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By Lindsay Brin, Exercise Science
I couldn’t do it anymore. I no longer enjoyed it. I thought High Intensity Interval Training (HIIT) provided the best results. But I wasn’t seeing results. In fact, I was fatigued and burnt out.
So I swapped every HIIT workout with walking. I was floored, absolutely floored, by the results. I’ve studied exercise science for 20 years so I dove into the research – why was walking more beneficial than HIIT? I conducted two focus groups. What I found was that 85% of our focus group of 700 saw the same results as I did.
Before I get ahead of myself, it’s important that you know the walking was in addition to strength training. These strength training workouts can be found here.
The fatigue I was feeling was counterproductive to my strength training routine. Here’s why. It was disrupting my recovery and giving me chronic inflammation. When pairing strength training with cardio the body thrives with recovery. During recovery our body repairs and rebuilds muscle tissue damaged during exercise, which is a normal response to exercise! The problem is when the acute inflammation turns into chronic inflammation. I needed cardio exercise that was going to decrease inflammation and not increase stress hormones. I needed zone 2 walking.
If cardiovascular exercise leaves you feeling tired or fatigued 1–2 hours after exercise or you feel highly stressed (hello motherhood!), it might be time to try a different type of cardio. Your individual preference is also a significant factor in the sustainability of any fitness routine.
The effectiveness, type, duration, and intensity of cardiovascular exercise that is best for you can vary widely based on your goals. If you’re training for a race or a sport, your cardio will be very sport-specific. If you are combining strength and cardio for fat loss, health and longevity, finding the best type of cardio is key.
During cardiovascular exercise the body’s demand for oxygen increases to fuel the working muscles. As a result, the heart pumps more blood to deliver oxygen-rich blood to the muscles, allowing them to produce energy aerobically. This process enhances cardiovascular health by improving the efficiency of the heart and circulatory system, increasing oxygen uptake, and promoting overall fitness and endurance.
“Steady state cardio” and “zone cardio” are two approaches to cardiovascular exercise, each with its own methods and goals. Steady state cardio involves maintaining a consistent, moderate level of intensity over an extended period eg. walking. Often referred to as LISS (low intensity steady state) or MISS (moderate intensity steady state), these types elevate your heart rate into a moderate zone, or zones 1 and 2. As you can see steady state cardio is simply zone 1 or 2 so don’t let that confuse you!
Zone 1, Zone 2, Zone 3, and Zone 4 cardio refer to different intensity levels of cardiovascular exercise based on heart rate zones. These zones are typically categorized based on a percentage of an individual’s maximum heart rate. But you don’t need a heart rate monitor to do zone cardio. I always say – keep it simple!
This zone corresponds to exercising at a very light intensity, typically around 50-60% of maximum heart rate. It helps improve circulation, aids in recovery from more intense workouts, and promotes overall relaxation.
Example: easy recovery walk.
Zone 2 cardio is moderate-intensity exercise, usually around 60-70% of maximum heart rate. This zone is effective for building aerobic endurance, improving cardiovascular health, and burning fat. It’s sustainable for longer durations and helps enhance the body’s ability to utilize oxygen efficiently.
Example: walking or hiking while carrying on a conversation comfortably without feeling out of breath.
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Zone 3 corresponds to exercising at a moderately high intensity, typically around 70-80% of maximum heart rate. This zone is often referred to as the anaerobic threshold or lactate threshold zone. Workouts in Zone 3 help improve lactate threshold, which is the point at which the body starts producing more lactic acid than it can clear. Training in this zone can enhance performance in endurance sports and improve overall fitness.
Example: running or kickboxing class — you may feel somewhat out of breath, but you should still be able to maintain the activity without pushing to maximum effort.
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Zone 4 cardio is high-intensity exercise, usually around 80-90% of maximum heart rate. This zone pushes the body into anaerobic metabolism, where energy is derived without the presence of oxygen. Zone 5 is maximum effort corresponding to 90-100% of maximum heart rate. Workouts in Zone 4/5 are intense and challenging. Usually you alternate these bursts of high intensity with recovery periods.
Example: HIIT, SIT or Cardio Burst exerting significant effort and may feel breathless and/or fatigued.
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Cardio workouts can indeed lead to an increase in cortisol levels, which is often referred to as the “stress hormone.” This response is part of your body’s natural way of dealing with physical stress. When you engage in any form of exercise, including cardio, your body responds by releasing cortisol to help manage and adapt to the stress of physical activity. This release can provide the body with glucose by tapping into protein stores via gluconeogenesis in the liver. This energy can then help fuel your workout.
However, the increase in cortisol levels is typically temporary and should return to baseline levels after recovery from the workout. It’s important to balance exercise with adequate rest and recovery to manage cortisol levels effectively.
As for how much cortisol is unhealthy, it’s not straightforward to pinpoint an exact “unhealthy” level of cortisol due to the complexity of the hormone’s effects and its variability throughout the day. Cortisol levels naturally fluctuate and are typically higher in the morning and lower in the evening. Chronic high levels of cortisol, however, can lead to various health issues such as immune dysfunction, weight gain, hypertension, high blood sugar, and can negatively impact mental health.
It’s best to manage stress, including exercise-induced stress, to maintain healthy cortisol levels.
The American College of Sports Medicine’s (ACSM) states —
A study published in JAMA Internal Medicine found that women who walked more steps per day had lower mortality rates compared to those who walked fewer steps. Each additional 1,000 steps per day was associated with a further reduction in mortality risk.
A study published in the Journal of Environmental Psychology found that individuals who walked in natural settings experienced greater reductions in cortisol levels (a stress hormone) compared to those who walked in urban environments.
I recommend aiming for 30 minutes (continuous or non-continuous steps) of walking per day. This is why:
Reduce Inflammation – Walking stimulates blood flow and circulation throughout the body. Improved circulation can help deliver oxygen and nutrients to tissues while removing waste products and inflammatory markers, thus reducing inflammation.
Stress Reduction – Walking, especially in natural environments or green spaces, can help reduce stress and promote relaxation. Chronic stress is associated with inflammation, so engaging in regular walking as an stress-relieving activity may help lower inflammation levels. Cortisol is a hormone produced by the adrenal glands in response to stress, and its levels typically fluctuate throughout the day in a circadian rhythm. While acute increases in cortisol levels during physical activity are normal and part of the body’s stress response, chronic elevation of cortisol due to ongoing stress can have negative health effects, including weight gain, increased abdominal fat deposition, and impaired immune function.
Regulation of Immune Function – Moderate exercise, such as walking, has been shown to have anti-inflammatory effects by modulating the immune system. Regular physical activity can help regulate the production of cytokines and other immune factors involved in inflammation, leading to a more balanced immune response.
Improvement in Insulin Sensitivity – Walking can enhance insulin sensitivity, which is beneficial for individuals with insulin resistance or type 2 diabetes. Improved insulin sensitivity is associated with lower levels of inflammation and reduced risk of chronic diseases.
But what about V02 max and aerobic capacity? V02 measures how quickly the body can take in 02 (oxygen) and use it. Which brings us back to cardio being highly personalized. What are your goals?
While this study found no significant difference in V02 max values between the brisk walking group and HIIT group, some studies suggest the intensity level may not be high enough in walking to significantly increase VO2 max in individuals who are already highly trained
Overall prioritize strength training, it also works your cardiovascular system. Add Zone 2 walking or a combination of 1 HIIT cardio workout combined with daily walks. Try our Weekly Schedule for free– strength training with your preferred cardio for the week.
