The Truth About Cardio: What Science Actually Says

Debunking common cardio myths and finding the right approach for your goals. The truth about cardio might surprise you—and it could change how you approach your fitness routine.

Cardio is one of the most misunderstood aspects of fitness. You've probably heard everything from "cardio kills gains" to "you need to do hours of cardio to lose weight." Let's separate fact from fiction and give you a practical framework.

The truth is, cardio is neither good nor bad—it's a tool. And like any tool, it's most effective when used correctly for your specific goals.

Common Cardio Myths Debunked

Myth 1: "Cardio Kills Gains"

The Myth: Doing cardio will make you lose muscle and strength.
The Truth: Cardio doesn't inherently kill gains. The issue is usually poor programming or excessive volume.
Reality: Moderate cardio can actually improve recovery and performance when programmed correctly.

Myth 2: "You Need Hours of Cardio to Lose Weight"

The Myth: Weight loss requires endless hours on the treadmill.
The Truth: Weight loss is primarily about calorie balance, not cardio volume.
Reality: You can lose weight with zero cardio if your nutrition is on point.

Myth 3: "Steady-State Cardio is Dead"

The Myth: HIIT is the only effective form of cardio.
The Truth: Both steady-state and HIIT have their place in a well-rounded program.
Reality: The best cardio is the kind you'll actually do consistently.

Myth 4: "You Should Do Cardio on an Empty Stomach"

The Myth: Fasted cardio burns more fat.
The Truth: While fasted cardio may burn slightly more fat during the session, it doesn't affect overall fat loss.
Reality: Do cardio when you feel your best and can perform well.

"The best cardio program is the one you'll stick to. Don't let perfect be the enemy of good."

Types of Cardio and When to Use Them

Low-Intensity Steady State (LISS)

What it is: Walking, light cycling, swimming at a conversational pace
Duration: 30-60 minutes
Best for: Recovery, beginners, active rest days, building endurance base
Benefits: Low stress on joints, improves recovery, builds aerobic capacity

Moderate-Intensity Steady State (MISS)

What it is: Jogging, cycling, rowing at a moderate pace
Duration: 20-45 minutes
Best for: General fitness, weight loss, endurance building
Benefits: Good calorie burn, improves cardiovascular health, manageable intensity

High-Intensity Interval Training (HIIT)

What it is: Alternating between high-intensity work and rest periods
Duration: 10-30 minutes
Best for: Time efficiency, improving anaerobic capacity, breaking plateaus
Benefits: High calorie burn, improves both aerobic and anaerobic fitness

Cardio for Different Goals

Goal: Weight Loss

Primary focus: Nutrition and strength training
Cardio role: Support calorie deficit and improve overall fitness
Recommendation: 2-3 sessions per week, 20-30 minutes each
Types: Mix of MISS and HIIT

Goal: Muscle Building

Primary focus: Progressive overload strength training
Cardio role: Support recovery and general health
Recommendation: 1-2 sessions per week, 20-30 minutes each
Types: LISS or MISS, avoid excessive HIIT

Goal: Endurance/Athletic Performance

Primary focus: Sport-specific training
Cardio role: Build aerobic and anaerobic capacity
Recommendation: 3-5 sessions per week, varying duration and intensity
Types: Mix of all three types based on sport demands

Goal: General Health

Primary focus: Balanced fitness program
Cardio role: Improve cardiovascular health and longevity
Recommendation: 2-3 sessions per week, 30 minutes each
Types: Whatever you enjoy and will do consistently

How to Program Cardio Effectively

For Beginners

Start with 2-3 sessions per week of low-intensity cardio. Focus on building the habit and improving your aerobic base.

For Intermediate

Add variety with different types of cardio. Consider your other training and recovery needs when scheduling.

For Advanced

Periodize your cardio based on your primary goals. Use cardio to support your main training focus, not compete with it.

Cardio and Strength Training: How to Balance

The key to balancing cardio and strength training is understanding that they're not mutually exclusive—they're complementary.

Timing Considerations

• Same day: Do strength training first, cardio second
• Separate days: Allow at least 6 hours between sessions
• Recovery: Use LISS on rest days or after intense strength sessions

Volume Management

• High strength volume: Reduce cardio volume and intensity
• High cardio volume: Reduce strength training frequency
• Balanced approach: Moderate volume of both

Practical Cardio Recommendations

If You're Short on Time

HIIT: 10-20 minutes, 2-3 times per week
Example: 30 seconds work, 30 seconds rest, repeat for 10-20 minutes

If You're New to Fitness

Walking: Start with 20-30 minutes, 3-4 times per week
Progress: Gradually increase duration and intensity

If You're Training for Strength

LISS: 20-30 minutes, 1-2 times per week
Focus: Recovery and general health, not calorie burn

If You're Training for Endurance

Mix: 3-5 sessions per week with varying intensity
Structure: 80% low intensity, 20% high intensity

Measuring Cardio Progress

Track your cardio progress with these metrics:

• Heart rate: Monitor resting heart rate and heart rate during exercise
• Perceived exertion: How hard the same workout feels over time
• Duration/distance: How far or long you can go at the same intensity
• Recovery: How quickly your heart rate returns to normal

Bottom Line

Cardio is a valuable tool in your fitness toolkit, but it's not the only tool. The best cardio program is the one that supports your goals and fits your lifestyle. Don't overthink it—start with what you enjoy and can do consistently.

Remember: consistency beats perfection. A moderate cardio program you stick to is far better than an intense program you abandon.

Ready to put this into practice? Check out our 20-minute home workout for a cardio-strength hybrid that fits any schedule.