Alteration in cardiac uncoupling proteins and eNOS gene expression following high-intensity interval training in favor of increasing mechanical efficiency.
OBJECTIVE
High-intensity interval training (HIIT) increases energy expenditure and mechanical energy efficiency. Although both uncoupling proteins (UCPs) and endothelial nitric oxide synthase (eNOS) affect the mechanical efficiency and antioxidant capacity, their effects are inverse. The aim of this study was to determine whether the alterations of cardiac UCP2, UCP3, and eNOS mRNA expression following HIIT are in favor of increased mechanical efficiency or decreased oxidative stress.


METHODS
Wistar rats were divided into five groups: control group (n=12), HIIT for an acute bout (AT1), short term HIIT for 3 and 5 sessions (ST3 and ST5), long-term training for 8 weeks (LT) (6 in each group). The rats of the training groups were made to run on a treadmill for 60 min in three stages: 6 min running for warm-up, 7 intervals of 7 min running on treadmill with a slope of 5° to 20° (4 min with an intensity of 80-110% VO2max and 3 min at 50-60% VO2max), and 5-min running for cool-down. The control group did not participate in any exercise program. Rats were sacrificed and the hearts were extracted to analyze the levels of UCP2, UCP3 and eNOS mRNA by RT-PCR.


RESULTS
UCP3 expression was increased significantly following an acute training bout. Repeated HIIT for 8 weeks resulted in a significant decrease in UCPs mRNA and a significant increase in eNOS expression in cardiac muscle.


CONCLUSIONS
This study indicates that Long term HIIT through decreasing UCPs mRNA and increasing eNOS mRNA expression may enhance energy efficiency and physical performance.
Faculty of Education and Psychology, Shiraz University, Shiraz, Iran.
Ali Asghar
AA
Fallahi
Department of Physiology, Arsanjan Branch, Islamic Azad University, Fars, Iran.
Shahnaz
S
Shekarfroush
Department of Physical Education, University of Kashan, Iran.
Mostafa
M
Rahimi
Institute of Biotechnology and Bioengineering, Isfahan University of Technology, Isfahan, Iran.
Amirhossain
A
Jalali
Sport Physiology Research Center, Baghiyatallah University of Medical Sciences, Tehran, Iran.
Ali
A
Khoshbaten
High-intensity interval training; UCP2; UCP3; eNOS