If you’ve been doing steady-paced cardio for a while and notice your progress slowing down, your body has probably adapted to the routine. While this shows your fitness has improved, it also means you’re not challenging your heart enough to keep making gains.
Interval training helps by mixing up the effort during your workout. This change keeps your body from getting too comfortable at one speed. It boosts how well you use oxygen and how quickly you recover between efforts. You don’t need to be super fit or have special equipment to start. Just use activities you already know, like walking or cycling, and change your pace.
How Interval Training Improves Fitness
When you exercise harder, your heart rate rises. This makes your heart work more to send oxygen to your muscles. Over time, your heart gets stronger, your muscles build more power, and your body gets better at clearing out waste.
Rest periods between hard efforts do more than just let you catch your breath. According to the American College of Sports Medicine, these easier times help your heart rate come down while you stay active. Switching between effort and rest trains your body to recover faster, which helps you perform better in daily life and other exercises.
Research in the British Journal of Sports Medicine found that interval training raises VO₂ max (the maximum amount of oxygen your body can use during exercise) better than steady moderate exercise. In studies of people who were inactive before, just two weeks of interval training showed clear improvements in how well they used oxygen. Some people showed gains of 8-10%.
The benefits of interval training last even after your workout ends. Harder effort periods cause an ‘afterburn effect’ called EPOC, which means your body keeps burning calories at a higher rate for hours as it recovers. The exact number of calories burned depends on the person and the workout, but research shows interval training can burn 25-30% more calories than steady cardio in the same amount of time.
Starting with the Right Effort
A common mistake when starting interval training is going too hard at first. If you’re used to steady cardio, you might think you can jump into tough intervals, but even people with good fitness need time to adjust to the new effort levels.
Start with work-to-rest ratios that favor rest. A simple starting point involves 1 minute of raised effort followed by 2-3 minutes of easy-pace rest. During the work period, you should reach a level where talking becomes hard but not impossible. This is typically 70-80% of your max heart rate if you’re watching it.
Use the rest periods to let your breathing return closer to normal, though your heart rate will still be a bit higher. You’re not stopping completely—you keep moving at a slower pace so your body can recover before the next round.
Start with sessions that last 15-20 minutes, once or twice a week. This gives your body time to adjust and helps prevent injuries that can happen if you do high-effort training every day. The NHS recommends beginners take at least one full day of rest or do light activity between interval sessions.
Spotting the Right Effort Levels
During the harder parts, you should feel challenged but not overwhelmed. Signs you’re at the right effort include faster breathing, a noticeable heartbeat, and tiredness in the muscles you’re using—like your legs when running or cycling, or your arms when rowing.
If you feel dizzy, lightheaded, can’t keep good form, feel sharp pain instead of normal muscle tiredness, or need extra time to catch your breath, you’ve pushed too hard. If this happens, take a longer rest or lower the effort in your next round.
After 4-6 weeks, intervals that once felt tough will start to feel easier. This means you’re ready to make things a bit harder—by making the work periods longer, shortening the rest, or increasing your effort.
Picking Your Interval Format
1. High-Effort Interval Training (HIIT)
HIIT means doing short bursts of almost maximum effort, then taking brief rests. For beginners, a session might be 20-30 seconds of hard work followed by 40-60 seconds of rest, repeated 8-12 times. This way, you get the most heart benefits in just 15-20 minutes, including warm-up and cool-down.
HIIT is tougher on your body than medium interval training. The British Heart Foundation recommends building up your fitness with several weeks of moderate exercise before trying real HIIT workouts. If you’re new to exercise, spend 4-6 weeks doing medium cardio or easier intervals before moving on to HIIT.
2. Medium Interval Training
Medium interval training uses smaller differences between work and rest. It’s a good choice for beginners or on days when you’re not fully rested. For example, you might do 2 minutes of fairly hard effort—where you can talk in short sentences but not have a full conversation—followed by 3 minutes of easy movement.
Medium intervals improve heart health without putting too much stress on your joints and muscles, which lowers your risk of injury as you get fitter. Many people find this style easier to stick with, especially when starting interval training.
3. Low-Effort Steady State (LISS) for Rest
LISS cardio isn’t interval training, but it’s still important. It means moving at an easy, talk-friendly pace for 30-45 minutes. These sessions help you recover between harder interval workouts and keep your heart active. Think of LISS as the foundation that helps you do better interval sessions.
Practical Gear Options
You don’t need special equipment for interval training. Any activity where you can change your effort works—like walking, jogging, cycling, swimming, or stair climbing. Many beginners start with walking intervals because it’s easy, gentle on the joints, and simple to adjust by changing your pace.
If you like using equipment, cardio machines such as treadmills, indoor bikes, and rowing machines make it easy to control and track your intervals. Most modern machines have built-in interval programs, but you can also adjust the speed or resistance yourself.
Bodyweight exercises are also great for interval training. You can do circuits that include moves like jumping jacks, high knees, modified burpees, and marching in place. These routines create natural work and rest periods, and you don’t need any equipment or have to leave your home.
The best equipment is whatever you’ll actually use regularly. If you like being outdoors, try running or cycling intervals. If you prefer working out at home, bodyweight circuits or a simple exercise bike are all you need.
Sample Beginner Interval Workouts
1. Walking Intervals
Start with a 5-minute easy warm-up. Then alternate 2 minutes of brisk walking—where you’re breathing harder but can still talk in short sentences—with 3 minutes of slow walking. Repeat this for 20 minutes, then finish with a 5-minute cool-down at an easy pace.
This workout is perfect for people who are new to interval training or have joint issues that make running difficult. To make it harder, try walking faster during the work periods, add hills or an incline, or gradually shorten the rest time to 2 minutes.
2. Cycling Intervals
Begin with 5 minutes of easy pedaling to warm up. Next, do 1 minute of hard pedaling—using high resistance or a fast pace—followed by 2 minutes of easy spinning. Repeat this 6-8 times, then cool down with 5 minutes of easy cycling.
Cycling puts less stress on your joints than running but still gives your heart a great workout. It’s a good choice for people with knee or hip problems, or for those who find running difficult.
3. Stair Climbing Intervals
If you have stairs at home, in your building, or at a park, climb them at a moderate pace for 1 minute. Then walk down slowly for 2 minutes to rest. Going down is your rest period, while climbing gives your heart a workout.
Start by repeating this 5-6 times, and gradually increase to 8-10 rounds as you get fitter. Stair climbing strengthens your legs and your heart, making it a very efficient workout.
4. Bodyweight Circuit Intervals
Do each exercise for 30 seconds, then rest for 30 seconds before moving to the next onee moving to the next one:
• Marching in place with high knees
• Changed jumping jacks (step side to side instead of jumping if needed)
• Bodyweight squats
• Plank hold (or changed on knees)
Repeat the whole circuit 3-4 times, resting 1-2 minutes between each round. This routine boosts your heart health and builds practical strength.
5. Rest and Moving Forward
Resting between interval sessions is just as important as the workouts. The American Council on Exercise suggests beginners do interval training only 2-3 times a week, with at least one full rest day between sessions. On other days, you can do steady cardio, strength training, yoga, or simply rest.
If you have muscle soreness that lasts more than two days, your performance drops even though you’re trying hard, you have trouble sleeping, or your resting heart rate is higher than usual, you may need more rest. If you notice these signs, reduce how often or how hard you train for now.
As your body gets used to it over 4After 4-8 weeks, as your body adapts, you can move forward in different ways. Try increasing your work period from 1 minute to 90 seconds, shortening your rest from 3 minutes to 2, or doing more intervals. Change only one thing at a time instead of everything at once.o supports continued getting better. You might do walking intervals one day, cycling intervals another day, and bodyweight circuits on the third interval session of your week. This variety works different muscle groups. It prevents the mental boredom that often leads to skipping workouts.
Safety Notes for Beginners
If you have heart disease, high blood pressure, diabetes, joint issues, or haven’t been active for several months, check with your doctor before starting interval training. The changes in effort put more strain on your heart than steady exercise, so getting medical advice is important for these groups.
Always start with a proper warm-up and finish with a cool-down. Doing 5 minutes of easy movement before your first interval helps your heart rate and body temperature rise gradually. After your last interval, another 5 minutes of easy movement helps your heart rate return to normal slowly.
Stop exercising and seek medical help if you have chest pain, severe shortness of breath that doesn’t get better with rest, ongoing dizziness, or an unusual heart rhythm. Interval training is safe for most people, but these symptoms should be checked by a doctor.
Focus on good form during all your intervals. Tiredness can make your technique slip, like slouching while running or rounding your back during rowing. If you can’t keep good form, lower your effort instead of continuing with poor technique, which can increase your risk of injury.
Building Habits That Last
People who stick with interval training long-term usually have realistic expectations. You don’t need to make your workouts extremely hard for them to be effective. Starting with manageable efforts and progressing slowly leads to better results than going too hard and burning out.
Keep track of your sessions in a notebook or app. Record your work-to-rest ratio, how many intervals you did, and how you felt. After 4-6 weeks, you’ll often see real progress—intervals that once felt tough now feel easier, or you’re able to do more rounds at the same effort.
Remember, interval training is meant to add to your routine, not replace other types of exercise. A balanced fitness plan includes intervals, steady cardio, strength training, and stretching. Each part helps the others—strength training lowers injury risk during intervals, and the heart fitness you gain from intervals boosts your strength workouts.
The goal isn’t to make every workout harder forever. It’s to find a pattern you can keep up with that pushes your heart enough to create change. It allows enough rest. For many people, that means 2-3 interval sessions weekly. Other days given to different training types or rest. This balanced approach supports long-term fitness building better than trying for max effort every session.
