Anyone else get sick with HIIT?

High intensity effort is fatiguing and stressful, inherently. HIIT - if we're talking true HIIT, max effort intervals - is currently both overrated, and overdone.

Elite athletes treat high intensity as a condiment, including it in the workout menu for specific reasons at specific times. This idea that everyone ought to do lots of it, regularly, is IMO trendy nonsense.

OK, rant out of the way.

In practice, doing more HIIT than our fitness level is ready for - which is going to vary by circumances - is, as I said, a physical stressor. The implication is that it can be good plan to phase it in slowly, not to go pedal to the metal all at once. Physical stressors cause our bodies to give us feedback in various ways; the symptoms you mention could be some of those ways. Sure, if you have a predisposition to IBS (I kinda do, too), your body might be more inclined to talk back via digestive symptoms. Our individual vulnerabilities will break down with stress sooner than our individual strengths do: That only makes sense, right?

There are lots of things called HIIT these days. The specific type might matter, in how you react. If the specific moves you're doing involve - for example - lots of compression and decompression and bouncing/jouncing of your midsection, that could lead to some digestive distress for anyone. (Timing of eating, and even what was eaten recently, can have implications for this. Some people can't eat much in the way of solid foods before workouts, for example, or high-fiber foods, or dairy - the specifics are potentially quite individual/idiosyncratic - experimenting might lead to insight.)

If you don't usually do high-intensity exercise, then that alone can cause reactions for some. For example, IMU some people experience severe digestive distress, to the point of vomiting, as a consequence of limited lactate tolerance. (Lactate accumulates with exercise, and may not be cleared as fast as it accumulates with intense exercise. Our bodies body can react to it negatively. It's an effect that can change with training, i.e., a person can become more lactate tolerant. There are specific strategies to train it, if it's important for you.) Just blood flow demands reportedly can cause the digestive distress effect, reportedly, in people who are sensitive.

HIIT is for sure optional. What are you trying to get out of it? Do you have other options to achieve those goals? Can you integrate it into your routine more slowly, and adapt to it (if it's really important to you, then the "add it gradually" option may help you; or you might consider other specific moves to achieve the result you seek, if the midsection-jostling, or dizziness, or something else move-specific seems like a contributor).

HIIT really shouldn't be done unless someone has a really strong cardio "base". And if someone doesn't know their HR max (and isn't in the shape to be able to do a HR max test), probably best to leave off HIIT.

HIIT should raise your HR from 85% to 90% of max HR (or more). Recovery from that type of HR needs to occur pretty rapidly. The better shape you are, the more rapid the recovery. If someone does HIIT not understanding some of these things, it can be quite dangerous. One pretty well known indoor rower died just last year after a sprint workout (one in which he held the World Record for a while).

I do HIIT twice a week, but I also do four to five days a week of pretty easy long endurance workouts. I understand what my max HR is and I know what my HR needs to look like for recovery. If I'm in the middle of a HIIT workout and don't see it recovering as fast as I think it should, I abort the workout.

I have a true HIIT workout planned today. Not looking forward to it. At all. I'll likely feel pretty awful on the last few reps, as I should. Anyone that reaches true 90% max HR will feel bad. Light headed, almost dizzy, blurry vision. Your brain and lungs struggling for oxygen, not terribly unlike suffocation.

My wife does a "HIIT workout" on YouTube. My wife hasn't seen 70% max HR in like 10 years. It's not a HIIT workout. Not even close to it. But she's 60 this year and I'm proud of what she does do. But I won't bust her bubble either.

scott_90345 wrote: »

HIIT workout helps in losing fats by keeping the insulin level lower.

What's your source for this? Doing any HIIT exercise DIRECTLY affects glycogen and not fat while being performed.

A.C.E. Certified Personal and Group Fitness Trainer
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Been in fitness for 30 years and have studied kinesiology and nutrition