Board Bulletins

Weight divisions in combat sports

Various modern combat sports apply different numbers of and different ranges of weight divisions. Within individual combat sports, these numbers and ranges have also changed over time.

• International Judo Federation has changed from a single (open) weight division in the 1950s, to 3 male weight divisions in the 1960s, to its present 7 weight divisions for male and 7 for female competitors in the Olympic Games.
• The number and range of weight divisions may vary between the type of tournament within a combat sport, for example there are 8 male and 8 female weight divisions in World Taekwondo World Championships, and 4 male and 4 female weight divisions in all World Taekwondo Grand Prix circuit events, Grand Slam competitions and in the Olympic Games taekwondo competition, composed of merged divisions from the World Championships format
• Similarly, World Karate Federation utilises 5 male and 5 female weight divisions for its World Championships, but employed 3 male and 3 female weight divisions in the 2020 Olympic Games Karate event (male -67 kg, -75 kg and +75 kg, and female -55 kg, -61 kg and +61 kg) by merging the world championship format’s two lowest and two highest weight divisions into the highest and lowest Olympic divisions;
• Similarly, International Boxing Association’s (IBA’s) 13 male and 12 female weight divisions for World Championships bouts are merged together to form the 8 male and 5 female divisions contested in the Olympic Games.
• Some combat sports have a maximum bounded upper weight division (the Olympic wrestling men’s freestyle division heavyweight division has a maximum weight in the heaviest division of 125 kg) while some other Olympic combat sports have a unlimited upper weight division (the Olympic boxing men’s super heavyweight division holds all athletes of 91 kg and above; similarly the Olympic taekwondo men’s heavyweight division holds all athletes of 80 kg and above).
• Different combat sports have different absolute ranges of each weight division of their fully bounded divisions, for example, the lowest and highest Olympic boxing male weight divisions are -52 kg and +91 kg respectively, while the lowest and highest Olympic taekwondo male weight divisions are -58 kg and +80 kg respectively.
• Different combat sports have different ranges within their bounded weight divisions, with ranges that tend to increase as the maximum division weight increases, for example: Olympic taekwondo’s male -68 kg division spans 10 kg (58 – 68 kg) while its -80 kg division spans 12 kg (68 – 80 kg); Olympic boxing’s female welterweight division spans 6 kg (60 – 66 kg) while its middleweight division spans 9 kg (66 – 75 kg); Olympic freestyle wrestling’s male -86 kg division spans 12 kg (74 – 86 kg) while its -97 kg division then, in a break from the common pattern, spans 11 kg (86 – 97 kg), and finally its 125 kg division spans 28 kg (97 – 125 kg).
• Two sparring disciplines are contested in BSTF taekwondo: WT rules sparring (Olympic rules, full contact) and ITF rules sparring (semi contact). Each, by default, has 8 male and 8 female weight divisions, for a total of 32 weight divisions across both disciplines. Furthermore, BSTF competitions divide competitors into 3 proficiency classes (A, B and C class) for a total of 96 unique Weight & Class divisions. 
• BSTF has delivered sparring matches in the tens of thousands over its decades of  competitions since 1986, with an adjacent division merger policy being applied where divisions have low athlete populations. This has provided as many athletes as reasonably practical appropriate divisions of competition, competitive divisions of competition, and enhanced development opportunities from the variety and number of competitors and matches in competition.
• Competition rules for BSTF Taekwondo competition, 2018 – present day, stipulate that adjacent weight categories be combined where there are less than four competitors in a division. Where applicable, this generates a new division with the lower of the adjacent division’s minimum weight and higher adjacent division’s maximum weight limits applied to its competitors. In practice, this is identical or directly analogous to the creation of the respective Olympic taekwondo weight division from its two World Championships weight divisions of origin.
• Algorithmically, the fewest mergers in a division are made to satisfy the division population rule. Where no directly adjacent weight division with competitors exists, no merger is made.
• Adjacent division mergers are standard practice throughout the majority of amateur domestic taekwondo and other martial art competitions
• Adjacent weight division mergers are applied in BUCS Karate
• Adjacent weight division mergers are applied in BUCS Judo 
• Adjacent weight division mergers are applied by default in the Olympic Games Taekwondo competition
• Defined weight divisions of competition, in combination with strictly applied weigh-in regulations and professional grade and calibrated scales, determine precisely an athlete’s own weight, and therefore the maximum variance between themselves and other competitors within any bounded division. 
• Unlike non-weight mediated contact sports like rugby, data including the maximum weight variance between taekwondo competitors in bounded divisions is known in advance to event organisers, athletes and their coaches. 
• In combat sports like boxing and taekwondo there also exist unbounded divisions (i.e., those divisions with all competitors below n_mindivmax kg and above n_maxdivmin kg and for the Olympic taekwondo male weight divisions these are the -58 kg and +80 kg divisions respectively. Therefore, 1 of the 4 male weight divisions is unbounded in its minimum permitted weight another 1 of the 4 unbounded in its maximum permitted weight.
• It is a vital responsibility of a taekwondo athlete’s coach, in concert with their athlete, and for all weight divisions, to continually assess their athlete’s ability to perform in their division of competition. This is true for every weight division, but even greater attention should be paid to unbounded weight divisions, since an athlete in heavyweight division might, for example, feasibly face an opponent more than 30 kg heavier than themselves.
• In any taekwondo competition, coaches are able to withdraw their athlete before, or at any point during a match. Such withdrawals are applied by coaches when they are aware/ become aware of a significant difference in skill level between their athlete and the opponent. If a skill difference is too high for their athlete to productively learn from the match and or protect themselves appropriately, it is the responsibility of the coach to withdraw the athlete. 
• In any taekwondo competition, athletes may withdraw themselves at any time

The influence of weight on performance

To determine if adjacent weight division mergers provide any advantage to either sub-set of sparring disciplines’ athletes, 2024-25 season’s Autumn and Winter Championships sparring draw and results data were analysed. The win to loss ratio were compared for matches between athletes matched in a merged division, where: one athlete made weight for the lower and directly adjacent weight division before it was merged and the other made weight for the higher and directly adjacent weight division before it was merged. These data were segmented from the full dataset of all sparring matches across these draws and compared.

• 115 matches met these criteria
• 57 of those matches (49.6%) were won by the athlete who made weight for the lower weight division before it was merged, and
• 58 of those matches (51.4%) were won by the athlete who made weight for the higher weight division before it was merged

These data suggest, at the domestic BSTF taekwondo level of competition, there is no average statistical match win rate advantage or disadvantage between sparring athletes in adjoining weight division competing against one another. Indeed, these results suggest the win rate is robustly 50-50, and that other factors like athlete conditioning and or skill are likely to be dominating factors in the outcome of any given match.

Raw data for this analysis can be fully derived from the published results online.

It is worth reiterating that in any taekwondo competition, coaches are able to withdraw their athlete before, or at any point during a match. Such withdrawals are applied by coaches when they are aware/ become aware of a significant difference in skill level between their athlete and the opponent. If a skill difference is too high for their athlete to productively learn from the match and or protect themselves appropriately, it is the responsibility of the coach to withdraw the athlete. Additionally, in any taekwondo competition, athletes may withdraw themselves at any time.

Example of BSTF discipline weight division merging

In this real world example of a BSTF tournament, a total of 93 athletes have entered Women’s WT Rules Sparring Weight & Class Divisions.

Table 1: Example Athlete Entries (93) into the BSTF Women’s WT rules sparring Competition, Pre (left) and Post (right) division mergers.

Prior to applying the BSTF Taekwondo weight division merger rules (Table 1: left side) the event comprises: 

• 1 athlete has a maximum of 0 matches available,
• 15 other athletes have a maximum of 1 match available, 
• 34 other athletes have a maximum of 2 matches available, 
• 43 remaining athletes have a maximum of 3 or more matches available,
• 11 of the 22 populated divisions (50%) would have 1 or more direct finalists (immediately guaranteed a gold/ silver medal) with zero match wins by luck of the draw
• Without the weight division merger policy applied: the competitiveness, and development value and opportunity of the competition are all significantly impaired
• Random chance would play a far greater role in the outcome of medal winners across each season

Processing the 24 Weight & Class divisions in this example (Table 1: left side), 8 new merged divisions will be formed according to the weight division merger criteria (Table 1: right side), creating an Olympic weight division in every case in this example (see Table 2). Also note, the WT rules Female C-class -46kg will not be merged as there is no permissible (populated and directly adjoining) division available. Following permissible division mergers the event comprises:  

• 0 athletes have a maximum of 0 matches available,
• 2 other athletes have a maximum of 1 match available, 
• 19 other athletes have a maximum of 2 matches available, 
• 72 remaining athletes have a maximum of 3 or more matches available,
• 1 of the 14 populated divisions (7%) would have 1 or more direct finalists (immediately guaranteed a gold/ silver medal) with zero match wins by luck of the draw
• With the weight division merger policy applied: the competitiveness, and development value and opportunity of the competition are greatly enhanced 
• Random chance influencing the outcome of medal winners across each season is hugely mitigated following division mergers

Review of BSTF Taekwondo athlete divisions of entry shows that the distribution of athletes’ divisions of entry tends to follow approximately a bell curve distribution, with the lowest and highest weight divisions typically the least populated. This means the following mergers occur most commonly: Male -54 kg & -58 kg, Female -46 kg & -49 kg, Male -87 kg & +87 kg, Female -73 kg & +73 kg (these four combined divisions being identical the standard Olympic divisions, see Table 2: World Taekwondo Competition Rules: World Championships weights vs Olympic Games weights).

Table 2: World Taekwondo Competition Rules: World Championships weight divisions vs Olympic Games weight divisions

BSTF competition regulations are developed and reviewed based on evidence. Uncompetitive divisions and limited match opportunities are known to be two major event negatives for a majority of student-athletes when attending events. The weight division policy in place is similar to other domestic and international taekwondo competitions, and that of other combat sports with similar risk profiles as reported in the academic literature. Major benefits are gleaned in competitive depth and development value of the events by the application of appropriate neighbouring weight divisions merging. No competitive advantage/ disadvantage was observed in analysis of results between athletes of adjoining merged divisions.