Outcome Of Fights Research Articles

Mini-review and Meta-analysis of effort ratios in mixed martial arts rounds: key insights for research and coaches

This study investigated the critical aspect of match intensity in MMA bouts and its impact on performance. MMA is a physically demanding sport, and understanding the dynamics of intensity throughout matches is essential for both athletes and trainers. To achieve this goal, we adhered to the PRISMA guidelines for comprehensive and ethical reporting of our findings. We conducted a thorough search of electronic databases, including PubMed, Bireme, CINAHL, SportDiscus, EMBASE, SCOPUS, and Cochrane, to identify relevant articles. Our search terms included "mixed martial arts athletes," "movement time study," "male athletes," "female athletes," "lactate," "heart rate," and "motor action." Our meta-analysis yielded compelling results. We found a statistically significant difference between the third and second rounds (p=0.0001) for both total high-intensity and low-intensity time. Additionally, significant differences were observed when comparing the second round to the first round for total high-intensity time (p=0.52) and total low-intensity time (p=0.58). These findings indicate a progressive increase in intensity throughout the rounds, with the third round significantly affecting the fight's outcome. Our results suggest that trainers and athletes should consider a specific strategy for the third round to address potential metabolic fatigue. Future research should delve deeper into strategies that can effectively manage intensity throughout MMA bouts, with a focus on factors like nutrition, recovery, and psychological aspects, which could provide valuable insights into optimizing performance in this demanding sport. Keywords: Technical-tactical analysis; Task performance and analysis; Exercise physiology; Martial Arts.

Assessing the Incidence of Head Trauma in Australian Mixed Martial Arts: A Retrospective Analysis of Fight Outcomes.

Mixed martial arts (MMA) is experiencing a surge in popularity in Australia. Previous research has suggested knockout (KO) and technical knockout (TKO) are frequent outcomes during competition, raising concern about the brain health of athletes. This study aims to describe fight outcomes in Australian MMA and to explore differences in fight-ending outcomes between male and female athletes, amateur and professional competition, and different weight classes. There is no difference in the incidence of KO/TKO between level of competition, sex, and weight class. Descriptive epidemiology study. Level 3. Retrospective analysis of 143 Australian MMA events from 2020 to 2023 was conducted using video replay to assess fight outcomes between sex and level of competition. Binary logistic regression analysis was used to determine relationships between weight class and KO/TKO fight outcomes. Male competition (34%) had a significantly greater number of KO/TKO secondary to head strikes fight outcomes compared with female competition (23%) (P = 0.01). The KO/TKO rate secondary to head strikes for amateur and professional male competition was 16.6 and 18.7 per 100 athlete-exposures (AEs), respectively. The amateur and professional female rate was 12.6 and 7.4 per 100 AEs, respectively. Amateur male light heavyweight and heavyweight, and professional male heavyweight were at greater odds of a KO or TKO compared with other weight classes in their equivalent level of competition. There is a sex and professional level disparity in the incidence of fight-ending head trauma in Australian MMA. The study findings highlight the urgent need for targeted safety protocols and medical oversight, particularly for men in heavier weight classes. This study highlights the need for enhanced safety protocols and medical oversight in Australian MMA, particularly for male athletes in heavier weight divisions.

Reduced fitness in losers of leg-biting male combat compared to uncontested males in Zophobas atratus

Sexual dimorphism and male combat are observed in many species. Often, the outcome of male combat affects the outcome of subsequent combats, mating success, number of sperm, and fitness of the male’s offspring. Also, the quantity and quality of sperm may be regulated by winning or losing, depending on species ecology and mating system. However, very few studies have experimentally examined the influence of fight outcomes on male offspring fitness. We studied male combat in the giant mealworm (Zophobas atratus) in which males bite each other’s hind legs. We hypothesized that subsequent fitness could differ between winners and losers in the escalated male combat of this species. We measured several fitness traits including the number of eggs laid by mated females, and the number of hatches sired by uncontested males, winners, and losers in escalated and non-escalated combat, and compared the fitness of each winner and loser to that of an uncontested male. We also measured mating duration. The numbers of eggs and the percentages of hatched eggs of losers in the escalated combat were significantly reduced compared to that of the uncontested males. This reduction may be due to injuries from escalated leg- biting fights and a result of the sperm amount of the uncontested males being greater than that of the loser males.

Life-course influences of poverty on violence and homicide: 30-year Brazilian birth cohort study.

Homicide is the leading cause of death among young people in Latin America, one of the world's most violent regions. Poverty is widely considered a key cause of violence, but theories suggest different effects of poverty, depending on when it is experienced in the life-course. Longitudinal studies of violence are scarce in Latin America, and very few prospective data are available worldwide to test different life-course influences on homicide. In a prospective birth cohort study following 5914 children born in southern Brazil, we examined the role of poverty at birth, in early childhood, and in early adulthood on violence and homicide perpetration, in criminal records up to age 30 years. A novel Structured Life Course Modelling Approach was used to test competing life-course hypotheses about 'sensitive periods', 'accumulation of risk', and 'downward mobility' regarding the influence of poverty on violence and homicide. Cumulative poverty and poverty in early adulthood were the most important influences on violence and homicide perpetration. This supports the hypothesis that early adulthood is a sensitive period for the influence of poverty on lethal and non-lethal violence. Results were replicable using different definitions of poverty and an alternative outcome of self-reported fights. Cumulative poverty from childhood to adulthood was an important driver of violence and homicide in this population. However, poverty experienced in early adulthood was especially influential, suggesting the importance of proximal mechanisms for violence in this context, such as unemployment, organized crime, drug trafficking, and ineffective policing and justice systems.

Does losing reduce the tendency to engage with rivals to reach mates? An experimental test.

Male-male contests for access to females or breeding resources are critical in determining male reproductive success. Larger males and those with more effective weaponry are more likely to win fights. However, even after controlling for such predictors of fighting ability, studies have reported a winner-loser effect: previous winners are more likely to win subsequent contests, while losers often suffer repeated defeats. While the effect of winning-losing is well-documented for the outcome of future fights, its effect on other behaviors (e.g. mating) remains poorly investigated. Here, we test whether a winning versus losing experience influenced subsequent behaviors of male mosquitofish (Gambusia holbrooki) toward rivals and potential mates. We housed focal males with either a smaller or larger opponent for 24 h to manipulate their fighting experience to become winners or losers, respectively. The focal males then underwent tests that required them to enter and swim through a narrow corridor to reach females, bypassing a cylinder that contained either a larger rival male (competitive scenario), a juvenile or was empty (non-competitive scenarios). The tests were repeated after 1 wk. Winners were more likely to leave the start area and to reach the females, but only when a larger rival was presented, indicating higher levels of risk-taking behavior in aggressive interactions. This winner-loser effect persisted for at least 1 wk. We suggest that male mosquitofish adjust their assessment of their own and/or their rival's fighting ability following contests in ways whose detection by researchers depends on the social context.

Learning from fights: Males' social dominance status impact reproductive success in Drosophila melanogaster.

In animals, the access to vital resources often relies on individuals' behavioural personality, strength, motivation, past experiences and dominance status. Dominant individuals would be more territorial, providing them with a better access to food resources and mate. The so-called winner and loser effects induce individuals' behavioural changes after experiencing a victory or a defeat, and lead to an individual persistent state influencing the outcome of subsequent fights. However, whether and how development of winner and loser effects affect individuals' fitness is controversial. The aim of this study is to evaluate how individuals' fitness can be influenced by previous fighting experience in Drosophila melanogaster. In this study, we assess various behavioural performances as indicators for dominant and subordinate fitness. Our results show that subordinates are less territorial than dominants although their locomotor abilities are not affected. We also demonstrate that in a non-competitive context, experiencing a defeat reduces males' motivation to court females but not the reproductive success while in a competitive context, it negatively affects males' reproductive success. However, we found no impact upon either males' ability to distinguish potential mates nor on females' choice of a specific mating partner. Overall, these results indicate that previous defeats reduce reproductive success, a commonly used estimate of individual fitness.

Age-dependent winner-loser effects in a mangrove rivulus fish, Kryptolebias marmoratus.

The outcomes of recent fights can provide individuals information about their relative fighting ability and affect their contest decisions (winner-loser effects). Most studies investigate the presence/absence of the effects in populations/species, but here we examine how they vary between individuals of a species in response to age-dependent growth rate. Many animals' fighting ability is highly dependent on body size, so rapid growth makes information from previous fights unreliable. Furthermore, fast-growing individuals are often at earlier developmental stages and are relatively smaller and weaker than most other individuals but are growing larger and stronger quickly. We therefore predicted winner-loser effects to be less detectable in individuals with high than low growth rates and to decay more quickly. Fast-growing individuals should also display stronger winner than loser effects, because a victory when small indicates a strength which will grow, whereas a loss might soon become irrelevant. We tested these predictions using naïve individuals of a mangrove killifish, Kryptolebias marmoratus, in different growth stages. Measures of contest intensity revealed winner/loser effects only for slow-growth individuals. Both fast- and slow-growth fish with a winning experience won more of the subsequent non-escalated contests than those with a losing experience; in fast-growth individuals this effect disappeared in 3days, but in slow-growth fish it did not. Fast-growth individuals also displayed winner effects but not loser effects. The fish therefore responded to their contest experiences in a way which reflected value of the information from these experiences to them, consistent with our predictions.

Dynamic changes to signal allocation rules in response to variable social environments in house mice

Urine marking is central to mouse social behavior. Males use depletable and costly urine marks in intrasexual competition and mate attraction. We investigate how males alter signaling decisions across variable social landscapes using thermal imaging to capture spatiotemporal marking data. Thermal recording reveals fine-scale adjustments in urinary motor patterns in response to competition and social odors. Males demonstrate striking winner-loser effects in scent mark allocation effort and timing. Competitive experience primes temporal features of marking and modulates responses to scent familiarity. Males adjust signaling effort, mark latency, and marking rhythm, depending on the scent identities in the environment. Notably, recent contest outcome affects how males respond to familiar and unfamiliar urine. Winners increase marking effort toward unfamiliar relative to familiar male scents, whereas losers reduce marking effort to unfamiliar but increase to familiar rival scents. All males adjust their scent mark timing after a contest regardless of fight outcome, and deposit marks in more rapid bursts during marking bouts. In contrast to this dynamism, initial signal investment predicts aspects of scent marking days later, revealing the possibility of alternative marking strategies among competitive males. These data show that mice flexibly update their signaling decisions in response to changing social landscapes.

Fight outcome influences male mating success in Drosophila prolongata

The outcomes of preceding fights can influence the probability of winning a subsequent fight, known as the winner/loser effect. However, we know relatively little about how the experience of a preceding fight influences subsequent mating success. Here, we investigated the influence of preceding fight outcomes on subsequent mating behavior in a fruit fly Drosophila prolongata. Subordinate males mated less in two-choice mating assays, showing that the fight outcome predicts male mating success in this species. This tendency remained in a no-choice mating assay where direct interaction between the dominant and subordinate males was eliminated, suggesting that the mating disadvantage of the subordinate males was dependent on the experience of the previous fight rather than the direct interference by the dominant male. When a no-choice mating assay was performed before the fight, the prospective subordinate males mated at the same rate as the dominant males, confirming that the intrinsic male qualities in fighting and mating performances were independent of each other in our experiments. These results indicated that the experience-dependent changes in the subordinate males led to the reduced mating success.

Evaluating drivers of female dominance in the spotted hyena

IntroductionDominance relationships in which females dominate males are rare among mammals. Mechanistic hypotheses explaining the occurrence of female dominance suggest that females dominate males because (1) they are intrinsically more aggressive or less submissive than males, and/or (2) they have access to more social support than males.MethodsHere, we examine the determinants of female dominance across ontogenetic development in spotted hyenas (Crocuta crocuta) using 30 years of detailed behavioral observations from the Mara Hyena Project to evaluate these two hypotheses.ResultsAmong adult hyenas, we find that females spontaneously aggress at higher rates than males, whereas males spontaneously submit at higher rates than females. Once an aggressive interaction has been initiated, adult females are more likely than immigrant males to elicit submission from members of the opposite sex, and both adult natal and immigrant males are more likely than adult females to offer submission in response to an aggressive act. We also find that adult male aggressors are more likely to receive social support than are adult female aggressors, and that both adult natal and immigrant males are 2–3 times more likely to receive support when attacking a female than when attacking another male. Across all age classes, females are more likely than males to be targets of aggressive acts that occur with support. Further, receiving social support does slightly help immigrant males elicit submission from adult females compared to immigrant males acting alone, and it also helps females elicit submission from other females. However, adult females can dominate immigrant males with or without support far more often than immigrant males can dominate females, even when the immigrants are supported against females.DiscussionOverall, we find evidence for both mechanisms hypothesized to mediate female dominance in this species: (1) male and female hyenas clearly differ in their aggressive and submissive tendencies, and (2) realized social support plays an important role in shaping dominance relationships within a clan. Nevertheless, our results suggest that social support alone cannot explain sex-biased dominance in spotted hyenas. Although realized social support can certainly influence fight outcomes among females, adult females can easily dominate immigrant males without any support at all.

Effects of starvation on the fighting ability of invasive and autochthonous ants

Effects of starvation on the fighting ability of invasive and autochthonous ants

Fight Outcomes In Mixed Martial Arts (mma) From 1991-2021: An Analysis Of 107,227 Competitions

Although MMA rules and regulations are similar around the world, they can vary by state, country, and organization. State athletic commissions sanction US-based events, while a governing body of the host nation typically sanctions international events. Accordingly, MMA athletes may have a differential injury risk based on where they fight or the organization for whom they fight. PURPOSE: To determine the distribution of fight outcomes, if outcome distribution varies among US and international organizations, and if major rule changes in US-based organizations have changed the distribution of fight outcomes. METHODS: We extracted data from the ESPN MMA database for fights that occurred between September 1991 and October 2021, capturing 115,512 fights. Fights that did not have a time (7045), round number (147), had rounds greater than five min (1091), or had more than five rounds (2) were removed, leaving 107,227 fights for analysis. When comparing organizations, we used four US (UFC, Bellator, Strikeforce, Invicta) and six international (ONE, Pride, Rizin, Pancrase, M-1 Global, Fight Night) organizations (30,510) and three US-based organizations when comparing pre- and post-adoption of the Unified Rules of MMA (UFC, Bellator, Strikeforce; 18,238). RESULTS: Fights were stopped due to submission (32.5%) or ended in decision (30.5%) most frequently, with knockout (6.3%), technical KO (19.0%), and KO/TKO (9.9%) comprising 35.2% of fight stoppages. When comparing US and international organizations, US fights were more likely to go to Decision (43.6% vs. 38.8%) or end in KO/TKO (23.8% vs. 17.6%), while international organizations had higher rates of Submission (24.6% vs. 21.9%), TKO (12% vs. 6.3%), and KO (3.2% vs. 2.0%). When comparing outcomes pre- and post-Unified Rules, we identified a 51.3% increase in the proportion of fights going to decision and a reduction in the proportion of fights ending in KO/TKO (33.3%) or Submission (28.4%), respectively. CONCLUSIONS: Despite varying rules and regulations across organizations and locations, historical MMA fight outcomes have been similar for US and international competition. Furthermore, implementation of the Unified Rules by US-based organizations is associated with a lower proportion of fights ending by KO/TKO, implying a positive impact on MMA athlete safety.

Rapid weight gain predicts fight success in mixed martial arts – evidence from 1,400 weigh-ins

ABSTRACT We aimed to analyze whether rapid weight gain (RWG) between the official weigh-in and the time of the fight was associated with fight success in MMA. A total of 700 professional MMA fights involving 1,400 weigh-ins from 21 MMA promotions regulated by the California State Athletic Commission were analyzed. Multilevel logistic regression accounting for individual (i.e. athlete) and cluster levels (i.e. fights) was used to analyze the association of all measures with a theoretical relationship with the dependent variable and without interdependency with one another (i.e. %RWG, sex, body mass division, competition level) with the fight outcome (i.e. win or loss). The odds ratios (OR) with 95% confidence intervals (95%CI) were calculated. The highest mean %RWG was found for the flyweight, bantamweight, featherweight, and lightweight divisions. The %RWG significantly predicted the fight outcome (ß = 0.044; OR = 1.045; 95%CI = 1.014–1.078; p = 0.005) so that for each 1% of additional RWG, the chance of winning increased by 4.5%. With the largest sample to date and in a “real-world” scenario, the present results suggest that the magnitude of RWG is linked to the chance of winning in MMA combats. It is suggested that regulatory commissions, confederations, and event organisers should consider regulating RWG, considering that, despite its detrimental impact on the athletes’ health and performance, the potential advantage might stimulate athletes to invest in rapid weight loss, followed by gain after the official weigh-in to increase their chance of winning.

Do not drop your gloves: “Winning” a fight in the National Hockey League does not improve chances to win the game

Sanctioned fighting has played an integral role in the National Hockey League (NHL) since its early days. Proponents argue that this practice helps teams win games. More specifically, they contend that when a player triumphs decisively in a fight, the outcome creates momentum or a spark for his teammates and thus increases his team’s odds of victory. We used on-line fans’ voting (validated by objective fight data) to assess fight outcome and demonstrated that “winning” the fight did not lead to winning the game when the score was tied. Additionally, in contrast with the “change in momentum” hypothesis, prevailing in a fight did not sway game outcome when the home or away team was one goal behind early enough in the game. Lastly, prevailing in a fight was not associated with scoring the next goal. We discuss the results in light of the strong conviction held by NHL players that fighting boosts momentum and explain possible mechanisms working to preserve this false belief.

Social context shapes cognitive abilities: associative memories are modulated by fight outcome and social isolation in the crab Neohelice granulata.

Cognitive abilities of an animal can be influenced by distinct social experiences. However, the extent of this modulation has not been addressed in different learning scenarios: are all tasks similarly affected by social experiences? In the present study, we analyzed the effect of social dominance in aversive and appetitive memory processes in the crab Neohelice granulata. In addition, we studied the influence of social isolation on memory ability. Social dominance experiments consisted of an agonistic phase immediately followed by a memory phase. During the agonistic phase, matched pairs of male crabs were staged in 10-min encounters and the dominant or subordinate condition of each member of the dyad was determined. During the memory phase, crabs were trained to acquire aversive or appetitive memory and tested 24 h later. Results showed that the agonistic encounter can modulate long-term memory according to the dominance condition in such a way that memory retention of subordinates results higher than their respective dominant. Remarkably, this result was found for both aversive and appetitive memory tasks. In addition, we found that isolated animals showed no memory retention when compared with animals that remained grouped. Altogether this work emphasizes the importance of social context as a modulator of cognitive abilities.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10071-021-01492-6.

The dark side of play: play fighting as a substitute for real fighting in domestic pigs, Sus scrofa

Play fighting can originate from different behavioural systems, including aggression and affiliation and can have a competitive and/or cooperative nature. Domestic pigs engage in vigorous play fighting that strongly resembles real fighting in motor patterns from their first days of life and heavier subjects usually win agonistic contests. Here we tested whether play fighting in piglets could be a substitute for real fighting and predicted that, if so: (1) play invitations would be more successful when not involving possibly dangerous body contact (Prediction 1); (2) piglets would preferentially play with similar-sized mates, easier to outcompete (Prediction 2); (3) play fighting and real fighting outcomes (winner/loser) and social networks would largely match (Prediction 3). We videorecorded three litters of preweaning piglets housed at the ethical farm Parva Domus (Turin, Italy) and analysed the play, aggression and suckling sessions. Sociomatrix and social network analyses were also used to compare play fighting and real fighting. Our findings confirmed all predictions, as they showed that piglets engaged in play fighting when the danger of being harmed was lowest (no-contact invitation patterns; Prediction 1) and their chance of winning was highest (similar weight players; Prediction 2). During the preweaning period, play fighting decreased as real fighting increased and just after suckling time declined, with piglets consistently winning/losing both playful and real fights and possessing comparable network centrality values in both play fighting and real fighting networks (Prediction 3). Although the mechanisms underlying the competitive nature of play fighting remain to be determined, this study provides evidence that it can be a harmless replacement for real fighting (possibly mediated by the oxytocin consumed via maternal milk). This study also points towards the more extreme hypothesis that play fighting is a different form of aggression that includes elements of play. • In piglets play fighting can function as a substitute for real fighting. • Play fighting in piglets decreases right after the suckling time reduction. • The same piglets occupy central positions in play and real fighting social network. • Play fighting and real fighting outcomes (winner/loser) largely match.

Differential effects of aerobic capacities on fight outcome in giant hissing cockroaches

When animals engage in contests, ‘fights’ are usually noninjurious, involving either signals or trials of strength. Such fights end once an individual assesses that it is the weaker opponent, or it has reached the threshold level of costs it is prepared to pay. We investigated the agonistic behaviours performed and the relative costs paid by winners and losers during aggressive interactions in two species of Madagascan hissing cockroaches (the wide-horned cockroach, Gromphadorhina oblongonota , and the flat-horned cockroach , Aeluropoda insignis ). By combining contest observations with measures of energetic expenditure and using X-ray computed tomography to compare the internal structure of the respiratory systems of the competitors, we revealed the differential physiological investment associated with resource-holding potential in these two species. Winners in G. oblongonota had larger respiratory volumes than predicted for their size compared to losers. Gromphadorhina oblongonota fought more aggressively and had larger respiratory systems overall than A. insignis , which engaged in less physical fighting. This indicates differential investment in fight tactics, and associated anatomy that may promote contest success. Invertebrate species at the upper limits of body size need to maintain efficient respiratory systems to support their size while also remaining subject to the influence of sexual selection. • Male hissing cockroaches compete over territories and access to fertilizations. • Weaponry and contest dynamics vary between species in this tribe. • X-ray CT scanning was used to compare the respiratory structures of competitors. • Respiratory volumes were higher in dominants of the more competitive species. • Sexual selection may act on respiratory anatomy that can promote contest success.

Analysis of the fight-ending chokes in the history of the Ultimate Fighting Championship™ mixed martial arts promotion

ABSTRACT Objective Knowledge of sportive chokes is vital to the practice of Sports Medicine when providing care at mixed martial arts and submission grappling events. This is a descriptive analysis of fight-ending chokes to help provide data on the topic not previously presented. Methods An analysis was done on every fight-ending choke in the history of the UFC™ mixed martial arts promotion. Investigators focused on the frequency of chokes, types of chokes, handedness of the chokes, and whether chokes resulted in loss of consciousness. This analysis was done using existing fight outcome reports and video analysis of every choke that ended a fight in UFC™ history. Results During the study period there were 904 such chokes, comprising 15.5% of fight outcomes and 76.2% of grappling submissions. The makeup of right (50.1%) and left (49.9%) handedness of the chokes has been essentially identical (χ2 [1] = 0.0011, p =.947, phi =.00). Most of the fight-ending chokes culminated in voluntary submission; however, 11% resulted in loss of consciousness. The rear naked choke (RNC) was significantly more frequent than other chokes, comprising 49.1% of the total choke finishes; 19 other choke types accounted for the remaining 50.9%. Conclusion Fight-ending chokes have been common in MMA. Many types of chokes have successfully ended UFC™ fights, with the RNC accounting for almost half of fight-ending chokes. Loss of consciousness occurred in 11% of fight-ending chokes. Right and left handed chokes were utilized equally.

Defensive structures influence fighting outcomes

Abstract In many animal species, individuals engage in fights with conspecifics over access to limited resources (e.g. mates, food, or shelter). Most theory about these intraspecific fights assumes that damage has an important role in determining the contest winner. Thus, defensive structures that reduce the amount of damage an individual accrues during intraspecific competition should provide a fighting advantage. Examples of such damage‐reducing structures include the dermal shields of goats, the dorsal osteoderms of crocodiles, and the armoured telsons of mantis shrimps. Although numerous studies have identified these defensive structures, no study has investigated whether they influence the outcomes of intraspecific fights. Here we investigated whether inhibiting damage by enhancing an individual's armour influenced fighting behaviour and success in the giant mesquite bug, Thasus neocalifornicus (Insecta: Hemiptera: Coreidae). We found that experimentally manipulated individuals (i.e. those provided with additional armour) were 1.6 times more likely to win a fight when compared to the control. These results demonstrate that damage, and damage‐reducing structures, can influence fighting success. The implications of these results are twofold. First, our results experimentally support a fundamental assumption of most theoretical fighting models: that damage is a fighting cost that can influence contest outcomes. Second, these results highlight the importance of an individual's defensive capacity, and why defence should not be ignored. A free Plain Language Summary can be found within the Supporting Information of this article.

Asymmetries affecting aggressive contests between solitary parasitoids: the effect of host species

Abstract Conflicts in animals are usually resolved based on asymmetries, where contest winners are often those that value a resource the most and/or those who have the greatest potential to retain it. In parasitoid wasps, contests between females determine which individual exploits hosts for offspring production. Previous studies on solitary parasitoids rarely considered the role of biotic factors generating phenotypic variation that could influence the strength of asymmetries. Some parasitoid species parasitize host species of various sizes, producing offspring that vary considerably in size and potentially fighting ability. In this study, we reared the egg endoparasitoid Telenomus podisi (Hymenoptera: Scelionidae) on two host species to measure the effect of body size on contest resolution and how it interacts with ownership and resource value (RV) asymmetries. Our results showed that ownership status best predicts the final contest outcome when similar-sized wasps fight over hosts. The frequency and outcomes of individual fights structuring contests were better explained by the difference in the number of eggs laid in the hosts by each female at a given time. When contestants varied in body size, larger intruders frequently dislodged small owners regardless of ownership and RV asymmetries. These results imply that body size is an important factor to consider in solitary parasitoid contests and that it can overshadow the effects of other asymmetries. Our study suggests that host community diversity could have a direct effect on parasitoid contests and that biotic communities, through their effects on animal phenotypes, may play an underrated role in contest resolution.