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Can I Exercise in the Danger Zone (above 85% Max Heart Rate)?

By Amanda Reck / April 10, 2018

Heart Rate Training can be a challenging thing to figure out. While there are charts and guidelines available in numerous resources, we are all unique individuals and what’s right for one person might not be right for you. The BuiltLean team sheds some light on your questions about heart rate, fitness, and nutrition in this week’s Q&A Roundup.

  1. Am I exercising in the “danger zone”?
  2. When should I do HIIT?
  3. What should I do to gain weight?
  4. Are lentils healthy?
  5. What type of protein shake should I get?

Question #1 – Am I exercising in the danger zone?

Question: In your chart “The Fat Burning Zone Myth,” heart rate zones over 85% are considered in the ‘danger zone.’ How does that fit in with doing HIIT? I can get my heart rate up to 182-184 (which is over 100% according to the max heart rate calculators) and always do when doing HIIT. A few times I got it up to 194! I thought it was an error the first time, but it happened a second time and both times I was so tired afterward I slept for the rest of the day. – Kristin
Answer: Hey Kristin, I think the “danger zone” should probably be a separate article! I think intensity really depends on fitness level and age. For someone who is fit and athletic, 95% of max heart rate is what is expected in a tough workout. 85% of max heart rate is definitely NOT the danger zone for a 20 year old sprinter in great shape. For someone who hasn’t exercised in a few months and is in their 70’s, 85% of max heart rate may cause nausea etc. and is likely dangerous. I wrote an article about max heart rate and how it can be highly variable => How to Calculate Max Heart Rate?. In my opinion, if you are concerned about your workout intensity, I would wear a heart rate monitor and cross reference how you feel with your heart rate. Also consider as you get in better shape, it will be harder to maintain a higher heart rate.


Marc Perry ( Marc Perry, CSCS, CPT)

Question #2 – When should I do HIIT?

Question: Hi Mark, just a quick question regarding HIIT — if I do strength training 3 times a week, should I do HIIT after this session or on the resting days? I read overtraining can have side effects. Thanks! – Tommy
Answer: Hey Tommy,

That really depends on your schedule and what works best for you. In the BuiltLean Program, HIIT is completed after the strength portion of the workout, which helps burn extra fat and reduce workouts to only 3 days per week, which is manageable for most people. With that said, opposite days are also acceptable. Frequency vs. duration of workouts is a topic that has been researched a lot, but the research is tougher to come across when mixing strength and HIIT. Generally, what the research says is that more frequent workouts can elicit better gains. At the end of the day, what I’ve found is that the quality of your results will come down to exercise adherence. If doing HIIT is easier for you on separate days, then do that. Alternatively, if you prefer doing HIIT after a workout, then that can work very well.

Marc (Marc Perry, CSCS, CPT)

Question #3 – What should I do to gain weight?

Question: Hi – could you recommend some exercises to gain weight? – Swolacius
Answer: I’m assuming that by “gain weight” you mean “gain muscle.” There is an article on the BuiltLean website called Best Exercises to Build Muscle that discusses exercises you’ll want to include in your program: squats, deadlifts, and kettlebell swings. Focus on fewer reps with heavier weights. Working the larger muscles in your body with a will induce the biggest testosterone boost and muscle growth. Also be sure to eat enough protein, eat a slight excess of calories, and rest between workouts.

Kristin (Kristin Rooke, CSCS, CPT)

Question #4 -Are lentils healthy?

Question: Hey BuiltLean.com team, I had a quick question for you. Is there something I’m missing about lentils?

The reason I ask is I recently started making lentil soup and it is a) delicious b) perfect for the winter c) seem really good for one (protein, fiber and other vitamins). Is there anything bad about lentils that I’m missing? – Alexander

Answer: Alexander,
Lentils possess a wide variety of beneficial nutrients, which you’ve already mentioned. The only downside to lentils is that they contain phytate acid, which reduces the availability of dietary minerals from digestion and can cause gastrointestinal issues. But, phytates can be reduced by soaking the lentils in warm water overnight.

Kwesi (Kwesi Peters, CPT, Community Manager)

Question #5 – What type of protein shake should I get?

Question: Is a blend protein with ingredients like: whey concentrate,isolate, hydrolyzed,egg albumin, casein, etc good for post workout? For instance, Nutrex Muscle Infusion black. Or should I buy a hydrolyzed whey isolate? Ex. Dymatize Iso 100. I mainly consume protein shakes post-workout. – Himanshu
Answer: Hi Himanshu,

There are a couple articles on the BuiltLean website that perfectly answer the question you have about protein supplements:

  1. Whey Protein Benefits, Risks and Top Picks
  2. Is Hydrolyzed Protein Better Than Whey?

These should give you a little more clarity on which supplements are the best in terms of reaching your goals.

Let us know if you have any other questions!

Kristin (Kristin Rooke, CSCS, CPT)


  • Peter says:

    A well known TV presenter here in the UK had a stroke whilst performing a high intensive workout on a rowing machine.

    Admitedly he is in his early fifties, but he runs marathons and is obviously quite fit.

    I think people should be aware of the possible dangers of raising your heart rate over 85% of its max, through short intensive burst of activity.

    Sure everyone has different fitness levels, but common sense tells you it's not a good thing to do, especially as you get older.

    There are far safer ways to raise your heart rate (such as strength training) that benefits the cardiovascular system.

    • Marc Perry, CSCS, CPT says:

      @Peter - Thanks for sharing. We recommend all beginners and individuals over 50 years old wear heart rate monitors and stay below 85%. For example, when I train my dad who is 65 years old, we don't go above 85%, ever. But I would disagree that someone who is not fit can't go above that range. Most sprinters are well above 85% max heart rate when they workout. Can be safe but still intense to go above 85% heart rate depending on the person. It's key to use judgement of course.

  • Leo says:

    I'm 58 years old. I've been running all my life and run a few half-marathons each year. If I took the advice above: "We recommend all beginners and individuals over 50 years old wear heart rate monitors and stay below 85%" I would have to stop running right now, because my average heart rate in a run is above that 85% (assuming the 220 - age "rule"), and sometimes peaks above 200bpm - and that's not going to my full limit. Sorry to be a bit rude - but what nonsense!

    • Marc Perry, CSCS, CPT says:

      Hey Leo, thanks for sharing. I wrote an in-depth article about Max Heart Rate which shows that it's highly individual, right here => How to Calculate Your Max Heart Rate.