Triathlon is an aerobic sport.

Posted on: January 23, 2019

As we have presented on numerous occasions, triathlon is an aerobic sport – whatever distance you race, it is aerobic! Therefore, most of your training needs to be aerobically focused. However, if used and performed correctly, strength sessions can be your secret weapon!

A little bit of biology

The body can only keep swimming, cycling and running for the duration of a triathlon if it is in an aerobic state. This means your effort must stay within your aerobic ceiling  (≥ 82.5% of max heart rate, top end of threshold) as this is where your body uses oxygen and fats as the primary energy source.

Energy production at aerobic levels is high, but “relatively” slow. In other words, you have a lot of energy available, but you need to keep the intensity low.

Glycogen (glucose in its stored form) is available for “fast burning” / “instant” fuel but in limited quantities. Glycogen is stored in the liver and muscles and is ready for immediate mobilisation for energy if needed.

When at aerobic intensities, glycogen is not needed. Up the intensity and effort and what happens? Everyone knows what happens – the body “bonks” or “hits the wall”!

Going at a higher than aerobic intensity levels means that the oxygen/fat metabolization can´t keep up the rate of energy demand. Your limited amount of glycogen stores will quickly run out (typically within 60-90mins – quicker still if intensity is elevated too high), meaning you literally run out of energy.

Simplistically, if you push above aerobic effort, the aerobic energy production pathway is too slow to provide the muscles with energy.

It is a very fine line between staying aerobic and tipping into anaerobic levels, it often happens without us being aware of it – until you bonk! This is where training at the right levels and using a heart rate monitor to monitor physiological signs is vital.

Strength session performed aerobically

Having said the above, we are now going to say that all triathletes should incorporate STRENGTH sessions in the swim, bike and run!


Strength training often paints the picture of ANAEROBIC workloads.

However, we prescribe strength sessions in a strict and precise way. By following our strict instructions strength training can and will be aerobic.

First, let’s establish that strength training is to build the musculoskeletal system (the body’s external muscles) and NOT the cardiac muscles (heart, lungs, etc). Any feedback from triathlon strength sessions MUST be felt in the legs, torso, core and arms. The heart and lungs should not be stressed; ie heart rate and breathing rate remain low.

You need strength training for many reasons:

  • to help build / maintain muscle mass
  • increase force production of the limbs
  • to keep muscles, ligaments and tendons healthy
  • increase / maintain testosterone levels (in men and WOMEN 1)
  • movement patterns ingrained faster
  • trains the neuromuscular system – nerves **
  • burning excess fat
  • mental toughness training

The list goes on. But one other reason we incorporate strength training aerobically is because it develops MUSCULAR ENDURANCE.

** The neuromuscular system is a system overlooked by almost all endurance athletes. This system is responsible for passing messages to muscles to get them working. If you do not expose it to high intensity training, it won’t develop.

Most people in endurance sports will experience neuromuscular system burn out. Think back to past races, when you came to a hill or at the end when trying to sprint finish. Your heart rate and breathing rate isn’t massively high.  Your muscles feel ok and aren’t burning, but you just can’t get the limbs moving any faster. This is because your nerves have fatigued and no longer able to pass on messages.

Muscular endurance

Muscular endurance is very important for triathlon! Not only do you need your aerobic system (everything involving oxygen transfer and delivery – heart and lungs) to be functioning at its peak, you need your muscles and neuromuscular system to be in tip-top shape too.

Low intensity aerobic training doesn’t place enough stress on the muscles and neuromuscular system – the body is too efficient at producing energy to stress them. This is where strength training comes in.

Introducing sessions that induces muscular stress and gets the neuromuscular system firing is vital if you want to perform strongly and on demand.

Sport (triathlon) specific strength sessions

You should perform strength training in each discipline of triathlon.

For most, there isn’t enough time in the week to sacrifice more time to a trip or two to the gym. Not only this, but no matter what you do in the gym, it is not truly specific to the sport you are doing it for!

(As a rule, only athletes we coach that consistently commit to 12hours + per week to TRIATHLON training are allowed to add extra time to gym sessions**)

** If you have been prescribed strength-based rehabilitation exercises, that’s different – keep doing these movements.**

How to make sessions strength based in each discipline:

  • Swimming – using hand paddles (ones the size of, or slightly bigger, than your hands)
  • Cycling – STOMPing down against a high resistance at a low cadence
  • Running – hill reps at 4-6% incline or speed work

Each of the above follow the same principal as that in the gym – want to stress the muscles and neuromuscular system? Move more load.

Hand paddles add a solid and slightly larger surface area to the arms.

STOMPing on higher resistances at lower cadences is loading up the body like squatting. Low cadences doesn’t mean you slow down, it means the resistance is such that you have no other option!. Tom Donhou, bike frame maker made a 104t front chainring to test maximum speed!

Running up hill or at speed on flats gets the body firing (contracting muscles harder) and moving your body weight.

The secret to aerobic strength training

Without being strict with two training variables, strength training can quickly turn into threshold training. Threshold training is hard work but is not a place you want to spend much time! Threshold training is known as the red or grey zone, where you train junk miles and develop the “One Speed Syndrome”.

The two key variables are REST and DURATION.

Rest is GOOD

Strength sets should have plenty of rest. Having adequate rest will allow the body to recover after each rep and stops the aerobic system from becoming strained. Resting means your body will have recovered and is able to load up the muscles to the same intensity, for the number of reps required.

Short… Durations

The duration of each repetition in a strength session should be short. 25m swimming, up to 1min STOMPing, up to 1min running. Keeping the reps short will ensure you work your skeletal muscles, and the effort isn’t too long that they fatigue and load up t aerobic system.

The idea is that you perform the strength reps to the best of your musculoskeletal systems ability.

If you fatigue too soon and your aerobic system kicks in to take over (because the rest and duration has been inappropriate set), it means you won’t be strength training anymore. It’ll be threshold training – the grey zone you should be trying to avoid!

Note, if you reach the point that the aerobic system takes over, you are no longer able to sufficiently work and stress the skeletal muscles. You won’t be stressing the muscles and neuromuscular system and won’t elicit a strength adaptation.

Besides, you’ll know if a strength session tips into an aerobic state – your breathing rate will increase to a point you cannot talk, or you can no longer breathe only through your nose. You’ll feel your heart beat pounding in your chest and temples.

Don’t neglect swim training

A final point, don´t underestimate the importance of the swim element of a triathlon. It has a big impact on your overall performance than you know. Ignore swim training, aerobic or strength based, and the bike and run legs will suffer!

The sessions

The attached strength sessions contain the key main sets for developing strength in the triathlon disciplines.

You should complete these sessions once per week, just not on consecutive days (especially the bike and run sessions). Remember, rest is important, both in the sessions but also in the days surrounding the sessions!

To get the best out of the strength sessions you will need:

  • Swim – hand paddles, a pull buoy or buoyancy shorts (make sure they provide enough lift – add a second pull buoy or use a pull buoy and buoyancy shorts) an ankle band (make one from an old inner tube)
  • Bike – a turbo with magnetic resistance levels*, gym spin bikes, Wattbikes or a local hill**
  • Run – a local hill**, track or long flat road/pavement

* turbos with the manual magnetic resistance levels tend to be the only turbos that provide enough added resistance to force a low cadence and elicit a strength response

** Local, so you don’t have to spend an hour getting there and back, which cuts out on strength training time.

Make sure you periodically refresh yourselves on what the sessions should feel like by re-reading the above or one of our previous blog, Types of sessions. Get the sessions right and you’ll have a healthier body, tougher mind and faster season!

You can modify the sessions after completing the 6-weeks provided. Strength rep duration slightly increased or the total number of reps increased. Don’t forget the rest!

Swim Strength Sessions

Bike Strength Sessions

Run Strength Sessions



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