Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    ISSN: 1432-0428
    Keywords: Hypoglycaemia ; counter-regulation ; glucose disposal ; muscle glycogen synthase activity ; glucose mass effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of the present study was to evaluate the role of muscle glycogen synthase activity in the reduction of glucose uptake during hypoglycaemia. Six healthy young men were examined twice; during 120 min of hyperinsulinaemic (1.5 mU · kg−1 · min−1) euglycaemia followed by: 1) 240 min of graded hypoglycaemia (plasma glucose nadir 2.8 mmol/l) or 2) 240 min of euglycaemia. At 350–360 min a muscle biopsy was taken and indirect calorimetry was performed at 210–240 and 330–350 min. Hypoglycaemia was associated with markedly increased levels of adrenaline, growth hormone and glucagon and also with less hyperinsulinaemia. During hypoglycaemia the fractional velocity for glycogen synthase was markedly reduced; from 29.8±2.3 to 6.4±0.9%, p〈0.05. Total glucose disposal was decreased during hypoglycaemia (5.58±0.55 vs 11.01±0.75 mg · kg−1 · min−1 (euglycaemia); p〈0.05); this was primarily due to a reduction of non-oxidative glucose disposal (2.43±0.41 vs 7.15±0.7 mg · kg−1 · min−1 (euglycaemia); p〈0.05), whereas oxidative glucose disposal was only suppressed to a minor degree. In conclusion hypoglycaemia virtually abolishes the effect of insulin on muscle glycogen synthase activity. This is in keeping with the finding of a marked reduction of non-oxidative glucose metabolism.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of medicine & science in sports 9 (1999), S. 0 
    ISSN: 1600-0838
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Sports Science
    Notes: To study the upper limit of glycogen storage in human muscle, two healthy male subjects were infused with glucose and insulin for 8 h reaching plasma concentrations of about 21 mM glucose and approximately 2000 μU/ml insulin. Prior to the infusion subjects performed for 1 h one-legged knee-extensor exercise at 75% of their maximum one-legged work capacity in order to lower muscle glycogen stores in one leg. During the 8-h hyperglycemic clamp procedure, glycogen concentrations increased and levelled off at 2- and 5-fold above the pre-infusion levels in the resting and the working leg, respectively. However, the absolute glycogen levels reached in both legs were quite similar, close to 4 g per 100 g wet muscle (about 1000 μmol/g d.w.), independent of prior exercise. Previous studies have shown that glycogen levels, after a bout of glycogen-depleting exercise and subsequent ingestion of a carbohydrate-rich diet for 3 days, can be increased to values around 3–4 g per 100 g wet muscle. It appears that the maximal attainable glycogen concentration in human muscle seems to be close to 4 g per 100 g wet muscle. This glycogen level can thus be reached either by a prolonged infusion of supra-physiological concentrations of glucose and insulin or by glycogen-depleting exercise followed by ingestion of a carbohydrate-rich diet.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Munksgaard International Publishers
    Scandinavian journal of medicine & science in sports 12 (2002), S. 0 
    ISSN: 1600-0838
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Sports Science
    Notes: (1) Age-associated loss of skeletal muscle mass and strength can partly be counteracted by resistance training, causing a net synthesis of muscular proteins. Protein synthesis is influenced synergistically by post-exercise amino acid supplementation, but the importance of the timing of protein intake remains unresolved. (2) The study investigated the importance of immediate (P0) or delayed (P2) intake of an oral protein supplement upon muscle hypertrophy and strength over a period of resistance training in elderly males. (3) Thirteen men (age 74 ± 1 years; body mass index (BMI), 25 ± 1 kg m− 2 (means ± SEM)) completed a 12-week resistance training program (three times per week) receiving oral protein in liquid form (10 g protein, 7 g carbohydrate, 3 g fat) immediately after (P0) or 2 h after (P2) each training session. Muscle hypertrophy was evaluated by magnetic resonance imaging (MRI) and from muscle biopsies and muscle strength was determined using dynamic and isokinetic strength measurements. Body composition was determined from dual-energy X-ray absorptiometry (DEXA) and food records were obtained over 4 days. The plasma insulin response to protein supplementation was also determined. (4) In response to training, the cross-sectional area of m. quadriceps femoris (54.6 ± 0.5–58.3 ± 0.5 cm2) and mean fiber area (4047 ± 320–5019 ± 615 μ m2) increased in the P0 group, whereas no significant increase was observed in P2. For P0 both dynamic and isokinetic strength increased, by 46 and 15%, respectively (P 〈 0.05), whereas P2 only improved in dynamic strength, by 36% (P 〈 0.05). No differences in glucose or insulin response were observed between protein intake at 0 and 2 h post-exercise. (5) We conclude that early intake of an oral protein supplement after resistance training is important for the development of hypertrophy in skeletal muscle of elderly men in response to resistance training.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1432-2013
    Keywords: Insulin ; Epinephrine ; Norepinephrine ; Glycogen ; Gluconeogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The significance of glucagon for post-exercise glucose homeostasis has been studied in rats fasted overnight. Immediately after exhaustive swimming either rabbit-antiglucagon serum or normal rabbit serum was injected by cardiac puncture. Cardiac blood and samples of liver and muscle tissue were collected before exercise and repeatedly during a 120 min recovery period after exercise. During the post-exercise period plasma glucagon concentrations decreased but remained above pre-exercise values in rats treated with normal serum, while rats treated with antiglucagon serum had excess antibody in plasma throughout. Nevertheless, all other parameters measured showed similar changes in the two groups. Thus after exercise the grossly diminished hepatic glycogen concentrations remained constant, while the decreased blood glucose concentrations were partially restored. Simultaneously concentrations in blood and serum of the main gluconeogenic substrates, lactate, pyruvate, alanine and glycerol declined markedly. During the post-exercise period NEFA concentrations in serum and plasma insulin concentrations remained increased and decreased, respectively, while plasma catecholamines did not differ from basal values. Muscle glycogen concentrations decreased slightly. These findings suggest that in the recovery period after exhaustive exercise the increased glucagon concentrations in plasma do not influence gluconeogenesis.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 82 (2000), S. 98-102 
    ISSN: 1439-6327
    Keywords: Key words Exercise ; Training ; Immune system ; Carbohydrate ; Fat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The purpose of the study was to investigate whether a carbohydrate-rich versus fat-rich diet influenced the effect of training on the immune system. Ten untrained young men ingested a carbohydrate-rich diet [65 energy percent (E%) carbohydrate] and ten subjects a fat-rich diet (62E% fat) while endurance training was performed 3–4 times a week for 7 weeks. Maximal oxygen uptake increased by 11% in both groups. Blood samples for immune monitoring were collected before and at the end of the study. Blood samples were also collected, in parallel, from 20 age-matched subjects, and data from these subjects were used to eliminate day-to-day variation in the immunological tests. Independently of diet, training increased the percentage of CD3–CD16+ CD56+ natural killer (NK) cells from [mean (SEM)] 14(1)% to 20 (3)% (P=0.05), whereas the NK-cell activity, either unstimulated or stimulated with interleukin (IL)-2 or interferon (IFN)-α, did not change. Furthermore, training did not influence the percentages of CD3+, CD4+, CD8+, CD19+ or CD14+ cells. However, when the two diet groups were compared, it was found that the NK-cell activity had increased in the group on the carbohydrate-rich diet [from 16 (3)% to 27 (2)%] and decreased in the group on the fat-rich diet [from 26 (2)% to 20 (4)%] in response to training. The effect of training on unstimulated NK-cell activity was significantly different between the groups (P=0.007). These data indicate that diet manipulation during training may influence natural immunity, and suggest that ingestion of a fat-rich diet during training is detrimental to the immune system compared to the effect of a carbohydrate-rich diet.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...