HIIT vs. Steady State Cardio: Which One is Best for Your Clients?

Which of the following is a more effective strategy for traveling from one place to another in the shortest period of time: (1) adding miles to your trip by driving the back streets of a city to avoid traffic jams; or (2) taking the shortest, most direct route even if it means sitting on a freeway so congested that you only move a few miles an hour?  And which approach burns more gas and places more wear and tear on your car: the frequent starting and stopping of city driving or highway driving at a constant rate of speed? 

This scenario provides a rough analogy of how the human body responds to different types of cardiorespiratory exercise. High-intensity interval training (HIIT), which, in this scenario, could be considered similar to city driving, can be extremely effective for burning calories and improving aerobic capacity but at the expense of placing high levels of physical stress on the body. Conversely, steady-state training (SST) focuses on maintaining a consistent, low-to-moderate intensity work-rate for an extended period of time, which is comparable to driving on a highway. Like HIIT, SST can be effective for aerobic conditioning and burning calories, but it can require an extensive amount of time to do the volume of work necessary to achieve the desired results. 

So, is one form of training better than the other? Like almost all fitness-related questions, the answer depends on a variety of factors. In the car analogy described above, both options can help you get to your destination. Which one you choose depends on your personal preference—would you prefer to sit in slow-moving traffic or being in constant motion? 

The following table lists the features, advantages, and disadvantages of HIIT vs. steady state cardio. There is a large body of research validating each mode as an effective form of exercise; however, it is up to you to determine which one is best suited to help your clients reach their fitness goals in the shortest period of time.

Steady-state Training

Features

• Maintain a consistent speed, level of intensity and work rate during an exercise session. 
• Training intensity can be measured by maintaining a consistent work rate at a specific percentage of maximum heart rate (MHR), heart rate reserve (HRR) or aerobic capacity (VO2 max). Another option is to use ratings of perceived exertion (RPE), which allows you to use a 1-10 scale to judge the level of difficulty (1 being easier and 10 the hardest).

Advantages

• Exercising below the ventilatory threshold for an extended period of time puts less physical stress on the cardiorespiratory system and can be an effective way to prepare for an endurance event. 
• It is an established and proven method for improving cardiorespiratory fitness and enhancing aerobic capacity. 
• Increases mitochondrial density in type I (slow-twitch) muscle fibers, which can improve aerobic metabolism. 
• Increases cardiac efficiency; specifically, elevating stroke volume and cardiac output at a lower heart rate. 
• Enhances ability to use fat as an efficient fuel source, which reserves muscle glycogen to be used for higher-intensity exercise. 
• Steady-state training to improve aerobic efficiency generates less metabolic waste and cellular damage than HIIT workouts.

Disadvantages

• If the goal is weight loss, steady-state training may require extended periods of training time to achieve the desired level of caloric expenditure. 
• Using steady-state training to improve aerobic capacity may require lengthy exercise sessions, which can be a challenge for a busy lifestyle. 
• Extended periods of exercise can increase the risk of repetitive stress injuries. 
• Certain individuals may find it difficult to maintain the focus necessary to train at a constant work rate for an extended period of time.

Interval Training

Features

• Alternate between periods of high-intensity exercise and lower-intensity, active or passive recovery. 
• Both the higher-intensity work intervals and lower-intensity recovery periods can be measured as a percentage of MHR, HRR, VO₂max or an individual’s RPE.

Advantages

• HIIT can be effective for improving aerobic capacity and/or calorie burning in less time when compared to high-volume, steady-state training. 
• The higher-intensity work intervals of HIIT can be based on an individual’s RPE, allowing that individual to start exercising at a relatively low intensity (as measured objectively) and progress from that initial starting point. 
• Interval training may be an effective strategy for individuals who become easily distracted or bored during longer exercise sessions. 
• Can improve efficiency of type II muscle fibers to produce energy via anaerobic glycolysis, resulting in greater metabolic efficiency. 
• Exercising above the lactate threshold can help stimulate production of muscle-building, fat-burning hormones such as testosterone, growth hormone and insulin-like growth factor. 
• Increases the effect of EPOC (excess post-exercise oxygen consumption), helping to burn calories after the exercise session is completed.

Disadvantages

• High-intensity exercise increases mechanical damage on muscle tissue, which could increase soreness and the perception of exercise as “painful” in deconditioned individuals.  
• Anaerobic metabolism results in an accumulation of metabolic stress that limits a muscle’s ability to function. 
• The high mechanical stresses of HIIT can increase the risk of a muscle strain. 
• The higher exercise intensities required to improve aerobic conditioning with HIIT may be uncomfortable or painful for some people. 
• An extended period of HIIT could deplete glycogen stores and result in gluconeogenesis, which is the metabolic process of converting protein to produce glycogen. This limits the amount of protein available to repair muscle tissue damaged by exercise.

5 Reasons Why HIIT Might Be the Best Choice (for You or Your Clients)

1. You have a busy schedule, which limits your training time; HIIT workouts can be done in 30 minutes or less, making them extremely effective for producing results in a limited amount of time.
2. You have been following the same cardio workout routine for a long time and have become stuck at a plateau, adding HIIT workouts could jumpstart your program so you continue experiencing results.
3. You want to train for a mud run or obstacle course race. These events feature physical challenges requiring anaerobic strength. HIIT can help you prepare to meet the demands of overcoming an obstacle, while also improving aerobic efficiency so you have the energy to finish the race.
4. You are exercising for weight loss. HIIT can help you burn more calories in a shorter period of time, while also providing an EPOC effect to help you continue expending energy even after the workout is over.
5. Because you like it. The best exercise in the world is the one you enjoy and will do on a regular basis. If HIIT works for you, go for it and have fun, but make sure you allow time for appropriate recovery because that’s where the real results happen.

5 Reasons Why Steady-state Training Might Be the Best Choice (for You or Your Clients)

1. You experience a period of high stress or find yourself wallowing in a grumpy mood. Steady-state workouts require lower levels of physiological stress, which could help you to clear your mind and change your mood.
2. You want to enter a race like a 10K, half marathon or marathon. According to the principle of specificity, the best way to train for an activity is to do the activity. If you want to complete an endurance race, you will need to plan on making time for long-distance, steady-state training.
3. You are visiting a city you have never been to before or have recently moved. A long, steady-state run, bike ride or walk can be a great way to get out and explore an area you have recently moved to or are visiting for the first time.
4. You are exercising for the health benefits. Regular, low-to-moderate intensity steady-state exercise can provide a number of health benefits, including helping to reduce the risk of developing a chronic condition like type 2 diabetes, high blood pressure or high cholesterol.
5. Because you like it. Some people simply enjoy going out for long runs or training for long-distance endurance events. There is no reason to change your workout habits as long as they provide you with the benefits you are looking for.

Regardless of whether you choose SST or HIIT, to keep seeing results it’s important to change workouts on a regular basis to keep from becoming complacent, which could result in getting stuck on a plateau and not achieving any results from the exercise program. The best workout program is the one that is done on a regular basis.