"To do or not to do": Strength Training for Endurance Athletes


Have you ever experienced it? I know I have: I'm a decently trained triathlete. I've completed 2 Ironman races and multiple shorter-distance ones. Yet if I climb stairs 2 or 3 steps at a time, I'm winded and I feel it in my muscles. 

At other times, I pick up a six-pack of water bottles and pull a muscle in my neck or lower back.

What gives!!! We're supposed to be hard-ass Ironman athletes, the fittest people in the world right! 

Well no, not right at all. Not in my opinion at least. Sure as an Ironman athlete, you could swim/bike/run for 10-15 hours non-stop, but if you strain your back putting your icebox in the back of the car, there is something missing from the picture right?

I'll tell you another personal story: a couple of years ago, on a freezing December Sunday morning, I went for a long run in New York. I was a few kms away from getting back home when a woman walking her dog stepped out from a door right in front of me. I jumped up and sideways over the dog and leash, and... wrenched by knee. It was the worse pain I had ever felt, and I had to hobble the rest of the way home.

The strange thing was that the sidestepping movement wasn't all that extreme. It's the kind of movement you see football players practice on the field all the time. Heck I even remember Jane Fonda doing those movements in 1980s aerobics videos, leg warmers and all!!! 

It doesn't take a stroke of genius to understand what's going on: the reason this movement caused me so much pain was because my body was very well trained but in one plane of motion: front and back (sagittal plane). I had been running, cycling and swimming for countless hours in that sagittal plane, but my body was not trained to support me in any sudden movements in any other direction.

Which brings me to the topic of this blog post: would strength training address all these issues? Would it even make me a faster athlete? And if so, why? how? when? what?

So let me try to shed some light on the matter (and probably fan the flames of debate in the process). It's a gigantic topic, so I'll try to simplify it by answering the main questions that come to mind:

1- The Why: Will it prevent injury? Will it make me faster?

2- The What: what type of strength training is best for endurance athletes?

3- The When: how do I incorporate strength training into my endurance training?

4- The BUT: what do the opponents of strength training for endurance say, and is there any truth to their claims?

5- Nutrition: do I need to adjust my nutrition if I add strength training?

And I'll tell you what, this was one of the hardest articles I've had to write. The amount of information on this topic is absolutely immense, and only dwarfed by the number of examples I could have listed for injuries caused by muscle weakness in endurance 


So I tried to be as concise as possible, trying to demonstrate the main principles and leave it to you all to apply across the board. I'm also splitting this blog post into

two parts, Part I is what you're reading here, Part II will follow in a few days



I'll start by listing the perceived benefits of strength training for endurance athletes. The list below is based on countless research papers and articles I've read, complemented with my own experimentation and experiences.

After listing those benefits, I'll delve a bit into the evidence behind these claims, including the results of some studies as well as 




Perceived Benefits of Strength Training for Endurance Athletes

RUNNING: improved running economy, stronger/faster sprint finish, stronger hill climbing ability, injury prevention

CYCLING: injury prevention, improved economy, stronger time trialling and sprinting ability

SWIMMING: injury prevention, improved efficiency, stronger propulsion

GENERAL HEALTH: improved bone health, better hormonal production and balance


What does "running economy' mean anyway? Simplistically, better running economy means your

ability to run faster and / or for longer without expending more energy

in the process.

Better running economy can be achieved through multiple means, including better


(for e.g. midfoot striking as opposed to heal striking), deeper and more controlled


, faster


, etc.

How can strength training improve running economy? Well studies on that subject are 


  Some show small / insignificant improvements while others show no improvement at all.

However, one thing I noticed is that most of these studies involved elite runners who by definition are already very 


  with very good 


 and more importantly good physiology.

Why is that important? Well because

one of the main reasons non-elite runners have worse running economy is because of a weak core / stabilizers combo

. Let me explain:

Let's start with picture (A): in this scenario, during the "push-off" phase of the stride, the force generated by your calves and hamstring will be directed primarily

vertically upward

- this combines with the

forward lean in your body

to produce an

upward and forward motion

, moving you forward. Again, simplistically, the result is that

most of the force generated ends up moving you forward


Elite athletes tend to


 have that Picture (A) type position.

Now consider picture (B): because of unstable hips, the force generated by the push-off is directed

up and to the side

. A lot of that force is "absorbed" by the tilt in the hips, instead of being used to propel you forward (

note that this scenario significantly increases the risks of many running injuries, which I'll address below).

One more thing to consider here: this argument is even more critical for triathletes than runners: by the time we get to the run, we're usually already quite tired and our "core" has already been working non-stop through the swim and bike. This hip stability becomes an even more critical factor for us.

One study has shown an 8% improvement in running economy among runners who strength train twice a week compared to those who rely only on run training.

There is one other aspect of running economy to consider: muscle elasticity. Now if you're familiar with proper running biomechanics, efficient runners will use a combination of gravity and the natural "elastic recoil" of the body to be efficient over long distance. What does that mean? It means the following:

       Muscles and tendons are naturally elastic. They are designed to

store and release energy like a spring

. When your foot lands (when running), the muscles compress like a spring, and the tendons stretch like a rubber band, and then they both release, giving you that "bounce" (you can experience that for yourself if you stand barefoot and "lightly" jump up and down).

     ==> Multiple studies (e.g. Saunders et al in 2004) have shown that strength training and plyometrics

significantly improve the ability of muscles to use elastic energy and reduce the energy wasted in braking forces

(when your foot lands when running for e.g.), thereby improving overall running economy. 

A study by Millet et al in 2002 showed that heavy resistance training led to

improved max strength and running economy in triathletes with no significant effects on V02max



Here the evidence from studies is clearer: there seems to be a consensus that specific

strength training among runners does improve peak speed as well as reduce "time to fatigue" 

in anaerobic zones


What does this mean in everyday language: it means you will be able to

sprint faster for longer

(at the end of a triathlon or running race for example). In fact, not only that:

that same attribute will allow you to

sustain power for longer when going up a hard hill or stairs

when you need to tap into that anaerobic zone.

Studies have also shown that

strength training improves the runner's ability to metabolize lactic acid

accumulated during anaerobic efforts. This becomes a critical factor in events that involve sudden bursts of speed (for e.g. a run course with multiple 180-degree turns or when trying to "break" an opponent a la

Gomez-Brownlee London 2013 ITU Final


A study by Sedano et al (2013) of 18 well-trained male endurance runners split into 3 groups: endurance group (E), theraband and endurance group (TE), resistance, plyo and endurance group (RPE). 12 week results: TE and RPE showed

increased muscle strength, running economy, peak running velocity, and faster 3km time trial


A study by Mikkola et al (2007) demonstrated that a simultaneous

explosive resistance training and endurance program improved power output in cross country skiers without compromising VO2max, providing power needed to overcome hills and sprint finishes



Ahhhh, the big one.... where do I start? I'll just focus on the most critical ones: implications of muscle weakness on

joint stability and function

The list of examples of joint pains or damage resulting from endurance training is endless, but I'm going to focus on the most common complaints and how

muscle weakness

plays a role.

Let's start with the lower half of your body, where people suffer the most: knee pain, shin splints, plantar 


, hip pain, etc.

You see whether running or cycling, the plane of movement is always the same: saggital (front to back). Essentially, your hip, knee and ankle joints move in the same direction whether running or cycling. Some are designed ONLY for this kind of motion (knee) while others have a wider range of motion (hip, ankle). 

Why is this important? Well because this is how these joints are

supposed to be moving

when running/cycling, but muscle weakness and imbalances lead to inconsistencies in how they

actually move

during these activities.

Consider this: you're increasing your run volume (or even your cycling volume) but your glutes (muscles in your bum) are weak. You see the

main function of your glute muscles is to stabilize your hip and keep it pointing in the right direction

. You want to know what direction your hip is in right now? Squat down and look at where your knee is pointing, that's a good indication - if it's like the pic on the left, you're likely suffering from weakness in your glutes / core (OK YOU CAN STOP NOW! PEOPLE ARE STARING!!).

The scenario in the picture on the left is very common. When your foot lands during running, your knee turns inwards instead of pointing straight towards the front.

Now look at the red line, the "force" of the impact from running is being applied to the knee when it's "stressed" by being pulled to the inside. OUCH!!! The knee is only designed to move front to back,  not laterally!

But hold on a second, it is NOT your knee that's rotating inwards, it's your entire hip! Remember your knee cannot rotate, but your hip can, so in fact YOUR ENTIRE LEG is rotating inwards. This is putting tremendous "torque" and pressure on the ligaments around your knee, as well as your cartilage.

You often hear people talking about ITB syndrome as a cause for knee pain - well one of the main reasons for that is this kind of hip rotation. Your ITB runs alongside the outside of your hip, then crosses over the knee towards the inside of your shin (

see ITB labeled in bold in the pic on the left

). If your knee collapses inwards when running, this

stresses/stretches the ITB and causes it to rub against the bone, causing that miserable pain


What causes this? In most cases, it's muscle weakness and imbalance: your glutes are the ones supposed to keep your hip stabilize and tracking in the right direction.

Strong glutes will rotate your hip back to the correct angle where your knee points straight ahead, and will keep it there.

This is even a

bigger problem for female athletes

, because their physiology already puts them at a disadvantage in terms of the angles of force produced when running (that's one of the main reasons why female runners are not as efficient as their male counterparts, but that's a whole different topic).

So any further imbalances caused by muscle weakness in female runners put them at an even greater injury risk than male runners


The Cascading Effect

But wait, the story doesn't end there... You see when your knee collapses inwards like this, it leads to

more muscle imbalances elsewhere

: Because your knee is now towards the middle of your body when your foot lands, but you

still want to move in a forward motion

, your

foot and ankle now have to rotate excessively


 to compensate

Without getting into too much anatomy, suffice it to say that this puts tremendous pressure on the "inside" of your shins and causes your "arch" to collapse.

Side note on overpronation, shoe choices and orthotics

: you walk into a shoe store and they make you stand on this mat that tells you whether you have normal or high/low arches. Then they tell you: oh you have a normal arch so no overpronation, go for neutral shoes without any arch support. A few runs later and you're suffering from shin pains! What happened? 

For starters, don't get me started about the knowledge level of salespeople at run shoe shops in Dubai! 

Second: yes you may have a "normal arch", but then if your knee is collapsing inwards every time you run, it is causing your

arch to collapse anyway

, causing you to


, overloading your


and causing you shin pain, shin splints and possible stress fractures!! (thanks to my physio Darren for pointing this out to me)

This is just ONE example of how muscle weakness and imbalances in your lower half can lead to a number of joint-related pains and injuries.

Another area where muscle weakness can lead to injury is when

force is exerted on a joint in the wrong direction due to a change in terrain or sudden unexpected movements

. Examples include offroad running, obstacle courses, or even the sudden stop/turn/go motion of turnaround points on run courses. All of these scenarios put sideways pressure on your ankles, knees, spine and neck. 

If the muscles surrounding these joints are not strong enough to stabilize these joints, then you run the risk of "shearing", which is not only painful, but could lead to long-term injuries


I'll leave this topic with one more piece of information: a study by

 Chuter and Janse de Jonge (2012) showed that

poor core stability is implicated in the development of foot and ankle injuries, ITB Syndrome, patello-femoral pain (runner's knee), and ACL


I'll give you one more example of a similar problem in your upper body. No I'm not going to talk about lower back pain due to weak lower back muscles, because that seems like a no brainer! I will talk about a problem that's recently happened to me, and which I've discovered has plagued a number of triathletes and swimmers: neck and shoulder pain.

Consider the picture on the left. The Scapula is your shoulder blade, the big wide bone in your upper back. The upper trapezius and levator scapulae muscles act on it by pulling it 


, while other muscles around and below the Scapula pull it downwards. All in all, it should stay

stable / balanced

There is a common problem that is identifiable with swimmers: swimming develops strong shoulder and upper chest muscles, including the upper trapezius and Levator Scapulae.

These muscles start "pulling" the Scapula (your shoulder blade) "up and in", towards your neck

(indicated by the red arrows). This has to be 


 by all the other muscles stabilizing your scapula pulling it back out and down. But unless these middle back muscles are strengthened, they will get overpowered by the stronger muscles used when swimming (labeled Area of weakness). 

In fact, 

any movement that bunches your shoulders up towards your ears works those upper trapezius and Levator Scapulae muscles hard: swimming, lifting heavy objects, sitting at your desk at work, and even being tense (notice how your shoulders move up when you're feeling stressed). If you don't train the lower muscles to

"pull the shoulder blades" back down

, the Scapula will gradually start moving upwards,

compressing the nerve conduits around your spine

, causing neck and shoulder pain, numbness in arm and fingers, and potentially bigger problems if untreated. The fix? Just work your middle back and lat muscles in the gym to counterbalance all the work being done on your upper shoulder muscles (trapezius and levator scapulae). 

If you're already seeing symptoms, then you may have to combine the strength training with treatment to release the upper trapezius and levator scapulae muscles to help "bring the shoulders back down"



Improved Cycling Efficiency:

 studies published in July 2012 in the Journal of Human Kinetics have shown that strength training

improves the "negative" phase of the pedal stroke, improving overall power produced by 7% in the process

. This was especially visible in the final strong sprint efforts at the end of 3 hours of aerobic cycling

Improved Swimming Efficiency:

 it is no coincidence that people drool over the washboard abs of professional swimmers. They do a ton of core work. As you know,

streamlining is paramount for efficient swimming

, and if you have a weak core, your body will be flopping around in the water, pretty much the complete opposite of the streamlined arrow you're looking for - Second: you don't swim with your shoulder muscles, you

generate power from your hips and use the big lat and chest muscles to propel yourself through the water

. Again, the stronger these muscles are the more powerful your stroke is going to be (a good way to increase your "distance per stroke").

Better Impact Absorption:

 as we discussed above, and thanks to their "elastic" nature, your muscles act as your shock absorbers. The stronger these muscles are, the better shock absorption you'll have in running or other high impact sports.

Note: that is one of the reasons professional Ironman athletes tend to be "bulkier" than short-distance triathletes


Bone Health:

 studies have shown that the increased tension on tendons and ligaments induced from strength training leads to

bone growth and 


 Furthermore, studies have shown that lifting heavy weights causes a (very slight) bend in long bones, again spurring the growth and strengthening in the skeletal system.

Hormonal Health:

 this is a hotly debated topic but the evidence is more and more convincing:

endurance training lowers testosterone levels

in men (

let me know if you want to know more about why, how and what to do about it

). On the other hand,

strength training boosts anabolic hormones

(including testosterone), which has the added benefit of having a beneficial impact on

body fat, mood, and sex life

(as evidenced in a 2003 study comparing levels of 


 Hormone, DHEA, Cortisol and Testosterone between endurance athletes and strength training athletes - "Effect of Training Status and Exercise Mode on Endogenous Steroid Hormones in Males").




coming in a few days

), we shall address the optimal approaches to integrating strength training into your endurance training regime (the when and how), as well as any nutritional adjustments you may need to implement. Of course, there are people opposed to strength training for endurance athletes, so we'll tackle some of the most common arguments too.

Train smart, train hard, train safe.