Heart Rate and caffine???

I have been using a heart rate monitor now during my workouts to better calculate the calories I am burning and sometimes I have a small coffee between work and the gym.  I notice that my heart rate starts off higher or I can get it up quicker when I have a little caffine before.  I was just wondering if anyone knew if that was bad or if this is then somehow giving me a false read out as far as how many calories I am burning.  Just wondering what other people might think about this topic.  I know some people drink energy drinks or redbull.  Does it matter and is it really unhealthy? 

I drink a small tea (or coffee) before working out as well. Here's why.

Also, Michael Geary says this about it in your diet:

"The Secret Fat Loss Benefits of Teas [and caffeine]:

Besides containing caffeine, several types of tea contain other compounds that can significantly enhance your fat loss efforts. Specifically, the teas that have been getting all of the attention for their fat loss benefits are green tea and oolong tea. Green tea and oolong tea contain substances called catechins and polyphenols, along with caffeine, and these substances work through several different mechanisms in our bodies to promote fat loss. Although black tea (the normal type of tea used for iced tea and the most common tea sold) does contain caffeine and antioxidants, and may also help promote fat loss.

There is ample evidence showing that green, oolong, and even white teas work through multiple mechanisms in your body to promote fat loss and a leaner body. To give you an extra fat loss advantage, I recommend brewing batches of a mixture of green, oolong, and white teas and refrigerate this as iced tea. If you have to sweeten it, use a non-caloric sweetener so you’re not adding extra sugar calories to your diet. Stevia is a good natural non-caloric sweetener that is not chemically processed like artificial sweeteners. Also, unless you have to avoid caffeine for some reason, I’d recommend staying away from the decaffeinated teas, since the caffeine contributes to some of the fat burning effect. A strategy you may want to try is drinking a glass of the iced tea mixture with each of your first three meals of the day (no later than mid-afternoon, so as not to interfere with your sleep at night). From my experience, you’ll see a noticeably quicker fat loss when you start adding 3 or 4 cups of this tea mixture to your diet on a daily basis. Again, if you’re eating too many total calories, none of this will matter, and you won’t see an increased fat loss."

Thanks that article you posted was really helpful.  I do like my jolt between work and the gym, it keeps me from going home and not going t the gym at all.  So thanks for the info.