What happens to your body when you do cardio every day?

Most people know that cardio exercises get your heart pumping and increase your breathing rate. But what actually happens to your body over time when you make cycling, jogging, or other cardio part of your daily routine? Here are six possible effects.

Cardio exercise can increase mitochondria, the parts of the cell that break down food and produce energy. The more mitochondria you have, the more energy your cells can generate. “Over time, this leads to better endurance, faster recovery, and improved overall fitness.” Erica Coviello, CPTsaid personal trainer, running coach, and owner of Run Fit Stoked health.

Cardio exercise — especially low-intensity exercise — strengthens your heart muscle, just as daily squats build your legs. “A stronger, more efficient heart is better at pumping blood,” Coviello said.

Over time, this improvement in circulation helps blood vessels relax and widen, which may reduce plaque buildup in the arteries. Having healthy arteries reduces the risk of high cholesterol, high blood pressure, stroke, heart attack, and heart disease.

Coviello explained that daily cardio exercises improve the efficiency of the respiratory system and enhance lung capacity. In other words, your lungs become faster and more efficient at delivering oxygen to your working muscles. This allows you to exercise longer and breathe more easily. Healthy lungs not only make exercise easier, but may also reduce the risk of conditions such as lung infections, bronchitis, and pneumonia.

Covello said cardio releases “feel-good” hormones such as endorphins, dopamine and serotonin. At the same time, it can help reduce stress hormones such as cortisol, which may improve mood and relieve 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 reduce your risk of metabolic disease, according to healthline. Or Artzy, CPTfounder of fitness platform Warriors.

Your muscles store glucose, the body’s main source of energy. During exercise, your muscles use this energy, pulling sugar from your bloodstream and lowering its levels. A 2024 meta-analysis found that cardio exercise can improve average blood sugar levels in people with type 2 diabetes in the 24 hours after exercise.

Maintaining blood sugar levels over the long term can help prevent conditions such as type 2 diabetes, stroke, and heart disease.

Coviello warned that some people who do cardio every day may notice signs of overtraining. High resting heart rate, persistent fatigue, mood changes, brain fog, decreased performance, frequent illnesses, loss of appetite, frequent injuries, severe pain, and sleep disturbances can all indicate that your body needs a break.

Women, in particular, face a greater risk of a condition called relative energy deficiency in sport (RED-S), which can occur when athletes do not eat enough to meet energy requirements during their training. According to Coviello, symptoms can include low energy, irregular menstrual cycles, stress fractures or other signs of weak bones. “These three symptoms are one giant neon sign that the body is undernourished, overstressed, and overtrained,” Coviello said.

Covello said daily cardio can be beneficial, provided it is “introduced or maintained thoughtfully and in the correct manner.”

That means supporting your body with adequate sleep, balanced nutrition, and staying hydrated, Artzi explained. She and Covello also recommend varying the intensity of your workout: Aim for about 80% of sessions to be easy, 10-20% moderate, and include a few hard sessions.

Rest days are also important, Coviello said, because they allow your body to:

• Repair muscle fibers so they come back stronger
• Reduces inflammation before it turns into injury
• Replenish glycogen so you are not exposed to fumes
• Reset your nervous system so that workouts become manageable
• Enhance long-term performance

“When the recovery process is skipped or underestimated, it can lead to persistent pain, fatigue, poor fitness, and increased risk of injury,” Artzi added.