I have not combined STS with Barre. That said I know You can't really replace cardio with Barre. Barre does not offer enough
metabolic response to burn a lot of fat. It does raise the heart rate to some degree but not enough to significantly improve your
cardio vascular abilities. This is probably not the truth you wanted to hear but I thought I may reply to your question.
All the best. Enjoy STS.
http://cathe.com/barre-workouts-can-they-change-the-shape-of-your-body
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The Downsides of Barre
If you have a substantial amount of weight to lose or you’re trying to greatly improve your functional strength or increase muscle size, barre shouldn’t be your only form of workout. It’s not metabolically challenging enough to burn significant amounts of fat and doesn’t work multiple muscle groups using high resistance, so it won’t give you a bodybuilder’s physique. It also doesn’t get your heart rate up enough to have substantial cardiovascular benefits, although you can increase the aerobic benefits by adding bursts of aerobic activity at intervals throughout the workout. Instead, you get the benefits of more flexibility, greater muscle endurance and will likely notice improvements in posture and the way you carry yourself.
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