The Economist - USA (2020-10-17)

68 Science & technology The EconomistOctober 17th 2020

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Sports science confirms what common ex-

perience suggests: most males are bigger,

stronger and faster than most females.

They have bigger muscles, bigger hearts

and bigger lungs, as well as a greater capac-

ity to transport and use oxygen, stronger

bones and tougher ligaments. The advan-

tage that all this grants varies from sport to

sport, from around 10% in running to more

than 30% in weightlifting (see chart). But

even at the lower end of the scale, it is

enough of a difference that some talented

male teenagers—despite having yet to fin-

ish puberty—can outperform the best fe-

male athletes in the world.

It is a similar story on the rugby field.

Emma Hilton, a biologist at the University

of Manchester, presented data to World

Rugby on strength and speed in top-flight

rugby players of both sexes. These showed

only a small overlap in the speed with

which male and female players could man-

age a ten-metre dash. Even the bulkiest

male players were only a fraction slower

than the nimblest female ones. The paciest

males left both in the dust. Data on the

bench press, a weightlifting exercise that

emphasises the arms, shoulders and chest,

revealed no overlap at all. The weakest,

smallest males could shift 10% more

weight than the biggest, strongest females.

The strongest male players could lift over

60% more.

A great deal of this sex-based advantage

arises from the actions of testosterone. Be-

sides being the primary male sex hormone,

it is the original anabolic steroid. Doping

with it and its chemical cousins remains a

popular way of getting an illicit advantage.

Suppressing its production might, there-

fore, be expected to undo some of the ad-

vantages it bestows.

But what evidence there is suggests oth-

erwise. A review written after the work-

shop by Dr Hilton and Tommy Lundberg, a

physiologist at the Karolinska Institute in

Stockholm, summarises existing research

on the effects of testosterone suppression

in trans women. Drs Hilton and Lundberg

analysed 11 scientific papers. Three mea-

sured strength directly. The rest measured

either muscle size or “lean body mass”, de-

fined as total body weight minus fat. Most

reported changes of the order of a 5% loss

after one to three years of suppression—far

too little to remove the physical advantages

possessed by males. Participants in the

studies had testosterone levels below even

the ioc’s guideline levels, says Dr Hilton.

That suggests no amount of testosterone

suppression in adulthood can bring male

athletes into line with female ones

On the other hand, Joanna Harper, a re-

searcher at Loughborough University,

points out that few of the studies summar-

ised in Drs Hilton and Lundberg’s paper

measured sporting performance directly.

Most came at the question from a medical

point of view rather than a sporting one. All

focused on strength, she says. None mea-

sured speed. And not all the evidence

points in the same direction. In 2015 Ms

Harper published a study into transgender

runners, which suggested that testoster-

one suppression cut performance sharply.

Ross Tucker, a sports scientist who con-

sults for World Rugby, points out in turn

that Ms Harper’s paper covered only eight

runners, lumped together recent transi-

tioners with those who had made the jump

years earlier, and did not attempt to control

for other variables, such as levels of train-

ing. He says that studies of men taking

treatment for prostate cancer—which also

suppresses testosterone—show that exer-

cise can avoid loss of muscle altogether.

Health and safety

Faced with this imperfect, but suggestive,

evidence, World Rugby has come down on

the side of a ban. The sport’s authorities

weighed questions of fairness, inclusion

and safety, says Dr Tucker, but it was safety

that clinched the decision. He points out

that, besides the evidence on strength, the

size of a player’s skeleton does not change

after transition. The sport is already wor-

ried about concussion, a common rugby

injury now known to cause more long-

term damage than previously thought.

“When we say safety is our number one pri-

ority, that’s not just lip-service,” he says.

World Rugby plans to review the sci-

ence every three years, and to update its de-

cision if necessary. Better data may yet

emerge. Ms Harper is trying to recruit par-

ticipants for a controlled, longitudinal trial

of trans women and sporting performance

that would follow participants for several

years. Dr Lundberg is keen on doing some-

thing similar. But Ms Harper cautions that

it is likely to be a lengthy process. Finding

volunteers is not easy, she says.

In the meantime, the governing bodies

of other sports, particularly contact and

combat sports, have been watching World

Rugby’s deliberations, says Dr Hilton. She

thinks some may adopt similar guidelines

of their own.

A more immediate question will be

whether the rest of rugby does the same. Al-

though World Rugby can rule on what hap-

pens in international matches, it can offer

only guidance to national unions. Authori-

ties in England have already said they will

ignore this guidance and carry on allowing

trans women to play the women’s game

within England. Rumblings suggest other

unions in both the northern and southern

hemispheres may follow suit. Excluding

trans women from women’s sport may

conflict with laws—or proposed laws—in

some countries, including America and

Canada. If anything, the arguments are

likely to get louder.^7

Citius, altius, fortius

Source:E.Hiltonand

T. Lundberg

*Boysthrowa heavierdiscusin

competitionthanwomendo

Baseball pitch

Weightlifting

Cricket bowl

Tennis serve

Football kick

Track cycling

Track running

Swimming

7550250 100 150125

Male athletic advantage

% of female level

Female level

Athletic world records

Event Schoolboys Elite women

100 metres 10.20 (age 15) 10.49

800 metres 1:51.23 (14) 1:53.28

1500 metres 3:48.37 (14) 3:50.07

Long jump 7.85 metres (15) 7.52 metres

Discus* 77.68 metres (15) 76.80 metres

R

adio wavesdo not travel well underwa-

ter. That is why ships employ sonar

rather than radar to plumb the briny

depths. Messages broadcast through the

ocean need to be sonic, too. For that pur-

pose people often use acoustic modems,

which can turn electronic signals into

sound, and vice versa, like an old-fash-

ioned acoustic coupler for a telephone.

Such instruments need power, though.

And if they are sitting on the seabed, re-

placing their batteries is a serious chore.

But Fadel Adib of the Massachusetts Insti-

tute of Technology (mit) may have the an-

swer. A device he has created and tested not

only broadcasts and receives sound—it is

powered by sound as well.

The core of Dr Adib’s invention is called

a broadband resonator. Typically, an object

resonates strongly at only one or a few fre-

quencies. This is why a singer can shiver a

wineglass into fragments by holding a par-

ticular note—but only that note, and no

other. A broadband resonator, by contrast,

can receive or transmit sound across a

range of frequencies.

Dr Adib’s resonator consists of two nest-

ed hollow ceramic cylinders with a layer of

An aquatic device that extracts energy

from ambient noise

Submarine communications

Good vibrations