Most people know that cardio exercise gets your heart pumping and your breathing rate up. But what actually happens to your body over time when you make biking, jogging, or other cardio workouts part of your daily routine? Here are six potential effects.
Cardio exercise can increase mitochondria, the parts of a cell that break down food and produce energy. The more mitochondria, the more energy your cells can generate. “Over time, this leads to better endurance, faster recovery, and improved overall fitness,” Erica Coviello, CPT, personal trainer, running coach, and owner of Run Fit Stoked, told Health.
Cardio—especially low-intensity exercise—strengthens the heart muscle, much like daily squats build up your legs. “A stronger, more efficient heart is better at pumping blood,” Coviello said.
Over time, this improved circulation helps blood vessels relax and widen, which can reduce the buildup of plaque in your arteries. Having healthy arteries lowers the risk of high cholesterol, high blood pressure, stroke, heart attack, and heart disease.
Daily cardio improves the efficiency of your respiratory system and boosts lung capacity, Coviello explained. In other words, your lungs become faster and more effective at delivering oxygen to your working muscles. This lets you exercise longer and breathe more easily. Healthy lungs not only make workouts easier but may also reduce your risk of conditions like lung infections, bronchitis, and pneumonia.
Cardio triggers the release of “feel-good” hormones such as endorphins, dopamine, and serotonin, Coviello said. At the same time, it can help reduce stress hormones like cortisol, potentially improving mood and easing anxiety. In fact, a 2024 study found that regular exercise may be an effective part of treating depression.
Doing cardio daily helps regulate blood sugar and may lower the risk of metabolic disease, according to Or Artzi, CPT, founder of the fitness platform Orriors.
Your muscles store glucose, the body’s main source of energy. During exercise, your muscles use this energy, pulling sugar from the bloodstream and lowering levels. A 2024 meta-analysis found that cardio can improve average blood sugar levels in people with type 2 diabetes in the 24 hours after a workout.
Keeping blood sugar levels in check over the long term can help prevent conditions like type 2 diabetes, stroke, and heart disease.
Some people who do cardio every day may notice signs of overtraining, Coviello warned. Elevated resting heart rate, persistent fatigue, mood changes, brain fog, declining performance, more frequent illness, loss of appetite, recurring injuries, severe soreness, and sleep disturbances can all signal that your body needs a break.
Women, in particular, face a higher risk of a condition called relative energy deficiency in sport (RED-S), which can happen when athletes don’t eat enough to meet the energy demands of their training. According to Coviello, symptoms can include low energy, irregular periods, and stress fractures or other signs of weakened bones. “This trio of symptoms is a giant neon sign that the body is under-fed, over-stressed, and overtrained,” Coviello said.
Daily cardio can be beneficial, provided it’s “introduced or maintained thoughtfully and in the right way,” Coviello said.
That means supporting your body with adequate sleep, balanced nutrition, and staying hydrated, Artzi explained. She and Coviello also recommend varying your workout intensity: aim for roughly 80% of sessions to be easy, 10-20% moderate, and include just a few hard ones.
Rest days are also important, Coviello said, because they allow your body to:
- Repair muscle fibers so they come back stronger
- Lower inflammation before it turns into injury
- Replenish glycogen so you’re not running on fumes
- Reset your nervous system so workouts feel manageable
- Boost long-term performance
“When recovery is skipped or underestimated, it can lead to persistent soreness, fatigue, fitness plateaus, and an increased risk of injury,” Artzi added.
