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The study aimed at evaluating changes in plasma levels of insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3), testosterone, growth hormone (GH), cortisol, and insulin in resistance-trained male athletes with (n = 9) and without (n = 9) left ventricular hypertrophy (LVH) in response to eccentric (ECC) and concentric (CON) arm exercise. 10 age-matched healthy non-trained subjects served as controls. M-mode and 2D Doppler echocardiography were used to estimate LV mass. Resting IGF-1 concentration was higher in LVH athletes compared to controls (52 ± 5 nM vs. 46 ± 7 nM, p < 0.05). ECC exercise resulted in higher (p < 0.05) serum IGF-1 concentrations in athletes with LVH (70 ± 11 nM, n = 9) compared to those without LVH (62 ± 10 nM, n = 9), and to untrained controls (54 ± 6 nM). Both CON and ECC exercise resulted in higher serum IGFBP-3 levels in LVH athletes compared to controls (242 ± 57 and 274 ± 58, athletes, vs. 215 ± 63 and 244 ± 67, controls, nM, p < 0.05). In ECC exercise, GH concentrations were lower in LVH than in non-LVH athletes (4.7 ± 2.1 vs. 6.1 ± 1.8 ng • mL-1 , p < 0.05). No differences in other hormones were found between groups. In conclusion, LVH is accompanied by elevated resting serum IGF-1 and enhanced response to eccentric arm exercise. These findings suggest a role of IGF-1, possibly released from contracting muscle, in stimulating LV hypertrophy in resistance training. [ABSTRACT FROM AUTHOR]

Endurance training elicits profound adaptations of skeletal muscle, including increased expression of several proteins. The 5′-AMP activated protein kinase (AMPK) may be one of these, considering the fact that acute exercise increases AMPK activity. Eight young (26 ± 1 year) lean, healthy males endurance trained one leg (while the other leg remained resting) on an ergometer bicycle for 30 min/day for four weeks (workload corresponding to ∼ 70% of maximal oxygen uptake). Muscle biopsies were obtained ∼18 h after the previous training session. On day eight GLUT4 protein expression was 36% higher in trained (T) compared with untrained (UT) (P < 0.05), but no further increase was seen at day 14 and 30 despite continuously increasing absolute workloads. Expression of AMPKα 2 and actin did not change with training. In contrast, expression of AMPKα 1 was 27% higher in T vs. UT muscle (P < 0.05) (measured only on day 30). Conclusions: GLUT4 protein expression increases substantially after seven days of endurance training with no further increase with prolonged training at progressively increasing workloads. AMPKα 1 and α 2 behave differently in their expression in response to endurance training. AMPKα 1 protein content is increased after one month of training, while no change in AMPKα 2 and actin expression was detected over the time course of the training period . [ABSTRACT FROM AUTHOR]

Investigates palmitic acid incorporation into intramuscular acylglycerols in rat skeletal muscles of different fiber types at various total and unbound albumin concentrations by means of the hind-limb perfusion technique. Data showing that simultaneously increasing total and unbound to albumin palmitic acid concentrations in the perfusion medium increases the incorporation of palmitic acid into acylglycerols.

The rate of fatty acid uptake, oxidation, and deposition in skeletal muscles in relation to total and unbound to albumin fatty acids concentration in the medium were investigated in the incubated rat soleus muscle. An immunohistochemical technique was applied to demonstrate whether the albumin-bound fatty acid complex from the medium penetrates well within all areas of the muscle strips. It was found that the percentage of incorporation of palmitic acid into intramuscular lipids was fairly constant, independently of the fatty acid concentration in the medium, and amounted to 63–72% for triacylglycerols, 7–12% for diacylglycerols-monoacylglycerols, and 19–26% for phospholipids. Both palmitic acid incorporation into the muscle triacylglycerol stores and its oxidation to CO[sub 2] closely correlated with an increase in both total and unbound to albumin fatty acid concentrations in the incubation medium. Under conditions of increased total but constant unbound to albumin palmitic acid concentrations, the incorporation of palmitic acid into triacylglycerols and its oxidation to CO[sub 2] were also increased, but to a lower extent. This supports the hypothesis that the cellular fatty acid metabolism depends not only on the availability of fatty acids unbound to albumin, but also on the availability of fatty acids complexed to albumin.Key words: skeletal muscle, fatty acids, triacylglycerols, phospholipids.Les taux d'entrée, d'oxydation et de stockage des acides gras dans les muscles squelettiques en fonction de la concentration totale des acides gras et de la concentration des acides gras non liés à l'albumine dans le milieu d'incubation ont été mesurés dans le muscle soléaire de rat. Une technique immunohistochimique a été utilisée pour vérifier si les acides gras complexés à l'albumine entrent bien dans toutes les régions des lambeaux musculaires. Le pourcentage d'acide palmitique incorporé dans les lipides musculaires est assez constant, peu importe la concentration de l'acide gras dans le milieu : il est de 63 à 72 % dans les triacylglycérols, de 7 à 12 % dans les diacylglycérols et monoacylglycérols et de 19 à 26 % dans les phospholipides. L'incorporation de l'acide palmitique dans les triacylglycérols musculaires et son oxydation en CO[sub 2] sont étroitement corrélées à une augmentation de la concentration totale de l'acide gras et de la concentration de l'acide gras non lié à l'albumine dans le milieu d'incubation. Lorsque la concentration totale d'acide palmitique est augmentée, mais que la concentration d'acide palmitique non lié à l'albumine demeure constante, l'incorporation de l'acide palmitique dans les triacylglycérols et son oxydation en CO[sub 2] sont également augmentées, mais moins fortement. Cela est en accord avec l'hypothèse que le métabolisme des acides gras dans les cellules est fonction non seulement de la disponibilité des acides gras non liés à l'albumine, mais également de la disponibilité des acides gras complexés à l'albumine.Mots clés : muscle squelettique, acides gras, triacylglycérols, phospholipides.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The aim of this study was to find out whether a low-carbohydrate diet (L-CHO) affects: (1) the capacity for all-out anaerobic exercise, and (2) hormonal and metabolic responses to this type of exercise. To this purpose, eight healthy subjects underwent a 30-s bicycle Wingate test preceded by either 3 days of a controlled mixed diet (130 kJ/kg of body mass daily, 50% carbohydrate, 30% fat, 20% protein) or 3 days of an isoenergetic L-CHO diet (up to 5% carbohydrate, 50% fat, 45% protein) in a randomized order. Before and during 1 h after the exercise venous blood samples were taken for measurement of blood lactate (LA), β-hydroxybutyrate (β-HB), glucose, adrenaline (A), noradrenaline (NA) and insulin levels. Oxygen consumption ( V˙O2) was also determined. It was found that the L-CHO diet diminished the mean power output during the 30-s exercise bout [533 (7) W vs 581 (7) W, P < 0.05] without changing the maximal power attained during the first or second 5-s interval of the exercise. In comparison with the data obtained after the consumption of a mixed diet, after the consumption of a L-CHO diet resting plasma concentrations of β-HB [2.38 (0.18) vs 0.23 (0.01) mmol · l−1, P < 0.001] and NA [4.81 (0.68) vs 2.2 (0.31) nmol · l−1, P < 0.05] were higher, while glucose [4.6 (0.1) vs 5.7 (0.2) mmol · l−1, P < 0.05] and insulin concentrations [11.9 (0.9) vs 21.8 (1.8) mU · l−1] were lower. The 1-h post-exercise excess of V˙O2 [9.1 (0.25) vs 10.6 (0.25) l, P < 0.05], and blood LA measured 3 min after the exercise [9.5 (0.4) vs 10.6 (0.5) mmol · l−1, P < 0.05] were lower following the L-CHO treatment, whilst plasma NA and A concentrations reached higher values [2.24 (0.40) vs 1.21 (0.13) nmol · l−1 and 14.30 (1.41) vs 8.20 (1.31) nmol · l−1, P < 0.01, respectively]. In subjects on the L-CHO diet, the plasma β-HB concentration decreased quickly after exercise, attaining ≈30% of the pre-exercise value within 60 min, while insulin and glucose levels were elevated. The main conclusions of this study are: (1) a L-CHO diet is detrimental to anaerobic work capacity, possibly because of a reduced muscle glycogen store and decreased rate of glycolysis; (2) reduced carbohydrate intake for 3 days enhances activity of the sympathoadrenal system at rest and after exercise. [ABSTRACT FROM AUTHOR]