In this guide
- What HIIT actually is (and what it is not)
- What the research says about fitness and health markers
- ACSM-style intensity, work and rest
- Three protocols I actually use
- A simple weekly plan that fits around lifting
- Mistakes that make HIIT useless or risky
- HIIT, stamina and your sex life
- My take
I spent years as a teenager living on intervals without calling them HIIT. In boxing you do rounds. You go hard, you recover, you go hard again. Gold at the Spanish Cadet Boxing Championship at 16, in the -69 kg class, did not come from jogging for an hour while listening to a podcast. It came from short, ugly efforts with a purpose.
Today my body is still part of my work. I do not have infinite hours, and I refuse to waste the ones I have on cardio theatre. That is why I care about high-intensity interval training: done properly, it is efficient. Done badly, it is just thrashing around until you hate exercise.
I am not a doctor or a sports physiologist, and this is not medical advice. If you have heart disease, chest pain with effort, uncontrolled blood pressure, diabetes, joint problems or you have been inactive for years, talk to a GP before you start hard intervals. The facts below come from ACSM materials, NHS activity guidance and peer-reviewed work on PubMed. The opinions are mine.
What HIIT actually is (and what it is not)
HIIT means repeated hard efforts separated by easier recovery. The hard bits are short enough that you can push intensity; the easy bits are long enough that you can go hard again. Typical descriptions used in ACSM-oriented writing put work intervals roughly in the 80 to 95 percent of maximum heart rate range, with recovery closer to an easy conversational pace, often repeated about 6 to 10 times, after a warm-up and before a cool-down. Total hard time is often only 10 to 20 minutes inside a 20 to 40 minute session.
What HIIT is not:
- A 45-minute class where everything is “hard” and nobody recovers.
- An excuse to skip strength training.
- A guaranteed six-pack protocol.
- The same thing as walking after dinner.
Sprint interval training (very short, near-maximal efforts) is a cousin of HIIT. Both raise fitness when programmed sensibly. Both punish egos when programmed like a punishment.
Intervals only work if the hard parts are hard and the easy parts are easy. If everything is medium, you just invented boring cardio with a new name.
What the research says about fitness and health markers
Cardiorespiratory fitness (often measured as VO2max or related peak aerobic capacity) is one of the strongest predictors of long-term health. That alone is a reason to care about training that raises it efficiently.
A 2024 umbrella review of systematic reviews and meta-analyses concluded that HIIT, including sprint-style variants, significantly increases cardiorespiratory fitness compared with non-exercise controls, and often shows favourable comparisons with moderate-intensity continuous training as well, across healthy adults, people with overweight and other groups (Poon et al., PubMed).
A 2023 meta-analysis of randomised trials in the general population found HIIT improved a wide set of cardiometabolic markers: peak aerobic capacity, blood pressure, resting heart rate, waist circumference, body fat percentage and several blood markers including fasting insulin and lipids (Edwards et al., PubMed). These are average effects from controlled trials, not a promise that your next session will rewrite your blood panel.
Men and women both respond. A systematic review with meta-analyses found similar relative VO2max improvements in men and women after HIIT interventions (Book et al., PubMed).
None of that means HIIT is the only tool. The NHS still recommends adults do at least 150 minutes of moderate activity or 75 minutes of vigorous activity a week, plus muscle strengthening on two or more days (NHS: physical activity guidelines for adults). HIIT can cover a lot of the vigorous side in less clock time. Walking and zone-2 work still help recovery, mood and the steps that keep you generally active. I wrote about that balance in how to build stamina and how many steps a day.
ACSM-style intensity, work and rest
You do not need a lab. You need honesty about effort.
Simple intensity checks
- Talk test: during hard intervals you can say a few words, not a paragraph. During recovery you can speak normally.
- Rate of perceived exertion: hard intervals should feel like 8 or 9 out of 10 for short efforts, or a strong 7 to 8 for longer 2 to 4 minute repeats. Recovery should feel like 3 to 4.
- Heart rate (optional): many HIIT descriptions use roughly 80 to 95 percent of estimated maximum for work bouts. Estimated maximum is often 220 minus age, which is rough, so treat it as a guide, not a law.
Work to rest
- Short sprints (15 to 30 seconds hard): rest often equal or longer than the work (for example 30 to 90 seconds easy).
- Classic aerobic intervals (1 to 4 minutes hard): rest similar length or slightly shorter once you are fit.
- Beginners: shorter hard bits, longer easy bits, fewer rounds.
Warm up 5 to 10 minutes. Cool down 5 minutes. Skipping both is how people feel wrecked for two days and then quit.
Three protocols I actually use
Pick one. Master it for four weeks before you invent a new torture.
1) Bike or rower: 10 x 30/60
- Warm up 8 minutes easy.
- 30 seconds hard, 60 seconds easy, ten times.
- Cool down 5 minutes.
Low impact, easy to control, kind to knees. Ideal if jumping hurts.
2) Run or assault bike: 6 x 2 minutes
- Warm up thoroughly.
- 2 minutes strong (hard but sustainable), 2 minutes easy, six rounds.
- Cool down.
This builds the engine you feel in long filming days and in boxing-style conditioning.
3) Bodyweight circuit intervals (when you have no machines)
Work 40 seconds, rest 20 seconds, for 8 to 12 minutes total, then rest 2 minutes and repeat once if you are conditioned:
- Fast march or high knees (low impact option: step-ups)
- Push-ups or incline push-ups
- Squat to stand or sit-to-stand from a chair
- Mountain climbers or dead-bug marches
- Optional: shadow boxing bursts
Form first. Sloppy jumping is not HIIT; it is joint gambling.
A simple weekly plan that fits around lifting
Men who only do HIIT often look smaller and feel flat. Men who only lift often gas out walking up stairs. Combine them.
Example week
- Monday: full-body strength (beginner strength plan)
- Tuesday: HIIT protocol 1 or 2 (20 to 30 minutes total)
- Wednesday: walk, mobility, easy day (stretching and mobility)
- Thursday: full-body strength
- Friday: optional second HIIT or boxing rounds
- Saturday: long easy walk or zone-2
- Sunday: rest or very light movement (rest days and overtraining)
Two HIIT days is plenty for most. If sleep is short or stress is high, drop to one. Sleep debt ruins intervals faster than a bad playlist. Details in how much sleep do men need.
Fuel the work. Hard intervals on an empty tank feel heroic and look stupid. Carbs before hard sessions help more men than another scoop of motivation. Protein still matters for the lifting days: how much protein to build muscle.
Mistakes that make HIIT useless or risky
Going hard every day. Intensity needs recovery. Without it you collect fatigue, not fitness.
Turning rest intervals into semi-hard jogging. Then the next work bout collapses and you never accumulate quality time at high intensity.
Copying elite protocols in week one. Eight all-out 30-second sprints sound cool until your calves, Achilles or ego explode.
Ignoring strength. Muscle and tendons are your injury insurance. A 2014 meta-analysis found strength training reduced sports injuries substantially (Lauersen et al., PubMed).
Using HIIT to “earn” junk food. Energy balance still rules fat loss. Intervals help the engine; the kitchen decides the mirror. See how to lose belly fat.
Skipping medical sense. Chest pain, dizziness, unusual shortness of breath or palpitations are stop signs. Get checked.
HIIT, stamina and your sex life
I get asked whether intervals help in bed. Indirectly, yes: better fitness, better blood vessels, better mood and better body confidence all matter. Direct magic, no.
Regular aerobic and interval training support the same vascular health that supports erections. I break down the evidence in exercise and erectile function. If stress is crushing your drive, intervals can help some men blow off steam, but sleep and stress management matter more than another Tabata video: how to reduce stress and sexual performance anxiety.
Discipline beats the motivational spike after one brutal session. If you need the mindset piece, read discipline vs motivation.
Progress for 8 weeks (keep it boring on purpose)
- Weeks 1–2: 6 rounds, generous rest, learn pacing.
- Weeks 3–4: 8 rounds, same work duration.
- Weeks 5–6: 8 to 10 rounds, or shorten rest slightly if form stays clean.
- Weeks 7–8: keep volume, add a little speed or incline, then take one easier week.
Track one number: rounds completed at the target effort, or average pace / watts on a bike. If the number crawls upward while you still sleep and lift, you are winning.
My take
HIIT is a tool, not a religion. Boxing taught me that short hard rounds build a different engine than long slow miles. The research now says the same thing in quieter language: intervals raise fitness efficiently and can improve cardiometabolic markers when you show up consistently.
Use two sessions a week. Keep the hard parts honest. Keep the easy parts easy. Lift. Sleep. Eat enough protein. Do not confuse suffering with progress.
If you want the human stories from this industry, read my columns on House of Maximo. Follow my work at maximogarciaworld.com, and for the 18+ side, fuckingpornstars.net.
Sources
- Poon ET et al. High-intensity interval training and cardiorespiratory fitness in adults: an umbrella review. Scandinavian Journal of Medicine & Science in Sports, 2024.
- Edwards JJ et al. High-Intensity Interval Training and Cardiometabolic Health in the General Population. Sports Medicine, 2023.
- Book J et al. Cardiorespiratory fitness adaptations to HIIT in men and women. Sports Medicine, 2023.
- Lauersen JB et al. Exercise interventions to prevent sports injuries. British Journal of Sports Medicine, 2014.
- NHS. Physical activity guidelines for adults aged 19 to 64.
- ACSM Health & Fitness Journal. High-Intensity Interval Training (overview of typical work/recovery heart-rate ranges and structure).
