I need some guidance about exercise heart rates. My doctor wants me to work at 75% max for 30+ minutes 4-5 days a week. That makes my target HR 132. I vary my exercise routine sometimes, and get up to 85-90% max. My question is, if the weighted average max of my total workout is 132 (including warm-up and exerting times), is that the same as working out for 30+ minutes at 132 continuously? If a car is more efficient at a steady speed, is that true of the human heart? Which method will be more effective for weight control? Thanks!