Conclusion Neither HIIT nor MICT is superior for altering TC , TRG , or LDL-C , or TC-HDL-C ratio .
To raise HDL-C , HIIT may result in a larger effect size compared with MICT .
Objective To compare the effects of moderate intensity continuous training ( MICT ) and high intensity interval training ( HIIT ) on  adult lipid profiles ;  to identify training or participant characteristics that may determine exercise-induced change in total cholesterol ( TC ) , triglycerides ( TRG ) , high-density lipoprotein cholesterol ( HDL-C ) and low-density lipoprotein cholesterol ( LDL-C ) .
Sprint interval and moderate-intensity continuous training have equal benefits on aerobic capacity, insulin sensitivity, muscle capillarisation and endothelial eNOS/NAD(P)Hoxidase protein ratio in obese men.
KEY POINTS Skeletal muscle capillary density and vasoreactivity are reduced in obesity , due to reduced nitric oxide bioavailability . Sprint interval training ( SIT ) has been proposed as a time efficient alternative to moderate-intensity continuous training ( MICT ) , but its effect on the skeletal muscle microvasculature has not been studied in obese individuals . We observed that SIT and MICT led to equal increases in capillarisation and endothelial eNOS content , while reducing endothelial NOX2 content in microvessels of young obese men . We conclude that SIT is equally effective at improving skeletal muscle capillarisation and endothelial enzyme balance , while being a time efficient alternative to traditional MICT . ABSTRACT Sprint interval training ( SIT ) has been proposed as a time efficient alternative to moderate-intensity continuous training ( MICT ) , leading to similar improvements in skeletal muscle capillary density and microvascular function in young healthy humans . In this study we made the first comparisons of the muscle microvascular response to SIT and MICT in an obese population . Sixteen young obese men ( age 25 ± 1 years , BMI 34.8 ± 0.9 kg m(-2 ) ) were r and omly assigned to 4 weeks of MICT ( 40 - 60 min cycling at ∼65 % V̇O2 peak , 5 times per week ) or constant load SIT ( 4 - 7 constant workload intervals of 200 % Wmax 3 times per week ) . Muscle biopsies were taken before and after training from the m. vastus lateralis to measure muscle microvascular endothelial eNOS content , eNOS serine(1177 ) phosphorylation , NOX2 content and capillarisation using quantitative immunofluorescence microscopy . Maximal aerobic capacity ( V̇O2 peak ) , whole body insulin sensitivity and arterial stiffness were also assessed . SIT and MICT  increased skeletal muscle microvascular eNOS content and eNOS ser(1177 ) phosphorylation in terminal arterioles and capillaries ( P < 0.05 ) , but the latter effect was eliminated when normalised to eNOS content ( P = 0.217 ) . SIT and MICT also reduced microvascular endothelial NOX2 content ( P < 0.05 ) and both increased capillary density and capillary-fibre perimeter exchange index ( P < 0.05 ) . In parallel , SIT and MICT increased V̇O2 peak ( P < 0.05 ) and whole body insulin sensitivity ( P < 0.05 ) , and reduced central artery stiffness ( P < 0.05 ) . As no significant differences were observed between SIT and MICT it is concluded that SIT is a time efficient alternative to MICT to improve aerobic capacity , insulin sensitivity and muscle capillarisation and endothelial eNOS/NAD(P)Hoxidase protein ratio in young obese men
Conclusion Neither HIIT nor MICT is superior for altering TC , TRG , or LDL-C , or TC-HDL-C ratio .
To raise HDL-C , HIIT may result in a larger effect size compared with MICT .
Objective To compare the effects of moderate intensity continuous training ( MICT ) and high intensity interval training ( HIIT ) on  adult lipid profiles ;  to identify training or participant characteristics that may determine exercise-induced change in total cholesterol ( TC ) , triglycerides ( TRG ) , high-density lipoprotein cholesterol ( HDL-C ) and low-density lipoprotein cholesterol ( LDL-C ) .