Estimating your 1RM with the Brzycki formula

Without ever lifting a max load, students estimate their one-rep max in the goblet squat and shoulder press from the reps they complete with a moderate weight. They then use that number to calculate working percentages for their strength plan.

How to play

1. Explain what a one-rep max is and why at school we estimate it with the Brzycki formula: weight × 36 / (37 − reps) (3 min).
2. In pairs, do warm-up sets of goblet squats with light weight to lock in form (4 min).
3. Each student picks a weight they think they can move 6 to 10 times and does one set stopping with two reps in reserve; the partner counts (5 min).
4. After 3 minutes of rest, repeat the process with the dumbbell shoulder press (8 min including rest).
5. Each student calculates their estimated max for both lifts and the weights for working at 60% and 75% (3 min).
6. Share-out: which goal would you train at each percentage? (2 min).

Rules

• No one lifts a true max: the formula exists to avoid that.
• End the set if form breaks down, even with reps left.
• Pick up and set down weights with a neutral back and bent knees.
• More than 10 reps makes the estimate invalid: go heavier on another set.

Variations

Adaptations

• Limited mobility: estimate strength in a seated shoulder press and seated row.
• Autism: provide a worksheet with the formula set up and boxes to fill in.
• Students new to lifting: use water bottles or bands and apply the same math.

Learning goals

• Estimate maximal strength safely with an indirect formula.
• Calculate training loads as a percentage of max strength.
• Match load percentages to different training goals.

Equipment for a class of 25

• kettlebells (4 kg / 9 lb): 13
• dumbbells: 26
• worksheets: 25
• pens: 13

Teacher tip

With 9-lb kettlebells many students will go past 10 reps: have heavier dumbbells ready or use two kettlebells. Supervise the weight area closely.

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