Effect Of Chronic Exercise On The Fatty Acid Composition Of Lipid Classes In Rat Tissues

Introduction
Studies addressing the effect of exercise, both acute and chronic, on the fatty acid composition of animal tissues have
been appearing in the literature at a rising rate in recent years. However, there is no consensus as to the effect of
exercise, probably because of the near uniqueness of each of these studies in terms of type of exercise, species,
subcellular fraction, lipid class and diet of the animals or humans examined. Therefore, the purpose of this study was to
provide additional data on this controversial topic by examining the effects of long-term wheel running on the fatty acid
composition of phospholipids (PL) and triacylglycerols (TG) in rat gastrocnemius, liver and adipose tissue.

Methods
Thirty-four male Wistar rats at the age of 7 weeks were divided randomly into a trained (n = 20) and an untrained group
(n = 14). The rats of the trained group exercised ad libitum for 8 weeks in cages equipped with a wheel. Upon
completion of the training period, the eleven most active trained animals (having run, on average, over 2 km/d) and the
untrained animals were decapitated and their gastrocnemius medialis, liver, epididymal adipose tissue and subcutaneous
adipose tissue (from the buttock area) were removed. The fatty acid composition of their PL and TG was determined by
a combination of thin-layer chromatography and gas chromatography and was expressed as both concentrations and
percentages. Differences between trained and untrained animals were examined by two-tailed independent Student’s t
tests. To determine the meaningfulness of the effect of exercise on fatty acid composition, effect sizes were calculated
as the difference between means divided by the SD of the untrained group.

Results
We found several significant differences between trained and untrained rats in the fatty acid profile of gastrocnemius PL
and TG, liver PL, and adipose tissue TG. There were also significant differences in the indices of the fatty acid profile,
as shown in the table.

Discussion/Conclusions
Judging from the magnitude of the effect sizes and the percentage differences between trained and untrained animals,
there were many large effects of chronic exercise on the fatty acid composition of the tissues examined. From the
results presented, it seems that TG underwent more changes than PL in their fatty acid profile. In conclusion, long-term
wheel running modified the fatty acid profile of PL and TG in rat skeletal muscle, liver and adipose tissue, and could
thus be considered as a modulator of tissue fatty acid composition.

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