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Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest.
Am J Physiol Regul Integr Comp Physiol. 2008 Mar; 294(3):R939-47.AJ

Abstract

The soleus muscle has been consistently shown to atrophy more than other leg muscles during unloading and is difficult to protect using various exercise countermeasure paradigms. However, the efficacy of aerobic exercise, a known stimulus for oxidative adaptations, has not been tested in combination with resistance exercise (RE), a known hypertrophic stimulus. We hypothesized that a concurrent exercise program (AE + RE) would preserve soleus fiber myosin heavy chain (MHC) I size and function during 60 days of bed rest. A secondary objective was to test the hypothesis that a leucine-enriched high protein diet would partially protect soleus single fiber characteristics. Soleus muscle biopsies were obtained before and after bed rest from a control (BR; n = 7), nutrition (BRN; n = 8), and exercise (BRE; n = 6) group. Single muscle fiber diameter (Dia), peak force (Po), contractile velocity, and power were studied. BR decreased (P < 0.05) MHC I Dia (-14%), Po (-38%), and power (-39%) with no change in contractile velocity. Changes in MHC I size (-13%) and contractile function (approximately 30%) from BRN were similar to BR. BRE decreased (P < 0.05) MHC I Dia (-13%) and Po (-23%), while contractile velocity increased (P < 0.05) 26% and maintained power. These soleus muscle data show 1) the AE + RE exercise program maintained MHC I power but not size and strength, and 2) the nutrition countermeasure did not benefit single fiber size and contractile function. The divergent response in size and functional MHC I soleus properties with the concurrent exercise program was a unique finding further highlighting the challenges of protecting the unloaded soleus.

Authors+Show Affiliations

Human Performance Laboratory, Ball State University, Muncie, IN 47306, USA. strappe@bsu.eduNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

18094071

Citation

Trappe, Scott, et al. "Human Soleus Single Muscle Fiber Function With Exercise or Nutrition Countermeasures During 60 Days of Bed Rest." American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, vol. 294, no. 3, 2008, pp. R939-47.
Trappe S, Creer A, Minchev K, et al. Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest. Am J Physiol Regul Integr Comp Physiol. 2008;294(3):R939-47.
Trappe, S., Creer, A., Minchev, K., Slivka, D., Louis, E., Luden, N., & Trappe, T. (2008). Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest. American Journal of Physiology. Regulatory, Integrative and Comparative Physiology, 294(3), R939-47.
Trappe S, et al. Human Soleus Single Muscle Fiber Function With Exercise or Nutrition Countermeasures During 60 Days of Bed Rest. Am J Physiol Regul Integr Comp Physiol. 2008;294(3):R939-47. PubMed PMID: 18094071.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Human soleus single muscle fiber function with exercise or nutrition countermeasures during 60 days of bed rest. AU - Trappe,Scott, AU - Creer,Andrew, AU - Minchev,Kiril, AU - Slivka,Dustin, AU - Louis,Emily, AU - Luden,Nicholas, AU - Trappe,Todd, Y1 - 2007/12/19/ PY - 2007/12/21/pubmed PY - 2008/11/1/medline PY - 2007/12/21/entrez SP - R939 EP - 47 JF - American journal of physiology. Regulatory, integrative and comparative physiology JO - Am J Physiol Regul Integr Comp Physiol VL - 294 IS - 3 N2 - The soleus muscle has been consistently shown to atrophy more than other leg muscles during unloading and is difficult to protect using various exercise countermeasure paradigms. However, the efficacy of aerobic exercise, a known stimulus for oxidative adaptations, has not been tested in combination with resistance exercise (RE), a known hypertrophic stimulus. We hypothesized that a concurrent exercise program (AE + RE) would preserve soleus fiber myosin heavy chain (MHC) I size and function during 60 days of bed rest. A secondary objective was to test the hypothesis that a leucine-enriched high protein diet would partially protect soleus single fiber characteristics. Soleus muscle biopsies were obtained before and after bed rest from a control (BR; n = 7), nutrition (BRN; n = 8), and exercise (BRE; n = 6) group. Single muscle fiber diameter (Dia), peak force (Po), contractile velocity, and power were studied. BR decreased (P < 0.05) MHC I Dia (-14%), Po (-38%), and power (-39%) with no change in contractile velocity. Changes in MHC I size (-13%) and contractile function (approximately 30%) from BRN were similar to BR. BRE decreased (P < 0.05) MHC I Dia (-13%) and Po (-23%), while contractile velocity increased (P < 0.05) 26% and maintained power. These soleus muscle data show 1) the AE + RE exercise program maintained MHC I power but not size and strength, and 2) the nutrition countermeasure did not benefit single fiber size and contractile function. The divergent response in size and functional MHC I soleus properties with the concurrent exercise program was a unique finding further highlighting the challenges of protecting the unloaded soleus. SN - 0363-6119 UR - https://www.unboundmedicine.com/medline/citation/18094071/Human_soleus_single_muscle_fiber_function_with_exercise_or_nutrition_countermeasures_during_60_days_of_bed_rest_ L2 - https://journals.physiology.org/doi/10.1152/ajpregu.00761.2007?url_ver=Z39.88-2003&amp;rfr_id=ori:rid:crossref.org&amp;rfr_dat=cr_pub=pubmed DB - PRIME DP - Unbound Medicine ER -