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Endurance training adaptations modulate the redox–force relationship of rat isolated slow‐twitch skeletal muscles
Author(s) -
Plant David R,
Gregorevic Paul,
Warmington Stuart A,
Williams David A,
Lynch Gordon S
Publication year - 2003
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2002.03794.x
Subject(s) - isometric exercise , medicine , endocrinology , soleus muscle , skeletal muscle , chemistry , endurance training , citrate synthase , catalase , fast twitch muscle , treadmill , biochemistry , oxidative stress , enzyme
Summary 1. Studies have shown that, in isolated skeletal muscles, maximum isometric force production (P o ) is dependent on muscle redox state. Endurance training increases the anti‐oxidant capacity of skeletal muscles, a factor that could impact on the force‐producing capacity following exogenous exposure to an oxidant. We tested the hypothesis that 12 weeks treadmill training would increase anti‐oxidant capacity in rat skeletal muscles and alter their response to exogenous oxidant exposure. 2. At the conclusion of the 12 week endurance‐training programme, soleus (slow‐twitch) muscles from trained rats had greater citrate synthase (CS) and catalase (CAT) activity compared with soleus muscles from untrained rats ( P < 0.05). In contrast, CAT activity of extensor digitorum longus (EDL; fast‐twitch) muscles from trained rats was not different to EDL muscles of untrained rats. The CS activity was lower in EDL muscles from trained compared with untrained rats ( P < 0.05). 3. Equilibration with exogenous hydrogen peroxide (H 2 O 2 , 5 mmol/L) increased the P o of soleus muscles from untrained rats for the duration of treatment (30 min), whereas the P o of EDL muscles was affected biphasically, with a small increase initially (after 5 min), followed by a more marked decrease in P o (after 30 min). The H 2 O 2 ‐induced increase in P o of soleus muscles from trained rats was less than that in untrained rats ( P < 0.05), but no differences were observed in the P o of EDL muscles following training. 4. The results indicate that 12 weeks endurance running training conferred adaptations in soleus but not EDL muscles. These adaptations were associated with an attenuation of the oxidant‐induced increase in P o of soleus muscles from trained compared with untrained rats. We conclude that endurance training‐adapted soleus muscles have a slightly altered redox–force relationship.