Monday, September 25, 2023

Does the modern game in schools produce boys who are overweight?

As we approach the Rugby World Cup, there are increasing concerns about rugby at schools level and the impact of young people putting on weight to gain elite status in the game, by Dr William Fennell

Much attention in Rugby Union circles is focused on the short and long-term effects of concussion. Increased player weight has been associated with an increased risk of injury.1,2 There is a lack of published data examining the life expectancy of rugby players, unlike American football. In the March 20, 2022, edition of the Irish Times the personal height and weight of the Irish Under-20 panel was profiled following their success in the Six Nations Championship.3,4

Mean weight was 100kg and eight players out of 31 met the United States Center for Disease Control criterion for obesity with a calculated Basal Metabolic Index, (BMI kg/M2) greater than 305. Much of this weight gain is facilitated by bulking up with high caloric intake and supplemental protein.5

On reviewing the entire Six Nations cohort of players 61 out of 98 forward position players had a BMI >30, all back position players had a BMI<30. This difference between forwards and backs was most marked in the front-row prop position where all players had a BMI>30.

This difference is unlikely to be attributed to higher muscle and bone mass alone. It is very likely that increased visceral and peripheral adiposity is contributing to the higher than normal BMI and weights. Below is presented the evidence in support of this hypothesis.

Rugby has been a source of enjoyment and exercise for over 200 years since William Webb Ellis, against the rules of the day and the run of play, took up the ball and ran with it in Rugby School in 1823. Over time it was said it was a game for all shapes and sizes (and men with odd-shaped balls – Ed). It may no longer be? With the introduction of television and live viewing its popularity increased enormously. Professionalism followed in 1995.

Newton’s second law of physics states force equals mass multiplied by acceleration and the third law states to every force applied there is an equal and opposite force. Mass equates with weight for all practical purposes. With scrums weighing more than 800kg and players travelling at speeds of more than 20km per hour, one can see how the forces being applied and received are considerable. It has been estimated scrums can generate forces >1600 Newtons, equivalent to being hit by a car at 30mph or 40kmph. In more recent times success has generally been achieved by the teams with the greatest weight.

One must ask what the downsides are, if any, of rapid weight gain in teenage years? What are the long-term effects in terms of later morbidity and life expectancy as a result of high-performance athletes using supervised protein/caloric supplementation, and whose playing time weights far exceed the norm for their age and height? The US Center for Disease Control has defined overweight at BMI>25, obesity at BMI>30, risk category 1, and >35 risk category 2. BMI > 30 is the cut-off entry point for clinical intervention trials of new therapies for obesity.5

The weights and heights of the individual under-20 Six Nations teams, England, France ,Ireland, Italy, Scotland, and Wales, were obtained from the respective national rugby union websites. A literature review, online, was made for weight and body composition studies of rugby players, underage and adult. In both France and the US there were two studies of rugby participants aged 11-15 years.6,7

The weight profiles in elite rugby players over the last 100 years has been reviewed and the influence of the advent of professionalism noted. The life expectancy of professional American footballers and baseball players has been documented. There is no corresponding information available for rugby union players.

On reviewing the entire Six Nations forwards under 20 years of age cohort, 61/94 had a BMI >30, all backs had a BMI<30, all 33 prop forwards had a BMI >30 and 11 had a BMI>35. 18/21 hookers had a BMI>30. In the non-front row forwards, there were 11/52 with BMI>30.

For comparison with other sports, Rafael Nadal and Roger Federer have BMIs of 24.8, The Liverpool FC team’ mean BMI in 2022 was 23.1 and the Kerry Gaelic football team in 2019 was 24.7 Mohammed Ali at his peak was 29. This information was obtained online.

There is a marked discrepancy between front-row forwards and non-front row forwards and backs. It is hard to attribute these differences to increased muscle and bone mass alone. It is likely that increased visceral and peripheral adiposity is contributing. This needs to be investigated.

There is controversy concerning the methodology for measuring body fat percentage and the reliability of BMI as an indicator of obesity. DEXA scanning has been the most reliable measurement up to now but does not measure visceral adiposity and organ penetration. MRI is the accepted standard for efficacy and safety,16 CT scanning is also effective, but radiation exposure would rule out routine use.

Gavarry et al studied weight patterns in 1,000 French school children playing rugby aged between 11 and 15 years.6 He noted a strong relationship between BMI and Body fat mass index, where the study population was 32.8 per cent overweight and 13.8 per cent obese. Skin fold thickness was used to calculate percentage body fat, body fat mass and fat-free mass index. Malani et al reported a similar incidence of overweight and obesity, combined 42.6 per cent in a study of 653 boys, 11 to 15 years of age, playing American football in 2007.7

Nirengi et al reported on the incidence of non-alcoholic fatty liver in 69 Japanese university rugby players with 29 age-matched controls.8

Mean age 19 years, BMI, 29 in forwards, 25 in backs and 22 in controls. Percentage fat in forwards was 22, 15 in backs and 14 in controls. They diagnosed fatty liver in 18 per cent of forwards, six per cent in backs and zero per cent in controls.

The criteria for diagnosis of fatty liver was biochemical AST >33 iu.L, ALT>43 iu.L and alcohol intake less than 20gm per day. Lean body mass at 77 per cent was less than backs and controls at 86 per cent. When LDL, total cholesterol, triglycerides, AST, ALT and alkaline phosphatase were combined there was a significant difference between forwards and controls.

Pontaga et al reported-on body fat composition in the Latvian rugby team, 19 players, mean age 29 years, mean weight 97kg, Mean BMI was 31 for forwards and 26 in backs. Body fat percentage was 24+/-4 in forwards and 15+/-4 in backs.9

Posthumus et al studied the physical and fitness characteristics in 39 elite New Zealand players. Using anthropometric measurements and DEXA scanning they documented average weights for all players were 108kg, forwards 116kg and backs 96kg. They demonstrated increased fat mass and percentage fat in forwards, 24.1 per cent as against 14.3 per cent in backs. They did not differentiate between front-row forwards and other forward positions. The calculated BMI was 31.7 in forwards and 28.6 in backs.10

A mortality study compared professional American football players with major league baseball, playing times between 1939-1988 and follow-up from 1979 to 2013.11 Average life expectancy was 59.7 years in footballers as against 66.7 in baseball players. The cardiovascular cause of death was strikingly greater in football than in baseball.

The highest mortality was in the positions of offensive and defensive linesmen, the positions requiring the greatest strength. Sumo wrestlers, whose physique most resemble front row forwards live on average 20 years less than the average Japanese male, (Wikipedia). The New York Times has editorialised on the “The American Football Obesity” epidemic.12

Hill et al reported on the evolution of high standard rugby players’ weight and height from 1905 to 1999. Body mass increased 2.6kg per decade and height by 1cm per decade. BMI increased by 0.4kg/M2 per decade.13 Tucker et al reviewed the weight profiles of World Cup participants from 1995 to 2015.14 They noted a 20 per cent weight increase between 1995 and 2011 as against a five per cent increase between 1955 and 1995.

The rugby union authorities state there are individual plans for each player in terms of exercise and dietary needs – supervised by qualified sports exercise and health professionals. The Irish Rugby Football Union has declined to answer any queries addressed by the author, citing GDPR regulations. However, no personalised information was requested. Queries to the English and Scottish Unions and World Rugby went unanswered.

Discussion: rugby and weight
My interest in the connection between weight and underage rugby resulted from a clinical conversation where a 17-year-old was advised to increase his weight by 12kg in the following six months to ensure his place as a prop/front row forward in his school team. His family had a striking history of premature coronary artery disease. I was taken back.

The causes of obesity are complex and multifactorial, but mostly because of excess caloric intake over energy output. Overweight and obesity has been closely linked to early onset hypertension, metabolic syndrome, and type 2 diabetes, as well as increased cardiovascular and other morbidity. An active exercise regime is the best preventive against excess weight at any age.

In the under-15 years of age studies in the US and France, there is concern that both codes encourage early weight increase, whether under peer pressure or parental pressure, to excel in the codes. The data presented raises concern when despite vigorous exercise and supervised high caloric diet, there is marked weight gain in players at a young age. What are the long- term effects?

“Welsh Rugby online” has documented the average caloric intake of elite players. Caloric intake for forwards at 4,880kcals/day and backs at 3,920kcals/day, fat intake at 135/138 grams per day was not different. Protein intake in grams/day was greater in forwards at 174 and 156 in backs. Carbohydrate intake was estimated at 735 grams /day in forwards and 520 in backs. These levels are at least two to three times greater than basic needs and population average.

The long-term effects and implications of these supervised exercise, weight-training and supplemented dietary regimens are not known in the underage group. Premature degenerative arthritis must be a likely later effect. Early joint replacements are well documented if not quantitated.2 In New Zealand weight streamed under-age competitions are not uncommon, clearly designed to minimize injury risks of mass/weight imbalance. Martial arts and boxing and wrestling have weight restrictions and streaming in place.

Should team maximum weights be considered? Should scrum weights be restricted? The added weight may facilitate success, but is not necessary for, and does not add to the enjoyment of the game for the spectator, but undoubtedly increases injury risks for the players.

There is controversy about the use of BMI as an indicator of obesity in athletes. The US NHANES study showed a close co-relation between BMI and %body fat in a population of over 300,000 US adults.15

It is likely that the use of skin fold measurements and DEXA scanning have underestimated %fat as they do not measure visceral adiposity or organ penetration by fat, such as fatty liver.16

The evidence presented here points to a need to monitor general health, BMI, and a search for cardiovascular and other morbidities in all underage high-performance rugby union athletes whose playing time weight exceeded the norm for their age,

In contracted players at all ages MRI should be performed to more accurately quantitate body fat percentage.

Screening for fatty liver should also be considered, as biochemical testing has limitations when alcohol intake is greater than 20 grams/day

At a minimum, the Rugby authorities should be able to assure players and parents of underage players and the public that long-term follow-up will be carried out after the end of playing careers in accordance with occupational health guidelines and legislation.

At schools’ level, the dietary advice should be explained and justified to parents, players and informed consent obtained.

Another concern is the role model status of elite players for younger aspirants who do not have the advantage of professional exercise and dietary supervision.

If one was to design an experimental model for metabolic syndrome, it would be hard to improve on the dietary /training regime for young elite rugby union players?

For the assessment of on field injuries one can make a strong case for this to be done by an independent medical professional, separate from the medical support team with a potential conflict of interest.

The constructive input of Brendan Buckley, Emmet Byrne, Noel Caplice, Jerome Fennell, Michael G. Molloy and Fergus Shanahan is gratefully acknowledged.


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      3. ‘Grand Slam Wlnners, Meet the Ireland Under-20 squad’, Irish Times, March 20, 2022.
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      11. Nguyen VT, Zafonte RD, Chen JT, et al, Mortality among Professional American style Football Players and Professional American Baseball Players. JAMA, Netw Open.2019 May 3;2(5):e194223. DOI: 10.1001/jamanetworkopen.2019.4223. PMID:31125098;PMCID: PMC 6632140.
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