Comparing Athletic Ability of Women in Olympic Weightlifting

Strength in Numbers: Comparing Athletic Ability of Women in Olympic Weightlifting

Marianne Huebner, David E. Meltzer, Aris Perperoglou

"This is the pre-peer reviewed version of the following article: Huebner M, Meltzer DE, Perperoglou A. Strength in numbers: women in Olympic style weightlifting. Significance Magazine 2021; 18(2): 20-25. which has been published in final form at https://doi.org/10.1111/1740-9713.01506. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions."

Lidia Valentín, Spanish weightlifter, snatches 118 kg on her way to becoming the 2017 world weightlifting champion in the 75-kg body weight category. She won medals at three Olympic Games (2008-Silver, 2012-Gold, 2016-Bronze) and four world championships (2013-Bronze, 2017-Gold, 2018-Gold, 2019-Silver). Photo credit: David Meltzer

Sarah Robles, USA weightlifter, snatches 126 kg on her way to becoming the 2017 world weightlifting champion in the over-90-kg body-weight category. Photo credit: David Meltzer

Hsing-Chun Kuo, Taiwanese weightlifter, at age 22 clean and jerks 133 kg for a bronze medal in the 58 kg body weight category at the World Championships in 2015. Photo credit: Bruce Klemens.

2 Olympic weightlifting requires speed, strength and technical expertise to lift weights from the floor to above the weightlifter’s head. But determining who is the overall best lifter in a competition is not as simple as seeing who can lift the most. Elite weightlifters with a higher body weight can lift more weight than those weighing less. For example, women’s world records for the total weight lifted range from 217kg set by Chinese weightlifter Yang Lian at 48kg body weight to 330kg set by Russian weightlifter Tatiana Kashirina at 107kg body weight.

Weightlifting athletes typically compete in body weight categories and thus can be successful in winning medals at a range of body weights. For example, the 71kg body weight category would include competitors weighing from 64.01 kg to 71.00 kg; the performances of these athletes would be compared directly to each other and whoever emerges with the highest total weight lifted would be the winner of that category. However, trophies for overall best lifter in different age categories are awarded in some championships, and the winners are determined by a statistical algorithm that standardizes performances.

Essentially, the algorithm seeks to answer questions such as, “What would be the total weight lifted of an athlete weighing 48kg if she were an athlete weighing 107kg of the same level of ability?” This question could be carried further: “What would be the total weight lifted of an athlete weighing 48kg at age 51 if she were an athlete at age 24 of the same level of ability?”

Attempts at standardizing performances by body weight have been made with regression models in which the total weight lifted is adjusted for body weight using Olympic Games and world record performances; the adjustment is achieved through multiplicative coefficients derived from the regression models. This mathematical formula was then applied to all ages, and, in addition to the body weight adjustments, age coefficients were derived for Masters weightlifters (those aged over 35) to account for age-associated performance decline. These approaches have limitations, however, since the standardization for body weight was derived for elite athletes in their mid-twenties, and the age coefficients were originally based only on male performance data.

The difficulty of developing age coefficients for women was due to their low participation in Masters weightlifting for many years. Women’s weightlifting became part of the Olympics only in 2000, when participation among older age groups was minimal. Women’s participation rates in all age categories have increased dramatically since then and performances have greatly improved. In fact, the substantial year-to-year changes in women’s performances greatly exacerbated the challenge of modeling their age-related performance declines. Thus, before establishing a standardized set of women’s age coefficients to be used in international competitions, it must first be clear that performances have stabilized. A more complex statistical problem is how to standardize performance simultaneously for both body weight and age, as the effect of body weight may vary for different ages.

Growth of women’s participation in weightlifting

Olympic-style weightlifting competitions include two lifts, the “snatch” and the “clean and jerk.” In the snatch, the weight is lifted from the floor to overhead in one continuous movement, while

3 in the clean and jerk the weight is first lifted to the shoulders, and then overhead in a second movement. The total weight lifted is the sum of the best snatch weight and the best clean and jerk weight, if there was at least one valid attempt among three attempts in each of these lifts. The lifts are judged by three referees according to the same rules for athletes of both sexes and all ages.

Organized competitions in Olympic-style weightlifting began at the end of the 1800s, but were exclusively restricted to male competitors for decades. In the United States, a handful of informal competitions for women were held during the 1940s, culminating in the very first official women’s weightlifting competition in the U.S., with nine competitors, in February 1947. However, it would be another 30 years before women began appearing on the competition platform with any regularity. At that time, women were only allowed to compete directly against men, although they were not always welcome in the male-dominated domain of weightlifting rooms. To win a medal, the women would have to outlift male competitors of the same body weight. It was not until the 1980s that female-only competitions would be organized on a regular basis. The first women’s world championship was held in 1987 in Florida, USA with 100 athletes from 22 countries.

Over the years, more and more women (and men) have entered the sport of weightlifting and this includes the older, Masters-age, athletes. In 2000 there were 382 participants in the Masters world championships, 13% of whom were women. In 2016, competitor numbers grew to 805, with 25% women, and by 2018 the proportion of women competitors had grown to 46% overall, with most concentrated in the younger age groups. As of 2020, the number of women participating in the USA National Masters championships has surpassed that of men — an unimaginable development as recently as 15 years ago (Figure 1). Nonetheless, the participation rate for women above 60 years of age is still low compared to men.

Figure 1: Number of men and women in World Masters Championships by age group.

Standardization of weightlifting performances

Weightlifting athletes compete in different body weight categories and age groups, and thus can be competitive within a range of morphological characteristics. When women began to compete directly against each other in women-only competitions, the weight categories were similar to those of the men except at the lower and upper weight limits, where categories were added and removed, respectively. Later, categories specifically for women would be created. Since athletes with higher body weight are generally able to lift more weight across all ages, athletes strive to attain the maximum body weight possible within each competition body weight category, and thus the distribution of competition body weight is multi-modal with distinct spikes (Figure 2).

Figure 2: Distribution of body weight for women at World Masters Championships 2016-2019.

To compare athletic ability and determine an overall best lifter, a body weight adjustment formula is often applied to the total weight lifted. This formula—known as the “Sinclair coefficients”—yields a point score that allows comparison of performances for lifters of different body weights. These Sinclair coefficients were derived by fitting a regression model to world records and Olympic Games performances separately for men and women1. These point scores are “predictions” of how much an athlete would have lifted, had he or she be in the heaviest body weight class. To be clear, they are not predictions in the normal sense, since a lifter who normally competes in the 49-kg category would never actually be able to gain enough body weight and muscular power to compete in the over-87-kg category with a performance commensurate with that made at the lower body weight. Instead, these coefficients should be interpreted as a “standardization” of a weightlifting performance independent of the lifter’s body weight. An example of how this works is provided by the 2017 World Weightlifting Championships in Anaheim, California, USA, a competition that included 139 women distributed over eight different body-weight categories. The highest two-lift total of all women

6 entered was 284 kg, made by Sarah Robles, USA, the 2016 Olympic bronze medalist and the 2017 world champion in the former over-90-kg category—the “superheavyweights.” Her body weight of 145.7 kg corresponded to a Sinclair coefficient of 1.001 and a point score of 284.3 (that is, 1.0009 × 284). By contrast, Lydia Valentín, Spain, the winner of the 75-kg category, only had a two-lift total of 258 kg; however, her body weight of 74.6 kg corresponded to a Sinclair coefficient of 1.1946 and thus a point score of 308.2. Valentín at age 32 had already competed in world championships since 2002 and won medals at three Olympic Games (2008- Silver, 2012-Gold, 2016-Bronze) and four world championships (2013-Bronze, 2017-Gold, 2018-Gold, 2019-Silver). However, Hsing-Chun Kuo, Taipei at age 24 lifted 240 kg at a body weight of 57.6 kg. This resulted in a standardized total of 333.1 (=1.3876 x 240) thus making her the “Best lifter” at the 2017 world championships. These calculations do not take into account that the age at peak performance is estimated to be in the mid-20s.3

Performance differences between men and women can be calculated directly for the 69-kg body weight category, since that category was common to both men and women from 1998 until 2018. The sex-related difference is smaller at younger ages, namely 18.6% for youth world records (record holders up to age 17) and 20.5% for junior world records (record holders up to 20 years old). This difference increases to 23.2% for the overall world records set in the senior age category (ages 21 to 34), and to 32.1% for Masters world records (at ages 35-39). A possible contributing factor is that elite-level athletes generally discontinue training or train at lower- intensity levels after age 35, since at that age they are typically no longer able to perform at a level that would merit financial support from their government or national sports authority. Participation in competition requires substantial financial resources for entry fees and travel costs.

Age-associated changes in performance

Performances increase from youth until mid-20s when the gender gap in performance widens. An examination of recent performances of weightlifters competing in high-level national and international events showed that the age at peak performance for this group was 25.6 years for women and 25.7 years for men. There is variation in this estimate that can be summed up with 95% confidence intervals. These intervals are overlapping for men (25.7, 27.1) and for women (24.7, 27.5), thus it is possible to conclude that men and women reach their peak performance at about the same age (Figure 3).

Figure 3. Changes in performance for the total weight lifted by men (red) and women (purple) for ages 25 to 34.

Due to biological processes of aging, performance starts to decline after the mid-twenties. The body weight adjustment described previously was derived for elite athletes in their mid 20’s and was then applied to athletes of all ages and abilities. Decreasing muscle strength and power with older age necessitates the development of age coefficients to compare performances of athletes of different ages.

Due to the small number of women competing in Masters weightlifting before and during the 1990s, such age coefficients were originally derived solely for male athletes based on performances through 19923 and then updated in 2015 to incorporate 22 years of performance data for male lifters. These “Meltzer-Faber” (MF) age coefficients were used to compare performances of both male and female weightlifters, despite never having been tested on the female population. However, additional research on performance deterioration by age and sex in weightlifting concluded that there is a steeper decrease in performance levels for women than for men. This was indeed the case in earlier periods, 1993-2000 (Figure 4).

As more women entered the sport of weightlifting creating a larger pool of athletic abilities, the female performances improved. There was no further improvement in the two most recent time periods 2013-2015 and 2016-2018, despite increasing numbers of women weightlifters, thus suggesting that performance has stabilized. The age-associated performance decline for female weightlifters mirrors the decline for men except for an accelerated decline during a 10-year period across the age range from late 40s to late 50s, thus coinciding with a transition into menopause.4 These results led to the development of age coefficients for women in 2019 that are now used alongside those for men in competitions to determine overall best lifters

8 (https://www.iwfmasters.org/calculator.html). A more rapid decline for women compared to men in this age range has also been seen in sports requiring explosive power such as the throwing and high jump disciplines in track and field.5

Figure 4: Age associated performance decline for female weightlifters for periods 1993-2000, 2001-2012, 2013-2015, and 2016-2018. As a reference the Meltzer-Faber (MF) performance decline for male weightlifters is also shown (adjusted to equal 1.0 at age 35 years).

These performance decline curves were derived by first standardizing the performance for body weight using Sinclair coefficients and then comparing performances made at different ages. However, there are several problems with this approach. Firstly, the Sinclair body weight adjustment was developed for elite athletes and senior world records. In addition, the sequential adjustment does not take into account that body weight may have a different effect at different ages. The statistical model, “quantile foliation”, takes into account a simultaneous standardization and thus allows us to compare athletic ability based on the total weight lifted across ages and body weights and also for different performance levels as measured by quantiles (Figure 5).6 Foliation is a mathematical term for a set decomposed into subsets called “leaves”. In geology this term refers to layers in rocks. For the weightlifting data the leaves refer to performance “surfaces” in which total weight lifted is shown as a function of both age and body weight, each surface corresponding to specific levels of performances such as the 0.5 quantile,

9 where half of the athletes perform better, and the 0.95 quantile, where only 5% of all athletes perform better.

Figure 5: “Leaves” for the 0.05 (lower ) and 0.95 (upper) quantiles for female weightlifters showing the total weight lifted in kilograms for different ages or body weights.

This also allows us to examine influence of the body weight on total weight lifted and study the effect of body weight changes with age. Athletes with higher body weight are generally able to lift more weight for both sexes. However, body weight has a smaller effect on performance at different ages. For Masters the body weight has less influence on the weight lifted at older ages compared to that influence at younger ages. (Figure 6).

Figure 6: Total weight lifted in kilograms across varying body weight for women ages 15 to 60 from world championships results.

In summary, Olympic weightlifting enjoys much popularity among women, and there has been a dramatic increase in participation levels in recent years. It is possible to derive age and body weight coefficients that can be used to standardize performances across different body weight categories and all age groups, and thus could be used in competitions to determine an overall ranking of weightlifting performances.

Venue of the World Masters Weightlifting Championships 2019, warm-up area and competition platforms. Montreal, Canada. Photo credit: Daniela Jantzen.

References:

1. Sinclair RG. Normalizing the performances of athletes in Olympic weightlifting. Can J Appl Sport Sci. 1985;10(2):94–8. 2. Huebner M, Perperoglou A. Performance development from youth to senior and age of peak performance in Olympic weightlifting. Front Physiol 2019. Aug 27;10:1121. 3. Meltzer DE. Age dependence of Olympic weightlifting ability. Med Sci Sports Exerc. 1994; 26(8):1053–67. 4. Huebner M, Meltzer DE, Perperoglou A. Age-associated Performance Decline and Sex Differences in Olympic Weightlifting. Med Sci Sports Exerc. 2019 Nov; 51(11):2302- 2308. doi: 10.1249/MSS.0000000000002037. 5. Gava P, Ravara B. Master World Records show minor gender differences of performance decline with aging. Eur J Transl Myol 2019 Aug 2; 29(3): 8327. doi: 10.4081/ejtm.2019.8327 6. Perperoglou A, Huebner M. Quantile foliation for modeling performance across body mass and life span in Olympic weightlifting. Statistical Modelling. 2020 (Aug).

Authors

Marianne Huebner is a Professor of Statistics and Probability at Michigan State University and Director of the Center of Statistical Training and Consulting. She has competed in weightlifting since 2016 and won two World Masters Championships.

12 David Meltzer is Associate Professor in the College of Integrative Sciences and Arts at Arizona State University, and has competed in weightlifting for the past 42 years.

Aris Perperoglou is a Visiting Professor of Statistics at Newcastle University and a Data Science Director in AstraZeneca, Cambridge. He obtained a degree in statistics at Athens University of Business and Economics in Greece and a PhD at Leiden University in the Netherlands.