When does strength training become a cardio workout?

There are other cardio activities that you can track to. How about using Circuit training? or Calisthenics? I don't know what you do so I can't really say.

Hi,

I wear my HRM for the duration of my sessions of 30 minutes of strength training and 30 minutes of cardio. My HRM tells me that with my strength training I usually burn around 200 calories which is determined by my heart rate. Cardio is very much part of my strength training as I have minimal rest between sets and lift heavy. My cardio sessions are around 300 calories as I do interval runs on the treadmill which has me huffing and puffing. I enter the strenght training in my exercise diary based on actual calories burnt not on a time that MFP estimates as it does not usually match.

i would say wear the hrm and see what your calorie burn is and use that. i teach a 60 min strength endurance training class. i sweat from start to finish. it's weights (but not in the traditional reps / sets) but also cardio drills. i get a cardio workout from it and i could that.

I wear a HRM when doing strength training, log it, and still lose weight. Everyone is different though. I will mention that I am close to my goal weight and so it should be harder for those last few pounds to come off. And yet, logging my strength training I still lose. Go figure.

If your heart rate is up that high then I would think yes you could wear your HRM. I think what most people are talk about is lifting weights like bicep curls, tricep presses, bench press etc. because when you do those type of exercises you aren't really raising your HR too much so you probably won't get a correct reading of calories burned.

You've obviously never done a heavy bench press....

...or a squat.

Most people consider the 10-15 rep range to be more about endurance rather than building muscle/strength. 8-12 is generally classified as hypertrophy, building muscle size not necessarily strength, and 1-5 being the number of reps for heavy, pure strength lifting. Also the thread starter noted on her rest times, rest times also increases as you lift heavier. 10-15 reps you would usually do between 0-60 second rests periods, 8-12 between 60-120 second and 1-5 anywhere between 120-300 seconds depending on how close to your 1RM for that exercise (multi-joint vs isolation, etc.).

The program you are describing is definitely on the endurance side and sounds more cardio than pure strength training. If you are keeping a constant or near constant 160 heart rate I would think the HRM would be accurate to use. That said all of these estimate tools (MFP, HRM) are educated guesses. Keeping track of what is working and your diary ultimately will determine how many calories you should eat.

When I lift heavy, especially bench as mentioned before..my heart rate goes up to 95% on my HRM...so your heart rate is elevated during lifting. If you reduce the break time between lifts you tend to get a cardio effect going. I usually sweat more lifting than I do during cardio.

This.

If done correct, cardio is not even needed. Hell, I would never do it to lose weight.

When it is no longer a strength workout.

OK, that's an oversimplification, but you get the point.

There is, more or less, an inverse relationship between resistance and oxygen uptake/calorie burning. In other words, the heavier the weight, the lower the VO2 and calories burned. In this case heart rate is, for all practical purposes, irrelevant. By that I mean that an elevated heart rate during heavy strength training is not due to the same physiological mechanism as an elevated heart rate during cardio. The HRM reads the same, but the body doesn't respond the same.

Conversely, there is a more direct relationship between resistance and increases in muscle strength.

So you have a continuum--at one end there is max resistance/muscle strengthening/low oxygen uptake/low direct calorie burn at the other end you have max oxygen uptake/max calorie burn/low resistance/low muscle strengthening.

Essentially, the more you move toward the "cardio" end, the greater the oxygen uptake, the greater the direct calorie burn, and the less muscle strengthening effect you experience.

There are lots of different combinations of interval/circuit training that will have different physical effects--it's hard to provide a general guideline that fits all situations.

In general, HRM calorie counts--assuming the HRM is set up correctly--will be most accurate at the "cardio" end of the continuum--the farther you move toward the "strength" end, the less accurate they become--usually by overestimating calories.

As an example, a strength/cardio circuit than involves a number of upper body exercises can distort the heart rate/oxygen uptake relationship so that an HRM overestimates calories by 30%-35%