What is considered moderate intensity aerobic exercise?

What is Considered Moderate Intensity Aerobic Exercise

Moderate-intensity aerobic exercise is defined as activity performed at 40-59% of VO2 max or heart rate reserve, corresponding to 55-69% of maximum heart rate, with a rating of perceived exertion (RPE) of 12-13 on the Borg scale, and an absolute energy expenditure of 4.8-7.1 METs in young adults. 1

Relative Intensity Measures (Individualized)

Moderate intensity should be defined in relative terms based on individual fitness level:

• 40-59% of VO2 max or heart rate reserve 1
• 55-69% of maximum heart rate 1
• RPE of 12-13 on the 6-20 Borg scale (or 5-6 on the CR10 scale) 1
• "Talk test": You can talk but not sing during the activity 1, 2

The relative approach is critical because the same absolute activity (e.g., brisk walking) may be light intensity for a fit 20-year-old but hard intensity for an 80-year-old. 1

Absolute Intensity Measures (METs)

Absolute intensity varies by age group due to declining fitness with age:

• Young adults: 4.8-7.1 METs 1
• Middle-aged adults: 4.0-5.9 METs 1
• Older adults: 3.2-4.7 METs 1
• Very old adults: 2.0-2.9 METs 1

One MET equals 3.5 mL O2/kg/min, representing resting energy expenditure. 1

Practical Examples of Moderate-Intensity Activities

Common moderate-intensity activities include:

• Brisk walking at 3-4 mph 1, 2
• Water aerobics 1, 2
• Stationary cycling (moderate effort) 1
• Resistance training with moderate loads 1
• Household activities: gardening, washing windows, raking lawn 1
• Recreational activities: doubles tennis, swimming continuously, cycling at comfortable pace 2
• Active transportation: brisk walking, climbing stairs 1

Recommended Duration and Frequency

Adults should accumulate at least 150 minutes per week of moderate-intensity aerobic activity, distributed over most days of the week:

• Minimum: 150 minutes/week (2.5 hours) 1, 2
• Optimal range: 150-300 minutes/week for substantial health benefits 2, 3
• Session duration: Activities can be accumulated in bouts of ≥10 minutes 1, 4
• Frequency: At least 3-5 days per week, preferably daily 1

Equivalency with Vigorous Exercise

Moderate-intensity exercise can be substituted with vigorous-intensity activity at approximately a 2:1 ratio:

• 150 minutes of moderate activity = 75 minutes of vigorous activity 2, 3, 4
• 300 minutes of moderate activity = 150 minutes of vigorous activity 2
• Combinations of both intensities can be used to meet recommendations 1, 4

Important Clinical Considerations

Key caveats for prescribing moderate-intensity exercise:

• Medications affecting heart rate (e.g., beta-blockers) require using RPE or talk test rather than heart rate targets 1
• Fitness level matters: Less fit individuals require higher relative effort to perform the same absolute activity 1, 5
• Progressive approach: Individuals unable to meet 150 minutes should start with any amount and gradually increase 1, 3
• Reassessment needed: As training adaptations occur, the absolute intensity corresponding to moderate relative intensity will increase 5

The major advantage of moderate-intensity exercise over vigorous exercise is the decreased likelihood of complications, though vigorous exercise accomplishes cardiovascular conditioning goals in less time. 1