), secondary (early detection and reversal), and tertiary (prevention or delay of complications). The major purpose of physical exercise for primary prevention and treatment of lifestyle-related diseases is to improve insulin sensitivity.

Effects of keishi-ka-jutsubu-to (traditional herbal medicine: Gui-zhi-jia-shu-fu-tang) on in vivo insulin action in streptozotocin-induced diabetic rats.

This study investigated the effects of the traditional herbal medicine, Keishi-ka-jutsubu-to (KJT) on insulin action in vivo and insulin signaling in skeletal muscle in STZ-induced diabetes. Rats were divided into single and 7-days oral administration groups. Euglycemic clamp (insulin infusion rates: 3 and 30 mU/kg/min) was used in awaked rats and the insulin signaling in skeletal muscle was evaluated.

Exercise training increases the activity of pyruvate dehydrogenase complex in skeletal muscle of diabetic rats.

The effects of diabetes and exercise training on the activity of pyruvate dehydrogenase (PDH) complex in skeletal muscle were examined in rats. Male Sprague-Dawley rats were divided into four groups as follows: non-diabetic sedentary, non-diabetic trained, diabetic sedentary, and diabetic trained groups. Diabetic rats were prepared by a bolus injection of intravenous streptozotocin (50 mg/kg body weight).