Determining the Dependence between Weightlifting Results in Different Weight Classes

Mochernyuk, V., Draga,V., 
Submitted for Publication 11/7/2001

Translated by Andrew Charniga, Jr.

Do not reproduce or republish in part or in whole without the expressed consent of the author. © 2001

A positive dependence between the athlete's bodyweight and his strength indicators has long since been established. However, the interconnection between a weightlifter's bodyweight and his results is more complex.
An analysis of the existing systems employed to assess equivalent results in weightlifting, revealed that they stipulate equal proportion between the results in different weight classes for all levels of mastery.
We endeavored to compare the results of athletes of different bodyweight in order to determine their equivalent results. We constructed a theoretical model in order to answer the question as to how the results (x) change if the athlete's bodyweight is (y). We determined the changes in absolute and relative strength which accompanied the changes in bodyweight. We also looked at how this in turn affected sport results, the athlete's power (absolute and relative) and the quantity of work he was able to execute in the competition exercises.
Competition results in weightlifting are not directly proportional to absolute strength. Therefore, it is necessary to determine not only the correlation between absolute strength of athlete's of different bodyweights, but also, the correlation between their results in specific exercises. During the movement of the athlete's body or its links in the execution of the weightlifting exercises different portions of the absolute strength are expressed in the direction of the expended effort. Therefore, it is not possible to use one formula to compare results in the weightlifting exercises.
The effort expended by the beginner in shifting his own body during the execution of the classic exercises (40  60% of the absolute strength) is quite different from the highly qualified athlete (20  30%). In order to complete our task it is necessary to answer the question as to how much strength increases with the increase in weight class; relative to how much additional effort is required for the lifter to move his body during the execution of the weightlifting exercises. Therefore, it necessary to determine the proportions between the results in each concrete case.
We accept the notion that all things being equal, strength will be proportional to the cross  sectional area of the muscles. The parameters of the weightlifter's body change with the rise in weight class. These changes in proportions are important, because strength depends on the area of the cross  sectional diameter and not upon the athlete's height. Therefore, it necessary to reveal how body proportions are different in the various weight classes. We analyzed the average height and bodyweight of the weightlifters of the 1996 Olympiad. Analysis of the data revealed a high rate of growth in the diameter of the body with the rise in weight class.
Table 1 
Changes in Body Proportions Relative to Increasing Weight Class

Weight Class 
54 
59 
64 
70 
76 
83 
91 
99 
108 
>108 
Average Height, cm 
156 
161 
163 
164 
170 
171 
174 
178 
179 
183 
Increase in height, % 
1 
1.03 
1.05 
1.05 
1.09 
1.1 
1.12 
1.14 
1.15 
1.17 
Increase in area, % 
1 
1.06 
1.13 
1.23 
1.29 
1.4 
1.51 
1.61 
1.74 
1.92 

For example, a 108 kg class athlete is an average of only 15% taller than a 54 kg lifter; but, should be 26% taller if the body proportions were equivalent. Therefore, one can assume in subsequent calculations of highly  qualified athletes (except the superheavyweights who have a significant amount of body fat) that absolute strength corresponds to the cross  sectional area for the various weight classes. Utilizing Microsoft Excel we were able to construct a graphic dependence depicting the interconnection between strength and the highly  qualified lifter's bodyweight. Utilizing Lagand's polynom we were able to determine the relationship between bodyweight and strength for bodyweights in excess of 30 kg.
Figure 1. The Dependence Between Bodyweight and the Strength of Highly  Qualified Weightlifters.
This relationship can be expressed by the formula: F = 0.00007 m2 + 0.0224m; with a reliability of approximation R2= 0.98
So, in order to determine the equivalent results in the competition exercises for athletes in different weight classes we made the following calculations. We can determine the equivalent results between a 105 kg lifter and a 56 kg lifter. A 56 kg lifter has a biathlon result of 275 kg (112.5 + 152.5) a sixth place at the 2000 Olympics. Now what is the equivalent result of a 105 kg lifter? First we have to establish the absolute strength of the first athlete. The limiting strength factor in the clean and jerk is the absolute strength of the legs. Therefore, we calculte the front squat results (r = 0.7 from the result in the clean and jerk) to determine the strength o the thigh extensors. We can use 1.14 as the clean and jerk ratio (this is the ratio of front squat to clean and jerk of qualified athletes) and add 0.9 times the athlete's bodyweight (this is the portion of the athlete's bodyweight which changes position in this exercise). As a result we obtain 224.3 kg. Then 224.3 kg is multiplied by (0.00007 *105 squared + 0.0224 *105) (this is the formula which depicts the ratio of the absolute strength between athletes of different bodyweight  105 and 56 kg in this instance) subtract 0.9 of his bodyweight (94.5 kg) and divide by 1.14 (the front squat to clean and jerk ratio) to obtain a result of 227.5 kg rounded off to the nearest 2.5 kg. This will be the equivalent result in the clean and jerk for a 105 kg lifter in comparison with a result of 152.5 kg for a 56 kg lifter. The corresponding results for the snatch and total will be 187.5 kg and 415 kg respectively.
Presented in the following table are the calculated equivalent achievements for the all of the weight classes.
Table 2 
A Draft of Classification Norms for Weightlifting

Weight Class 
MSIC 
MS 
CMS 
Cl. I 
Cl/ II 
Cl. III 
Yu. I 
YU.II 
YU.III 
56 
275 
220 
197.5 
177.5 
160 
145 
130 
117.5 
105 
62 
310 
247.5 
222.5 
200 
180 
162.5 
147.5 
132.5 
120 
69 
332.5 
265 
237.5 
215 
192.5 
172.5 
155 
140 
125 
77 
355 
282.5 
255 
227.5 
205 
182.5 
165 
147.5 
132.5 
85 
375 
297.5 
267.5 
240 
215 
192.5 
172.5 
152.5 
137.5 
94 
395 
312.5 
277.5 
250 
222.5 
200 
177.5 
157.5 
140 
105 
415 
322.5 
287.5 
257.5 
230 
205 
180 
160 
142.5 
105+ 
430 
332.5 
295 
260 
230 
202.5 




MSIC  Master of Sport International Class; MS  Master of Sport; CMS  Candidate for Master of Sport; Cl. I  III  Class one, two etc.; Yu.  Youth class
We used a total of 275 kg for the 56 kg class (sixth place at the 2000 Olympics) as the initial point for our calculations. The norms for MSIC (master of sport international class) obtained by our calculations would be a place fifth in the 62 kg class; sixth in the 69, 77 and 105 kg classes; and seventh in the 85, 94 and 105+ classes. This conformity between the calculated equivalent achievements and the actual events confirms the correctness of the methods.
Our system stands in contrast to the existing, in that the proportions between the results of the athletes in different weight classes are not constant. The proportions are 1.36 (for the 105 and 56 kg classes) for the lower qualified athletes and 1.50 for the higher qualifications. Accompanying the rise in sport qualification there is a deviation between results of a constant magnitude, because the qualified athlete expends less effort in shifting his own bodyweight.
