The Core Calculator
By Carl Valle C.S.C.S USATF II
For Elitefts.com

The purpose of this article is not to argue the needs or philosophy of core training, but to quantify loading methods by giving core exercises stress values. Some experts will justify huge volumes of reps while others will argue that the abdominal and low back will be prepared by indirect work from deadlifts, Olympic lifts, and squats. Many performance coaches will most likely fall in the middle, and agree that much of the high intensity loading will help indirectly but some isolation work can help assist core strength. My beliefs are that core training should include both moderate loading protocols and include the stresses from absolute strength. Core training is nothing new, but here are some common methods used to improve spinal strength and they are ranked form low to high-intensity. Whatever the philosophy, this simple way to quantify core training will help you track volumes of what you are doing to prevent injury. Many times athletes will over train or under prepare the core, a path that could lead into injury of the skeletal system.

(1) Classic prone exercises- Movements on your side, back, and front such as sit-ups, crunches, and other means are the lowest of intensity but isolate the most directly. This type of work requires huge volumes to be effective.

(2) Medicine ball Training- This method uses a weighted ball and loads flexion, rotation, and extension of the spine. Since most of the balls range from 2-16 pounds, the stress of the movement patterns is in fact higher then most prone exercises. 

(3) Physio ball and dynamic movements- The advanced exercises that use physio balls stress the body by making the spine act as a bridge between the hand and leg contact points. Other movements that require the core to transfer stability or energy in bridge-like exercises are more demanding the medicine ball training.

(4) Special Strength exercises-Reverse Hyperextensions and trunk chops with 45 pound plates are those of the highest intensity save absolute exercises like squats and deadlifts. Although they may isolate, the loads are very high and must be considered the most intense direct core work.

(5) Absolute Training- Heavy weightlifting, sprint training, Olympic lifting, and plyometrics are the most demanding but rarely identified and included into the calculations of training volume.
The first step in calculating core volume is to think in units instead of reps. An example is that one crunch might be one unit and one medicine ball twist equals two-five units. Squats might equal 20-50 units depending on the time under tension and load. While not perfect or exact, looking at the five categories above and adding up the totals one can gage if their training is on the mark. Here are the multipliers:

Classic prone exercises- This method should include a multiplier of 1-3 
Medicine ball Training- This method should include a multiplier of 5-10
Physio ball, and dynamic movements- This method should include a multiplier of 10-15
Special Strength exercises- This method should include a multiplier of 15-20
Absolute Training- This method should include a multiplier of 20-50


Example calculation would be 3 x 25 side crunches and 4 sets of 8 physio ball roll-outs. Doing the math the volume would be 3 x (1 x 25) + 4 x (10 x 8) or 395 units. As you can see the numbers add up quickly so athletes can be doing thousands of units per day. In summary, this way of calculating volume better evaluates the true amount of work done in training. Like any part of training, the balance must be precise to achieve optimal results and the core calculator can help you do just that. If one quantifies the work of the core as accurately as bench numbers and squat percentages then the training will be far more effective.