I have dedicated the majority of my professional life to the fitness industry, which spans over 30 years. Throughout my career, I have always sought ways to achieve the best results with the least amount of training. This is not because I am lazy, but rather because I value efficiency and believe that time and energy are precious resources that should not be wasted. Additionally, many individuals claim that they do not have enough time to exercise, which is a common reason for missing workouts. Studies have shown that as many as 50% of people give up on their fitness routines within 3-6 months of starting [1]. To address this issue, there are certain strategies that can be adopted to maintain consistent exercise habits. In this article, I will compare and contrast two time-efficient training methods: high-intensity interval training (HIIT) and high-intensity repeat training (HIRT). By understanding the differences between these two approaches, you will be able to choose the one that best suits your needs.
High-Intensity Interval Training Overview
High-intensity interval training, commonly referred to as HIIT, has been a popular exercise method for several decades. However, in case you are not familiar with it, HIIT involves alternating between short periods of intense activity and brief periods of rest. For example, you could sprint for 60 seconds, walk for 60 seconds, and repeat this cycle ten times to complete a 20-minute HIIT workout. There are numerous ways to incorporate HIIT into your routine, such as using cardio activities, calisthenics, or strength training exercises. Some workouts even combine multiple training modalities. To learn more about integrated circuit training, refer to our article on the topic. The key characteristics of HIIT workouts include:
1. High-Intensity Efforts: As the name suggests, HIIT workouts involve high-intensity efforts. Although you may not be working at 100% intensity, you will come close to it. Given the number of repetitions and short rests, it is important to hold back slightly to ensure that you can complete the entire HIIT workout. Pushing yourself too hard too soon can lead to premature exhaustion and an inability to finish the session.
2. Incomplete Recoveries: Rest periods between HIIT efforts are generally kept short, ranging from 30-60 seconds. Consequently, there is not enough time to fully recover between intervals. During intense exercise, your body utilizes the ATP/CP and lactate systems for energy. Both of these systems require several minutes to replenish. As a result, you start each interval feeling slightly fatigued, and this fatigue gradually increases throughout the workout. This can lead to a decrease in exercise performance, an increase in heart rate, or a higher perceived exertion level. In other words, most HIIT workouts start off feeling manageable, but become increasingly uncomfortable as you progress.
3. Exercise Discomfort: It is no exaggeration to say that HIIT workouts can be extremely challenging. The combination of near-maximal efforts and inadequate rest periods causes lactate levels to rise rapidly. Your muscles will burn, your heart will race, and your breathing will become heavy. While some individuals may welcome this level of discomfort, others may find it off-putting. In fact, individuals who are less physically fit may find this level of discomfort intolerable and potentially even dangerous. Therefore, HIIT workouts are generally not recommended for beginners or individuals who are very unfit.
4. Multiple Intervals: Although HIIT workouts are typically shorter than traditional cardio exercises such as low-intensity steady state (LISS) or Zone 2 training, they can still be quite lengthy. This is because most HIIT workouts involve multiple intervals. For example, you might perform 8-10 one-minute intervals with two-minute rests, which adds up to approximately 24-30 minutes. However, there are exceptions to this rule. Tabata intervals, for instance, only last for 20 seconds with ten-second rest periods. As a result, a Tabata workout usually only lasts for about four minutes. Nonetheless, the majority of HIIT workouts involve multiple intervals.
HIIT Benefits
HIIT workouts offer a range of notable benefits, including:
1. Time Efficiency: HIIT workouts are generally shorter than traditional cardio workouts, making them ideal for individuals with limited time.
2. Increased Caloric Burn: HIIT burns more calories per minute than conventional cardio exercises.
3. Boosted Metabolic Rate: HIIT can elevate your metabolic rate for hours after exercise, which can aid in weight management. This phenomenon is known as the afterburn effect or excess post-exercise oxygen consumption (EPOC).
4. Improved Insulin Sensitivity: HIIT has been shown to improve insulin sensitivity, reducing the risk of type 2 diabetes. Better insulin sensitivity can also enhance fat loss and prevent weight gain.
5. Improved Cardiovascular Health: HIIT can improve cardiovascular health by increasing cardiorespiratory efficiency and endurance.
6. Muscle Building and Maintenance: HIIT can help build or maintain muscle mass, especially when combined with strength training exercises.
7. Better Aerobic Fitness: Despite being anaerobic in nature, HIIT can improve aerobic fitness, as indicated by an increase in V02 max.
8. Variety and Flexibility: There are countless ways to incorporate HIIT into your routine, which helps prevent exercise boredom.
9. Mental Health Benefits: HIIT can boost mood and mental health due to the release of endorphins during intense exercise.
To summarize, high-intensity interval training (HIIT) delivers an intense training effect in a relatively short amount of time. By involving multiple efforts and short rests, HIIT workouts overload your ATP/CP and lactate energy systems, resulting in an uncomfortable and potentially painful workout experience.
