Cardio question

[ARN]

How fast should I be running on the treadmill? Should I be running at a constant speed or should I be doing do intervals? Where should my heart rate be around? I'm in my bulking phase right now and I just want to keep myself from getting too chubby I'm 23, 5'10 around 150lbs. TIA

 

[diamonddiceclay]

don't do cardio when bulking-just eat clean

 

[aaron10121]

220-23=197
197X.60= 118.2
197x.70= 137.9

heart rate should be between 118 and 138. thats the perfect range, 60 to 70% of ur maximum heart rate to keep body fat down.