21 day core challenge

About this 21 day core challenge

21 day core challenge

Intensity level: intermediate/advanced

Benefits: trains all the core abdominal muscles

Safety: please read the general safety information here. Please also be aware that static contractions like plank holds can cause an increase in blood pressure. This is not a problem for healthy individuals, but if you have high blood pressure it’s not advisable to do static holds.

What you need: you need an exercise mat, or some other form of cushioning for your spine. See an exercise mat buying guide here.

 21 day core challenge chart

There are 5 exercises in the challenge: bicycle crunch, scissors, double leg stretch, V-sit and plank. The chart shows the reps for each exercise every day (and hold times for the plank). Instructions for the exercises are below the chart.

21 day core challenge chart

Exercise instructions

Bicycle crunch


21 day core challenge - Double leg stretch

21 day core challenge - V sit


The plank – benefits and limitations

The plank exercise perhaps the best known exercise for strengthening the core muscles, but while it does have core training benefits, there are also limitations to “planking” for core strength.

Benefits of the Plank Exercise:

  1. Engages the deep core muscles: The plank  is an effective way to strengthen the core muscles, which provide stability and support for the spine and help prevent back pain.

  2. Improved Balance and Stability: Engaging the core muscles during the plank exercise can improve balance and stability, reducing the risk of falls and injuries.
  3. Engages Multiple Muscle Groups: The plank exercise is a full-body exercise that engages multiple muscle groups.

Limitations of the Plank Exercise:

  1. Improper Form: Improper form during the plank exercise can strain the neck, back, and shoulders. Unfortunately, poor form is a common problem. It is important to maintain a neutral spine and engage the core muscles throughout the exercise, keeping the legs and back in a straight line.

  2. Static contraction: The plank exercise is an isometric exercise, meaning the muscles are engaged in a static position. The muscles are therefore only trained in one position.

  3. Not a Complete Core Workout: The plank exercise focuses primarily on the anterior core muscles. While it is an effective exercise for strengthening these muscles, it is important to incorporate exercises that target other core muscles, such as the obliques and lower back muscles.
  4. Not Suitable for Everyone: The plank exercise may not be suitable for individuals with certain medical conditions, such as back pain or injuries, or pregnant women.

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