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Estimating IRM

Mark Jones is a keen rugby player but last season, though fast on his feet, he lacked strength and only made the second team at his local club. He’s determined to be selected for the first team this coming season - he’s trained successfully to increase muscle size - now he just wants to increase strength. How should he do it?

There are two methods for working out how to adapt his training programme:

  • Quick method

  • More accurate method.

Quick method 

At the moment, Mark lifts 35kg for 10 repetitions on the bench press. To gain strength he needs to aim for fewer reps at higher weights. So, he settles on performing only five repetitions during the next stage of his training and he uses the table below to find the right weight for him. The nearest weight to 35kg in the table is 34.5kg in the 10 Reps column – the area Mark is currently working out in. Following the row across to the 5 Rep column, Mark sees that he needs to do 5 Reps at 40.3kg to improve his strength.

%1RM 100 93.5 91.0 88.5 86.0 83.5 81.0 78.5 76.0 73.5
Repetitions 1 2 3 4 5 6 7 8 9 10
Weight Lifted (kg) 44.6 41.7 40.6 39.3 38.4 37.3 36.2 35.0 34.0 32.8
46.8 43.8 42.6 41.5 40.3 39.1 37.9 36.8 35.6 34.5
49.0 45.9 44.6 43.4 42.2 41.0 39.7 38.6 37.3 36.1

 

NOTE These tables should only be used as a guide for establishing training loads and figures may vary depending on the type of table used.

If Mark wants to be more accurate he can use the same table to determine his 1RM. For someone lifting 10 Reps of 35kg, the nearest weight in the table is 34.5kg at the 10 Reps column. Following the row across to the one Rep column, show that 46.8kg is Mark’s 1RM.

Now that Mark’s established his 1RM, he can calculate the amount he needs to lift during the next stage of his training. To increase strength, he needs to alter his training intensity to do fewer repetitions at heavier weights.

Technically, what he wants to do is train at Stage Three of the three intensities of training.

At stage three training, people train with weights of more than 80% of their 1RM. To calculate Mark’s load at 80% of his 1RM:


(46.8 (Mark’s 1RM) X  80)/100  =  37.4

Mark now knows that during stage three of his training programme he should start using a weight of about 37.4kg. Mark uses the table once more to find out how many Reps he needs to do at this weight. Using the same row in the table, Mark sees he needs to do between seven and eight repetitions at this weight.