What Happens Inside Your Body When You Do Cardio? Simple Explanation
Whether you are walking, cycling, or running after your dog in the park, your body is doing many important things. I am telling you this as a physiotherapist and trainer with 20 years of experience helping people like you. Let’s understand what really happens when you do cardio and how to get the best benefits.
What Happens During Cardio and Why It Is Important
When you start moving, your body works like a well-coordinated team:
Your fast heartbeats leads to transport oxygen-rich blood to your muscles.
Your lungs consumes in more air to fulfil supply of oxygen.
You start sweating — this helps cool your body.
Your muscles use stored energy called glycogen to keep you moving.
Your brain releases endorphins — these chemicals make you feel happy and good.Common Mistakes People Make
Many people do these mistakes:
Skipping warm-up: Like a car cannot start without ignition, your body needs warm-up before exercise.
Starting too fast: If you are new or coming back after a break, start slow.
Thinking cardio alone will reduce weight: Cardio is only one part; food and strength training are also important.
Bad posture: Looking down on treadmill can cause neck pain.
Not drinking enough water: Even small dehydration can make you tired and slow recovery.How to Do Cardio Correctly Without Getting Tired Early
Follow these steps:
Warm-up (5–10 minutes):
Simple movements like marching on spot, shoulder rolls, leg swings.
Very important for elderly, people with joint pain, or recovering from injury.Choose Cardio Type That Suits You:
Walking: Easy and good for all ages.
Swimming: Gentle on joints, good for arthritis or overweight people.
HIIT: High-Intensity Interval Training, very effective but start with expert help if new.Posture and Breathing Tips:
Stand straight and look ahead — not down at phone.
Breathe deep through belly, not shallow chest breathing.Check Your Effort Level:
Can you talk while exercising? Good.
If you get out of breath after one sentence, slow down.
Use heart rate monitor or smartwatch if possible.Cool Down (Don’t Skip):
Walk slowly and do light stretches.
Helps body relax and prevents muscle pain.Simple Cardio Plan for Beginners (15–20 Minutes)
3 minutes: March on spot.
5 minutes: Brisk walk or slow cycling.
2 minutes: Bodyweight squats or step-ups.
5 minutes: Slow walk and stretch calves, back, hamstrings.Remember — Cardio Alone Is Not Enough
More cardio does not always mean faster fat loss. Cardio helps heart, mood, and fat loss, but without good food, sleep, and strength training, results will be less.
Too much cardio without balance can raise stress hormones, especially for elderly, diabetics, or people with metabolism problems. I see this often in clinic.
Safe Supplements (Ask Doctor First)
Electrolytes — replace what you lose in sweat.
Beta-Alanine — helps improve stamina.
Omega-3 — good for heart and joints.
Caffeine (small amount) — helps focus but avoid if you have high BP.Avoid fat burners or powders promising quick results — they are not safe.
Final Advice — Make Cardio Your Friend, Not Enemy
Think cardio as a long-time friend, not punishment. You don’t have to run endlessly. Work with your body, be consistent, and enjoy the journey.
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Written by a physiotherapist(20 years) and certified trainer with experience helping people recover, train, and stay healthy.
