Many people believe that a good workout should leave them sore or exhausted. However, Taylor Samale, a senior health fitness coordinator at Houston Methodist, suggests that effective exercise does not always require pushing to the limit. Instead, Samale recommends focusing on “zone 2” cardio, which is a moderate-intensity aerobic workout.
“If I had to tell everyone to work one intensity in their cardio, I’d say zone 2,” says Samale. “You’re still getting all of the health benefits of physical activity without the fatigue and soreness that comes with long bouts of high-intensity training,” she adds. “There are lots of benefits to elevating your heart rate a little bit instead of to your max.”
Zone 2 cardio is defined as exercising at about 60 to 70 percent of your maximum heart rate. At this level, you should be able to speak in full sentences but may notice slightly heavier breathing. According to Samale, this intensity is optimal for fat-burning and can help train the body to use fat as a primary fuel source rather than relying on carbohydrates.
Samale outlines several benefits of zone 2 training. These include improved fat burning, reduced exercise fatigue and overtraining, better energy levels, enhanced heart health, and improved mental wellbeing. She notes that after a zone 2 workout, recovery time is minimal, allowing for more frequent exercise sessions.
Zone 2 training can also increase the efficiency and density of mitochondria in cells, which helps convert food into energy. “It’s not all about keeping your heart rate super high for the duration of your workout,” says Samale. “It’s actually more beneficial to keep it in this lower, moderate-intensity state because you increase your mitochondria and get more energy all while still being very gentle on the body.”
Over time, regular zone 2 workouts can strengthen the cardiorespiratory system. This can lead to a lower resting heart rate, which is considered beneficial for overall health.
Samale also highlights mental health benefits. She explains that regular physical activity can improve cognitive function and reduce the risk of depression and dementia.
To determine your zone 2 heart rate, subtract your age from 220 to estimate your maximum heart rate. Then calculate 60 to 70 percent of that number. For example, a 30-year-old would have a maximum heart rate of about 190 beats per minute (BPM), making their zone 2 range roughly 114 to 133 BPM. For experienced athletes with lower resting heart rates, Samale recommends using the Karvonen method for a more accurate calculation.
Samale suggests using the “talk test” as a simple way to gauge exercise intensity. In zone 2, you should be able to talk but not sing. If you are breathing heavily and cannot speak comfortably, you may be in a higher intensity zone.
The amount of zone 2 cardio recommended per week depends on individual goals. For those new to fitness or returning after a break, Samale advises starting with most or all cardio in zone 2. For athletes or those seeking higher performance, about 80 percent of cardio time should be in zone 2 and 20 percent in higher intensity zones.
National guidelines recommend that adults aim for at least 150 minutes of moderate-intensity cardio or 75 minutes of vigorous cardio per week. Moderate-intensity activities include brisk walking, slow jogging, relaxed swimming, and dancing. Vigorous activities include running, swimming laps, singles tennis, and high-intensity interval training.
Samale emphasizes that exercise should be enjoyable and energizing. “Working out does not have to be miserable,” she says. “In fact, you want to feel more energized after these activities, and if you’re doing zone 2, you should feel great and energized afterwards, not like you just ran a marathon.”
