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Energy metabolism in intensively exercising calf muscle under a simulated orthostasis

Zange, Jochen und Beisteiner, Mareike und Müller, Klaus und Shushakov, Vladimir und Maassen, Norbert (2008) Energy metabolism in intensively exercising calf muscle under a simulated orthostasis. Pflügers Archiv, European Journal of Physiology, 455 (6), Seiten 1153-1163. Springer Verlag.

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Offizielle URL: http://www.springerlink.com/content/qwu5571272411vu4/

Kurzfassung

We conducted non-invasive methods to investigate the mechanisms how an orthostasis improves fatigue resistance in human calf muscle during intense exercise. Eleven healthy volunteers performed two series of ten intervals of maximum dynamic exercise (15 s) and recovery (45 s) at almost horizontal body position under both, control conditions (CON) and lower body negative pressure (LBNP, -40 mbar). As from the second work interval, LBNP significantly improved fatigue resistance shown as a lower reduction in work and in contraction velocity (P < 0.01). During each work interval, EMG showed a small increase in amplitude (P < 0.01) and a steep drop by 20% in median frequency (P < 0.01). Under LBNP, both EMG parameters completely recovered during subsequent rest, whereas under CON recovery was incomplete (P < 0.01). During the first work interval, consumption of phosphocreatine (PCr) was almost the same for both conditions. In periods of recovery under LBNP, resynthesis of PCr and inorganic phosphate were significantly faster. PCr reached 10 to 20% higher levels (P < 0.01). LBNP caused an initial increase in intracellular pH (0.08 U (P < 0.01)). The subsequent time courses of pH were similar for CON and LBNP. During work, pH steeply increased by about 0.3 U. During subsequent recovery, pH dropped to values between 6.3 and 6.5. LBNP caused significantly higher levels of total haemoglobin and oxy-haemoglobin (P < 0.05). A simulated orthostasis increased fatigue resistance during high intense interval exercise because of a faster PCr resynthesis and may be because of improvements in the maintenance of motoneuronal activity.

Dokumentart:Zeitschriftenbeitrag
Titel:Energy metabolism in intensively exercising calf muscle under a simulated orthostasis
Autoren:
AutorenInstitution oder E-Mail-Adresse der Autoren
Zange, JochenNICHT SPEZIFIZIERT
Beisteiner, MareikeNICHT SPEZIFIZIERT
Müller, KlausNICHT SPEZIFIZIERT
Shushakov, VladimirMedizinische Hochschule Hannover
Maassen, NorbertMedizinische Hochschule Hannover
Datum:März 2008
Erschienen in:Pflügers Archiv, European Journal of Physiology
Referierte Publikation:Ja
In ISI Web of Science:Ja
Band:455
Seitenbereich:Seiten 1153-1163
Verlag:Springer Verlag
Status:veröffentlicht
Stichwörter:Muscle physiology, Energy metabolism, Magnetic resoance spectroscopy, Orthostasis, Lower body negative pressure,
HGF - Forschungsbereich:Verkehr und Weltraum (alt)
HGF - Programm:Weltraum (alt)
HGF - Programmthema:W FR - Forschung unter Weltraumbedingungen (alt)
DLR - Schwerpunkt:Weltraum
DLR - Forschungsgebiet:W FR - Forschung unter Weltraumbedingungen
DLR - Teilgebiet (Projekt, Vorhaben):W - Vorhaben Beschleunigungsinduzierte Effekte (alt)
Standort: Köln-Porz
Institute & Einrichtungen:Institut für Luft- und Raumfahrtmedizin > Weltraumphysiologie
Hinterlegt von: Dr.rer.nat. Jochen Zange
Hinterlegt am:18 Feb 2008
Letzte Änderung:27 Apr 2009 14:27

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