Skeletal muscle is extremely adaptable to a variety of metabolic challenges, as both traditional moderate intensity endurance (ET) and high intensity interval training (HIIT) increase oxidative potential in a coordinated manner. While these responses have been clearly demonstrated in healthy individuals, it remains to be determined if both produce similar responses in the context of hypertension, one of the most prevalent and costly diseases worldwide. Therefore, in the current study we utilized the Dahl sodium sensitive rat, a model of hypertension, to determine the molecular responses to 4 weeks of either ET or HIIT in the red (RG) and white gastrocnemius (WG) muscles. In the RG, both ET and HIIT increased the content of electron transport chain proteins and increased succinate dehydrogenase (SDH) content in type I fibres. While both intensities of exercise shifted fibre type in RG (increased IIA, decreased IIX), only HIIT was associated with a reduction in eNOS and an increase in HIF1α proteins. In the WG, both ET and HIIT increased markers of the electron transport chain, however, HIIT decreased SDH content in a fibre-specific manner. ET increased type IIA, decreased IIB fibres and increased capillarization, in contrast HIIT increased the percentage of IIB fibres, decreased capillary to fibre ratios, decreased eNOS, and increased HIF1α protein. Altogether, these data show that unlike in healthy animals, ET and HIIT have divergent effects in the skeletal muscle of hypertensive rats. This suggests ET may be optimal at improving the oxidative capacity of skeletal muscle in animals with hypertension.
- high intensity interval training
- mitochondrial content
- capillary density
- Copyright © 2015, American Journal of Physiology - Regulatory, Integrative and Comparative Physiology