Secular trends in adiposity and musculoskeletal dimensions of elite heavyweight boxers between 1889 and 2019

Data were collected from published media, primarily newspapers [6, 7], and supplemented by information from sports magazines, official match programmes, books, encyclopedias [8, 9] and official websites [10] of all internationally recognised Heavyweight World boxing championships, from the first ever official contest (August 8th, 1889) to the latest (February 8th, 2019).

Demographic information of male boxers measured at the time of the championship contests was collected including age, champion/challenger status (champions of any of the recognised World boxing titles, principally World Boxing Council, World Boxing Association, World Boxing Organization and International Boxing Federation [11], and unsuccessful challengers who contested but never prevailed in any of the World title bouts), nationality (categorised to North America, Europe and others), and ethnicity (American white, African American, European white, and others including mixed race, Hispanic, Samoan and African) [12].

Anthropometric measurements of boxers have been meticulously documented and closely regulated by boxing governing bodies since the first official contest to ensure fair play. We grouped these measurements into four anatomical categories: (1) body lengths (height and reach), (2) body mass and indices of adiposity (weight, BMI and waist circumference, WC), (3) muscle dimensions (neck, normal and expanded chest, biceps, forearm, thigh and calf circumferences), and (4) skeletal dimensions (fist, wrist and ankle circumferences). Data on individuals were obtained from as many sources as possible to verify consistency. When there were discrepancies in reported values between sources, the average was used.

“Contest years” were defined as the period between the first ever official Heavyweight World Championship contest on 08-08-1889 (baseline) and the current contest on 08-02-2019 (year 130). Each contest year indicates specifically the date (precisely to the day-month-year) in which a championship bout took place which coincides with the time when the boxers had their anthropometry measured, e.g., if the contest took place in 1899, the contest year would be 10.

Partial correlations (adjusted for age, champion/challenger status, nationality and ethnicity) were performed separately for champions and for challengers to assess the associations between anthropometric measurements and contest years. Linear and polynomial regression models were used to evaluate the associations of contest years with BMI and with WC. Independent t tests were performed to assess for differences in anthropometric measurements between champion boxers and unsuccessful challengers. Analyses were conducted using SPSS v23.0 (IBM Corp., NY, USA). The null hypothesis was rejected when p < 0.05.

The observations of increasing weight and height over the past 130 years are in line with secular changes observed in sport [1] and general populations across developed countries [2, 3]. Our data also provide additional information on secular changes in other anthropometric measurements including neck, chest, biceps, forearm, thigh, calf and ankle circumferences which indicate that in this group of athletes, and likely in other sports performers, the musculoskeletal structures have increased progressively over the years.

An important finding emerged from our analysis which revealed a disparity in secular changes in BMI and WC (often used as indices of adiposity). It is likely that the increasing BMI overtime reflects a continuing gain in musculoskeletal mass rather than adiposity. The drawback of the use of BMI as index of adiposity lies in its inability to distinguish between musculoskeletal and adipose components [19], i.e., a BMI of 28 or 30 kg/m² can be perfectly normal for a person participating in power sport such as a rugby player [21, 22] or heavyweight boxer. For any given BMI, the body composition (proportion of musculoskeletal tissue relatively to adipose tissue) of boxers in the twenty-first century is likely to differ from that of boxers in the early nineteenth century. It is therefore important to interpret published reports from national health surveys with caution with respect to the use of BMI to indicate prevalence and incidence of overweight and obesity without considering secular changes in body composition. Based on the trends observed in the present study, BMI and WC of the challengers are set to continue to rise while BMI of the champions has plateaued and the rise in WC is less sharp than that seen in the challengers. These increasing trends BMI in heavyweight boxers are similarly observed in national or state rugby union players from the UK, USA and Australia from 1905 to 1999 [21] and in English Premiere rugby players between 2002 and 2011 [22].

Heavyweight champions are considered to be one of the most elite group of athletes and the very best of boxers. We found a number of key measurements that distinguished champion boxers from unsuccessful challengers including their heavier weight, taller stature and longer reach as well as larger arm dimensions while their BMI and WC were similar to those of the challengers’. Although a bigger heavyweight contestant is generally more successful than a smaller heavyweight, we do recognise that the right balance of power and endurance, skills, and psychological factors all play vital roles for a boxer in prevailing over an opponent [24].

The strengths of the present study lie in its unique data on both BMI and WC and detailed anthropometric measurements to enable analysis of secular trends in adiposity that dated back to the early twentieth century. The data appear very stable on repeated measurements during the time the boxers were at their prime indicating reliability of data collection and reporting. The age of boxers was similar throughout contest years and well matched between comparative subgroups. This type of data is the only record that is available publically for male boxers therefore our findings should only be inferred to this group of athletes. Anthropometric measurements are well regulated and standardised by international boxing boards but there might be inter-observer errors. Our measurements relied on historical records in the public domain but appear consistent between different media. Information on demographic data, weight and height were almost complete for every boxer while other measurements of musculoskeletal dimensions were not in a proportion of boxers but these subjects’ characteristics including age, weight and height did not differ from the study sample. We could only verify information on nationality but not ethnicity. Although most champions were from the USA, we found no significant differences in anthropometry or body composition between athletes from other continents suggesting that nationality (and possible presumed ethnicity) may not play a major role in secular changes among these athletes.

In conclusion, all elite professional heavyweight boxers have increased in size over the last 130 years. Being heavier, taller with longer and bigger arms, but with similarity in BMI and waist, appear to be differentiating factors between champions and challengers.