Introduction
Most people are generally aware of the health benefits of exercise: better heart health, reduced cancer risk, lower incidence of metabolic syndrome and type 2 diabetes, better sleep, and better mental health are just a few of the best known perks of staying active.[1]
For anyone looking to jumpstart a fitness regimen from scratch, moderate activity is the best place to begin; not only is it more accessible for all fitness levels, but the risk of injury is much lower. But for those who are already active, it’s important to understand the different benefits of moderate versus vigorous activity. While many of the overarching health benefits are similar across both types of activity, there are compelling reasons to engage in both.
How are moderate and vigorous activity defined?
In order to understand the different benefits of different activity levels, it’s first essential to understand what constitutes moderate versus vigorous activity.
When talking about activity levels, people often refer to a target heart rate range. For moderate activity, this range is roughly 50-70% of your maximum recommended heart rate (MHR). For vigorous activity, it’s 70-85% of maximum.[2] Zone training[3] splits these out further, with zone 1 ranging from 50-60%, zone 2 ranging from 60-70%, zone 3 from 70-80%, zone 4 from 80-90%, and zone 5 from 90-100%. Each zone confers different training benefits (zone 3, for example, is targeted for aerobic endurance, while zone 2 focuses more on “base” fitness levels), but when focusing on broader health benefits from each type of activity, the simpler “moderate versus vigorous” metric is adequate.
A simple, long-standing formula suggests subtracting your age from 220 to get your maximum heart rate in beats per minute, or bpm;[4] for a 40-year-old, max heart rate would be 180 bpm. While there is some individual variation in MHR, for most individuals this is a “good enough” starting point. The simplest way to then estimate your target heart rate would be to simply take the target percentages of that maximum number; so for a 40-year old, moderate activity would range from 90-126 bpm, and vigorous activity from 126-153 bpm. Recently, exercise science more commonly uses the Karvonen method of determining target ranges;[4] this takes into account your self-inputted MHR and resting heart rate (RHR) to determine a window that more accurately reflects individual differences in fitness and genetics. An online calculator to determine your heart rate via this formula is here.
Target heart rates can be a useful guideline, especially when beginning an exercise routine, but an even simpler way to determine whether what you’re doing qualifies as either moderate or vigorous activity is to use the “talk test.” If you can carry on a conversation while performing the activity (but can’t sing), you’re in the moderate activity zone. If you need to take a breath every few words while speaking, you’re in the vigorous activity zone.[5] What qualifies as moderate versus vigorous will vary by individual, and will shift as you become more physically fit. Even a relaxed jog might be extremely vigorous for a previously sedentary individual, but for a regular runner, might move into the moderate range over time.
It’s important, too, to give some perspective on what commonly qualifies for each of these forms of activity. “Brisk” walking is often defined as moderate activity; for reference, the CDC pegs this to a pace anywhere above 3 miles/hour. Generally speaking, moderate activity should be something you feel comfortable continuing for a prolonged period without breaks; vigorous activity should feel difficult.
But be warned: if it feels too difficult, you may not be doing yourself any good. If you injure yourself while exercising, then you may be forced to take a break for a while, which may end up being worse for you than exercising at an appropriate pace with good form.
Unique benefits of moderate versus vigorous exercise
While intuitively a harder workout seems like it should offer more benefits, there are certain benefits of exercise that are unique to moderate activity:
- Improved weight loss: Though vigorous activity feels like it should burn more fat, weight loss is actually much likelier if you stick to moderate activity. This is due to the science of how your body accesses various energy sources; when your heart rate is very high, you take in less oxygen, which is required in high quantities to burn fat. Without enough oxygen, your body will turn to more easily-oxidized energy sources–such as carbohydrates or protein–for fuel; a lower overall percentage of calories burned comes from fat in the body. Longer, sustained moderate activity burns is therefore a much more effective way to encourage your body to burn fat than briefer stretches of vigorous activity.[4]
- Blood sugar regulation: Researchers have found that moderate activity leads to better glucose control than vigorous activity.[6] This is because different intensities of exercise appear to release hormones–including insulin, implicated in blood sugar control–at different levels. Studies have found vigorous activity actually increases insulin concentrations, while longer stretches of moderate exercise reduce it. Additional studies found that regardless of the intensity of the exercise, glycemic control appears to be limited to the day when exercise occurs; with vigorous exercise, individuals often take rest days to allow the body to recover, but on recovery days they’re losing out on this valuable health benefit. This has significant implications for metabolic disorders, such as type 2 diabetes–if this is a concern, longer sessions of moderate exercise may be a better option than short bursts of intense exercise.
Similarly, vigorous exercise carries benefits that individuals are unlikely to access via moderate exercise alone:
- Improved musculoskeletal fitness: Musculoskeletal fitness encompasses strength, endurance, and flexibility, and affects the bones, muscles, and joints. Vigorous activity not only more effectively recruits the musculoskeletal system–demanding more of the muscles requires them to build and repair more, which also contributes to greater bone density.[7] It may in fact be required if you want to prevent the musculoskeletal decline associated with aging. A longitudinal study of adults over 50 concluded that vigorous activity at least once/week was necessary to avoid chronic musculoskeletal pain; even participants with significant amounts of moderate exercise were subject to this decline if they did not include regular vigorous exercise.[8]
- Time efficiency: Many of the most compelling reasons to exercise–heart health, improved sleep, mental clarity, and reduced risk of many diseases–can be achieved with either a vigorous or a moderate exercise regimen, but working out vigorously allows you to access those health benefits faster. Studies have shown that fitness levels (as measured by “gold standard” metrics such as peak oxygen consumption, or VO2 max) are more or less equal after consistently committing to either a vigorous or moderate exercise regimen,[9] but the duration of activity recommendations are cut in half for vigorous exercise.
It’s important to reiterate that vigorous exercise also comes with a higher risk of injury, particularly for individuals who are starting at lower fitness levels.[10] These injuries are usually minor–such as muscle tears or strain–but can have significant impacts on wellbeing and one’s ability to maintain a fitness plan. If you plan to include vigorous exercise in your health plan, it’s suggested you build up to that activity level over the course of at least a few weeks.
What’s the best exercise plan?
Moderate and vigorous activity can both impart the vast majority of health benefits one gains from exercise, but a mix of the two is not only more sustainable for most individuals, it’s likely to confer the most benefits, including those unique to each type of activity. Current guidelines recommend at least 150 minutes/week of moderate activity or 75 minutes/week of vigorous activity, but for maximal benefit, all individuals should incorporate both types of exercise into their routine.
It’s also important to remember that strength-building exercises at least twice a week are a vital element of any exercise routine. These should target specific muscle groups in order to maintain musculoskeletal health, and can involve weights, resistance bands or devices, or rely on body weight. These workouts “count” as either moderate or vigorous activity, instead of adding an additional burden.
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