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Glycogen depletion pattern and lactate accumulation in leg muscles during recreational downhill skiing (1978)

Nygaard, E. ; Andersen, P. ; Nilsson, P. ; [et al.]

Springer

European journal of applied physiology 38 (1978), S. 261-269

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ISSN: 1439-6327

Keywords: Muscle glycogen ; Muscle and blood lactic acid ; Fibre type glycogen depletion

Source: Springer Online Journal Archives 1860-2000

Topics: Medicine

Notes: Summary Twenty-eight adult female and male subjects performed recreational skiing, which took place in terrain with short and long slopes. Muscle biopsies were obtained before and after the skiing from the lateral portion of the quadriceps femoris for histochemical evaluation of glycogen depletion in individual fibres and biochemical analysis of glycogen and lactate content. Blood lactate was also determined. After a day of skiing the decline in muscle glycogen averaged 33 mM/kg in both short and long slope terrain. Technically advanced skiers had a reduction of 38 mM/kg and less advanced skiers had a reduction of 28 mM/kg (p〈0.05). In most subjects there was a predominant loss of glycogen from the slow-twitch fibres (ST). In the most talented skiers glycogen depletion was also observed in the fast-twitch a fibres (FTa). In contrast a pronounced depletion of the fast-twitch b fibres (FTb) was observed in the technically unskilled skier. Muscle lactate concentrations ranged 2–8 mM/kg, the higher values observed in the technically better skiers. Blood lactate values reflected muscle lactate at a 1–2 mM/l lower level. The obtained results suggest that recreational downhill skiing performed by experienced skiers can be characterized as dynamic exercise and that glycogen depleted muscle fibres may contribute to the fatigue experienced after a day of skiing.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00423108

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Crystal nucleation in sheared polymer melts (1978)

Andersen, P. G. ; Carr, S. H.

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 18 (1978), S. 215-221

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ISSN: 0032-3888

Keywords: Chemistry ; Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: A semiquantitative procedure has been developed for analyzing crystal nucleation in undercooled polymer melts that are undergoing flow. This analysis was applied to the specific ease of molten high density polyethylene experiencing low levels of shearing flow. A custom-made concentric cylinder viscometer, which could be operated by the Rheometrics mechanical spectrometer instrument, was used to make simultaneous measurements of transmitted torque and optical anisotropy in isothermal melts, The result of the analytical procedure developed here was molecular Size-dependence of chain distensions caused by prevailing shear. This distribution function was verified by testing against experimentally obtained values of birefringence. Total entropy reduction resulting from this distorted state was then calculated, and the corresponding increase in free energy was found to be at least enough to account for comparable crystal nucleation rates in flowing melts at higher temperatures and in quiescent melts at lower temperatures.

Additional Material: 7 Ill.