There is almost no part of the population which does not benefit from strength training.
Certainly so, this applies to almost every physical activity we can think of - and endurance sports are no different.
How does strength training improve endurance performance?
First of all, let's determine what constitutes an endurance event such as a 5k run, a 20k cycle race, or a 1k rowing race.
Distance events (long or short) are predominantely characterised by repeated SUB-MAXIMAL contractions of the muscular system.
These contractions do not require a huge deal of force production compared to say a shot-putting or hammer throw event.
However, endurance events require a delay in fatigue to maintain sub-maximal force production over long periods of time.
Stronger muscles improve the body's ability to expend less energy with each contraction.
Less energy expended with each contraction means more energy left for longer and more forceful contractions.
This has likely to do with the fact that a) Fewer muscle fibers are involved in each contraction as they are now stronger and require less "support" from surrounding fibers - and b) Due to greater strength in the muscles and thicker connective tissue, there is now a greater recoil happening in each contraction - meaning that the musculo-tendonous system produces a more economic force transfer to propel the body forward (think of a spring).
Imagine the amount of foot strikes you take in a marathon run: what happens when you make those strides more forceful and less energy-consuming? Multiplied by tens of thousands of times?
The effect of stronger contractions gives you a faster running time and less fatigue towards the end of a race.
The second largest benefit of strength training for endurance sports is greater JOINT LONGEVITY. I consider this an equally important - if not MORE important - factor for better endurance performance.
Whil I argue that running is a sub-optimal activity for general health and fitness (as it mostly improves heart and lung function - compared to the mannifold benefits strength training gives), here is how a stronger body creates a longer endurance career:
The tendons, ligaments, capsules, connective tissue sheaths, and bones are exposed to thousands of impact moments in an endurance event.
In running, there is also ground reaction force involved with each stride - which means REPETITIVE IMPACT on the body.
There is inherently nothing wrong with impact as it provides a stimulus for our body to react and adapt.
However, when sudden impact happens hundreds of thousands of times over weeks, months and years of training, the body experiences MICROTRAUMA in the muscular and connective tissue system (picture microtrauma as a rubber band which is cut on its edges with a pair of scissors again and again).
If the body does not have the capacity to buffer the damage caused by repetitive microtrauma, pain and injury occur.
One response to repetitive microtrauma is inflammation - a natural mechanism that immobilises the joint to tell it to "rest".
The body says " Take it easy. I'm not ready to handle the stress you're putting me under."
Weak connective tissue is susceptible to pain and injury due to its inability to handle repetitive forces.
Stronger connective tissue can handle repetitive loads better, has greater resilience to stress, requires less energy and time to heal, and makes you perform better.
The crucial thing to understand is that tendons, bones and other types of connective tissue require HEAVY LOADING to become thicker and stronger.
When we apply a heavy load (say - 150kg deadlift for a runner) onto the muscular system, the muscles have to produce high amounts of force. This force is then transferred to the connective tissue which has to respond accordingly with an adaptation.
The connective tissue says "Hang on - this guy is serious about training. I need to adapt to a higher level."
It responds by growing, by getting thicker, and by laying down more connective tissue fibers. And now it can handle greater levels and frequency of impact.
Heavy squats are undoubtedly the best movement to build muscular and connective tissue strength in the knee and hip joint - two of the most common injury sites in runners.
Deadlifts are fantastic for building back health and strength (I argue that no other movement comes close).
Last but not least: upper body strength is important for endurance events as it provides structural balance across the body as well as improving performance in running due to a better arm swing. So get your press, bench press and pulls up to speed.
The goal for a passionate runner or other endurance athlete is not to deadlift three times their body weight or squat twice of the same.
The goal is to build sufficient amounts strength and resilience for a longer-lasting and more enjoyable endurance career.
Another reason for why STRONGER IS BETTER.