100 day ab challenge to flatten & tone

Focus on improving your abs with this 100 day ab challenge. There are 5 exercises which between them will work all of the ab muscles, for a flat, trained look. You’ll get up to 90 reps a day by the end of the challenge, but you’ll work up to it gradually, increasing your strength and endurance as you go along.

100 day ab challenge PDF

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100 day ab challenge workout format

The challenge is split into blocks of 6 days – 5 days of exercise and one rest day. On each of the exercise days you do a different combination of 3 exercises and the number of reps increases with each block. The schedule is here in the post and you can also get a printable PDF version (see below).

Notes on doing this workout

You will need an exercise mat, or some other sort of cushioning for your back, such as a folded blanket.

Before you do this workout, please read these general exercise guidelines.

The exercises

#1 Reverse crunch

Reverse crunch

  1. Lie on your back and extend your legs so that they are vertical.
  2. Engage your lower abs as you curl your lower spine off the mat. It should be a smooth curling movement.
  3. When your lower back has left the floor, start to reverse the movement – curl your spine back down under control.

#2 Double leg stretch

100 day ab challenge double leg stretch

  1. Lie on your back with your knees and hips bent at right angles and your hands behind your head, as shown
  2. Curl your head and shoulders off the floor as you straighten your legs
  3. Return to the start position.

#3 scissors


  1. Start in the same position as for double leg stretch above.
  2. Straighten your legs so that they are vertical.
  3. Making sure you don’t let your back arch, lower and raise one leg at a time.

#4 bicycle crunch

Bicycle crunch

  1. Again, the start position is as for the double leg stretch.
  2. Extend your right leg to a 45° angle with the floor.
  3. At the same time, bring your left knee towards your upper body and lift your right shoulder off the floor to reach your elbow towards your knee.
  4. Now extend your left leg and bring your left elbow towards your right knee.
  5. Keep alternating for the given number of reps.

#5 straight leg crunch

Straight leg crunch

  1. Get your legs into the vertical position, as for the scissors exercise.
  2. Curl your head and shoulders off the floor as you reach your hands towards your feet.

100 day ab challenge schedule

Here are the reps for each day of the challenge – enter your e-mail address below to get a link to a PDF download.

100 day ab challenge PDF page 1

100 day ab challenge PDF page 2

100 day ab challenge PDF page 3

Get the PDF printable (3 sheets of A4 or letter)

Sign up for My Fitness Planner updates and get the free printable download link e-mailed to you:

After you sign up, you’ll get 2 e-mails, one will have a link to your printable download and the other will be a welcome e-mail.

If the e-mails haven’t turned up within a few minutes, please check your junk folder, as some service providers have very strict filters.

Related to 100 day ab challenge

LOWER AB CIRCUIT1000 rep ab workout

Ab workouts FAQ

The stock answer to this is that you can’t get rid of fat from a specific area. This  is repeated frequently and emphatically by almost everyone involved in fitness. Given that it’s the go-to answer, you would think that there’s a pile of evidence to support it. In fact, the evidence is surprisingly weak. On the other hand, there’s no evidence that you can exercise to burn fat from a specific area either.

What we do know for sure is that our bodies have preferred places to store fat – and the abdominal area is one of them. So you’re not likely to have a fat-free belly until you’re a healthy weight. The best way to be a healthy weight is of course to have a healthy diet and to exercise regularly. Any exercise helps with weight control.

Even if it doesn’t burn belly fat, regular ab exercise will make a difference though. The deep core muscles pull the abdominal area flat and having a strong core can make a real difference. In fact it’s often the case that what people think is fat is just poor muscle tone allowing the abdomen to protrude.

So, the best things you can do to look slimmer around your middle are to make sure you’re a healthy weight and do some core training.

Plank holds have been an enormously popular abs exercise for years now. This is probably due to the buzz surrounding the exercise in the form of challenges and extreme hold times, rather than being due to its merits as an effective exercise.

Done correctly, the plank will engage the deepest abdominal muscle, the transverse abdominis (TA). This is the one that plays the biggest part in pulling the abdominal area in flat, as well as playing an important role in pelvic and spinal stability. It’s a challenging exercise and most people will struggle to hold the correct position for more than a minute. These are the good points. However, the plank has its drawbacks:

  • Doing it with correct technique is difficult for those who are not used to core training. To be effective, the back and legs must form a straight line (like a plank). Inexperienced exercisers fail to do this.
  • It’s a static exercise (ie the muscles are held contracted). There are two problems with static exercises. One is that the muscles are only worked in one position and the other is that it causes blood pressure to increase.
  • It’s not functional – we do nothing vaguely resembling the plank in every day life. If we want to train our TA to engage when we’re active, then holding it in a static contraction isn’t the best way.

So should you do plank holds? Yes, it’s good to add them to your abs routine sometimes or to do a plank challenge for variety. But you should make sure your technique is correct and you shouldn’t waste your workout time trying to build up excessively long holds.

As with most “best exercise” questions, the answer depends on what you’re trying to achieve. The two main goals people have are flat abs and 6 pack abs. To have a flat abdominal area you need to train the deeper abdominal muscles. This is done by doing core stabilising exercises. The 6 pack muscles are the top layer of ab muscles and are trained by crunches and similar exercises – any exercise in which the upper body and lower body come closer together against a resistance.  If you want to train all your ab muscles, bicycle crunches are a good all-round exercise.