Using a treadmill for fat loss requires training the body to preferentially burn stored fat for fuel, a process known as fat oxidation. This process is most efficient when exercise intensity falls within a specific physiological window. Finding the correct combination of speed and incline allows you to manipulate your heart rate and muscle recruitment for an effective fat-burning workout. Adjusting the treadmill’s settings intentionally helps maximize this metabolic effect by maintaining an optimal intensity level.
Understanding the Fat-Burning Zone
The body utilizes a mix of fat and carbohydrates for energy. To maximize the use of fat as a primary fuel source, you should aim for the “Fat-Burning Zone,” which corresponds to a moderate intensity. This zone is typically defined as maintaining a heart rate that is 60% to 70% of your estimated Maximum Heart Rate (MHR).
You can estimate your MHR using the simple formula of 220 minus your age. For example, a 40-year-old would have an estimated MHR of 180 beats per minute (bpm), making their fat-burning zone between 108 bpm and 126 bpm. If a heart rate monitor is unavailable, the Rate of Perceived Exertion (RPE) offers a subjective measurement, where the fat-burning zone feels like a comfortable pace you can maintain for an extended time while still being able to hold a conversation.
Optimizing the Incline: The “Treadmill Hike” Strategy
Incorporating incline is an effective strategy to boost intensity without increasing speed to a running pace, creating what is often referred to as a “treadmill hike.” Walking on an incline significantly increases the metabolic cost compared to walking on a flat surface, leading to a greater total calorie burn. This adjustment forces the recruitment of larger, powerful muscle groups, particularly the glutes, hamstrings, and calf muscles, which increase overall energy expenditure.
A challenging incline walk involves setting the treadmill to an incline between 5% and 15%. A common protocol involves walking at a speed of 3.0 to 3.5 miles per hour (mph) while maintaining a steep incline, such as 12%. This combination allows you to elevate your heart rate into the fat-burning zone while keeping the exercise low-impact, making it a good choice for individuals concerned about joint stress. Studies have shown that walking at an incline of 5% can increase calorie expenditure by over 50% compared to a flat walk at the same speed.
Integrating Speed: Steady State vs. Interval Training
The speed component of your treadmill workout should be integrated to either sustain your heart rate in the fat-burning zone or to push it beyond that zone in short bursts. Two primary methods utilize speed differently: Low-Intensity Steady State (LISS) and High-Intensity Interval Training (HIIT).
LISS cardio involves maintaining a consistent, moderate pace for an extended period, typically 30 to 60 minutes. For fat burning, this means holding a speed and incline that keeps your heart rate consistently within the 60-70% MHR range. For example, a LISS session might involve walking at a 1% incline at 3.5 mph for 45 minutes, ensuring a steady state of fat oxidation.
Conversely, HIIT involves alternating short periods of intense effort with brief recovery periods, using speed to spike the heart rate to 80-95% of MHR. A sample HIIT protocol on the treadmill could involve a one-minute burst at a high speed, such as 6.0-8.0 mph, followed by two minutes of recovery walking at 3.0 mph, repeated for 15-20 minutes.
While a lower percentage of calories come from fat during the high-intensity intervals, the total calorie burn is maximized, and the workout triggers Excess Post-exercise Oxygen Consumption (EPOC). EPOC, often called the “afterburn effect,” means your body continues to burn calories at an elevated rate for a period after the workout concludes. The most comprehensive approach for fat loss often involves rotating between these two methods, using LISS for foundational conditioning and HIIT for metabolic boosts and time efficiency.