Transcript for New report sheds light on accuracy of fitness trackers

Back now with the big board. Jesse palmer, T.J. Holmes at the table which means I have to grow a beard. I'm just following along. Following along. That's right. We'll start out with warping for anybody who uses a fitbit or any fitness tracker a new report reveries they may not be as accurate as you think. These are wildly popular as you know and for tracking your steps and other things pretty good for heart rate everybody needs to be aware. This is a major study and what they found these things can be wildly off when it comes to exercising and measuring your heart rate. When you're sitting it does a pretty good job of your resting heart rate but when you are exercising is when a lot of people use these things they can be and what they found consistently between 20 and 40 beats per minute. That's a big deal if you're looking down thinking I'm good but it's actually 40 beats -- In both directs. It can flukt wait so that can be an issue. Are there any explanation of why so inaccurate. It's weird how they work. It uses L.E.D. Light to actually reflect the light off your skin to measure the blood volume to see what your heart rate. Sounds complicated but that's fine when you're sitting and resting, running, active, sweating and all these factors are coming into play so it can be off. I guess last week we did a story about a woman who says fitbit saved her life. How is fitbit responding. That woman is in her 70s resting. She was measuring her heart rate by resting which these can do a pretty good job and saw her heart rate was off, way off and went to the hospital and it was a good thing she did. But when you're exercising is the issue. Fitbit gave us a statement, one of several that were tested here and can put that up but they're saying this is not meant to be a medical device. Not intended to be a medical device. They work into your everyday life to give several days worth. Don't throw them out. Supposed to give you some sort of measure, an idea of your heart rate but don't use it to check your cardiac health. At any single moment in time. Accurate condition. Leave that to a doctor. 20 to 40 is a lot of beats. That's huge. Difference between me taking the stairs and not taking the stairs. I thank you, T.J. This next story is not for the faint of heart. This video is going viral of a daredevil preparing to work on air. Well, he's not walking on air. He is taking a step into the sky balance, 42 stories high. It's in Texas where they do everything big in Texas and, Jesse, you have more on that. Tell us about it. In case you've ever wondered what it is like to walk out over downtown Houston Texas, market square tower has the swimming pool for you and posted this video on Facebook calling this the sky pool. It's on the 42nd floor about 500 feet above street level. What makes this pool unique, though, it extends ten feet off the side of the building and the only thing keeping that guy from becoming a speed bump on Preston street 42 floors below is eight inches of plexiglas. That's it. You watch that. That doesn't even look real. I can't look at it. It looked superimposed. Good for you, you don't have to use the pool. The building has a pool on the fourth floor terrace. They'll eventually call it a kiddie pool. We have to assume it is safe or they wouldn't have built this and one in China as well. Glass bottom bridge in China connected to this mountain. It suspends 3, 500 feet. The crazy thing, you see the glass panel, there's only three of them on the bottom. Each glass pane is just 27 millimeters thick. Now, the people that created this bridge say it's safe but there is a story -- look at that picture there. There is a story on the news someone dropped a stainless steel cup and cracked one of the glass panes so immediately I took this bridge off 40 things I have to do before I turn 40. I have a question. Who would try the pool? Who would swim in that. Made out of glass, right? And glass crack, right? The pool hasn't cracked yet. Sober I'm not doing it. Wow. That wasn't the question. Champagne campaign, I'll do it. That's how he starts every night. No, I'm teasing. I'm not doing it unless -- no. Better chance of me doing the pool than that, that skywalk. The real headline is you're not 40 yet. No, I got some time. Dude, you can still grow a beard. That's the real headline. Going to grow a beard, everybody. All right, fella, thank you very much.

This transcript has been automatically generated and may not be 100% accurate.