Skeletal muscle transcriptome profiles related to different training intensities and detraining in Standardbred horses: a search for overtraining biomarkers.

Training horses improves athletic capabilities by inducing skeletal muscle-specific and systemic adaptations. However, rest is required to recover from exercise or else overtraining may occur and affect performance and welfare. Biomarkers would be useful to identify early chronic overtraining in animals.

Protein supplementation during resistance-type exercise training in the elderly.

Introduction: Resistance training has been well established as an effective treatment strategy to increase skeletal muscle mass and strength in the elderly. We assessed whether dietary protein supplementation can further augment the adaptive response to prolonged resistance-type exercise training in healthy elderly men and women.

Methods: Healthy elderly men (n = 31, 70 ± 1 yr) and women (n = 29, 70 ± 1 yr) were randomly assigned to a progressive, 24-wk resistance-type exercise training program with or without additional protein supplementation (15 g·d-1).

Effects of intensified training and subsequent reduced training on glucose metabolism rate and peripheral insulin sensitivity in Standardbreds.

Objective: To determine the influence of intensified training and subsequent reduced training on glucose metabolism rate and peripheral insulin sensitivity in horses and identify potential markers indicative of early overtraining.

Animals: 12 Standardbred geldings.

Procedures: Horses underwent 4 phases of treadmill-based training.

Assessment of endogenous growth hormone pulsatility in gelded yearling horses using deconvolution analysis.

Hypothesis/objectives: Defining normal Growth Hormone (GH) secretory dynamics in the horse is necessary to understand altered GH dynamics related to issues like welfare and disease.

Animals And Methods: Twelve healthy yearlings and two mature Standardbreds were used to quantify GH secretion. Endogenous GH half-life was determined after administration of 1.

Plasma acylcarnitine and fatty acid profiles during exercise and training in Standardbreds.

Objective: To evaluate alterations in skeletal muscle carnitine metabolism during exercise and training by measuring changes in plasma acylcarnitine concentrations in Standardbreds.

Animals: 10 Standardbred geldings with a mean +/- SD age of 20 +/- 2 months and weight of 384 +/- 42 kg.

Procedures: In a 32-week longitudinal study, training on a treadmill was divided into 4 phases as follows: phase 1, acclimatization for 4 weeks; phase 2, 18 weeks with alternating endurance and high-intensity exercise training; phase 3, increased training volume and intensity for another 6 weeks; and phase 4, deconditioning for 4 weeks.

(Over)training effects on quantitative electromyography and muscle enzyme activities in standardbred horses.

Too intensive training may lead to overreaching or overtraining. To study whether quantitative needle electromyography (QEMG) is more sensitive to detect training (mal)adaptation than muscle enzyme activities, 12 standardbred geldings trained for 32 wk in age-, breed-, and sex-matched fixed pairs. After a habituation and normal training (NT) phase (phases 1 and 2, 4 and 18 wk, respectively), with increasing intensity and duration and frequency of training sessions, an intensified training (IT) group (phase 3, 6 wk) and a control group (which continued training as in the last week of phase 2) were formed.

Whole-body vibration induced adaptation in knee extensors; consequences of initial strength, vibration frequency, and joint angle.

It was hypothesized that both vibration frequency and muscle length modulate the strengthening of muscles that is assumed to result from whole-body vibration (WBV). Length of knee extensor muscles during vibration is affected by the knee joint angle; the lengths of the knee extensors increase with more flexed knee joint angles. In an intervention study 28 volunteers were randomly assigned to 1 of 4 groups.

Influence of acute exercise on hyperglycemia in insulin-treated type 2 diabetes.

Introduction: The impact of exercise on blood glucose homeostasis has not been assessed in long-standing type 2 diabetes patients receiving exogenous insulin treatment.

Purpose: To study the effects of an acute bout of exercise on the subsequent 24-h blood glucose excursions under free-living conditions in insulin-treated type 2 diabetes patients.

Methods: Eleven male type 2 diabetes patients (59 +/- 2 yr) performed an acute bout of exercise.

Effect of exercise on activation of the p38 mitogen-activated protein kinase pathway, c-Jun NH2 terminal kinase, and heat shock protein 27 in equine skeletal muscle.

Objective: To investigate the effects of exercise on activation of mitogen-activated protein kinase (MAPK) signaling proteins in horses.

Animals: 6 young trained Standardbred geldings.

Procedure: Horses performed a 20-minute bout of exercise on a treadmill at 80% of maximal heart rate.

Glycaemic instability is an underestimated problem in Type II diabetes.

The aim of the present study was to assess the level of glycaemic control by the measurement of 24 h blood glucose profiles and standard blood analyses under identical nutritional and physical activity conditions in patients with Type II diabetes and healthy normoglycaemic controls. A total of 11 male patients with Type II diabetes and 11 healthy matched controls participated in a 24 h CGMS (continuous subcutaneous glucose-monitoring system) assessment trial under strictly standardized dietary and physical activity conditions. In addition, fasting plasma glucose, insulin and HbA(1c) (glycated haemoglobin) concentrations were measured, and an OGTT (oral glucose tolerance test) was performed to calculate indices of whole-body insulin sensitivity, oral glucose tolerance and/or glycaemic control.

Effects of increasing insulin secretion on acute postexercise blood glucose disposal.

Background: Coingestion of protein and/or free amino acids with carbohydrate has been reported to accelerate postexercise muscle glycogen synthesis due to an increase in the insulin response.

Purpose: To determine the extent to which the combined ingestion of carbohydrate and a casein protein hydrolysate with or without additional free leucine can increase insulin levels during postexercise recovery in endurance-trained athletes. To determine how this affects whole-body plasma glucose disposal during postexercise recovery.

Effects of short- and long-term recombinant equine growth hormone and short-term hydrocortisone administration on tissue sensitivity to insulin in horses.

Objective: To determine the effects of short-term IV administration of hydrocortisone or equine growth hormone (eGH) or long-term IM administration of eGH to horses on tissue sensitivity to exogenous insulin.

Animals: 5 Standardbreds and 4 Dutch Warmblood horses.

Procedure: The euglycemic-hyperinsulinemic clamp technique was used to examine sensitivity of peripheral tissues to exogenous insulin 24 hours after administration of a single dose of hydrocortisone (0.

Inhibition of adipose tissue lipolysis increases intramuscular lipid and glycogen use in vivo in humans.

This study investigates the consequences of inhibition of adipose tissue lipolysis on skeletal muscle substrate use. Ten subjects were studied at rest and during exercise and subsequent recovery under normal, fasting conditions (control trial, CON) and following administration of a nicotinic acid analog (low plasma free fatty acid trial, LFA). Continuous [U-13C]palmitate and [6,6-2H2]glucose infusions were applied to quantify plasma free fatty acid (FFA) and glucose oxidation rates and to estimate intramuscular triacylglycerol (IMTG) and glycogen use.

A single session of resistance exercise enhances insulin sensitivity for at least 24 h in healthy men.

The aim of the present study was to determine whether a single session of resistance exercise improves whole-body insulin sensitivity in healthy men for up to 24 h. Twelve male subjects (23 +/- 1 years) were studied over a period of 4 days during which they consumed a standardized diet, providing 0.16 +/- 0.

The effects of exercise and adipose tissue lipolysis on plasma adiponectin concentration and adiponectin receptor expression in human skeletal muscle.

Objective: It has been suggested that adiponectin regulates plasma free fatty acid (FFA) clearance by stimulating FFA uptake and/or oxidation in muscle. We aimed to determine changes in plasma adiponectin concentration and adiponectin receptor 1 and 2 mRNA expression in skeletal muscle during and after prolonged exercise under normal, fasting conditions (high FFA trial; HFA) and following pharmacological inhibition of adipose tissue lipolysis (low FFA trial; LFA). Furthermore, we aimed to detect and locate adiponectin in skeletal muscle tissue.

Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects.

The present study was designed to determine postexercise muscle protein synthesis and whole body protein balance following the combined ingestion of carbohydrate with or without protein and/or free leucine. Eight male subjects were randomly assigned to three trials in which they consumed drinks containing either carbohydrate (CHO), carbohydrate and protein (CHO+PRO), or carbohydrate, protein, and free leucine (CHO+PRO+Leu) following 45 min of resistance exercise. A primed, continuous infusion of L-[ring-13C6]phenylalanine was applied, with blood samples and muscle biopsies collected to assess fractional synthetic rate (FSR) in the vastus lateralis muscle as well as whole body protein turnover during 6 h of postexercise recovery.

A modified PAS stain combined with immunofluorescence for quantitative analyses of glycogen in muscle sections.

Simultaneous analyses of glycogen in sections with other subcellular constituents within the same section will provide detailed information on glycogen deposition and the processes involved. To date, staining protocols for quantitative glycogen analyses together with immunofluorescence in the same section are lacking. We aimed to: (1) optimise PAS staining for combination with immunofluorescence, (2) perform quantitative glycogen analyses in tissue sections, (3) evaluate the effect of section thickness on PAS-derived data and (4) examine if semiquantitative glycogen data were convertible to genuine glycogen values.

Investigation of the expression and localization of glucose transporter 4 and fatty acid translocase/CD36 in equine skeletal muscle.

Objective: To investigate the expression and localization of glucose transporter 4 (GLUT4) and fatty acid translocase (FAT/CD36) in equine skeletal muscle.

Sample Population: Muscle biopsy specimens obtained from 5 healthy Dutch Warmblood horses.

Procedures: Percutaneous biopsy specimens were obtained from the vastus lateralis, pectoralis descendens, and triceps brachii muscles.

Intramyocellular lipid content in type 2 diabetes patients compared with overweight sedentary men and highly trained endurance athletes.

Recent evidence suggests that intramyocellular lipid (IMCL) accretion is associated with obesity and the development of insulin resistance and/or type 2 diabetes. However, trained endurance athletes are markedly insulin sensitive, despite an elevated mixed muscle lipid content. In an effort to explain this metabolic paradox, we compared muscle fiber type-specific IMCL storage between populations known to have elevated IMCL deposits.

Subcellular immunolocalisation of fatty acid translocase (FAT)/CD36 in human type-1 and type-2 skeletal muscle fibres.

Limited information exists about the putative role and expression in human skeletal muscle cells of the 88-kDa integral membrane protein fatty acid translocase (FAT), highly homologous to the human leucocyte differentiation factor CD36. Therefore, we investigated in healthy male individuals the muscle (m. vastus lateralis) fibre type specific expression and subcellular localisation of FAT/CD36.

Immunohistochemical identification and fiber type specific localization of protein kinase C isoforms in equine skeletal muscle.

Objective: To investigate whether protein kinase C (PKC) isoforms are expressed in equine skeletal muscle and determine their distribution in various types of fibers by use of immunofluorescence microscopy.

Animals: 5 healthy adult Dutch Warmblood horses.

Procedure: In each horse, 2 biopsy specimens were obtained from the vastus lateralis muscle.

Intramyocellular lipids form an important substrate source during moderate intensity exercise in endurance-trained males in a fasted state.

Both stable isotope methodology and fluorescence microscopy were applied to define the use of intramuscular triglyceride (IMTG) stores as a substrate source during exercise on a whole-body as well as on a fibre type-specific intramyocellular level in trained male cyclists. Following an overnight fast, eight subjects were studied at rest, during 120 min of moderate intensity exercise (60 % maximal oxygen uptake capacity (VO2,max)) and 120 min of post-exercise recovery. Continuous infusions of [U-13C]palmitate and [6,6-2H2]glucose were administered at rest and during subsequent exercise to quantify whole-body plasma free fatty acid (FFA) and glucose oxidation rates and the contribution of other fat sources (sum of muscle- plus lipoprotein-derived TG) and muscle glycogen to total energy expenditure.

Amino acid ingestion strongly enhances insulin secretion in patients with long-term type 2 diabetes.

Objective: Insulin secretion in response to carbohydrate intake is blunted in type 2 diabetic patients. However, it is not clear whether the insulin response to other stimuli, such as amino acids, is also diminished. Recently, we defined an optimal insulinoptropic mixture containing free leucine, phenylalanine, and a protein hydrolysate that substantially enhances the insulin response in healthy young subjects when coingested with carbohydrate.