The Sports Gene by Sports Illustrated journalist

I am very enthusiastic about this book and mentioned it at the Swim Ireland Performance Advisory Group earlier this year. National Performance Director, John Rudd, asked that I write this review, largely for coaches. What resulted (see below) should be of more general interest to all of those interested in competitive sport. I submitted the finished review to John Leonard of the American Swimming Coaches Association and he agreed to publish it in their Newsletter.

I strongly recommend this book for your Christmas reading. It is even reported that Barrack Obama was seen buying a copy!

Review of The Sports Gene: talent, practice and the truth about success.

By David Epstein, 2013. Yellow Jersey Press, London.

(Published in the American Swimming Coaches Association Newsletter, November 2018)

The Sports Gene by Sports Illustrated journalist, science graduate and middle distance runner David Epstein is an intriguing, widely researched and informative book. It should be required reading for all those interested in competitive sport. Perhaps this reviewer, being both a professional geneticist and swimming coach, is biased, but the way Epstein presents things, using a mixture of stories about individual athletes and modern research concepts, should appeal to a very wide audience.

    Though the title suggests that this book is all about genetics and how genetic principles apply to sport, it is in fact much wider than that. The broader question is whether elite sporting prowess is a consequence of genetics (“nature”) or the environment (“nurture”) or some mixture of both. Despite favouring one or the other in different sections of the book, Epstein concludes, in a more recent afterword to the Paperback edition, that obviously both are involved. Regardless of genetically-based aptitude for a particular sport (the “nature” part), a person will not perform optimally, particularly in endurance sports like most competitive swimming, without a huge amount of training (conditioning or “physiological adaptation”) augmented by technique optimisation, and accompanied by additional elements like nutrition and positive psychology-the “nurture” part. The book makes little reference to competitive swimming, concentrating instead on track and field athletics (the author’s specialisation), baseball and basketball, but most of these examples have general sports science relevance.

    The Introduction identifies individuals with exceptional sporting talent and frames the nature vs nurture question. Epstein then describes the Human Genome Project which was completed in 2003 and shows how this led to a series of experiments which attempted to relate single genes to variation in performance. However we know that for the majority of traits (the so-called phenotype i.e. the trait that can be observed and measured), multiple genes plus the environment are involved, greatly adding to the complexity of detection. (Think human height, where so many genes are involved that inheritance is described as omnigenic and where there is also obvious environmental influence, e.g. nutrition, health etc.). Several individuals can undertake the same training regime and yet perform very differently in races so the must be a major genetic component to performance. In contrast, Chapter one entitled “Beat by an Underhand Girl” describes a situation where experience rather than genetics is paramount. The softball pitcher Jeannie Finch was able to beat professional baseball players because they were unfamiliar with her technique and therefore could not “read” the direction of flight of the ball from her wind up. It seems that what is involved here is not lightning fast reactions, though these are endemic in top softball and baseball players, but lack of familiarity with either’s technique. The chapter then goes on to describe how experts (e.g. chess grand masters) vary from “just” good players by their ability to read the game and “chunk” information into packages, which, of course, brings us back to genetics. In the conclusion of this chapter and into the next, a variety of slightly confusing but intriguing case studies are presented. The 10,000 hour rule is discussed. This is the idea that 10,000 hours of practice are required for a person to reach their full potential in a specific activity, be it a sport or in orchestral music. (This idea was proposed by a psychologist working with young elite musicians but was leapt on by the popular press as an invariant “rule”.) A description is given of a golfer who is half way through that number of hours of practice and hopes to reach the top ranks. Frustratingly, the final outcome is not described but it turns out that 10,000 hours is an average figure with a wide variance, and, in any case, is influenced by innate ability. It is also interesting that in longitudinal studies (looking at the same individual over time) future elite performers often do less practice in a specific sport or other activity initially, than less able performers. They only start to put in longer hours in response to progress to elite level, perhaps arguing against early specialisation in a particular sport.

    A mixture of relevant topics is then presented. Two world class high jumpers are discussed, one of whom had particularly stiff Achilles tendons enabling greater spring, but then also practised intensively, and another with amazing natural ability. Visual acuity as an asset within a sport like baseball or tennis (but not between sports as mentioned above) is then presented. This is followed by something rather different-the difference between male and female performance. Sex testing at top International level was originally based on sex chromosomes, but testosterone level is now the approved measure. The latter can of course be influenced by ingestion of anabolic steroids (banned substances), which result in females getting closer to male performance and accentuation of male performance.

    The chapter entitled “The talent of trainability” is perhaps the most relevant and important for swimming coaches. It begins by describing the incredible improvement of the World Record mile runner Jim Ryun; showing a high level of innate ability and then great improvement on one of the heaviest training regimes then extant. The scientific basis is demonstrated in the HERITAGE study by Claude Bouchard and colleagues. When they tested the aerobic improvement, expressed as improvements of V02max, of a large number of college students it was shown that while the majority showed average improvement, a minority improved very little (termed low responders) and another small group improved greatly (the high responders). Similar results were found in the GEAR study and more recently in a study in Nottingham University in England. These results held regardless of initial level. Obviously, for endurance sports, high responders have an advantage. Further molecular work has isolated 29 genes, each of which occurs in two alternative forms, which act as predictors of this talent. There is a strong association between individuals which have the “beneficial” form in a majority of these gene markers and great response to aerobic training.

    In this and the next chapter the theme of muscle fibre composition is explored. Human and other vertebrate animal skeletal muscles consist of fibres of two distinct types-white fast twitch explosive largely anaerobic fibres and red slow twitch aerobic “endurance” fibres. The proportion of these fibres is genetically determined-nature again; as proven by identical twin studies where the twins have been trained in completely different ways. Among elite runners those excelling in sprints have high proportions of fast twitch fibres (>75%) with middle distance specialists (and much of humanity) at 50:50 and long distance types having a preponderance of slow twitch fibres (up to 80%), as demonstrated by calf muscle biopsy. Improvements in strength again have a major genetic component with individuals gaining from 0 to 250% improvement with training in leg and chest presses in trials. Variants of certain well-characterised genes such as IGF-2 and myostatin are involved here. Matching muscle composition to event has been particularly successful for example in moving a Danish kayaker from short to long events resulting in Olympic qualification and World Class performances.

    The next chapter describes how body types in specific sports have morphed from what was considered a single ideal “sporting” body type in the early 20th century to the present situation where there are highly specific body types in most sporting events. This is followed by a detailed consideration of extreme height in professional basketball players. All of this implies extreme selection of those that can excel in many sporting events today. There follows a chapter on human evolution and the so-called “Out of Africa” hypothesis of modern humans. This subject has been described in far more detail elsewhere and is perhaps less relevant to the main theme of the present book. Jamaican sprinters are then considered, focussing particularly on the part of the island where Usain Bolt was born. Again, while it is not specifically stated, the mixture of genetics (nature) indicated by a high preponderance of explosive fast twitch fibres and the environment (nurture), since sprinting in Jamaica is regarded as the most important National sporting activity, is evident. This high proportion of fast twitch muscle fibres in individuals whose ancestors were brought forcibly to the Americas from West Africa is considered by some scientists to be a response to natural selection caused by malarial infection in ancestral regions of Africa.

    The focus then switches to distance running and the supremacy of the Kenyan Kalenjin in this sport. Here both the environment (nurture-running long distances in daily activities and the high altitude of their natal area) and genetics (nature) underlying body type are important. Most top Kalenjin runners have proportionately long legs with narrow light extremities, enabling a highly efficient running style. The physiological characteristics produced by being born and growing up at altitude are obviously beneficial for distance runners, but it is also interesting to learn that different physiological adaptations occur in East Africa, Nepal and the Andes. As an aside, the subject of high altitude training for sea level athletes is evolving all the time, though of course no direct genetic correlation is suggested here.

    Themes like the breeding of Alaskan sled dogs for long distance races and genes that have detrimental effects in exercising humans (for example those genes involved with cardiac myopathy) are then introduced. The final descriptive chapter deals with a single gene mutation in a Finnish cross country skier. This very rare variant involving the haemoglobin gene resulted in the individual having significantly more circulating red blood cells than normal, catapulting him to world class. However, it is interesting to observe that his lifestyle involved a huge amount of skiing as a youngster and later as a border patrol agent, providing the perfect combination of nature and nurture. The Sports Gene concludes with an Epilogue called The Perfect Athlete, which again reiterates that having the ”right” genetics for a particular sport ( and there may be several varieties of “right”) certainly helps, but this is useless without many years of dedicated practice. And genetics is not sufficiently developed to do more than help in the effort to develop more proficient athletes!

Relevance to competitive swimming: So what does all this mean for developing elite competitive swimmers? In the first place genetics of traits for athleticism are not sufficiently understood to recommend any form of early testing of individuals i.e. testing 8 to 10 year olds and on the basis of results saying that the potential is there to reach the top after several years of optimal training, or at the other extreme-“you are wasting your time in this sport”. A big problem is to define natural (=genetic) ability. Which trait are we seeking? Is it the ability to learn to swim quickly; to optimise techniques such as starts, turns, finishes and underwater and surface strokes, pacing and other racing techniques; to improve rapidly through the stages of the competitive programme; to appear at one with the water in terms of feel of strokes and streamlining; superior ability in speed or endurance; ability to train and compete hard over many years; to avoid chronic illness and recover from injury, or some other trait? All of these traits are likely to have a genetic basis, and in all probability a somewhat different suite of genes will be involved in each. It is also likely that each of these traits are influenced by multiple genes (what geneticists refer to as polygenic inheritance), where each gene has a small cumulative effect. Traits influenced by single genes in humans or other animals (what geneticists refer to as monogenic inheritance), are extremely rare. Think of the cross country skier referred to above who seems to be the only individual amongst millions of humans having this specific mutation. Thus the search for the Olympic champion single gene is likely to be illusionary, and even if detected, genetic technology is not sufficiently advanced to allow safe manipulation. Given these considerations, what might be usefully done with genetic testing?

    Testing takes two overlapping forms-tests which provide information which do not allow manipulation (measuring height in fully grown individuals) and the more useful measurements where some action can be taken (like measuring VO2max regularly as the season progresses). Two recommended “genetic” tests, given the current state of knowledge, are muscle fibre proportion and trainability. In the case of muscle composition, while the “gold” standard is muscle biopsy, a simple vertical jump test (see Maglischo and other earlier swimming literature for details) gives a good measure of muscle fibre composition. The result when applying the vertical jump test to a large number of performance pathway swimmers will be a normal distribution (a bell-shaped curve where the majority will be 50:50 in terms of fast and slow twitch fibres), but a minority of individuals will be high in explosive fast twitch fibres (sprinters) or slow twitch fibres (800, 1,500 and open water specialists). Even though this is a test of phenotype (phenotype = genotype plus environment; termed G + E), it gives a good measure of genetic differences, because most of good competitors within a geographic region will be experiencing a similar environment. We have tested this with high school students in a PE class and found excellent correlation with running sprint speed (unpublished results). It may be that we are trying to train athletes in the wrong events because muscle fibre proportion is an innate trait influenced very little by conditioning i.e. one cannot make a sprinter great at 1,500m or vice versa for a distance type in the 50m, and the optimal training regimes are very different.

    Another trait which can be measured in trainability. Of course, this can be measured empirically i.e. how do elite swimmers respond to say 12 weeks of a good training regime in terms of VO2max. However, as mentioned above there is a significant positive correlation with having a majority of certain variants at 29 designated gene marker SNPs (single nucleotide polymorphisms) and high levels of trainability. An inexpensive and rapid molecular genetic test will determine genotype at these 29 genes. If for example a swimmer scores low on the trait of endurance trainability, one may be dealing with a potential sprinter (as a simultaneous muscle fibre composition test should show) and/or the swimmer might be encouraged to make additional efforts in technique development. Similar tests of potential strength acquisition are available and more tests will become available as the rapidly advancing genetic field progresses. It is not suggested that genetic testing should supersede other physiological, anatomical, biochemical, nutritional, biometric, hydrodynamic (video) and psychological tests; but they should form part of the “toolbox”, when more efficiently attempting to produce faster competitive swimmers.

Tom Cross

Great performances at the 2018 Irish Short Course National Championships in Lisburn

This was my third consecutive year at this meet and my most enjoyable so far. Described by Head Coach Richard Cassidy as his “favourite meet of the year”, Lisburn is a great venue! The racing pool is the 25m eight-lane format with a separate warm up/warm down pool. All events are Senior, with A and B finals in all individual events, except the 800 and 1500 freestyle which are HDW and the six 4 x 50 relays (two Women’s, two Men’s and two Mixed), which only have an A final. Spectator accommodation, though restricted, gives a very good view of the races.
At 21, we had the biggest SWSC team in recent years-nine female and 12 male qualifiers. Their performances were really impressive with 77 personal best swims, and six club records- three for Liam Custer (400 IM, 400 & 1500 freestyle), two for Beth Nolan (100 & 200 breast stroke) and one for Luke O’Sullivan (200 freestyle). Good morning heat swims meant many swimmers made A or B finals.
Despite all of this we didn’t win any medals since, as stated above, this is a Senior meet and our team is relatively young. Also, Irish swimming is rapidly improving with eight National records broken. One of the best of these was by Mona McSharry in the 100 freestyle, where she broke Michele Smith’s record from 1995 (which I was present for at the Nationals in the Grove pool in Belfast). The National Centres in Dublin and Limerick and UCD, with great access to facilities and full time coaches, are particularly successful.
Having said that, SWSC swimmers had great representation in A and B finals. In A finals, Liam Custer featured in three (two 4ths, 8th), Andrew Feenan in one (5th), Luc Galland in two (5th, 7th) and Sharon Semchiy in four (5th, 6th, 7th, 8th). Many made B finals-Liam (9th, 10th, 11th), Andrew (9th, 12th, 15th), Luc (13th), Paul Higgins (13th), Ellen Lee (11th), Rory Lee (14th), Beth (two 10ths, 12th, 13th, 16th), Luke (13th) and Sharon (two 9ths, 10th, 11th). In addition we featured in four of six relay finals, finishing with two 6th places and two 8th places.
For me, our best swims were Liam in middle distance events (great strokes and turns), Andrew and Beth at 200 breast stroke (true grit), Sharon at 100 and 200 freestyle, and 100 butterfly (doing everything right), but also from others like Lauren Farr at 50 back stroke, Ilann Wall at 100 freestyle and Ellen at 50 and 100 Butterfly, and many many more!
So what do we need to improve faster than the rest of Ireland? The “secrets” are more time (already Richard has instituted 06.45 starts in the mornings), consistency and constant attention to technique. Ards swim 16 hours each week! Why don’t we? Does everyone turn up for all sessions? We’re doing very well, but let’s try harder!
(Details of swims are on the SWSC website and John Rudd’s comments of top performers on the Swim Ireland website.)

Tom Cross

President’s Notes – July 2018

In April 2018 I attended the Commonwealth Games swimming in Australia. The venue was a 50m outdoor pool on the Gold Coast south of Brisbane with seating for 8,000 spectators. I had forgotten the excitement of major live events; last time being the 2005 World Championships in Montreal. Granted you see more detail on television but totally miss the atmosphere! The extremely partisan Australian crowd really got behind their team. Their Women’s 4 X 100 Freestyle Relay set a World Record of 3:30.05 on the first night, with Cate Campbell anchoring in 51.00, the fastest relay split ever. Another highlight was the Women’s 100 Backstroke final. Despite torrential tropical rain, both the winner Canadian Kylie Masse (58.63) and second place local Emily Seebohm (58.66) finished within 0.6 sec of Masse’s world record from Rio. There were also upset victories by swimmers from countries neighbouring Ireland. Duncan Scott of Scotland (with really great stroke technique) won a very tight Men’s 100 freestyle in 48.05, while Alys Thomas from Wales won the Women’s 200 butterfly in a superb 2:05.46. The latter is 28 years old and has persisted through sometimes difficult times. In the shorter fly events her stroke lacks flow, whereas it really worked in this longer event. While the Commonwealth Games only involves about one third of the world’s top swimmers, the results were of a very high standard. Teams from smaller countries get to compete for final and podium positions, with for example the team from Northern Ireland performing very well.

For me there were several “take home” messages which I think are relevant at club level:

  1. In general, the medallists had the best techniques in terms of starts, turns finishes and underwater and particularly surface strokes. To be the best one must optimise fitness and technique. The skilled and fit swimmer will nearly always beat the “just” fit swimmer! Do you know what works best for you and think about it all the time in practice?
  2. Top swimmers do far more warming up and down than most Irish swimmers. I know this is constrained by absence of additional practice facilities at many venues. However, where these are available at, for example, most Irish National events, I think we don’t use them enough.
  3. Most swimmers at the Commonwealth Games were aged between 18 and 30. Swimmers are physically best at these ages. Why do so many individuals of great potential in SWSC quit when in their mid-teens? With detailed organisation it is possible to excel both in swimming and at school. In fact, a recent study by an English neurologist has indicated that people do better in exams if they continue to do reduced training. My friend Jim Martin, who coached SWSC with me in the early 1970s and is now Head of Medicine at McGill University in Montreal, says that sportspeople make the best PhD students, because of their level of planning and their determination. As a University educator, I heartily agree! We want individuals to treat swimming as a lifelong sport through Masters events and triathlon!

The European Championships are being held in Glasgow from 3-9 August this year. I hope you will be watching. I know I will! See you at the Summer Nationals!


Tom Cross,

SWSC President

Presidents Notes March 2018

General Introduction:

Most swimming books are aimed at coaches and are highly technical. These notes instead are aimed at competitive swimmers and their parents. What I’ll try to do is present a single theme monthly. The opinions are my own (and so are any errors), but they are designed to make you think and to start discussion. They are the product of nearly five decades of coaching and observing elite swimming, but also stem from my background as a professional biological educator and researcher. I welcome questions, comments and criticisms from swimmers, and also from parents and club coaches (but directly not electronically). These notes are not designed to replace your interactions with your club coaches (and will all be approved by Director of Aquatics and Head Coach Richard Cassidy). Good interactions with your coaches are absolutely essential to optimising performance.  Instead they attempt to assist efforts to make you as good as possible!

Tom Cross, March 2018

Number 1: Being as good as possible!

When Director of the American Swimming Coaches Association John Leonard visited Ireland a few years ago, he was asked what he thought was the most important thing in competitive swimming. He said “Turn up (to all training session and meets)”. He then went on to tell us that Michael Phelps had not missed a single training session in seven years! Can any SWSC swimmer match that record even for the last season? Are you going to achieve it this season?

So what’s “enough” per week. For secondary school age swimmers of your stage it’s probably about 15 hours in the pool and a few hours of land work, consistently through the year, covering c50K per week in the pool. This will give the best chance of improvement. If you do half that number of hours/meters per week you will get about a quarter or less of the potential improvement. (Bill Sweetenham refers to 7-8 hours per week as the “twilight zone”).

No one can make top International level and achieve their full potential without maximal training both in the pool and on land. The two previous Cork Olympians in swimming went to other set ups in their last year before the Olympics, where they got 50%+ more quantity and considerably more intensity. But they had a background of consistency and high mileages in their own clubs. However, others have made great improvements in a domestic setting. One boy who swam for SWSC in the 1970s improved his 100m fly time by over 10% in the year between 14 and 15. He did this by upping his water time by 50% in the old 25 yard pool at Eglington Street.

You train long and hard so you can race better. Training results in improvement in both condition (termed physiological adaptation, with associated improvements in power and flexibility) and technique (behavioural adaptation in pacing; starts, turns and finishes; underwater and particularly surface stroke). It’s now a fashion in sports to say “enjoy what you’re doing”. It’s hard to “enjoy” getting out of bed at 5am on a dark, cold and wet morning to train for two hours (and repeating this more than 300 times in the season!). But it is necessary, if you are to achieve better and better performances in races. You should commit fully for each year at a time. Then at the end of each year you should assess your progress. How much did your competition times improve, did you enjoy the whole experience, how did you manage school and swimming, how good do you think you could be? Being as good as possible in competition is the really enjoyable thing! Being as good as possible in competitive sport is very time consumming but in the words of walker Rob Heffernan after the World Championships “It’s great when you win“.

How Anemia is Hurting Swimmers – Swimming World

“For many athletes, being perpetually tired is just a way of life. Training is intense, school has its demands, and often there are simply not enough hours in the day to check everything off the to do list. However, there is a distinct difference between feeling lethargic on a Thursday afternoon after three days of doubles, and having chronic fatigue that affects every aspect of athletic performance. Many athletes, especially females,  find themselves so tired that sleeping and relaxing more does not seem to have any effect on their energy levels, and they cannot perform their sport to the best of their ability. ”


Click here for full article.

Swim Swam – “The Best Breathing Pattern In The 100 Freestyle”

“The human body is equipped with two systems to produce energy for fast swimming, aerobic (requires oxygen) and anaerobic(no oxygen required). Both are used in tandem to produce ATP, the fuel for our muscles, but there are significant differences between the two energy systems that you should consider when choosing a breathing pattern for a specific race.

While the purpose of this article is not to describe these different energy systems in detail and how they work, it is to try to come up with the best possible breathing solution for the 100 freestyle. The reason that the breathing pattern in the 100 freestyle (and butterfly) is more controversial than for other distances is that for events shorter than 100 meters, the energy is predominantly derived from the anaerobic system. In events longer than 100 meters, the energy is predominantly derived from the aerobic system. In the 100 meters, the energy derivation is about half aerobic and half anaerobic.”


Click here for full article.

Nutrition for Aquatic Athletes

FINA President’ message
“It is my great pleasure to introduce the FINA Yakult Nutrition Brochure, a very useful publication aiming at giving practical information on an important matter: the nutritional needs of our aquatic athletes.
FINA is fortunate to have great Stars in our six aquatic disciplines and much has been said and
written about their meticulous and demanding preparation for our major competitions. The
technique, the biomechanics, the dryland training, or the prevention of injuries are recurrent
themes in the specialised literature, but I believe that the specific theme of nutrition also
deserves a thorough work like the one presented in this brochure.
Based on a specific Conference hosted by FINA and Yakult in London (GBR), in 2013, this
publication details all the aspects related to a healthy strategy in this field, highlighting the
specific needs in each of our sports. It has also in consideration different groups (young
athletes, female competitors…) and multiple situations (training, travelling, competition…).
Our FINA Sports Medicine Committee has been very active in researching and publicising all matters related with the health of our athletes. The organisation of the FINA World Sports Medicine Congress, every two years, is a concrete example of this effort and is already a fundamental rendezvous for all the experts in this domain.
I am sure that this brochure will, once more, be a powerful tool to disseminate this message in such an impor
tant matter.
I take this opportunity to sincerely thank all those responsible for its publication and I also express my gratitude to the experts that gave their contribution on athletes’ nutrition.
Finally, I address my appreciation and recognition to our partner Yakult for its involvement and support to this project.
The best reward to this valuable work will be given by our Stars. Thanks to these guidelines, their preparation will improveand, in consequence, their performances will be even better. This will continue bringing additional value to Aquatics in the five continents!”

Click here for full PDF