100 day cardio challenge

About this 100 day cardio challenge

Intensity level: intermediate

Benefits: improvement to cardio fitness (meaning a healthier heart and circulatory system), fat burning, leg toning

Safety: please read the general safety information here

Challenge format: the challenge alternates running with indoor cardio exercises

Warm up:

  • On the running days, walk for 2 mins first to warm up.
  • On the indoor cardio days, you should warm up your muscles and joints by doing the warm up exercises shown in the exercise instructions section below.

Cool down:

As your heart rate will be raised significantly doing the challenge, you should cool down after each day’s effort. On the running days, walk for 2 minutes at the end of your run. On the indoor workout days, march in place for 2 minutes.

What you need:

  • Training shoes that will absorb some of the impact of the running and high impact cardio exercises.
  • Clothing that allows you to stay cool, or layers that you can remove.
  • A bottle of water.
  • Something to time your runs and cardio sets – either a fitness watch or a stopwatch app.

Planning a route

If you’re running outdoors, you’ll need to plan a route. Each day you’ll cover a different distance, so to keep route planning simple:

  • Plan a route that is around 7km / 4.5 miles in length. This should be long enough for all the runs, including warm ups and cool downs, unless you are a very fast runner.
  • Each day, run along your route for half that day’s time and then turn around and come back. So, for example on day 1 you would follow your route for the warm up plus 2.5 minutes running before turning around. As you progress through the challenge, you will be travelling further along your route each day.

Running indoors

You can also do this challenge on a treadmill. There are advantages to both indoor and outdoor running.

Advantages of the treadmill

With a treadmill it’s easy to set your walking speed and keep your speed continuous.  You don’t need to worry about route planning and, if you want the challenge of an uphill walk then it’s easy to increase the gradient. Timing your intervals is taken care of too. You also aren’t affected by bad weather.

Advantages of walking outside

On the other hand, the predictable conditions of the treadmill make it less of an all-over body challenge because you don’t have to cope with uneven surfaces and changes in direction. Walking in the street or park is also free of course, whereas gym membership or buying a home treadmill can be expensive. You’ll get the benefit of fresh outdoor air, which is good for mental as well as physical health.

See a treadmill buying guide here.

100 day cardio challenge chart

The chart shows the circuit sets and the run times for each day and instructions for the exercises are below the chart. For the circuit a “set” means doing each of the exercises for the time given. When you’ve done 1 set, start again. Keep doing this until you’ve done the number of sets given for each day.


100 day cardio challenge chart

Exercise instructions

Warm up

Do these warm up exercises for the circuit workouts – 16 repetitions of each:

Warm up Knee lift Warm up Lunge behind Warm up Calf raise

Circuit exercises

Mountain climber 100 day cardio challenge



Jump 100 day cardio challenge

Side leaps 100 day cardio challenge

The benefits of cardio exercise

Engaging in activities that increase your heart rate, improves your health in a number of ways.

Heart and circulatory benefits

Over time, cardio exercise helps strengthen the heart muscle, improve blood circulation, and reduce the risk of heart disease. Regular cardio workouts can lower blood pressure and decrease levels of LDL (bad) cholesterol, reducing the likelihood of a heart attack or stroke.

Weight control benefits

Cardio exercise can help with fat loss. They burn calories, helping you create a calorie deficit when combined with a balanced diet. When there is a calorie deficit (ie calorie intake is less than calories used), the body breaks down fat stores for energy.

Mental health benefits

Cardio exercise triggers the release of endorphins, which are natural mood lifters, and reduces stress hormones like cortisol. Engaging in cardio workouts can help reduce symptoms of anxiety and depression, enhance your overall sense of well-being, and boost your ability to cope with stress.

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