Effect of high-intensity exercise training on functional capacity of limb skeletal muscle.
The purpose of this study was to determine whether a program of regular sprint exercise training alters the functional properties or protects against the development of fatigue in fast- and slow-twitch rat skeletal muscle. The training program consisted of 6 sprints of 4.5-min duration at 40 m/min and 15% slope with 2.5-min rest intervals, performed 5 days/wk for 6 wk. The exercise program significantly increased (P less than 0.05) citrate synthase activity (mumol X g-1 X min-1) in the predominantly type I soleus (SOL) from 28 +/- 2 to 44 +/- 2; the type IIb superficial region of the vastus lateralis (SVL) from 10 +/- 1 to 16 +/- 1; and the type IIa deep region of the vastus lateralis (DVL) from 34 +/- 2 to 53 +/- 2. Phosphofructokinase activity (mumol X g-1 X min-1) also increased with training in the SOL (17 +/- 1 vs. 23 +/- 1) and the DVL (64 +/- 5 vs. 79 +/- 5). Sprint training reduced (P less than 0.05) the contraction time (CT) (111 +/- 7 vs. 92 +/- 3 ms) and the one-half relaxation time (118 +/- 3 vs. 104 +/- 2 ms) in the slow-twitch soleus. The exercise program also induced a decreased CT in the fast-twitch extensor digitorum longus (EDL), but significance was limited to the P less than 0.1 level. Muscle fatigue was produced by electrical stimulation at 45 trains/min and either 15 trains/min in SOL or 10 trains/min in the EDL and SVL for 1, 5, or 10 min.(ABSTRACT TRUNCATED AT 250 WORDS)
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002950:Citrate (si)-Synthase / Q000378:metabolism; D005121:Extremities / Q000502:physiology; D005260:Female; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology*; D010725:Phosphocreatine / Q000378:metabolism; D010732:Phosphofructokinase-1 / Q000378:metabolism; D010805:Physical Conditioning, Animal; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains
D007773:Lactates; D010725:Phosphocreatine; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D002950:Citrate (si)-Synthase; D010732:Phosphofructokinase-1