Muscular Endurance Training for Runners: Adelaide Running Coach
Muscular Endurance (ME), as defined by coach Yuri Verkhoshansky, is a muscle's ability to exert a high percentage of its maximum force for numerous repetitions. The required intensity required for endurance performance varies from discipline-to-discipline i.e. rock-climbers require different ME traits for solving complex boulder problems as compared to long-distance runners, however the underlying principles remains the same.
Strengthening a muscle's maximum force enhances its endurance potential.
A solid foundation of muscular strength coupled with good aerobic conditioning paves the way for quality implementation of ME training.
STRENGTH IS NOT ENOUGH
In understanding the essence of ME and why simply just being strong does not wholly correlate with enhancing endurance performance, we can look to the real-world example of powerlifters; they clearly exhibit principle #1 however we don’t see them winning any endurance events as their performances A. don’t require the development of a large aerobic base and B. require large amounts of oxygen-hungry muscle mass and associated added weight that would be highly inefficient to move over long distances.
ALL ABOUT FIBERS
This real-world example is underpinned by the physiological differences in muscle fiber types (the individual cells within muscles) and how those fibers are promoted via different strength training protocols.
Fast Twitch fibers (FTb) are crucial for promoting maximal force and are stimulated via training protocols aimed towards raw strength. The flipside is that these FTb fibers lack endurance properties due to having lower mitochondrial density (less energy-producing units) than their Slow Twitch (ST) counterparts.
In contrast to FTb fibers, Slow Twitch fibers (ST) have smaller cross-sections (less weight), denser capillary beds (aiding the exchange of oxygen amongst other processes), and higher mitochondrial mass (more energy-producing units). These ST fibers create an essential aerobic foundation, supporting the higher-intensity work of the third fiber type, Fast Twitch aerobic fibers (FTa). These intermediary fibers combine FTb strength with ST endurance, and promoting their development highlights the interplay essential for effective muscular endurance training.
In working to achieve optimal muscular endurance, understanding the relationship between Slow Twitch (ST) and Fast Twitch Aerobic (FTa) fibers is crucial so that we may better set the stage for, then implement, quality ME training.
WHAT DOES ME TRAINING DO EXACTLY?
In the words of coach Scott Johnston, ST fibers act as an "aerobic vacuum cleaner," efficiently utilizing the lactate produced by hard-working FTa fibers. If we are wanting to enhance FTa fiber endurance, then we must isolate and load the fibers near or at their endurance limit and in our attempts to do so, we have a couple of different levers that can be pulled:
Using event-specific training modalities.
Adding resistance where practical
Adjusting repetitions and reducing rest periods to create greater muscle overload.
In the case of ME training modalities (outside of regular weekly mileage or long runs), we can look to speed-work, hill reps, downhill conditioning, and strength work (using bodyweight, light resistance, and/or plyometrics).
GLOBAL VS. LOCAL FATIGUE
While effective at promoting significant muscle load, traditional Zone 3 or 4 intervals i.e. tempo and threshold runs, often induce significant global fatigue and require sizeable recovery times. In contrast, ME workouts can often be quite short in duration and target specific muscle groups with more repetitions (rather than significant weight) so recovery is generally much quicker and the fatigue less expansive.
On the topic of Zone 3 or 4 workouts, consider if you’ve ever experienced the following; a decrease in speed over the course of multiple intervals whilst also seeing a reduction in heart rate during those intervals. In this case, it could well be that the muscular fatigue accumulated in your legs is the primary endurance limitation rather than a lack of cardio. The reason being, if your muscles are forced to do less work due to fatigue, the heart simply doesn’t need to supply as much oxygen to them because the muscles can’t make use of it.
Returning to Scott Johnston (who noticed this performance reduction in his ski athletes), Scott implemented a multi-week, pre-interval ME block which led to immediate and impressive results once his athletes resumed traditional interval training. The skiiers displayed improved repetitions at higher speeds and heart rates, making subsequent traditional intervals more effective. This strategic approach to ME training, away from simply just doing harder intervals, prioritized local fatigue over global fatigue, allowed for quicker recovery, and ultimately enabled a higher volume of essential Zone 1 and 2 training to be maintained.
HOW TO DO IT
In looking at what exercises can be included as part of a ME workout, I highly recommend two sources of information from highly experienced coaches with extensive experience in both running and strength training circles.
Evoke Endurance (progressive workout is at the bottom of the article)
Both sources of information provide progressive workouts and feature video tutorial links demonstrating the various exercises.
Rather than provide an exhaustive list of workout variations (I will leave that to the more experienced voices above), the below is a summary of application that will hopefully create broader clarity over the workout specifics you'll find online.
Muscular Endurance (ME) training requires careful integration into a broader training program.
ME training is most effective when paired with a well-developed aerobic base.
The aim of ME workouts is to create local fatigue easily felt via a burning sensation in the legs; work in a 10-15 rep range and reduce recovery as strength improves.
This local fatigue is a powerful stimulus for developing running-specific strength, ultimately improving fatigue resistance or ‘fatigue-ability’.
If new to ME training, start with bodyweight only (this is especially true if one is new to strength training in general).
If weekly running volume is low, 2x ME workouts p/wk is fine. You might well find 1x workout p/wk is enough if you’re an athlete with slower recovery rates or are new to consistent run training.
Wherever possible, focus on movement patterns that are as running specific as possible i.e. dual and single-leg skipping, box step-ups/ step-offs, forward and/or side lunges, jumping split squats, stair-steppers etc.
6-8 weeks of consistent ME training is the minimum period to see sufficient gains.
In conclusion, ME training works, and under the right conditions, it works very well. We need to realise however that ME strength work is not a replacement for a lack of aerobic training. If an athlete has a huge multi-year base of aerobic conditioning, then they may well still perform very well at longer ultras (despite running lower mileage) by implementing ME training as part of their preparation, however if that is not the case, focus on consistently running more and add strength where possible.
