Why We Need to Rethink Cardio
- Jennifer Hawkins
- Jun 20
- 6 min read
Updated: Jun 23
What makes a workout great? What makes it effective? If you lived through the 90s and early 2000s, the marketing images that come to mind around mainstream "health" may be low calorie snacks, salads, smoothies, detox juices.... and cardio, cardio, cardio!!!
But new research is showing us that frenzy-focused fitness actually works against the physiology of women's bodies that already live under the weight of nutritional depletion, daily stress, busy schedules, and fluctuating hormones.
So much of the mainstream narrative around fitness has been based on men's bodies, and only now are we beginning to see more research on women's bodies that includes hormonal rhythms, stress responses, and unique recovery needs. Medical Journals, such as The Journal of Sports Science and Medicine now report that too much high intensity cardio raise cortisol, which is linked to fat retention (especially belly fat), poor sleep, menstrual irregularities, increased anxiety, and thyroid disfunction.
What does too much cardio look like?
If you've ever felt burned out, stiff and achy, bloated, or anxious after a week packed with cardio, your body isn't broken. It's asking for something different.
How many of these are true for you?
1. You’re often tired—even after a full night’s sleep.
Overtraining can spike cortisol and deplete your energy reserves, leaving you feeling wired but exhausted.
2. You’re not seeing results.
If you're doing more but noticing weight gain, muscle loss, or plateauing progress, your body may be in survival mode—holding onto fat and burning through muscle.
3. You’re craving sugar and carbs all the time.
Too much intense cardio can cause blood sugar swings and hormone imbalances, leading to increased cravings, especially late in the day.
4. Your cycle is irregular or missing.
High volumes of stress (including physical stress from exercise) can disrupt ovulation and menstruation, especially in women with high cortisol levels.
5. You feel more anxious or emotionally fragile.
Excessive cardio can keep your nervous system in a constant state of fight-or-flight, making it harder to regulate emotions and feel grounded.
6. Your workouts feel like a chore—or a punishment.
If you dread exercise or feel guilt when you take a rest day, that’s a sign your relationship with movement may need to shift.
7. You’re frequently sore or nursing small injuries.
Too much cardio, especially without adequate strength training or recovery, can lead to inflammation, joint pain, and overuse injuries.
8. You’re struggling with sleep.
High-intensity cardio too close to bedtime—or in excess overall—can make it harder to fall or stay asleep by dysregulating natural cortisol and melatonin rhythms.
If most of these apply to you, it's probably time to look at how you're fueling and nourishing your body, what kinds of workouts you're doing, and how much you're recovering. If a few of them apply to you, you may be teetering on the edge of a deeper imbalance and some small tweaks could make a big difference!
What do we need instead?
Women don't need to shut down and stop moving, we just need to redefine what an effective workout looks and feels like.
What to look for in an effective workout...
1. You feel energized-- not exhausted.
An effective workout is challenging but leaves you feeling full of energy instead of exhausted, and somehow also calm and clear headed.
2. You're seeing progress over time.
It takes almost 8 weeks just to begin seeing new muscle growth, but there are little signs along the way that prove you're getting stronger. The first several weeks, you feel more connected to your body. Around week 5-6, you should notice increased stamina and overall energy. And by weeks 7-8, you may be getting into deeper ranges of motion, slightly increasing weights, and maybe seeing some visible muscle growth.
3. Your form is improving.
You're building muscle control and increasing strength, so you're able to control your movements and get deeper into positions and ranges of motion.
4. You may be sleeping better.
Great workouts, combined with adequate nourishment, help to regulate your nervous system and improve deep sleep.
5. Your mood improves.
You feel less anxious, more grounded in your body, more focused, and more emotionally regulated. Effective movement connects your mind and body to support mental health.
6. You feel stronger and more capable.
Rather than feeling exhausted, sore, or stiff, your body works better in everyday life!
7. You enjoy it and want to come back!
A workout that feels sustainable is the one you'll keep coming back to. Rather than tearing your body down in an anxious pursuit of faster results, working with your body means creating a lifestyle of healthy movement that grows with you through life.
So how much cardio do women actually need?
Some cardio is great for strengthening your nervous system responses and strengthening your heart. It absolutely has its place. You just need to know how to measure it.
Know your Heart Rate Zones:
Find Your Maximum Heart Rate
Subtract your age from 220. Example for a 35 year old: 220-35 = 185 Max HR
1- Mild Heart Rate Zone: 50-60% of your Max HR
2- Moderate Heart Rate Zone: 60-75% of your Max HR
3- High Intensity Heart Rate Zone: 75-90% of your Max HR
4- Peak/Max Zone: 90-100% of your Max HR
If you don't wear a fitness tracker, here is a quick check using "The Talk Test".
Mild Heart Rate Zone: You can talk and breathe easily.
Moderate Heart Rate Zone: You can talk, but not sing.
High Intensity Heart Rate Zone: You can say a few words at a time.
Peak/Max: Talking is nearly impossible
Know your season:
High Stress Season where rest and nourishment aren't priorities and other signs of high cortisol are present (many women live here and think this is normal)
Nourished and Rested where you are able to sleep 6-8 hours, fuel with carbs before a workout and get 100g+ protein per day
Performance Focused where nutritious meals are planned around your workouts and managing stress and getting 8 hours of quality sleep are the focus
Season | Your Body's State | Movement Recommendation | Why It Works |
High Stress Season | - Rest and nourishment aren’t priorities- Signs of high cortisol (poor sleep, anxiety, fatigue)- Feeling depleted or overwhelmed | 🟢 Stay in Mild Heart Rate Zone👟 20 min daily walk or gentle movement like stretching or light barre | Avoids cortisol spikes and supports nervous system regulation while still moving your body |
Nourished & Rested | - Sleeping 6–8 hours- Fueling with carbs pre-workout- Getting 100g+ protein daily | 🟡 Moderate Zone Cardio🏃♀️ ~150 min/week (60–75% HR Max)🔥 ~30 min/week of High Intensity | Builds cardiovascular fitness without overtaxing the body; balances exertion with recovery |
Performance Focused | - Meals are planned around workouts- 8 hours of quality sleep- Stress is well-managed | 🔴 All Levels of Cardio💪 2+ hours/week with a strategic mix of mild, moderate & high intensity | Improves performance by matching training load with recovery and nutritional support |
*Regardless of Your Season, Stop Chasing Cardio alone...
Cardio alone can raise cortisol, where balanced movement regulates stress hormones.
Cardio alone actually risks muscle loss, where balanced movement builds lean muscle.
Cardio alone may disrupt sleep cycles, where balanced movement improves sleep.
Cardio alone burns calories during the workout, but balanced movement builds muscle and transforms your metabolism.
Where do In Bloom Barre Classes Fall on the Cardio Spectrum?
This can be unique to each person, but this gives you an idea of the intended Cardio Intensity for each class and ways to raise or lower the cardio intensity for each. Also keep in mind, that all of our classes include a layer of targeted strength work and a full cool down, lowering cortisol levels and leaving the body ready to recover.
Barre Foundations: Mild - Moderate Intensity
-Decrease intensity by taking resets and modifications offered.
+Increase intensity by staying in holds longer, working more on muscle control, and progressively going an inch deeper into ranges of motion.
Barre Bounce: Mild to High Intensity
-Decrease intensity to mild by keeping feet connected to the rebounder and pumping heels.
+Increase intensity to moderate or high by pressing more deeply into the rebounder mat for more bounce and adding arm and leg movements.
Barre Flow: Mild - Moderate Intensity
-Decrease intensity with smaller ranges of motion during the peak of class, or take resets.
+Increase intensity with more controlled, intentional movement and deeper ranges of motion.
Barre Fire: Moderate - High Intensity
This class is designed to keep cardio in the upper moderate to high range. If you need mild intensity, this class is not recommended. It is still possible to keep the intensity range down to moderate by taking modifications that you learned in Foundations.
Barre Bootcamp: High Intensity
This class is designed to keep your heart rate right up there where you can only say a few words at a time, just below your Max, for 20-30 minutes! It is not for anyone struggling with signs of elevated cortisol or not able to focus on nourishment and proper rest.
(coming to the schedule Fall 2025)
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