GLORIA

GEOMAR Library Ocean Research Information Access

X

Your email was sent successfully. Check your inbox.

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

Proceed reservation?

Export
Filter
  • American Physiological Society  (5)
  • 2005-2009  (5)
Material
Publisher
  • American Physiological Society  (5)
Person/Organisation
Language
Years
  • 2005-2009  (5)
Year
Subjects(RVK)
  • 1
    Online Resource
    Online Resource
    Effect of training in the fasted state on metabolic responses during exercise with carbohydrate intake
    American Physiological Society ; 2008
    In:  Journal of Applied Physiology Vol. 104, No. 4 ( 2008-04), p. 1045-1055
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 104, No. 4 ( 2008-04), p. 1045-1055
    Abstract: Skeletal muscle gene response to exercise depends on nutritional status during and after exercise, but it is unknown whether muscle adaptations to endurance training are affected by nutritional status during training sessions. Therefore, this study investigated the effect of an endurance training program (6 wk, 3 day/wk, 1–2 h, 75% of peak V̇o 2 ) in moderately active males. They trained in the fasted (F; n = 10) or carbohydrate-fed state (CHO; n = 10) while receiving a standardized diet [65 percent of total energy intake (En) from carbohydrates, 20%En fat, 15%En protein]. Before and after the training period, substrate use during a 2-h exercise bout was determined. During these experimental sessions, all subjects were in a fed condition and received extra carbohydrates (1 g·kg body wt −1 ·h −1 ). Peak V̇o 2 (+7%), succinate dehydrogenase activity, GLUT4, and hexokinase II content were similarly increased between F and CHO. Fatty acid binding protein (FABPm) content increased significantly in F ( P = 0.007). Intramyocellular triglyceride content (IMCL) remained unchanged in both groups. After training, pre-exercise glycogen content was higher in CHO (545 ± 19 mmol/kg dry wt; P = 0.02), but not in F (434 ± 32 mmol/kg dry wt; P = 0.23). For a given initial glycogen content, F blunted exercise-induced glycogen breakdown when compared with CHO ( P = 0.04). Neither IMCL breakdown ( P = 0.23) nor fat oxidation rates during exercise were altered by training. Thus short-term training elicits similar adaptations in peak V̇o 2 whether carried out in the fasted or carbohydrate-fed state. Although there was a decrease in exercise-induced glycogen breakdown and an increase in proteins involved in fat handling after fasting training, fat oxidation during exercise with carbohydrate intake was not changed.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.01195.2007
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2008
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 2
    Online Resource
    Online Resource
    ACTN3 (R577X) genotype is associated with fiber type distribution
    American Physiological Society ; 2007
    In:  Physiological Genomics Vol. 32, No. 1 ( 2007-12), p. 58-63
    Details
    In: Physiological Genomics, American Physiological Society, Vol. 32, No. 1 ( 2007-12), p. 58-63
    Abstract: α-Actinin-3 is a Z-disc structural protein found only in type II muscle fibers. The X allele of the R577X polymorphism in the ACTN3 gene results in a premature stop codon and α-actinin-3 deficiency in XX homozygotes. Associations between the R577X polymorphism and the muscle-power performance of elite athletes have been described earlier. About 45% of the fiber type proportions are determined by genetic factors. The ACTN3 variant could be one of the contributing genes in the heritability of fiber type distribution through its interaction with calcineurin. The aim of this study was to quantify the association between the polymorphism and muscle fiber type distribution and fast-velocity knee extension strength. Ninety healthy young men (18–29 y) were genotyped for ACTN3 R577X. Knee extensor strength was measured isometrically (45°) and at different dynamic velocities (100–300°/s) on a programmable dynamometer. Twenty-two XX and twenty-two RR subjects underwent a biopsy of the right vastus lateralis muscle. Fiber type composition was determined by immunohistochemistry. Homozygotes for the R allele show significantly higher relative dynamic quadriceps torques at 300°/s, compared with XX carriers ( P 〈 0.05). Fiber type characteristics differed significantly between the two genotype groups. The percentage surface and number of type IIx fibers were greater in the RR than the XX genotype group ( P 〈 0.05), and α-actinin-3 protein content is systematically higher in type IIx compared with type IIa fibers (staining intensity ratio IIx to IIa = 1.17). This study shows that the mechanism, by which the ACTN3 polymorphism has its effect on muscle power, might rely on a control function of fiber type proportions.
    Type of Medium: Online Resource
    ISSN: 1094-8341 , 1531-2267
    URL: Article
    DOI: 10.1152/physiolgenomics.00173.2007
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2007
    detail.hit.zdb_id: 2031330-5
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 3
    Online Resource
    Online Resource
    Fiber type-specific muscle glycogen sparing due to carbohydrate intake before and during exercise
    American Physiological Society ; 2007
    In:  Journal of Applied Physiology Vol. 102, No. 1 ( 2007-01), p. 183-188
    Details
    In: Journal of Applied Physiology, American Physiological Society, Vol. 102, No. 1 ( 2007-01), p. 183-188
    Abstract: The effect of carbohydrate intake before and during exercise on muscle glycogen content was investigated. According to a randomized crossover study design, eight young healthy volunteers ( n = 8) participated in two experimental sessions with an interval of 3 wk. In each session subjects performed 2 h of constant-load bicycle exercise (∼75% maximal oxygen uptake). On one occasion (CHO), they received carbohydrates before (∼150 g) and during (1 g·kg body weight −1 ·h −1 ) exercise. On the other occasion they exercised after an overnight fast (F). Fiber type-specific relative glycogen content was determined by periodic acid Schiff staining combined with immunofluorescence in needle biopsies from the vastus lateralis muscle before and immediately after exercise. Preexercise glycogen content was higher in type IIa fibers [9.1 ± 1 × 10 −2 optical density (OD)/μm 2 ] than in type I fibers (8.0 ± 1 × 10 −2 OD/μm 2 ; P 〈 0.0001). Type IIa fiber glycogen content decreased during F from 9.6 ± 1 × 10 −2 OD/μm 2 to 4.5 ± 1 × 10 −2 OD/μm 2 ( P = 0.001), but it did not significantly change during CHO ( P = 0.29). Conversely, in type I fibers during CHO and F the exercise bout decreased glycogen content to the same degree. We conclude that the combination of carbohydrate intake both before and during moderate- to high-intensity endurance exercise results in glycogen sparing in type IIa muscle fibers.
    Type of Medium: Online Resource
    ISSN: 8750-7587 , 1522-1601
    URL: Article
    DOI: 10.1152/japplphysiol.00799.2006
    RVK:
    WA 15000
    RVK:
    XA 52094
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2007
    detail.hit.zdb_id: 1404365-8
    SSG: 12
    SSG: 31
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 4
    Online Resource
    Online Resource
    Correlation of cardiac performance with cellular energetic components in the oxygen-deprived turtle heart
    American Physiological Society ; 2009
    In:  American Journal of Physiology-Regulatory, Integrative and Comparative Physiology Vol. 297, No. 3 ( 2009-09), p. R756-R768
    Details
    In: American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, American Physiological Society, Vol. 297, No. 3 ( 2009-09), p. R756-R768
    Abstract: The relationship between cardiac energy metabolism and the depression of myocardial performance during oxygen deprivation has remained enigmatic. Here, we combine in vivo 31 P-NMR spectroscopy and MRI to provide the first temporal profile of in vivo cardiac energetics and cardiac performance of an anoxia-tolerant vertebrate, the freshwater turtle ( Trachemys scripta) during long-term anoxia exposure (∼3 h at 21°C and 11 days at 5°C). During anoxia, phosphocreatine (PCr), unbound levels of inorganic phosphate (effective P i 2− ), intracellular pH (pH i ), and free energy of ATP hydrolysis (dG/dξ) exhibited asymptotic patterns of change, indicating that turtle myocardial high-energy phosphate metabolism and energetic state are reset to new, reduced steady states during long-term anoxia exposure. At 21°C, anoxia caused a reduction in pH i from 7.40 to 7.01, a 69% decrease in PCr and a doubling of effective P i 2− . ATP content remained unchanged, but the free energy of ATP hydrolysis (dG/dξ) decreased from −59.6 to −52.5 kJ/mol. Even so, none of these cellular changes correlated with the anoxic depression of cardiac performance, suggesting that autonomic cardiac regulation may override putative cellular feedback mechanisms. In contrast, during anoxia at 5°C, when autonomic cardiac control is severely blunted, the decrease of pH i from 7.66 to 7.12, 1.9-fold increase of effective P i 2− , and 6.4 kJ/mol decrease of dG/dξ from −53.8 to −47.4 kJ/mol were significantly correlated to the anoxic depression of cardiac performance. Our results provide the first evidence for a close, long-term coordination of functional cardiac changes with cellular energy status in a vertebrate, with a potential for autonomic control to override these immediate relationships.
    Type of Medium: Online Resource
    ISSN: 0363-6119 , 1522-1490
    URL: Article
    DOI: 10.1152/ajpregu.00102.2009
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2009
    detail.hit.zdb_id: 1477297-8
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
  • 5
    Online Resource
    Online Resource
    Evaluation of intramyocellular lipid breakdown during exercise by biochemical assay, NMR spectroscopy, and Oil Red O staining
    American Physiological Society ; 2007
    In:  American Journal of Physiology-Endocrinology and Metabolism Vol. 293, No. 1 ( 2007-07), p. E428-E434
    Details
    In: American Journal of Physiology-Endocrinology and Metabolism, American Physiological Society, Vol. 293, No. 1 ( 2007-07), p. E428-E434
    Abstract: The study compared the net decline of intramyocellular lipids (IMCL) during exercise ( n = 18) measured by biochemical assay (BIO) and Oil Red O (ORO) staining on biopsy samples from vastus lateralis muscle and by 1 H-MR spectroscopy (MRS) sampled in an 11 × 11 × 18-mm 3 voxel in the same muscle. IMCL was measured before and after a 2-h cycling bout (∼75% V̇o 2 peak ). ORO and MRS measurements showed substantial IMCL use during exercise of 31 ± 12 and 47 ± 6% of preexercise IMCL content. In contrast, use of BIO for IMCL determination did not reveal an exercise-induced breakdown of IMCL (2 ± 9%, P = 0.29) in young healthy males. Correlations between different measures of exercise-induced IMCL degradation were low. Coefficients were 0.48 for MRS vs. ORO ( P = 0.07) and were even lower for BIO vs. MRS ( r = 0.38, P = 0.13) or ORO ( r = 0.08, P = 0.78). This study demonstrates that different methods to measure IMCL in human muscles can result in different conclusions with regard to exercise-induced IMCL changes. MRS has the advantage that it is noninvasive, however, not fiber type specific and hampered by an at least 30-min delay in measurements after exercise completion and may overestimate IMCL use. BIO is the only quantitative method but is subject to variation when biopsies have different fiber type composition. However, BIO yields lower IMCL breakdown compared with ORO and MRS. ORO has the major advantage that it is fiber type specific, and it therefore provides information that is not available with the other methods.
    Type of Medium: Online Resource
    ISSN: 0193-1849 , 1522-1555
    URL: Article
    DOI: 10.1152/ajpendo.00112.2007
    Language: English
    Publisher: American Physiological Society
    Publication Date: 2007
    detail.hit.zdb_id: 1477331-4
    SSG: 12
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...