Effects of Concurrent Training on Oxidative Capacity in Rat Gastrocnemius Muscle

REGULA FURRER, ARNOLD DE HAAN, NATHALIE BRAVENBOER, DORIEN KOS, PAUL LIPS, RICHARD T. JASPERS
2013 Medicine & Science in Sports & Exercise  
Purpose: Training for improvement of oxidative capacity of muscle fibers may be attenuated when concurrently training for peak power. However, because of fiber type-specific recruitment, such attenuation may only account for high-oxidative muscle fibers. Here, we investigate the effects of concurrent training on oxidative capacity (as measured by succinate dehydrogenase (SDH) activity) by using task-specific recruitment of the highand low-oxidative compartment of rat medial gastrocnemius muscle
more » ... (GM). Methods: Forty rats were subjected to 6 wk of peak power training (PT, n = 10), endurance training (ET, n = 10), concurrent peak power and endurance training (PET, n = 10), or no training (control, n = 10). SDH activity, mRNA expression of SDH, peroxisome proliferator-activated receptor-F coactivator 1> (PGC-1>), receptor-interacting protein 140, and BCL2/adenovirus E1B 19 kDa-interacting protein 3 as well as PGC-1> protein levels were analyzed in the low-and high-oxidative region of the GM. Results: In the low-oxidative compartment, PT and PET induced a 30% decrease in SDH activity of Type IIB fibers compared with controls and ET (P G 0.001) without changes in mRNA or protein levels. In the highoxidative compartment, after ET, SDH mRNA levels were 42% higher and RIP140 mRNA levels 33% lower compared with controls, which did not result in changes in SDH activity. Conclusion: These results indicate that in compartmentalized rat GM, peak power on top of endurance training attenuated transcription of mRNA for mitochondrial proteins in high-oxidative muscle fibers. In low-oxidative Type IIB fibers, peak power training substantially decreased SDH activity, which was not related to lower SDH mRNA levels. It is concluded that PT and PET enhanced mitochondrial degradation in the low-oxidative compartment of rat GM. FIGURE 1-Effects of training on running performance. (A) Effects of peak power training (PT) alone and in combination with endurance training (PET) are shown on maximum running velocity. (B) Effects of PET and endurance training (ET) alone are shown on maximal running duration. Rats were trained for 6 wk, 5 dIwk j1 , performing PT, ET, or PET. All values are mean T SE. *Significant difference (P G 0.05).
doi:10.1249/mss.0b013e31828fc65f pmid:23475169 fatcat:vutrrbzajzh7jgrdvbimzc4gge