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Percent Heart Rate Reserve Intensity Exercise Zones and Rate of Perceived Exertion |
- The "Vigorous intensity exercise duration = 2x moderate intensity duration" note on the side of the chart is simply intended to draw this key information to attention. If you look at the numbers given in the last row at the bottom of the chart you'll see energy expended at the start of the vigorous intensity zone is twice that at the start of the moderate intensity zone which is the reason vigorous intensity exercise is considered to have twice the duration value of moderate intensity exercise.
- At rest the human body consumes 1 Met (Metabolic equivalent) of energy.
- Moderate intensity exercise consumes about 3 Mets up to about 6 Mets.
- Vigorous intensity exercise consumes about 6 Mets up to about 9 Mets.
- Maximal intensity exercise consumes about 9 Mets and above.
- Heart rate intensity exercise zones
- These are numeric exercise intensity ranges (usually in % or if in absolute values in bpm [if heart rate based and calculated for a specific individual]) categorised into named zones where the names attempt to describe the key impact upon your body when the intensity of the exercise performed gets your body working in a particular zone.
- On this site I use Zone names that are consistent with exercise guidance recommendations which in order of increasing heart rate are; Very Light, Light, Moderate, Vigorous and Maximal (<30 30="" 40="" 60="" to="">90 %HRreserve).
- Garmin wearables use a metric called Intensity Minutes to record the amount of time spent per day exercising in Moderate and upwards zones.
- Fitbit wearables use a metric called Activity Minutes to record the amount of time spent per day exercising in Moderate and upwards zones.
- Garmin uses zones named; Warm Up (Z1), Easy (Z2), Aerobic (Z3), Threshold (Z4) and Maximum (Z5) (50 - 60, 60 - 70, 70 - 80, 80 - 90, 90 - 100 %HRreserve) as standard defaults although these are user configurable. User specific HRrest and HRmax values should be configured too to ensure optimal device outputs.
- Fitbit seem to use zones named; Fat Burn, Cardio and Peak.
- There are lots of other zone names used and quoted on the web and adopted by different exercise monitoring devices e.g.Recovery, Active Recovery, Healthy Heart, Weight Control, Endurance, Hard, Tempo, Very Hard, VO2 Max, Max Effort, Anaerobic, Neuromuscular, etc. However many of the names are really misleading, as, for example, fat is still burnt outside the zone often referred to as the "Fat Burn" zone and in fact more fat may be able to be burnt in other zones in an exercise session (the same applies to the "Weight Control" zone) as the impact of any exercise is due to a combination of both intensity (zone) and duration.
- When the ranges are stated as percentages they can be defined as % of Maximum Heart Rate or as % of Heart Rate Reserve or less commonly, outside research, as; % of VO2 Max or % of VO2 Reserve or as a % of MET Max.
- Heart Rate Reserve intensity exercise zones are probably optimal to use (although a little more complicated to calculate and therefore less simple to use than Maximum Heart Rate based zones) due to taking into account two parameters (HRmax and HRrest) for each individual rather than just one (HRmax). This reduces the risk of under or over estimation of intensity compared to just using HRmax but a good estimate of HRmax is still important to determine. They are also simpler than VO2 or MET based zones as both of these are harder to determine and to monitor.
- To determine a particular Heart Rate Reserve percentage exercise intensity (%HRreserve) in beats per minute use the following formula:
- {([HRmax - HRrest] x %HRreserve) + HRrest}
- Worked example:
- For a person with HRmax = 185bpm, HRrest=60 and wishing to exercise at in the Vigorous intensity zone (60 to 90% HRreserve) they would need to exercise at between:
- ([185 - 60] x 0.6) + 60 = 135bpm and
- ([185 - 60] x 0.9) + 60 = 172.5bpm
- For an article about the importance of understanding exercise zones / levels see the following link:
- For a research article that provides background information about HRreserve see the following link:
- Increased fitness
- An increase in fitness provides the ability for an individual to increase the workload attained at a given heart rate or to be able to exercise longer at a similar workload.
- For an article about heart rate and workload (power output) see the following link:
- A similar chart to the above could be drawn to show the impact of different levels of fitness on blood lactate levels. In this case blood lactate level would be represented on the y-axis and although the curves would look different (they would look exponential like) the line indicating increasing fitness would also be shifted to the right.
- Categories of broad exercise zone ranges that may be helpful to consider
- Cardiorespiratory fitness focus.
- Moderate and Vigorous Intensity.
- The time spent at respective levels of Intensity and the duration of the session is determined by the cardiorespiratory fitness outcome required or the time available to exercise.
- Fast high total calorie burn focus.
- Vigorous Intensity.
- The maximum duration of the session will be determined by the total calorie burn required or fatigue.
- For body weight reduction ensuring an appropriate nutrient balanced calorie deficit diet is going to be key though.
- Slow fat burn focus.
- High Moderate Intensity.
- The duration of the session would need to be very long but exercising at an overall lower intensity will enable much longer sessions and therefore potentially much greater fat burn.
- For long sessions you'll need to consider the need to hydrate and to "Fuel" optimally to be able to sustain the session whilst maximising fat burn.
- For body weight fat reduction ensuring an appropriate nutrient balanced calorie deficit diet is going to be key though.
- Slow high total calorie burn focus.
- High Moderate combined with Vigorous Intensity.
- The duration of the session would need to be long compared to the first two category types but exercising at an overall relatively lower intensity than those will enable much longer sessions and therefore potentially much greater total calorie burn.
- For long sessions you'll need to consider the need to hydrate and to "Fuel" optimally to be able to sustain the session whilst maximising calorie burn.
- You'll probably also want to consider the impact on your overall "Energy" levels for anything else you may also wish to accomplish in that day following such a session.
- For body weight reduction ensuring an appropriate nutrient balanced calorie deficit diet is going to be key though.
- For a video that provides a good, cycling based, overview but which has a general relevance to other forms of exercise see the following link:
- https://youtu.be/Fne9-LW0ivc
- For information about Reduced Energy Deficiency in Sports (REDS) mentioned in the video see the following link:
- For a video that provides a good overview of Ketogenic Diets and exercise with a cycling focus but also with wider exercise relevance see the following link:
- https://www.youtube.com/watch?v=0dggm2eGlCw
- For a concise video that provides a wider perspective on Ketogenic Diets see the following link:
- For an article that identifies some wider Ketogenic Diet nutritional issues see the following link:
- For a video that identifies some wider Ketogenic Diet nutritional issues see the following link:
- Endurance fitness focus.
- Similar to the previous category but with a focus on endurance fitness rather than calorie burn so hydration and "Fueling" to optimally sustain the exercise undertaken is going to shift the focus.
- For a video that provides information about an overall training approach to optimally building endurance fitness see the following link:
- Very intensive high level of fitness focus.
- The link that follows is an example of a cycling based approach to building a high level of fitness in a relatively short time frame. You should have a reasonable level of fitness already though before embarking on the suggested programme. It is one of a series of four videos but the core content is in the following video:
- Exercise science
- For a clear and comprehensive explanation of the biological processes of exercise and exercise performance see the following link:
- Human limits on maximum sustained energy expenditure
- If you ever wondered what maximum short to long term human calorie burn can be, see below:
- (A) Blue circles and trend line: Short events (<0.1 days; 800 m to marathon). Red circles: Events 0.5 to 95 days. Gray open circles: Estimates for ultramarathon world records and other well-documented endurance events. Purple cross: Other high metabolic scope measurements. Red trend line with 95% confidence interval (CI): SusMS versus duration limit. (B) SusMS versus duration relationship flattens out at ~2.5× BMR. Cumulative average metabolic scope is shown for elite cyclists over a touring season, arctic trekking, RAUSA runners, and pregnancy and lactation. (C) Habitual metabolic scope (“physical activity level”) for n = 130 cohorts from a diverse global sample (29) cluster below 2.5× BMR (red line).
- Extreme events reveal an alimentary limit on sustained maximal human energy expenditure
- Caitlin Thurber, et al.
- https://advances.sciencemag.org/content/5/6/eaaw0341
- FatMax
- The intensity that an individual optimally burns fat is significantly influenced by diet (recent and ongoing), training status, duration of exercise (longer burns more), gender and genetics and possibly exercise type and environment too, to the extent that it is not possible to estimate it accurately enough at an individual level to give anything other than a very broad exercise zone at best ("Fat Burn" zones given are often quite narrow) which renders it of little use to determine the optimal intensity for optimal fat burning for a specific individual. To actually determine an individuals optimal intensity for burning fat a Maximum Fat Oxidation (MFO) / FatMax (FatMax = the exercise intensity that MFO is achieved) test would need to be undertaken in a sports physiology lab where respiratory gases are analysed at progressively increased exercise intensities. It is also arguable that the whole fat burn concept is pretty meaningless too from a practical perspective, as the concept has come about from considerations about weight loss where the focus should probably be on total calories burnt and diet considerations rather than the amount of fat calories burnt particularly as this is so difficult to determine at the individual level. Knowing your MFO / FatMax and exercise intensity fat burning profile may be interest from a change in fitness perspective but this is not something that can accurately determined outside a sports physiology lab and would also need to have new tests as your fitness changed to be used for MFO purposes.
- See the following link to research that compared fit trained men to untrained men and determined that fitter individuals burned more fat relative to carbohydrate and consequently suggested that this ratio could be used as a fitness indicator:
- If you did have your MFO / FatMax determined and then worked through the maths for different exercise intensities and durations as well as taking into account diet you should be able to come up with optimal personal fat burning session attributes but this is probably going to be too investment heavy for most people. However calorie deficit is the most important factor when it comes to fat and weight loss and not whether fat loss occurs during a particular exercise session.
- For a videos (which show preserved human body parts) about exercise and fat burning see the following links:
- Some endurance training strategies contain a significant FatMax training component aimed at enhancing the bodies ability to utilise a greater proportion of fat as a fuel. However such training aims to improve endurance rather than being a fat reduction strategy. For a video about this subject with a cycling context see the following link:
- Having noted the above for many people FatMax is reasonably likely to occur in the range of about 50 to 65% of HRreserve so in the top half of the Moderate intensity zone and at the bottom of the Vigorous intensity zone (although some research suggests the lower value may be 45% and the upper 70%). When considering what exercise zone is optimal to exercise at you'd want to consider the benefits of more fat burnt (e.g. improved insulin response) versus the greater amount of calories that would be burnt in the same amount of time exercising at a higher intensity (which, depending on the amount and assuming calorie deficit, could lead greater fat burnt / weight loss overall and additional health benefits associated with that) and also the time efficiency benefits and potential greater health benefits of exercising at Vigorous intensity.
- It is worth noting however that relatively more fat is burnt the longer a Moderate intensity exercise session goes on so there is this fat burning benefit to longer Moderate intensity exercise sessions. You should also be able to exercise for much longer compared to exercising at Vigorous intensity and have no / a reduced need to refuel as well. Although it is again worth saying no overall fat / weight will be lost unless your are in overall calorie deficit.
- Rate of fat oxidation (μmol ⋅ kg−1 ⋅ min−1) during cycling exercise in which moderately trained healthy young men were studied under the following 4 conditions. Low intensity and in a Fasted state (Low-Fast) or Low intensity in a Fed state (Low-Fed) and 68%VO2 peak Moderate intensity in a Fasted state (Mod-Fast) or Moderate intensity in a Fed state (Mod-Fed). * = Significantly lower than Low intensity in a Fasted state,P < 0.05. † = Significantly different from 20- to 30-min value, P< 0.05. Source:
- See the following link for an article with some further information about fat burning:
- If you are interested in a consumer respiratory gas measuring and analysis device see the Lumen link below:
- https://lumen.me/
- However it should be noted that to get an accurate readings from this device a significant amount of time has to be left after exercise or after consuming food before a measurement can be taken and that 2 or 3 measurements are required to get a reading. This means that it is not suitable to use to determine FatMax. If used before and after an exercise session it can be used to determine whether the proportion of fat to carbohydrate burning has changed as a result of the impact of the exercise and to determine how long this lasts which may be of use. The provision of ratio change over time may also provide lifestyle change insight.
- However if your motivation re this subject is about loosing fat it should be noted that so long as you have a nutritionally balanced diet and your activity results in an ongoing calorie deficit you will loose fat so long as you take the minimal precautions required not to loose muscle mass (a nutritionally balanced diet and the minimum recommended amount of strength exercises). The best way to monitor this is to keep an eye on your body composition which is probably easiest done using a body composition scale.
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