Effects of Rapid Weight Loss on Judo Athletes: A Systematic Review (1)
CLakicevic, N; Roklicer, R; Bianco, A; Mani, D; Paoli, A; Trivic, T; Ostojic, S; Milovancev, A; Maksimovic, N;Drid, P.
The practice of weight-cutting for sports, in particular its safety and effectiveness, has been cause of a great deal of debate and controversy, as well as scientific investigation. As most combat sports are contested in weight categories, manipulation of body weight in order to gain a competitive advantage over an opponent is commonplace as a strategic intervention. Whilst most combat athletes and coaches consider having a larger relative body mass in comparison to an opponent advantageous, this advantage is thought to be greater in grappling arts such as judo and wrestling, but to a lesser degree in jiu jitsu. As such, deliberate weight cutting is believed to be engaged in by up to 90% of both male and female competitive judo athletes (2).
The process of achieving a large reduction in body weight in a short period of time prior to the event weigh- in, before attempting to replace as much of this lost body weight as possible prior to the event, is referred to in the literature as rapid weight loss, or RWL. As in many combat sports organisations the weigh-ins are the day before the competition, the window to regain weight and recover sufficiently to maximise performance is seen by many as adequate. Common methods of RWL focus on manipulating and maximising fluid loss, and include dehydration techniques, dietary interventions and exercise in often-artificial high-temperature conditions. Pharmacological interventions are also thought to be utilised to different extents, although their use is widely prohibited in most sporting bodies. The average amount of weight lost by judo athletes during this process is around 5% of total body weight (2).
Research into the impact of RWL on measures of health and performance has tended to focus on assessments of physical performance, physiological biomarkers, and psychological outcomes, however some studies have shown that the process of deliberately reducing weight
advantageous in judo (3), as well as in other combat sports such as wrestling (4).
The aim of this study was therefore to conduct a review of the existing literature pertaining to the effects of RWL on physiological and psychological performance markers in judo athletes.
The authors conducted a thorough search of the literature using the keywords:
“Rapid Weight Loss” “Weight Reduction”
In combination with: “Judo”
“Combat Sports” “Martial Arts”
A three-step article screening was then performed by 3 investigators, with inclusion criteria including:
-Peer-review journal articles, both qualitative and quantitative articles
-Publication date range 1996-2019
-English language publicationsArticles had to include judo participants
-RWL had to be approximately 5% of total body weight Studies including pharmacological interventions were to still be included
Following this process, 14 studies, involving 1103 athletes, were included in the review.
Five studies looked at strength outcomes. Two studies showed a decrease in grip strength compared to a control group (5,6). One study failed to show any significant change in isometric force production in arm, leg and trunk flexion and extension following RWL (7), whilst another study showed decreased isometric strength in a high weight reduction (>3%) group compared to a low weight reduction (<3%) group (8). The fifth study showed no difference in isometric trunk strength or grip strength between high and low reduction groups (9).
Two studies looked into the impact of RWL on reaction time with one showing improved reaction time (8) and the other showing negatively-impacted reaction time in large RWL groups compared to moderate or control groups (9).
The one study investigating balance and RWL showed a significant negative effect compared to a control group (9).
Decision making performance
One study looked at decision making performance using the game performance assessment instrument (GPAI), and found compromised performance in the RWL group compared to a control (11).
4 studies examined the effects of RWL on physiological biomarkers. One study showed increased creatinine levels following a period of RWL (1). Another study showed increases in free fatty acids, glycerol, uric acid, urea, adrenocorticotropic hormone (ACTH), cortisol, dehydroepiandrosterone sulfate (DHEA-S), a decrease in triglycerides, testosterone, testosterone/cortisol ratio, DHEA-S/C, insulin, and thyroid hormones ratio, and no change in ammonia, glucose or alkali reserve (6).
Judo Specific Performance
Judo specific performance was analysed for total number of attacks, and failed to identify a difference between a RWL and a control condition.
Special Judo Fitness Test
Performance in the special judo fitness test (covered in last month’s issue) was negatively impacted for both number of throws and 1-minute heart rate recovery in a RWL group compared to a control group (12).
3 studies looked at different psychological mood characteristics using the POMS questionnaire, applied both before and after the RWL period. One study showed increased levels of depression and decreased levels of vigour, compared to a control group (5). Another study showed increases in fatigue and anger at follow-up, compared to the initial assessment (6), while a third study demonstrated greater increases in tension and fatigue, as well as a decrease in vigour (13).
This review was well set-out in terms of conducting a thorough search, filter and critical appraisal of the current literature. The authors note that they originally set out to perform a meta analysis, however due to the sparsity and inconsistency of the data, only a systematic review could be performed. Whilst the findings from this study are useful and do contribute to the overall body of evidence regarding the topic, this paper highlights the fact that there is still a lot that we don’t know.
When we look at the effects of RWL on performance, there are so many confounding factors that it is difficult to take the current data and apply it in the form of blanket statements and recommendations. Whether RWL leads to an increase or decrease in judo competition performance (which is ultimately what coaches and athletes are most concerned about) is likely extremely individual, and as such requires an individualised approach for each athlete. As the current evidence we have comes from studies on competitors from a range of competition levels, ages, genders, and athlete physical characteristics, we also don’t know to what degree these factors play a part in the overall response to RWL.
Overall the data seems to point towards negative consequences of RWL, in terms of reduced physiological capacity, which would infer a possible decrease in judo competition performance. Some of the parameters, for example decreased grip strength, would theoretically be of major concern in terms of carryover to sport performance. However, despite the findings, we still see evidence of improved performance (3). In addition to this, the weight cutting process is still extremely prevalent, and it is unlikely that this would be the case if there was not significant anecdotal evidence from athletes and coaches regarding the effectiveness of this strategy. We must consider then, how relevant these physiological markers are in terms of the overall competitive performance in the sport. It may be that while factors such as strength and power are important for performance, even a certain drop from their baseline levels do not affect competition performance, and that technique and strategy play a far greater part in the process of match-day success. Even with the psychological findings, whilst depression and vigour are negatively affected, this may be countered by the ensuing confidence in being bigger than the opponent, or even some other self-efficacy gleaned from the ability to survive a difficult weight cut.
Whilst the health of athletes participating in RWL practices was not the focus on this review, if we speculate that RWL does not negatively affect performance, then whether it is safe is obviously the next logical argument. Whilst we see in some (but not all) studies acute changes in important biomarkers, we need substantially more data regarding chronic implications of repeated weight-cutting, as well as the impact of frequency and size of weight cuts on long-term health outcomes. Given that we have already seen deaths in intercollegiate wrestlers from weight cutting, it will likely require an overwhelming body of evidence to encourage meaningful change in this long-standing culture. Whilst some combat sports organisations are taking measures to control and decrease the magnitude of RWL possible for athletes, logistically speaking, the ability to do this decreases with the level of competition and size/funding of organisations. Naturally junior and amateur athletes are the ones less likely to participate in events where RWL practices are more tightly controlled, and arguably it is at this stage in an athlete’s career that these types of practices are instilled.
With any potentially advantageous and/or harmful practice, athletes need to weigh-up the risk vs reward ratio, and without any clear perspective on either the risks or the rewards, athletes are often left to follow traditional practices.
In order to optimise the safety of both the athletes themselves, and the longevity of the sport, further research needs to be undertaken regarding the multitude of outcomes associated with this common practice. This review focused on weight loss in the 3-6% range, however in some combat sports we see significantly larger cuts, and there likely exists thresholds for both safety and performance, and so further research should focus on the impact of different degrees of weight loss.
In both this issue and our previous issue we have explored the validity and utility of combat sports-specific fitness and performance, however only one of the studies in this review made use of them. Given the validity shown for these assessments, their use as a proxy for competition performance outcomes would be an encouraging sign for the external validity of research findings.
This paper is an important contribution to the current body of evidence regarding rapid weight loss in combat athletes, and gives rise to many further questions regarding the practice, and hopefully avenues for further investigation.
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