Manipulating training intensity and volume in already well-trained rats: Effect on skeletal muscle oxidative and glycolytic enzymes and buffering capacity

Authors

Paul Laursen, Edith Cowan University
SA Marsh
DG Jenkins
JS Coombes

Document Type

Journal Article

Publisher

NATL Research Council Canada-NRC Research Press

Faculty

Faculty of Computing, Health and Science

School

School of Exercise, Biomedical and Health Science

RAS ID

4957

Comments

Laursen, P. B., Marsh, S. A., Jenkins, D. G., & Coombes, J. S. (2007). Manipulating training intensity and volume in already well-trained rats: effect on skeletal muscle oxidative and glycolytic enzymes and buffering capacity. Applied Physiology, Nutrition, and Metabolism, 32(3), 434-442. Available here

Abstract

Well-trained endurance athletes undergo periods of high-intensity interval training (HIT) or high-volume training (HVT) to improve exercise performance, but little is known about the mechanistic changes that occur during this time. The purpose of this study was to examine the influence of HIT and HVT on the activities of citrate synthase (CS) and phosphofructokinase (PFK), and on intramuscular buffering capacity (β_m) in already well-trained rats. At 4 weeks of age, Wistar rats were divided into sedentary (SED; n = 18) and exercise training groups (n = 38). Following a 10 week preliminary training program, trained rats were divided randomly into 3 further groups that completed 4 additional weeks of continued endurance (CON, n = 14), high-intensity training (HIT, n = 12), or high-volume training (HVT, n = 12). Soleus (SOL), red and white gastrocnemius (RG and WG), and red and white vastus (RV and WV) muscles were removed 24–48 h after a final run-to-fatigue performance test (30 m·min^–1; 25% grade) to determine the activities of CS, PFK, and β_m. No differences in run time to exhaustion were found between the groups. However the HIT group possessed CS and PFK activities and β_m in WV muscle that were 60%, 24%, and 10% higher, respectively (all p < 0.05), compared with the HVT group; differences were not found between the HIT and CON groups. Although no differences in run performance were found, HIT compared with HVT in already well-trained rats resulted in significantly higher oxidative and glycolytic capacities of fast-contracting fibres. No differences were shown in fast-contracting muscle between HIT and CON.

DOI

10.1139/H07-006