approach to coaching really brings out the best in your
performance" Chris, Berkshire
How Do I Stop The Burning Pain In My Legs When
|Have you come to triathlon from
team sports ? Are you naturally fast, but cannot
maintain a good pace over race distance? Do you
legs always start to burn after a few minutes training
or racing? Read on...
At our lake last summer (www.openwaterswim.co.uk)
I was asked the following question by a rugby player
who swims with us regularly.
Question: I'm new to triathlon but have played
rugby for a few years. I am really strong for the
first 10 minutes of any training session, but then
my legs burn up and I slow down dramatically. I
have a busy life style and only train about 4-5
hours a week. Can I stop this happening?
Answer: Team games are stop and go
sports. In rugby, the maximum distance you will
run in one go is anything up to 100m sprint, usually
a lot shorter. The sport involves powerful bursts
of energy, interspersed with longish recovery periods.
A professional rugby player is estimated to cover
about 8km in 80 minutes, of this only few minutes
will be all out sprinting, the rest will be jogging,
walking or slower pace running. On top of this all
rugby games have 10-15mins rest at half-time.
Playing rugby, the body has become accustomed to
running very fast over short distances, with longish
recovery periods. You must now teach your muscles
to sustain a slower work rate, but maintain their
power output for longer periods of time.
Triathlon is different from team sports. A typical
Olympic distance event, will take most age group
triathletes over 2 hours. Thus, to do well in competitions,
your body must perform at the limit of its ability
for over two hours.
A basic knowledge of the different energy systems
should help you to understand, why your "muscle
burn" is occurring.
The quickest form of energy is called adenosine
triphoshate, (better known as ATP). It is a high
energy compound, providing energy for muscle contraction.
ATP cannot be obtained from the blood or other tissues
for that matter, which means it is rapidly used
up, and can only power the muscles for a few seconds
at a time. Since ATP continuously needs to be resynthesised,
it is only really good for immediate energy.
For more prolonged activity our bodies must burn
off the food we eat to provide energy. Typically
fats are preferred for energy at slower work rates
and carbohydrates at higher effort intensities.
The rate that fats and carbohydrates are converted
into energy is measured by the rate of oxygen consumption.
Thus if someone has large efficient lungs powered
by a big strong heart, he will be capable of consuming
high volumes of oxygen. Having a large oxygen utilisation
capability (often expressed as VO2max) is no good
if your muscles are not trained to use oxygen efficiently.
In a triathlon 99% of the energy supplied to the
muscles is transported by oxygen (aerobically).
Consequently it is vital that you develop your aerobic
system to the maximum.
The other main energy source comes from the breakdown
of glycogen. But the by-product of this is lactic
acid. If all the energy for exercise is provided
aerobically, the muscles do not produce lactic acid.
However, above a certain threshold of intensity,
commonly called the anaerobic threshold (AT), the
pace of exercise uses up more energy than can be
supplied aerobically. The deficit is supplied by
glycogen and results in the accumulation of lactic
When you are sprinting on the football field, and
the heart and lungs temporarily can not meet your
muscles energy demands aerobically, the deficit
can be made up from the break down of glycogen.
Thus the body has a temporary method of keeping
up a high work rate even when it is in oxygen debt.
All debts must be repaid in full
When we use glycogen for energy (anaerobically),
we pay for it with a build up of lactic acid in
the muscles. When this happens, it inhibits the
provision of energy aerobically. It is very important
to understand this.
Triathletes must attempt to maximize oxygen utilization
and minimize lactic acid build up. Footballers on
the other hand, need maximum bursts of energy for
short periods of time and so anaerobic energy is
a vital top up for them when the aerobic system
can not keep up with demand. But footballers unlike
triathletes have a chance to recover within a game,
and thus allow some of the lactic acid to dissipate.
Going back to your original question, I would suggest
that your anaerobic system is highly developed,
allowing you to make many short fast sprints and
tolerate large quantities of lactic acid build up.
Since you find it easy to sprint, it is only natural
that you set off in training at too fast a pace,
even though it may be slower than your sprinting
speed on the rugby field. The lactic acid build
up in your muscles, is ultimately your undoing,
and prevents the transportation of oxygen. As you
struggle on, this leads to the burning sensation
you describe in your bike training, and then results
in your dropping back into the pack.
The heart is the mechanical pump for the energy
system, and your heart rate can be used to determine
how hard you are working and whether or not you
are working aerobically or anaerobically. If you
do not have a heart rate monitor (HRM), I suggest
buying one as they are very good tools to aid your
training. However, you should never rely totally
on the HRM. Listen to how your body feels, and monitor
at what speeds the burning sensation starts. Although
more difficult to do initially, listening to you
body while training will make you a better athlete
than if you just rely on a heart rate monitor, to
fix your training and race pace.
Research as has proved that, by training at, or
close to your anaerobic threshold (AT), you will
become more efficient, and able to hold a faster
pace without building up lactic acid. If you also
work close to the limit of your maximum rate of
oxygen consumption (VO2MAX), you will develop your
heart and lungs, i.e. make the system bigger, so
that you are able to pump more oxygen to the muscles.
In order to make your aerobic system bigger and
more efficient, it is important to have a rough
idea of your AT.
There are various ways recommended to calculate
this. It is not necessary to go to great expense
and have blood samples taken while training at different
intensities. A great starting point is training
at 80-90 % of your maximum heart rate. Unless advised
otherwise by a physician, you may want to run to
exhaustion, to find out your maximum heart rate.
A much easier, but less accurate way, is to subtract
your age from 220. To develop a tolerance to lactate
build up in the muscles, a 40 year old with a theoretical
max of 180, should train between 144 and 162 HR.
Over time and with training, you should find that
you are able to hold a slightly higher heart rate,
and race faster, before that burning sensation sets
To simplify the advice, my suggestion is for you
to raise your lactic threshold and try to improve
your VO2 max. This means interval training for about
30 mins a week in each discipline, with short rest
periods. Long rest times means more recovery time,
lactate levels will drop and oxygen consumption
rates will be lower.
Swim: 15x 100m with 1/3 rest, at 1,500m race
pace. eg: if you swim 1,500m in 30minutes aim to
do each 100m in 2minutes, take 40 seconds rest between
each interval (Note: It is difficult to monitor
HR while swimming)
Bike and Run: 6x5min @ 80-90% Max HR. Max
rest 4 mins. Min rest 2 mins
Note: Start at about 4 mins rest and try
to reduce it by 30 seconds each week, until 2 mins
As you train for only 4-5 hours a week, it is important
that your AT sessions do not go over 1/3 of your
total training time. If you do the three sessions
that I have outlined you will be just under 1hour
30 of hard training, which will be ok so long as
the rest of your training is easier aerobic work,(around
60-70% max HR). If the percentage of hard training
is too high you will be susceptible to injury or
These are sample sessions, even if you vary them
the principles are the same.
1. Try to do 3 AT sessions a week.
2. Keep AT work to 1/3 of total training time
3. Max HR attained during the hard efforts should
be no more than 90% of max HR.
4. Aim to get rest times down to about 30% of hard
interval training times.
Why not go beyond the article and have us train
you 1-to-1 to meet and exceed your running and triathlon
goals - contact us.