HIIT vs Cardio: Differences & Benefits

HIIT offers improved athletic performance, weight loss, positive mental health effects, increased insulin sensitivity, calorie afterburn, enhanced heart health, and reduced abdominal fat.

• Performance Boost: While steady-state cardio targets the aerobic system, combining aerobic and anaerobic HIIT reaps benefits from both, according to the National Institute of Health [1].
• Insulin sensitivity: PubMed and Medical News Today research highlights HIIT's effectiveness in improving insulin sensitivity, making cells more efficient in utilizing blood glucose [2] [3].
• Weight Loss Advantage: HIIT cardio provides enhanced weight loss and surpasses steady-state exercises in maximizing calorie burn, as per PubMed research [4].
• Calorie Afterburn: The "after-burn effect" or EPOC occurs after a HIIT workout, maintaining elevated Resting Energy Expenditure when done at least three times a week , according to Harvard Medical School [5].
• Abdominal Fat Reduction: HIIT reduces abdominal fat, especially in individuals with type 2 diabetes, positively impacting aerobic and anaerobic fitness, according to Journal of Obesity [6].
• Heart Health Improvement: Research from Science in Sports and Exercise indicates that engaging in twenty HIIT sessions enhances heart health and overall physical fitness [7].
• Shorter, Impactful Workouts: Even a brief 10-minute HIIT session, thrice a week, positively impacts the body, increasing oxygen delivery to muscles and improving metabolic health, as per Journal of Sport Sciences [8].
• Mental Health Benefits: HIIT, besides physical benefits, positively affects mental health, particularly for individuals with mental illnesses, as per PubMed research [9].

"HIIT is a great regimen for people who are young and healthy. If you’re older or have heart disease, check with your doctor before trying it."

- I-Min Lee, Professor of Medicine

Cardio offers benefits like reduced cardiorespiratory stress, increased endurance, quicker recovery, effective weight loss, improved aerobic metabolism, enjoyable workouts, and the convenience of requiring no gym equipment.

• Reduced cardiorespiratory stress: According to Medical News Today, moderate-intensity cardio enhances endurance without excessive strain, making it beginner-friendly [10].
• Increased endurance: A longer, moderate-intensity cardio workout can increase endurance in both your cardiovascular system and muscles.
• Enhanced well-being: Similar to HIIT, steady-state cardio swiftly delivers oxygen, reduces blood pressure, and aids fat loss for overall health, as per PubMed [11].
• Accelerated recovery: Less stress in steady-state cardio reduces recovery time, beneficial post-weightlifting.
• Improved fat burning: Steady-state cardio emphasizes fat burning over carb usage, unlike high-intensity exercises, according to MDPI research  [12].
• Increased aerobic metabolism: According to PLOS Biology, prioritizing steady-state aerobic exercise develops efficient slow-twitch muscles, improving aerobic metabolism [13].
• Enjoyable workouts: Cardio workouts, unlike intense HIIT, trigger endorphins without overwhelming discomfort, as per the National Institute of Health [14].
• No gym equipment needed : Cardio exercises with just body weight are accessible, eliminating the need for fancy equipment

Related Article: The Best Cardio Workouts for Weight Loss

“While there are days when it's ok to partake in less intense cardio—like when you're super sore from a workout you conquered the day before—consistent days of steady-state cardio in which you don't challenge your cardiovascular fitness will likely not produce desired results.”

- Kira Stokes, Personal Trainer 

In my fitness training experience, cardio takes a lot of time and can get boring, while HIIT, although it can be tough and more likely to cause injuries, might be too much for beginners and could make people feel overwhelmed.

Cardio Limitations:

• Time-consuming: Steady-state cardio demands longer durations, potentially discouraging those unable to commit an entire hour to exercise.
• Risk of injury: As per Harvard Medical School, cardio workouts may lead to injuries without proper technique; experts advise limiting sessions to 150 minutes weekly to prevent overtraining [15].
• Potential boredom: Steady-state cardio can become monotonous, especially on treadmills, due to extended durations and fewer intense spikes.
• Weight-loss plateaus: Relying solely on steady-state cardio for weight loss may result in plateaus; incorporating varied workouts is crucial.

HIIT Limitations:

• Discomfort: HIIT's high intensity can be uncomfortable, pushing individuals to exert themselves significantly.
• Not beginner-friendly: HIIT may not suit beginners or those returning from injury; starting with aerobic interval training is recommended.
• Increased injury risk: Compared to cardio, HIIT poses a higher injury risk, particularly in the knees and shoulders, according to ScienceDaily [16].
• Burnout or overtraining risk: The intense nature of HIIT raises the likelihood of burnout, potentially causing individuals to drop out of their fitness routine.
• Form and technique crucial: Proper form, core strength, flexibility, and warm-up/post-exercise stretching are essential in HIIT to avoid injury.

“Boredom is the number one enemy of fitness. If you're bored or sick or your workout, you're far less motivated to get through it. Changing things up—going for a run outside, taking your bike for a ride, joining a dance class, or trying kickboxing, for example—will go a long way toward keeping you on track with your fitness efforts.”

- Andrew Peloquin, Fitness Editor