"In my opinion, and broadly speaking, exercise intensity must be relatively high in order to gain cardiovascular conditioning from brief, interval style workouts," Martin Gibola, a short exercise-enthusiast and McMaster's Professor, wrote in an email. "That is essentially the trade-off for the reduced time commitment involved. While there is no hard and fast rule, average heart rate during the intervals should be at least ~80-85 percent of maximum."

The key to exercising quickly is to get your heart rate right

The key to high-intensity burst workouts is to strike that delicate balance between collapse-to-the-floor exhaustion and a pleasant sweat. If I train too easy, my body won't think it needs to make physiological improvements; If I work too hard in the beginning, I won't be able to finish all of the movements.

A clever group of fitness researchers at the Human Performance Institute designed a circuit training routine that brings exhaustion to most major muscle groups in 7 minutes flat. The published results of the so-called "Scientific 7-minute workout" went viral: now, even the New York Times and the Pebble smartwatch have apps for users eager for a convenient way to incorporate it into their routines.

This is where technology plays a vital role: training at the very specific 80 percent of maximum heart rate is difficult to do. (Maximum heart rate is more obvious, at least for anyone who's ever run until their knees buckled.) If I rely on solely on my intuition, the incentive to take it easy overrides my sense of intensity.

Getting accurate data is important, but carrying a professional grade chest strap everywhere is a real pain in the neck. Fortunately, two new wearables, the Basis Peak and the Microsoft Band, promise to track my heart rate in real time.

Previously, popular health trackers only did resting heart rate (sub-130 bpm). The only non-chest strap alternative was the Mio Alpha watch — but it wasn't meant to be worn all day, so I still had to remember to carry some extra device on me.

To test out how well each of the new 24/7 wearables could handle short-burst workouts, I wore 4 devices during my workout and checked my heart rate during each minute. The baseline is the chest strap: the closer each gets to a Polar H7, a professional-grade device, the more accurate.

The workout

The scientific 7-minute workout is twelve exercises, thirty seconds each, ten seconds of rest between: jumping jacks, wall sit, pushups, crunches, step-up onto chair, squats, tricep dips on chair, plank hold, high-knee runs, lunges, pushup one-handed hold, side plank. (Since it was designed for beginners, I increased the intensity of each workout to include a jump.)

Minute One, Jumping jacks: I feel like I could do this forever, and begin seriously question whether the 7-minute "workout" is even doing anything for me. I look down at my watch, and see only 144 beats per minute (and I should be at least 160). I crank jumping jacks into high gear to spike my heart rate.

Minute two, jumping push-ups: I finally hit 167 bpm and am feeling a good stride. Now it feels like a workout! I bang through a dozen pushups without a rest. I got this.

Minute three, jumping on onto chair: my optimism fades as I barely squeak through without stopping to rest. My effort slightly dips to 165 bpm; it's already noticeably harder to sustain the same level of effort.

Minute four, tricep chair dips: I hit my runners’ high. Embracing the pain, I burn through dips as fast as gravity will allow. 172 bpm. Did I overdo it? Eh, probably not.

Minute 5, stationary high knee running: I definitely over did. Why did I over do it!? I get through half the 30-second sprint before slowing to a crawl. Thankfully, I'm at 170 bpm and realize I can slow down a bit as I edge toward the finish.

Minute 6, jumping lunges: I get a second runners high, fueled by nothing but the optimism that I'm going to make through. I clock in at 173 dpm. I'm way overdoing it; I don't care. I will beat this damn workout! I will own it!

Minute 7, holding one-arm side plank: I realize how long seven minutes of pain can seem. I push as hard as I can to maintain good form, barely holding myself up from falling. As the time buzzes, I collapse to the ground. I made it.

It is here, on the floor, covered in sweat, that I realize 7 minutes can, indeed, be workout. My heart rate proves that.