Effects of exercise on soleus in severe burn and muscle disuse atrophy

Melody R. Saeman, Kevin Despain, Ming Mei Liu, Brett A. Carlson, Juquan Song, Lisa A. Baer, Charles E. Wade, Steven E. Wolf

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Background Muscle loss is a sequela of severe burn and critical illness with bed rest contributing significantly to atrophy. We hypothesize that exercise will mitigate muscle loss after burn with bed rest. Materials and methods Male rats were assigned to sham ambulatory (S/A), burn ambulatory (B/A), sham hindlimb unloading (S/H), or burn hindlimb unloading (B/H). Rats received a 40% scald burn or sham and were ambulatory or placed in hindlimb unloading, a model of bed rest. Half from each group performed twice daily resistance climbing. Hindlimb isometric forces were measured on day 14. Results Soleus mass and muscle function were not affected by burn alone. Mass was significantly lower in hindlimb unloading (79 versus 139 mg, P < 0.001) and no exercise (103 versus 115 mg, P < 0.01). Exercise significantly increased soleus mass in B/H (86 versus 77 mg, P < 0.01). Hindlimb unloading significantly decreased muscle force in the twitch (12 versus 31 g, P < 0.001), tetanic (55 versus 148 g, P < 0.001), and specific tetanic measurements (12 versus 22 N/cm2, P < 0.001). Effects of exercise on force depended on other factors. In B/H, exercise significantly increased twitch (14 versus 8 g, P < 0.05) and specific tetanic force (14 versus 7 N/cm2, P < 0.01). Fatigue index was lower in ambulatory (55%) and exercise (52%) versus hindlimb (69%, P = 0.03) and no exercise (73%, P = 0.002). Conclusions Hindlimb unloading is a significant factor in muscle atrophy. Exercise increased the soleus muscle mass, twitch, and specific force in this model. However, the fatigue index decreased with exercise in all groups. This suggests exercise contributes to functional muscle change in this model of disuse and critical illness.

Original languageEnglish (US)
Pages (from-to)19-26
Number of pages8
JournalJournal of Surgical Research
Issue number1
StatePublished - Sep 1 2015
Externally publishedYes


  • Bed rest
  • Burn
  • Critical illness
  • Muscle atrophy

ASJC Scopus subject areas

  • Surgery


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