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Key Takeaways
- A recent study found that HIIT helped healthy older adults lose body fat and maintain lean muscle mass.
- HIIT works best as part of a balanced routine that also includes resistance training, adequate protein intake, lower-intensity aerobic exercise, and recovery.
- HIIT isn’t appropriate for everyone, and beginners should build an aerobic foundation before gradually adding one or two HIIT sessions each week.
When you lose weight, you don’t just lose body fat—you also lose some lean muscle mass. Research suggests that about 20% to 40% of weight lost typically comes from fat-free (lean) mass. Because muscle naturally declines with age, preserving it becomes increasingly important for maintaining strength, mobility, and independence.
A recent study suggests that high-intensity interval training (HIIT) may help older adults preserve muscle while reducing body fat.
HIIT May Help Preserve Muscle During Weight Loss
Researchers followed 123 healthy adults with an average age of 72, who completed supervised exercise sessions three times a week for six months. Participants were assigned to one of three groups:
- HIIT
- Moderate-intensity continuous exercise
- Low-intensity exercise
Both the HIIT and moderate-intensity groups lost body fat and reduced visceral (abdominal) fat. However, only the HIIT group maintained lean body mass while lowering body fat percentage. The moderate-intensity group lost a small amount of lean mass alongside fat loss.
The researchers pointed out that the differences between the groups were small and might not be important for real-life health or physical function. In other words, the results do not show that HIIT is much better than other types of exercise. Instead, HIIT may give a small benefit for improving body composition in healthy older adults.
Why HIIT May Help Preserve Muscle
HIIT alternates short bursts of vigorous exercise with recovery periods. According to Lekshmi Kumar, MS, a certified exercise physiologist with Human Powered Health performance labs, those intense intervals place a greater demand on the muscles than steady-state exercise.
“During high-intensity efforts, your body recruits more fast-twitch muscle fibers than it does during steady-state moderate exercise,” Kumar said. “These fibers help generate force and power, and if they are stimulated, they can help preserve lean muscle while you’re also in a calorie deficit.”
HIIT increases calorie burn during and after exercise through a process called excess post-exercise oxygen consumption (EPOC). However, Kumar said this only adds a small amount to the total calories burned.
HIIT also triggers several changes throughout the body that may help explain why it can help preserve muscle. Kumar said the intense exercise recruits more muscle fibers involved in strength and power, improves how muscle cells produce energy, and strengthens the heart’s ability to pump blood and deliver oxygen to working muscles.
HIIT Is Just One Part of Preserving Muscle
With age, we naturally lose muscle through a process called sarcopenia. This can reduce strength, balance, movement, and overall health. Maintaining your muscle mass helps you stay independent, keep your bones strong, and manage blood sugar as you get older.
While the study shows that HIIT may help maintain muscle mass, experts warn against relying on it alone.
“Resistance training is arguably the most important stimulus to maintain lean muscle during weight loss,” Kumar said. “Adequate protein intake provides the building blocks for muscle protein synthesis, and sleep, nutrition, and allowing enough time between hard workouts are when adaptation can occur.”
Rather than viewing HIIT and lower-intensity exercise as competing approaches, Kumar recommends combining them. “Zone 2 [cardio] builds the aerobic foundation, while HIIT improves high-intensity performance,” she said.
Zone 2 refers to moderate-intensity exercise, such as brisk walking, cycling, or easy jogging, performed at an effort you can sustain while still able to carry on a conversation. Kumar said that combining this type of exercise with HIIT, resistance training, adequate protein intake, and recovery creates a more balanced program for long-term health and body composition.
Is HIIT Right for Everyone?
Some people should exercise caution before engaging in HIIT exercises, including those who are:
- New to exercise or haven’t exercised regularly in a long time
- Recovering from an injury
- Living with untreated heart disease
Kumar says it is important to build up your fitness with activities like walking, cycling, or jogging before starting HIIT. This means getting fit enough to comfortably do moderate exercise before moving on to harder workouts. People with uncontrolled heart or metabolic problems should talk to their healthcare provider before starting HIIT.
Ultimately, the best exercise plan is one you can stick with over time. For most people, this means combining regular movement, strength training, lower-intensity aerobic exercise, and occasional HIIT sessions rather than relying on any single workout.
Read the original article on Verywell Health
