HIIT Terminology: A Complete Glossary of Interval Training Terms

HIIT (High-Intensity Interval Training)

A training method that alternates between short, intense bursts of activity (work intervals) with periods of lower intensity or complete rest (rest intervals). True HIIT requires working at 80-95% of your maximum heart rate during work intervals.

Example: Sprinting for 30 seconds, then walking for 30 seconds, repeated for 8 rounds.

Work Interval

The period during a HIIT workout when you're performing high-intensity exercise at the target intensity level. Work intervals are typically measured in seconds or minutes.

Example: In a "30-30" protocol, the 30 seconds of all-out effort represents the work interval.

Rest Interval (Recovery Interval)

The period between work intervals when you're either completely resting or performing very low-intensity activity to allow partial recovery before the next work interval.

Example: Walking or light jogging between sprint intervals, or standing still between sets of burpees.

Work-to-Rest Ratio

The relationship between the duration of work intervals and rest intervals, often expressed as a ratio (e.g., 1:2 or 1:1). This ratio is a key factor in determining the intensity and difficulty of a HIIT workout.

Example: A 1:2 work-to-rest ratio might involve 30 seconds of work followed by 60 seconds of rest.

Common ratios:

• 1:4 or 1:3 - Beginner-friendly, allows substantial recovery
• 1:2 - Moderate intensity, good for building endurance
• 1:1 - Challenging, balanced work and recovery
• 2:1 - Advanced, limited recovery time

Round (Cycle)

A complete sequence of one work interval plus one rest interval. HIIT workouts typically consist of multiple rounds.

Example: If you do 8 rounds of 30 seconds work/30 seconds rest, you've completed 8 full cycles of the interval pattern.

MaxHR (Maximum Heart Rate)

The highest heart rate an individual can achieve during all-out effort. Often estimated with the formula "220 - age" although this is just a rough approximation and can vary significantly between individuals.

Example: A 30-year-old might estimate their MaxHR as 220 - 30 = 190 beats per minute.

%MaxHR (Percentage of Maximum Heart Rate)

A way to quantify exercise intensity based on what percentage of your maximum heart rate you're working at. True HIIT typically involves working at 80-95% of MaxHR during work intervals.

Example: If your MaxHR is 190 bpm, working at 90% would mean a heart rate of about 171 bpm.

RPE (Rate of Perceived Exertion)

A subjective scale used to measure exercise intensity based on how hard you feel you're working. Typically used on either a 0-10 scale or a 6-20 scale (Borg Scale).

Example: On a 0-10 RPE scale:

• 1-2: Very light activity (e.g., casual walking)
• 3-4: Light activity (easy to maintain and talk)
• 5-6: Moderate activity (breathing heavier but can still talk)
• 7-8: Vigorous activity (difficult to speak in full sentences)
• 9-10: Maximum effort (cannot talk, all-out exertion)

HIIT work intervals should typically be performed at an RPE of 8-10.

Talk Test

A simple method to gauge exercise intensity based on your ability to speak while exercising.

Example:

• Able to sing: Low intensity
• Able to speak in full sentences: Moderate intensity
• Able to speak only in short phrases: High intensity
• Unable to speak: Very high intensity

During HIIT work intervals, you should only be able to speak in short phrases or be unable to speak at all.

Tabata

A specific HIIT protocol developed by Dr. Izumi Tabata, consisting of 20 seconds of maximum-intensity exercise followed by 10 seconds of rest, repeated for 8 rounds (4 minutes total). The original research used stationary bikes, but the protocol is now applied to various exercises.

Example: 8 rounds of 20 seconds of all-out burpees with 10 seconds rest between rounds.

EMOM (Every Minute On the Minute)

A workout structure where you perform a specific exercise or set of exercises at the beginning of every minute, then rest for the remainder of that minute before starting the next round.

Example: At the start of each minute, perform 15 kettlebell swings. If it takes you 25 seconds to complete the swings, you get 35 seconds of rest before the next minute begins.

AMRAP (As Many Rounds As Possible)

A workout format where you perform as many rounds of a prescribed circuit as possible within a set time frame. Though not strictly an interval protocol, AMRAP workouts often incorporate HIIT principles.

Example: In 15 minutes, complete as many rounds as possible of: 10 push-ups, 15 squats, and 20 mountain climbers.

Pyramid Intervals

A workout structure where the work intervals (and sometimes the rest intervals) either increase then decrease in duration throughout the workout, or continuously increase or decrease.

Example: Work intervals of 30 seconds, 45 seconds, 60 seconds, 45 seconds, 30 seconds with consistent rest intervals between each.

Descending Intervals (Countdown)

A format where each subsequent interval gets shorter in duration, often creating a sense of becoming more manageable as the workout progresses.

Example: Work intervals of 60 seconds, 45 seconds, 30 seconds, 15 seconds with consistent rest between each.

Ladder Intervals

Similar to pyramid intervals, but in a ladder format, the work duration or reps continuously increase or decrease, without returning to the starting point.

Example: Performing 10, 20, 30, 40, and 50 seconds of work with equal rest periods.

Preparation Phase (Prep Time)

A short countdown period before each work interval begins, allowing you to get into position and mentally prepare for the upcoming effort.

Example: A 5-second countdown before each sprint interval begins.

Transition Time

The time allocated to switch between different exercises in a circuit-style HIIT workout.

Example: 10 seconds allowed to move from the squat station to the push-up station in a circuit.

Time Under Tension (TUT)

The total time a muscle is working during an exercise set. In HIIT, manipulating TUT by changing the tempo of exercises can alter the stimulus even with the same work interval duration.

Example: Performing push-ups with a 3-second lowering phase and 1-second pushing phase increases TUT compared to regular-tempo push-ups.

EPOC (Excess Post-exercise Oxygen Consumption)

The increased rate of oxygen intake following strenuous activity. Often called the "afterburn effect," EPOC represents the body's recovery process and continued elevated calorie burning after a workout has ended.

Example: After a high-intensity Tabata session, your body continues to burn calories at an elevated rate for hours as it restores oxygen levels and repairs tissues.

VO2 Max

The maximum rate at which an individual can consume oxygen during exercise, reflecting cardiorespiratory fitness. HIIT is particularly effective at improving VO2 Max.

Example: An elite athlete might have a VO2 Max of 70 ml/kg/min, while an average person might be around 30-40 ml/kg/min.

Anaerobic Threshold (Lactate Threshold)

The exercise intensity at which lactate begins to accumulate in the blood faster than it can be removed. Working above this threshold can only be sustained for limited periods, making it relevant to HIIT work intervals.

Example: During a 30-second all-out sprint, you're working well above your anaerobic threshold, which contributes to the burning sensation in your muscles.

Active Recovery

Low-intensity exercise performed during rest intervals instead of complete rest. This approach can help clear metabolic byproducts while maintaining elevated heart rate.

Example: Walking or light jogging between sprint intervals instead of standing still.

Passive Recovery

Complete rest during recovery intervals, with minimal or no movement.

Example: Standing or sitting completely still between burpee intervals.

Interval Timer

A specialized timer (physical device or app) designed to track work and rest periods in interval workouts. Unlike standard timers, interval timers can be programmed with multiple rounds of varying durations and provide audible/visual cues for transitions.

Example: The Peak Interval app is an interval timer that allows you to set custom work and rest periods with audio alerts.

Heart Rate Monitor (HRM)

A device that measures heart rate during exercise, often used to ensure you're reaching target intensity levels during HIIT work intervals. HRMs come as chest straps, wrist-based monitors, or armbands.

Example: Using a chest strap HRM to verify you're reaching 85-90% of your maximum heart rate during sprint intervals.

Rated Perceived Exertion (RPE) Chart

A visual scale used to help individuals gauge their exercise intensity subjectively.

Example: A wall-mounted RPE chart in a gym showing the 0-10 scale with descriptions of each level.

HIIT Block

A designated portion of a training program focused specifically on high-intensity interval work, often as part of a larger training session or periodized plan.

Example: A 15-minute HIIT block at the end of a strength training session.

Density

The amount of work performed within a given time frame. In HIIT, increasing density might mean shortening rest periods or increasing the work-to-rest ratio while maintaining the same exercise selection.

Example: Changing from a 1:2 to a 1:1 work-to-rest ratio increases the density of a HIIT workout.

Volume

The total amount of work performed, typically measured by duration, number of intervals, or total repetitions.

Example: Increasing from 6 to 8 rounds of Tabata increases the volume of the workout.

Progressive Overload

The gradual increase of stress placed on the body during exercise to stimulate adaptation and improvement. In HIIT, this could involve increasing intensity, volume, density, or complexity over time.

Example: Starting with 6 rounds of 20:40 intervals, then progressing to 8 rounds, then eventually moving to 30:30 intervals as fitness improves.

Periodization

The systematic planning of training to reach peak performance for specific goals. HIIT can be periodized by manipulating intensity, volume, and frequency across training cycles.

Example: In a 12-week plan, gradually increasing HIIT frequency from once to three times per week, while progressively shortening rest periods.