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In case you have never heard of ‘CrossFit’, it is probably worth a quick google, but I have saved you the trouble; “A form of high intensity interval training, CrossFit is a strength and conditioning workout that is made up of functional movement performed at a high intensity level.”

I started CrossFit near the end of summer 2020 and given COVID, other than some long walks, I had found myself largely inactive on the sport and exercise front until then. A year prior, I had moved to Stevenage with my partner, and we knew no one in the area. Within six months we were stuck at home in lockdown. CrossFit has given us a place to train, to take care of our physical health, but more than anything it has given us a sense of belonging in a community. Many of whom we now call friends. So much so, there is even talk of a ski trip! I feel like CrossFit is for everyone! Anyway, that is enough of that, let’s get to some of the maths of CrossFit.

Most of our members know I am a maths teacher. I am often the go-to for help with a quick calculation. This is usually needed when doing weightlifting work where percentages of a 1RM (1 Repetition Maximum) are needed. Thus, having a 1RM of 100kg (about the weight of a professional basketball player) is always a good thing for the calculations and you’ll be pleased to know people do not ask me to do calculations when that is the case.

But for example, take a 1RM of 110kg (about 242.51 lb.) and then imagine you must do working sets at 80% of that. Thus, 88kg. (0.8 x 110 or 110 -(2 x 11) or 11 x 8, however you may go). Working out the required weight is one thing but then summing up the weights on the bar is next. In competitions the standard barbell is 20kg for male competitors and 15kg for females. However, I often train with the smaller bar as it has a slightly smaller diameter which means I can get a better grip.

Below, are the standard plates available (25 kg, 20kg, 15kg, 10kg, 5kg, 2.5kg, 1.25kg, we also have some 0.5kgs knocking about). So here is your question, how would you load your bar to 88kg?

It is not always easy to stay exact with awkward numbers and you often enter the world of decimals (not here though, it is possible). Personally, I try to stay exact, but you will find most will just go to 85kg or 90kg depending on how strong they are feeling! Given you warm up to this heaviest weight (88kg). Knowing what weights you will need for your end goal (I.e., 80%, 88kg) is useful to work out at the start.

A couple of possibilities for a 20kg or 15 kg barbell are given below:

0.5kg, 0.5kg, 0.5kg, 2.5kg, 5kg, 25kg<———-20Kg Barbell———->25kg, 5kg, 2.5kg, 0.5kg, 0.5kg, 0.5kg

          0.5kg, 0.5kg, 0.5kg, 15kg, 20kg<———-15Kg Barbell———->20kg, 15kg, 0.5kg, 0.5kg, 0.5kg

At the time of writing (17/02/2023), the CrossFit Open 2023 (yearly event with 3 workouts to do) has just started. The first workout is below. The right version is scaled to make it more accessible (I will do this version as I cannot do the toes-to-bars or muscle-ups gymnastic movements yet).

You have 14 minutes (840 seconds) to work from the top down through those exercises and do as many reps as possible (AMRAP). If you manage to finish  all the work prescribed, you go back to the top and start again (highly unlikely for most). On the scaled version, my aim will be to get to the chin-over-bar pull-ups, as I cannot do them. The following is how I’ll look to pace myself, using some maths.

  • Average 20 calories a minute so 3 minutes
  • 5 sets of 10 reps (30 seconds a set with a few seconds between sets) so say 3 minutes
  • 4 sets of 10 reps (25 seconds a set with a few seconds between sets) so say 3 minutes
  • 3 sets of 10 reps (45 seconds a set with a few seconds between sets) so say 3 minutes
  • Thus after 12 minutes I’ll hope to be done early so will either have some time to try and get my first ever pull up or just slack time if the above timings do not go to plan!

Being International Women’s Day today (Wednesday, 8 March 2023), why not find out more about CrossFit and look back on some of the outstanding performances of the athletes in this year’s CrossFit Open.

Please check out our website for information about girls’ involvement in advanced maths, which includes research, strategies and recourses to aid schools/colleges in encouraging female students to pursue post 16-maths.   

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