Many people feel that they need to be dripping in sweat after their workout in order for it to be effective. The truth is, how much you sweat is not an accurate predictor of how many calories you’ve burned during your workout.
What’s the deal with sweat anyways? Why do we sweat in the first place?
Sweating is a physiological reaction to an increase in our core temperature. Humans aren’t very good at adapting to temperature changes, and an internal temperature of more than +/- 10 degrees away from normal is usually fatal. A normal internal temperature is 98.6 degrees F, and when we exercise this number begins to rise. Sweating is the mechanism our body uses to cool itself down and force the rising internal body temperature to drop back to normal levels. As our core temperature rises, our bodies release water onto the surface of the skin. This sweat draws heat away from our body through the process of evaporation.
While an increase in sweat production can represent an increase in internal body temperature, the source of this temperature increase could be caused by a variety of factors independent of exercise intensity, including:
- Environmental factors: It’s no surprise that you will sweat more in hotter environments, regardless of exercise intensity. On the other hand, you may sweat less under cooler conditions. It’s entirely possible to have an intense workout in cooler temperatures and experience very little, if any, sweat.
- Fitness level: Body fat acts as an insulator—trapping body heat. The higher your body fat percentage, the earlier you will begin to sweat (and in greater amounts). This is not necessarily a product of your workout being harder, just an indication of your body’s ability to release this excess heat. Additionally, individuals with high fitness levels will begin to sweat sooner as well, due to their body’s increased efficiency to cool itself (and likely due to the effect of having more muscle mass).1
- Hydration status: If you are dehydrated you will sweat less, because your body has less excess water to delegate toward temperature regulation.2 Additionally, if you are properly hydrated you may find that you sweat a little more than usual.
As you can see there are numerous factors that determine how quickly and how much an individual will sweat during their workout. The amount a person sweats is not an accurate predictor of exercise intensity or effectiveness.
There are a few better measures of exercise effectiveness, which include: heart rate measurements, rate of perceived exertion (RPE), and momentary muscular failure.
(Estimated) Heart Rate Measurements
Heart rate-based training has grown in popularity. Some fitness companies, Orange Theory Fitness being one of the most popular, use heart rate monitors worn by each client to more accurately assess the intensity of each workout.
Moderately-intense exercise generally falls within 50-70% of estimated maximum heart rate (HRmax), while vigorous-intensity falls within 70-90% of estimated HRmax.
To find your estimated HRmax, simply subtract your age from 220. This number in beats per minute) is your 100% HRmax. For example, a 40 year-old man would have an estimated HRmax of 180bpm. Therefore, their moderate-intense zone would fall between 90-126bpm. Their high-intensity exercise should put them at a heart rate of between 126-162bpm.
Heart rates can be measured using various heart rate trackers, or taken manually by checking the pulse on the neck or wrist.
Rate of Perceived Exertion (RPE)
The rate of perceived exertion is a subjective scale created for clients to rate the relative difficulty of an activity based on the sensations they feel within their bodies. Although the reliability of these subjective measurements isn’t clear, they can be useful in guiding the progression of exercises in an individuals workout.3,4,5,6
Below is the original scale used for measuring exercise intensity using RPE:
However, an updated version as been introduced that uses a ten-point scale (this is the scale we use with our clients at A-Team Fitness):
Ratings of between 4-7 correspond to moderate-intensity heart rates, whereas RPE between 8-9 correspond with high-intensity heart rates. The RPE scale can be used to help assess the overall difficulty of an exercise, and give guidance on either increasing or decreasing the difficulty.
Momentary Muscular Failure
Momentary muscular failure is the point during a resistance exercise where you are physically incapable of completing any additional repetitions with the given weight. Some studies suggest that reaching failure during resistance training isn’t necessary to create sufficient stimulus, but greater increases are seen when resistance training to failure.7,8
When performing a chest press for 12 repetitions (reps), for example, if the 12th rep is still pretty easy to perform, then it is likely you are not performing the exercise at an intense enough level. However, if the 12th rep is barely doable with good form, then you are likely at a much more appropriate intensity for your given strength levels.
All of the above methods for measuring exercise intensity are far more accurate than relying on the amount that you sweat during your workout. Remember, there are a variety of unrelated variables that affect how much you might sweat at any given time. This doesn’t mean it doesn’t feel good to get a good sweat in, simply be aware that this can often be misleading in measuring overall exercise intensity.
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