Women and Cycling - What makes women different to men ?
The fundamental difference between men and women
is that the latter have two X chromosomes whereas
the male has one X and one Y chromosomes. Although
the rest of the chromosomal make up of men and women is
the same the genetic differences caused by the differences in the
chromosomes are responsible for all of the differences between the genderes.
The Y chromosome contains the genes
for development of the testes - which produce the male
hormone testosterone. Although this hormone is also present
in women the larger amounts in males accounts for the male
primary and secondary characteristics including body
fat distribution and muscle bulk. Without testosterone all men would
be women ! On the converse females develop ovaries right from the
embryonic stage which produce oestrogen leading to the development
of female characteristics.
It is these fundamental differences in hormones which lead to the
differences observed between the genders. These can be summarised as…
biomechanical differences
physical size
body fat distribution and percentage
dietary requirements
effects of training
puberty and ageing
psychology and behaviour
Biomechanical differences.
Women tend to have relatively longer legs in comparison
with their height than men, with the thigh often accounting
for a greater percentage of leg length. These factors need
to be taken into account when setting up a female cyclist’s
position or ordering a frame. Long thigh bones mean the
saddle will need to be further back and the seat angle shallow.
However, women with short legs (relative to their total height) will need
a steeper frame angle and the seat further forward. Women also tend
to have a shorter reach and weaker upper body than men of a similar
height. This means that they need a relatively smaller frame size
to allow for a reasonable stem length to be fitted (8/10cms minimum).
As women are naturally more flexible a greater seat to bar height difference
can usually be accommodated. Too many women are wrongly advised, purchase
too larger frame and compensate by pushing their saddle forward and using
a short stem. Thus the handling of the bike and the potential power output are impaired.
Women also tend to have smaller feet than men. As the foot forms part
of the functional lever system when cycling the "109% of inside leg
length rule" for saddle height cannot be applied (Gregor and Rugg, 1986).
Indeed in one of the rare studies on female cyclists the optimum saddle
height was 107% of pubic symphysis height. This may not seem much
but computes to around 1.5cm for the "average" female. This study
only looked at 10 women and foot size was not recorded (Nordeen-Synder, 1977).
A women with a 28" inside leg and small feet would need
the saddle considerably lower than a male with a similar leg length
and size 12 feet ! Very little work has been published on the role
of foot size in cycling but it certainly has an effect on rider position.
Similarly, cra0nk length may need to be adjusted with smaller women ,
with petite feet, possibly benefiting from 165mm, as opposed to the standard 170cm, cranks.
The key muscles involved in the flexion and extension of the ankle,
and thus in transmitting force along the foot lever to the pedal
interface, are the calf (gastrocnemius) and shin (tibialis anterior)
muscles. The shorter the distance from the ankle to the pedal interface
(the ball of the foot) the greater the force required in this muscles.
Thus the rider with larger feet has a greater mechanical advantage over
the small footer rider.
Due to this mechanical disadvantage the fore and
aft positioning of the saddle is even more critical.
The saddle should be positioned so that maximum efficiency is
attained in the transfer of muscle power from the knee extensor
muscles (the quadricep group) to the pedal. Positioning the saddle
so that a point just behind the patella (knee-cap) is vertically
above the pedal spindle has been shown to be the most effective.
Similarly, a smooth pedalling action with minimum resistance applied to
the up-pedal stroke is required.
Physical size.
Women tend to be physically smaller than men.
Larger cyclists have a lower oxygen requirement
relative to body weight than small cyclists at
a given speed meaning that women are disadvantaged even
in flat time trials (Swain et al, 1988). In the hills percentage
body fat and absolute body weight are more important so most women
are again handicapped. Like their male counterparts small,
lightly built women are more suited to hilly courses than taller,
heavier riders who tend to excel at events on level ground.
Body fat distribution and percentage.
The key physiological differences between men and women
relates to the fact that the male hormone testosterone is
a much more potent anabolic agent than female oestrogen thus
men tend to have larger, stronger muscles and less subcutaneous
fat than women. On average women are 7-10% fatter than men. Top female
runners tend to have 12-20% body fat compared to 5-10% for their male counterparts.
This contrasts with 18-25% for elite female cyclists and 10-15% for elite males.
This additional body fat is a consequence of being female and a difference
that needs to be accepted by women athletes in general. Because body weight
is supported in cycling fat does not present such a drawback as in running
but accounts for the greater differences between men and women in hilly
events as compared to flatter events.
The additional body fat does not seem to offer any benefits
to women in endurance events even though up to 50% of the
energy requirements may be met through fat metabolism. This is because
a woman’s additional body fat is stored in localised deposits
or sub-cutaneously rather than intra-muscle. The differences between
male and female world records in endurance running events is greater
than in the speed events although there have been instances where females
have out-performed males. For example, in cross channel swimming several
of the records are held by women and the late, great Beryl Burton OBE
held the 12hr cycling record outright. In both these
events weight bearing is less than in running and, in
swimming, the higher body fat of women improves insulation
and buoyancy and reduces drag. However, in general, there is no
scientific evidence to suggest body fat offers women any advantages
in endurance events such as cycle racing.
Presently, there are no well defined limits
for body fat and inter-personal differences are great. There are many factors
which may influence disruption of menses, including weight loss, low weight,
nutritional inadequacy, physical or emotional stress, and levels of certain
hormones such as endogenous opiates and cortisol. It is likely that the cause
lies in a combination of factors rather than one alone.
reduced immunity from bacterial and viral infections
increased recovery time from training
reduced effectiveness of training.
In summary, whilst women cyclists should endeavour to keep their
body fat down to a reasonable level, they must ensure that their
diet contains enough calories and carbohydrate to support the rigours
of training and competition (Shangold and Mirkin, 1993).
Girls tend to reach puberty earlier than boys. This means
the advantages of early maturity seen in the junior boys ranks
are less prevalent in girls racing. It also means that whilst
13 year old girls will often be able to beat boys of the same age
in races, by the age of 14 or 15 when the boys have started to go
through puberty the advantage has been lost. Excessive exercise tends
to delay puberty by about 5 months for every year of training with the
associated medical, physical and psychological problems. At the other end
of the scale there is no evidence that exercise has any effect on the date of
the menopause. Exercise will however protect against some of the side effects
such as fatigue and bone loss although over-training may
exacerbate the problems.
The contraceptive pill offers women some protection against hormonal fluctuations
caused by increased levels of training. It also alleviates PMS symptoms and can,
in special circumstances, be used to manipulate periods but this should only
be carried out with the consent of a medical practitioner. The reduced blood
loss during "periods" will also be of benefits to athletes who often experience
anaemia. Although a few women may experience mild side effects (most of which
can be alleviated by changing formulations) the contraceptive pill, or hormone
replacement therapy, offers female athletes numerous benefits. There
is no evidence to suggests that these hormonal therapies have a deleterious
effect on athletic performance.
Dietary requirements.
Despite the observation that women tend to perspire less than men
there is no evidence that they need less fluid nor that they can tolerate
heat better. Women also need as much protein and fat as men relative
to their body weight. The dietary requirements for men and women are
broadly similar with a few exceptions :
fewer total calories : because less weight and less muscle mass
extra iron and calcium to prevent anaemia and maintain or promote bone density
athletes on the contraceptive pill should take a multivitamin / mineral supplement
as these drugs may affect absorbtion and metabolism of certain vitamins (Liska, 1997)
The absolute amount of carbohydrate required will depend upon the individual concerned
and the duration and intensity of training/competition. Total carbohydrate requirements
of 2000 calories per day are not uncommon even for women endurance cyclists.
However, experience has shown that most women cyclists (as in common with many
other female athletes) are over pre-occupied with their weight and underestimate
their nutritional needs. Like most endurance athletes women cyclists are often
guilty of eating far too little carbohydrate and would benefit from additional
intake without risk of increasing weight. This is due to an increase in the training
potential of the body and a resultant increase in metabolic rate (Anderson, 1997).
Training and recovery.
The differences between the performances of men and women athletes are
greatest in the lower ranks. This can be explained by the differences in
lean body mass and muscle fibre size.
Interestingly, the differences between the VO2max of elite men and women
athletes can almost all be accounted for by the differences in lean body mass,
red blood cell number and physique. Absolute maximal oxygen consumption (L.min-1)
is typically 40% or more greater in men than women of similar athletic standing.
When body weight is taken into consideration (ml. min- kg-1) this difference is
reduced to 20%. It decreases to less than 10% if expressed relative to lean body weight.
Thus body fat accounts for almost all of the differences in VO2 max between men and women.
The remaining differences being accounted for by physical (eg gait) and haematological
factors (Shangold and Mirkin, 1993)
Women use the same number of calories per hour of exercise as men -
(relative to lean body weight) and have similar ratios of Type
I and Type II fibres. The production and clearance of lactic
acid is also the same. Women, however, tend to have smaller hearts
than men and higher heart rates at the same level of exertion, even when
expressed as a percentage of maximum attainable. This needs to be taken
into consideration when prescribing training levels purely on heart rate
(visa vi BCF guidelines - which were based on a male). Using perceived rate of
intensity as an additional tool is recommended. A number of texts recommend
the equation 226 minus age for predicting maximal heart rates in females although,
like 220-age, this rule only applies in around 55% of instances ! The
variation in maximum heart rate and the relationship between VO2 and heart
rate varies considerably between individuals , thus all
athletes must learn to listen to their own bodies and training accordingly.
Psychology and behaviour.
The hormonal differences between men and women may also be responsible
for the distinctions in behaviour pattern. Testosterone and related male hormones
are often considered as responsible for aggression and drive. When training
females it is possible that they may need to be driven harder in order
to attain the levels of training overload needed for effect.
The gender gap.
Several articles published in the early 1980’s predicted that, based
on trends at that time, women’s athletic performances would catch
up with men’s by 1998 for the marathon and early in the 21st century
for shorter events. These predictions are clearly not going to be achieved.
Indeed, women’s records are now falling at a slower rate than the men’s -
both in athletics and cycling. Thus the difference between male and
female records is now wider than ten years ago as illustrated in the figure below.
It has been suggested that the decrease in the rate of
improvements in records is due to the success of drug testing in
reducing the use of anabolic agents (Seiler and Sailer, 1997).
Due to the lower normal testosterone levels women would clearly
be more advantaged by the use of such drugs and, conversely,
furthering records in the absence of pharmacological aids would
be harder. Nevertheless, records continue to be broken, all-be-it at
a slower rate by "clean" athletes based on hard work and dedication.
Summary
The effects of training on the female body are the same as the male
and the main differences between possible levels of attainment are
body fat percentage, physical differences in stature and the anabolic effects of testosterone.
Women athletes must learn to be proud of being female and accept their
differences (and not overly compare themselves with their male counterparts).
A rationalised and specific training programme coupled with a good diet and
appropriate recovery will help a female athlete attain her goals and help her compete
equally against other females.
|
