Beef extract supplementation increases leg muscle mass and modifies skeletal muscle fiber types in rats

Hiroyuki Yoshihara, Jun Ichiro Wakamatsu, Fuminori Kawabata, Sunao Mori, Atsushi Haruno, Toshiya Hayashi, Takeshi Sekiguchi, Wataru Mizunoya, Ryuichi Tatsumi, Tatsumi Ito, Yoshihide Ikeuchi

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


The objective of this research was to investigate the effects of beef extract on fat metabolism, muscle mass and muscle fiber types in rats. We also investigated the synergetic effect of endurance exercise. Twenty-four male rats weighing about 270 g were assigned to two diets containing 0 or 6% beef extract (BE). Half the rats fed each diet were subjected to compulsory exercise (CE) for 30 min every other day. After 4 weeks feeding, the blood was collected and various organs were dissected. The muscle fiber type of the soleus and extensor digitorum longus (EDL) muscles were evaluated by histochemical and electrophoretical analyses. Rats supplemented with BE showed a decrease in fat content in liver and abdomen and an increase in the activity of carnitine palmitoyl transferase II in liver. BE as well as exercise increased the relative weights of both soleus and EDL. BE alone and BE plus CE did not affect the distribution of muscle fiber types in soleus. BE without exercise decreased in type lib of EDL from 54% to 44% with compensatory increase in type IIa from 41% to 49% and type I from 5% to 7% compared with the nonsupplemented, nonexercised control group. No synergetic effect on a fast to slow fiber conversion due to the combination of BE and CE was detected. Thus, BE supplement increased muscle mass and slow type fiber in EDL. The effects of BE supplement on muscle characteristics were similar to those of exercise.

Original languageEnglish
Pages (from-to)183-193
Number of pages11
JournalJournal of Nutritional Science and Vitaminology
Issue number3
Publication statusPublished - Jun 2006

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Nutrition and Dietetics


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