REHIT Training – The 9 Minute Cardio for VO2max, Fat-Loss, and Fitness
If you’re looking for the most effective way to boost VO2max, say hi to REHIT training. It also comes with benefits like improved insulin sensitivity, potent fat-burning effect, and boost in aerobic capacity. In less scientific words it makes you live longer, be fitter and healthier. All that in just 9 minutes, twice weekly.
At vitalscend, we’re not really into hacks or quick fixes. We like to address the primary issue, like a sedentary lifestyle. The fix is moving more, doing mobility, strength training, and steady-state cardio. But if you have these things dialed in, there’s a potent, very effective protocol around the block – REHIT training.
REHIT training stands for reduced exertion high-intensity training. It’s similar to HIIT, or high-interval intensity training – extracting the most beneficial parts of it. The powerful thing about REHIT is time efficiency and effectiveness.
See, HIIT sessions can last up to 30-45 minutes which goes against its main point – to reach a maximal intensity. We can’t perform at 100% for that long. Most HIIT workouts actually get you to train lactate threshold and local muscle endurance, leaving your system taxed afterward.
REHIT is about squeezing in all of that in 2x 20-second all-out sprints. What’s in between? Recovery and steady-state cardio. It’s less taxing, quicker, and scientifically proven to achieve most of HIIT’s more effectively. (1)
There are numerous benefits of HIIT cardio. It’s the optimal way to increase aerobic capacity, boost VO2max, improve cholesterol profile and heart health, stimulate EPOC effect, deplete glycogen stores, and so much more. (2) (3) (4) (5)
VO2max is the maximal oxygen uptake your muscles can effectively use to produce energy. For great accuracy, it is measured in a lab test on a cycle ergometer, but health trackers and smartwatches aren’t far off.
Higher VO2max means higher aerobic capacity and efficiency at transporting and using O2. It’s one of the strongest predictors of longevity, a key marker of health. The good news is we can train to increase VO2max – and the most powerful tool is interval training. (6) (7) (8)
There are three effective training protocols to boost VO2max:
Longer intervals. Running for 3 minutes at the velocity of your VO2max at (speed 8/10) with 3 minutes of active recovery at 50% that speed. 5 sets in total, 3 min. activity and 3 min. recovery.
Short intervals. Cycling for 30 sec. intervals at a submaximal intensity (speed 9/10) with 30 sec. active recovery at 40-50% that speed. Repeat 10-20x cycles of 30s. on with 30s. recovery.
Short sprints. After a proper 5-minute warm-up you perform 10 cycles of 10-second all-out sprint (speed 10/10) with a 3-minutes active recovery in zone 2 (light cardio, slow speed)
The REHIT method uses the 3rd, short sprints method of 10-20 seconds all-out maximal effort. This is intensity way higher than 100% VO2max which stimulates the lungs and the heart to work at it’s maximum. Peripherally, it depletes muscle glycogen which comes with myriad of benefits related to metabolic health.
Science: VO2max and REHIT Cycling
Science strongly supports that training at a short sprint intervals can increase VO2max. Let’s look at two studies that used the CAROL bike – a bike specifically designed to bring this benefits in a time-efficient manner. We’ll touch on it later.
- 1st study by Western Colorado University. 1st group did 3x REHIT trainings on the CAROL bike weekly, while the 2nd group did 5×30 minutes of MICT or moderate intensity training. 1st group increased VO2max by 12.3%, almost double as the second group – 6.9%. (9)
- 2nd study published in the European Journal of Applied Physiology looked at minimal amount of exercise for improving metabolic health. Again the REHIT exercise improved insulin sensitivity by 28% in males, and VO2max peak increased by 15% for males and 12% for females. (10)
It’s vital to understand the training zones, which are training intensities determined by the % of HRmax of VO2max. The higher the % the more intense it is. We split this into five zones, increasing from the lowest 1st (walking) to the highest 5h (sprinting).
|Zone 1||Great for Recovery, Warm up||50-60% HRmax|
|Zone 2||Trains Endurance, Burns Fat||60-75% HRmax|
|Zone 3||Improves Aerobic Fitness||70-85% HRmax|
|Zone 4||Trains Lactate Threshold, Speed Endurance||80-95% HRmax|
|Zone 5||Increases VO2max & Anaerobic Function||90-100% HRmax|
The first 2 zones are low-intensity, aerobic zones that burn fat for fuel. These are the warm-up and recovery intensities we’ll use in our 9-minute protocol. Zone 3 is moderate intensity for aerobic fitness, and zone 4 is hard intensity for lactate (muscle endurance). What’s important for us is zone 5 – as we’ll jump to the maximal intensity in our 2-3x all-out sprints. This is anaerobic, very hard, and burns glycogen for fuel.
Learning the 5 training zones will make you much more independent when doing your cardio. You’ll understand when you’re in an aerobic or fat-burning zone, when you’re training for endurance or VO2max. The ability to asses it by RPE or HRmax % enbles you to train in the correct zone.
The 9 Minute Cardio
Our 9 Minute Cardio Protocol uses the short sprint method. This means our goal is to go all-out maximal sprinting for 2-3 cycles of 15-20 seconds. But to be able to do it properly, and achieve our VO2max, we’ll have to include some warm-up, recovery, and cool down in between.
|Warm-up||2 minutes||low-intensity (40%)|
|Sprint 1||15-20 seconds||maximal intensity (100%)|
|Recovery||2 minutes||low-intensity (40%)|
|Sprint 2||15-20 seconds||maximal intensity (100%)|
|Recovery||2 minutes||low-intensity (40%)|
|Sprint 3||15-20 seconds||maximal intensity (100%)|
|Cool Down||3 miuntes||low-intensity (40%)|
- Low intensity for warm-ups, recovery, and cool-down is around zone 1 and 2. It hovers around 50-70% of HRmax, it’s light and sustainable activity.
- Maximal Intensity for the 2-3 Sprints is zone 5. Purely anaerobic, all-out sprints with a heart rate of 100% HRmax, not sustainable for more than 10 sec. in total.
The reason you’d want to learn to assess training intensity (zones) is to train accurately. While there’s an awesome bike that can do all this for you, for someone who doesn’t have 2.4k lying around – by understanding the zones you can do it on a budget. You need a heart monitor or an accurate smartwatch, and some sort of cardio equipment.
Why REHIT training should be done on an indoor cycle or assault bike?
Your best bet is an assault bike or stationary cycle ergometer – that can provide resistance. The reason I wouldn’t do sprinting on the track is joint stress and poor technique (injury). We only train the aerobic system, we need low-impact and large muscle mass involvement. You can do the ski-erg or rower, but I’d stick to the bike for the best results, as the first two mainly indulge your upper body musculature.
The point of the REHIT is to get to the 2-3 short sprint intervals. For that, we must warm up, recover, and cool down properly. Never skip any of these. Doing so diminishes how much lactate you flush out, how fast you regenerate and how many toxins accumulate.
The Most Effective HIIT Workout
When we say the most effective, we’re planning on extracting the highest benefit for the lowest effort and time. Businessmen think of this as ROI, return on investment. What’s the benefit? Heart health, cholesterol profile, insulin sensitivity, VO2max, we can go on and on.
Before you do the 9-minute protocol, you should understand one thing. 9 minutes of exercise won’t undo all the sitting we do. Period. Is it better to do the 9 minutes combined with a couch potato lifestyle, than just sitting? Yes. Is it enough? Absolutely not.
If we’re sedentary, we must find ways to move more. The most effective and shortest way to increase VO2max is HIIT, but isn’t necessarily the best. The best way is to combine low steady-state cardio (zone 2) 2x weekly with HIIT or REHIT training (zone 5) 1-2x weekly for maximal benefits.
That’s because high-intensity work emphasizes VO2max, anaerobic power, and glycogen depletion. That’s just one piece of the puzzle in terms of health and stamina. Low intensity is great for mitochondria function, heart enlargement, burning fat as fuel, metabolic efficiency, etc. These are fundamental steps to vitality, so combine both zone 2 and zone 5 training.
The CAROL bike has been actually created around this idea of finding the minimal effective dose of cardio. It uses the same REHIT training protocol of around 7-10 minutes, with 2-3 20s sprints.
It’s a premium bike that gives you a great experience, for a premium price. Yes, the CAROL bike modifies the resistance based on your strength. It comes with a monitor, and guides you with its music and coaching. Yes ,it recommends a type of exercise based on your HRV or fatigue, it has its pros.
While it’s a great tool, it can be pretty expensive for many. If you don’t have 2.4k lying around for a bike, no worries. The whole point of learning the training zones and how to assess them, was for this purpose – to do it on a budget. Will you be 100% accurate to the CAROL intensity? Probably not. But I’d assume you’d be 80-90% there (in terms of benefits) if you accurately measure training intensity.
You really only need to determine 2 intensities – zone 2 which is light or easy and zone 5 which is maximal effort. Using a smartwatch or heart rate monitor for more accuracy will do it.
The reason we mentioned the bike is the strong scientific evidence around it, which emphasizes the benefits of REHIT training. It boosts VO2max, (11) improves insulin sensitivity, (12) has substantial EPOC and fat-burning effect, (13) and supports metabolic health. (14)
EPOC stands for excess post-exercise oxygen consumption. Say you had a sweaty high-intensity cardio session in the gym. You’re still burning calories afterward, as you pay off your oxygen debt.
See, doing these short sprints gets you in an anaerobic state. To properly recover you need more-than-usual oxygen. The rate of O2 you use increases, along with your metabolic rate, thus burning more calories.
Research in ACE Fitness shows 15-minute CAROL bike rides burned more calories than a 30-minute run. They did a REHIT training with short sprints, increasing the amount of oxygen cells used. This significantly increased metabolic rate for 3 hours afterward, during which 60% of total calories were burned. (15)
It’s very well known that high-intensity work can be great for metabolic health. HIIT cardio is known to improve insulin sensitivity, improve glucose tolerance and increase glucose uptake in the muscles. (16) (3)
With maximal effort, the all-out sprints we do in this 9-minute cardio deplete muscle glycogen reserves. While some research shows depleting glycogen stores isn’t the major factor that improves insulin sensitivity, (17) doing so prevents extra glucose to be turned to fat and instead is used to replenish the muscle stores. (18) This is good news for preventing obesity and diabetes.
Doing REHIT training or 10-min sessions with 2x 10-20s sprints showed strong improvement in insulin sensitivity by 28%. (19) Another 3x weekly short CAROL bike trainings lead to a 62% reduction in diabetes T2 risk in only 8 weeks. (20)
Improving the machinery around glucose control prevents metabolic deficits which lead to poor energy, hence why we eat more sugars – leading to diabetes and obesity. High-intensity exercise works great at making the muscle a better glucose-sucking tissue.
Cholesterol says a lot about our cardiometabolic health. On the topic of improving cholesterol profile, we aim at lower LDL and Triglycerides, while increasing HDL cholesterol. It seems that HIIT is pretty effective at doing this. (21)
Research specifically done on 3 short CAROL bike workouts for 8-weeks shows: (22)
- reduction in blood pressure by 5%
- reduction in triglycerides by 10%
- increase in the good HDL cholesterol by 6%
- reduction in blood sugar by 2%
All in all, it was more effective than a 30-minute moderate-intensity continuous training or MICT.
Importance of LISS
Just to repeat. It goes without saying that quick 9 minutes cardio won’t undo our weekly sitting. The path to great heart health, endurance, stamina, and longevity is a combination of both zone 2 (LISS) and zone 5 (HIIT) training.
Low-intensity steady-state cardio takes care of the fundamentals like heart enlargement, mitochondria function, and fat-burning. HIIT boosts VO2max, anaerobic power, metabolic health and cardiorespiratory fitness. Get your 10,000 steps a day, before thinking of a quick fix.
That being said, the 9-minute REHIT cardio is absolutely amazing. One of the most time-effective training modules we’ve come across. Cholesterol, EPOC effect, insulin sensitivity, VO2max boost,… you get the point.
- The fastest way to increase VO2max is by doing HIIT or high-interval intensity training. VO2max is a key measure of cardiorespiratory function, heavily correlated with longevity.
- Our 9-minute workout contains 2 minutes warm-up and cool down at zone 2 (low intensity) with intervals of short 15-20 s. maximal sprints with 2 min. recovery (low intensity) in between.
- Learning the training zones allows us to do this effective REHIT training on a budget. For those who want a premium experience, the CAROL bike is an awesome fit – music, guidance, smart features, adjusted resistance, heart rate variability, etc.
- Science strongly supports the effectiveness of short sprints or REHIT training on improving insulin sensitivity, metabolic health, boosting VO2max, and improving cardiorespiratory fitness. Plus, it has a strong and long-lasting EPOC effect.