What are the roles of training volume and intensity on performance?
There are three primary variables that can be manipulated in endurance training: 1) frequency, 2) intensity, and 3) volume. Frequency, of course, is how frequently ones engages in the training activity (i.e., how many times does one run each week). Intensity is the level of effort or output of each session. Training intensity can be low or high depending on the purpose of the session. Finally, volume is the overall weekly distance or duration that one spends engaging in the training activity. In the case of a runner, she may run 6 times per week (frequency) with 2 hard sessions and 4 easy/moderate sessions (intensity), giving her a total weekly mileage of 40 miles run. To progress, one of the three training variables, or a combination of training variables, are manipulated so that the runner sees progression over time.
Frequency is most commonly manipulated for beginner athletes. A new runner may run 3 times per week and progress this weekly frequency until she is running daily, sometimes even having days in which she performs multiple running sessions. More advanced athletes need to have training intensity and volume manipulated constantly or else they will plateau. However, the act of manipulating training intensity and volume is both an art and a science.
A few common questions that many endurance athletes have when looking at their training plan include: “How often should I train hard?”, and “How much should I train each week?” The answer will always be: “It depends…” This is a somewhat vague, but honest truth because there is no such thing as an exact volume and intensity of training that works for everyone. Even among a single athlete, there are a lot of factors to take into account when determining what is best in terms of their weekly training frequency, intensity, and volume.
Over time, however, research has begun to shed some light on what level of training intensity and volume may be “best practice” for long-term progression and reduction of injury and burnout. Notice here that I say, “best practice”, as that is what research tells us. It does not give us a prescription that should be applied to everyone as research has yet to proveanything in the realm of endurance sport. To prove something takes heaps and piles of evidence supporting ones claim with none or very little evidence to refute it. Over time, we have gathered evidence to support AND refute many claims, but sometimes the evidence supporting a claim is stronger than that which refutes it. This is where “best practice” comes from.
The research I discuss herein today, in the context of what other research says, provides us a piece of evidence that helps inform both athletes and coaches of what is “best practice” when it comes to training intensity and volume for long-term progression and reduced risk of injury and burnout.
Let’s dive into the research here before we put this research into context.
What did the researchers study?
Researchers asked 85 elite/world-class male distance runners to provide their best running times across different event distance as well as the number of the following types of run sessions they engaged in after 3, 5, and 7 years of structured, systematic training:
1. Tempo runs
2. Long-interval runs
3. Short-interval runs
4. Easy runs (recovery and aerobic)
Researchers then looked at the reported number and distance performed of each type of training session as well as their best times across each race distance they reported and looked at correlations between run session type and performance.
What are the major findings?
In sum, the researchers found large correlations on performance of total distance ran, volume of easy runs, volume of tempo runs, and volume of short-interval runs. Additionally, volume of easy runs and volume of tempo runs strongly predicted better performances.
What do these findings mean to YOU as an endurance athlete or coach?
Before we discuss the findings, I want to point out a couple of the potential limitations of the research here. First, this research was conducted in elite, and I mean very elite (the sample of athletes included some <2:10:00 marathoners…) runners. Most of us are not this caliber of an athlete and, therefore, these findings discussed herein should consider this. Second, researchers used a questionnaire to assess reported number/volume of training mileage and training sessions from 3, 5, and 7 years ago. There are certainly limitations to questionnaires that ask participants to report data from a long time ago, and so the accuracy of what the athletes provide is likely not 100% exact.
Now, what do these findings mean in the greater scheme of things for us endurance athletes? Well, first off, total distance ran was strongly correlated with and a strong predictor of performance. In other words, the higher the weekly running volume, the better the performance the athlete experienced. This we know to be true, up to a point of course, with higher weekly volumes being a greater stimulus for physical adaptation. Obviously, the athlete needs to be able to recover from the volume of exercise they are doing, so this is where the art of prescribing training volume comes into play as one has to know how much is enough and how much is too much (e.g., life stress, time constraints, travel, working hours, etc. all come into play here). In general, though, the more volume an athlete can perform, tolerate, and recover from, the better fitness benefits they will see.
Now, should ones training be easy all the time? Should it be hard all the time? Should it be easy 50% of the time and hard 50% of the time? This study didn’t aim to answer these questions, per se, but we do know from some prior research that the majority (~70%-80%) of one’s training should be easy. By easy, I mean aerobic or recovery. The researchers found here that volume of tempo runs and short-interval tempo runs were strongly correlated with performance. This makes sense as we know that tempo runs (moderately hard efforts of 10-20+ minutes) and short-interval runs (short, very, very hard efforts of 30 sec to 5-min) work to increase upper ends of one’s fitness, including VO2 max and anaerobic/lactate threshold. VO2 max and anaerobic/lactate threshold have been show to be highly predictive of performance, with higher threshold and VO2 maxes meaning a greater likelihood of success and faster times. Therefore, it is no surprise that these types of runs are associated with better performance. However, as I mentioned at the beginning of this paragraph, not all runs should be hard as prior research tends to suggest the majority of training intensity should be aerobic or easy.
Why? Well, easy and aerobic mileage develops our efficiency as an athlete (mechanical efficiency is also highly predictive of success), develops our cardiovascular and muscular endurance, develops our ability to burn fat as fuel. It does so while not stressing the body nearly the same as very hard sessions do. By doing A LOT of our work at easy intensities, we develop a very, very strong aerobic base of conditioning and can increase our total weekly volume with these types of sessions. You don’t want to increase total weekly volume by doing more intense sessions as this will be a sure recipe for injury and/or burnout in the long-term.
Consistency is our training frequency, training volume, and training intensity is the key to long-term progression. Smart manipulation of these key training variables, while keeping in mind that the majority of one’s training should be easy and/or aerobic, is paramount to improving fitness while reducing the likelihood of injury and burnout. The research here helps support these “best practices” that athletes and coaches should keep in mind when programming a training plan.
Train smart. Train easy often, and when it is time to train hard, train very, very hard.
Happy training and racing!
-Ryan Eckert, MS, CSCS
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