We’re back again for the latest in my series on strength training for endurance athletes!
I’ve written previously about how and when strength training should be used in a nuanced way- it’s not as simple as ‘strength is always good!’ Check it out: here, here, here and here.
Now, the next question: is there a downside to strength training? Time costs aside, are there risks or detrimental aspects to including strength training in your quest to be a better endurance athlete? That is what I am taking a quick look at in this article.
Muscle hypertrophy:
First and foremost, based on my previous articles, we know the goal of strength training is to improve our running economy without losing any other components of why we run well. However, it’s not as simple as ‘build power, go faster;’ it’s about how you maximize your power-to-weight ratio.
The other consideration is that if you put on muscle mass, the ratio of the density of blood vessels carrying oxygen to the muscles vs. the volume of muscles they supply goes down – once again, hurting endurance performance.
The key with this is that higher rep, lower weight exercises don’t seem to give the same boost in performance that high weight, low rep strength work does. The flip side to this is that low rep exercises are what builds mass – something we don’t necessarily need to be faster. So, what’s the balance?
If you lift heavy weights 2x/week or more all year round, you’re going to build mass; that’s the bottom line. Of course, the exact answer will also be influenced by your physiology.
Some of us pack on muscle mass much more easily from a genetic standpoint. And then, of course, demographics like age and gender play a role – to no surprise, studies show younger males are better equipped to pack on muscle in response to strength training compared to masters athletes and women.
However, when it comes to the best-recommended strategy from my previous articles (something along the lines of 8-16 weeks of 2x/week strength training), do we see an increase in mass?
Generally speaking, the answer is no. For instance, here, here, here and here showed that strength training did not result in a significant increase in body mass.
However, many of these types of studies show mild hypertrophy in the muscle groups that were hit the hardest with the strength work – such as HERE. In general, a 3-6% increase in the size of the targeted muscles is seen after a 10-16 week cycle despite no overall increase in body mass.
So eventually, lifting heavy weights will make you a little too jacked to be your optimal running self, but our overall recommendation of a 12-16 week offseason plan seems to be a pretty safe space!
Endurance training blocks hypertrophy?
Another important consideration to all of this is that it’s believed that if we lift weights while we continue with our endurance training, the odds of building mass go down.
This intuitively makes sense; lift weights, eat and rest vs. lift weights and go for a run – one is promoting mass, the other is promoting a light frame that floats on land. At the biochemical level, researchers are working on elucidating this relationship between resistance training and endurance training.
Without getting into the details, there is a complex, multi-step biochemical pathway that triggers muscle protein synthesis. For instance, studies like these show that the protein kinases (enzymes needed in this muscle-building cascade) are inhibited by heavy endurance exercise.
In other words, continue lifting weights, eating lots, sleeping just as much, but add at least a moderately high level of endurance training into your regime, and your ability to get jacked goes down (or your ability to stay light goes up).
But as runners or endurance athletes, this provides some evidence at the biochemical level that if we keep running while we incorporate strength training, we have more wiggle room when it comes to avoiding the unwanted extra mass.
Muscle Soreness, Increased Fatigue
This one is very difficult to find clear research on because it’s so multifactorial. Really, I could write another series of articles on this. But, let’s review come clear concepts.
First, as we all know, if you’re doing squats for the first time in a long time (especially when it’s an 8 rep, 3 sets type of day) you’re going to be sore for 24-48 hours, maybe beyond. Now, if you’re doing that 2x/week, all of a sudden you’ve lost 4+ days of fresh legs where you can properly execute your high-end quality days which are so crucial to building your fitness.
Of course, eventually, you adapt, and the time lost due to strength training DOMs (delayed onset muscle soreness) eventually goes down. But is there a significant drop in fitness in the meantime?
While I haven’t been able to find any studies that talk about dropping volume and ramping up strength training to see how fitness is impacted, we can go back to a previous article I wrote about detraining when you decrease your volume.
The overall ideas are this:
– If you stop training completely, your V02max drops quickly
– If you maintain frequency and intensity and drop your volume, you can maintain your V02max for weeks, and your running economy for months.
– For instance, if you completely stop running, you’re likely to lose 5-10% of your V02max in a few weeks.
– In another study, I discussed how a 4-week drop in volume of 66% showed no drop in V02max and only a 1.2% drop in 5K performance.
So the first key is if you’re adding strength training into your plan, you want to maintain at least 50% of your volume if it’s a short period to prevent any significant drop in your hard-earned V02max. More running is probably better depending on your timing and goals.
Taking this to the next level, studies have shown that it can take multiple YEARS of consistent training to fully max out your V02max and lactate threshold. If you are still on an upward trajectory with your running, and the goal is to be a better runner, limiting everything within your control that takes away from your running volume in your development months/years is crucial.
It’s one thing to try to tack on some strength training on top of what you’re already doing; it’s another to take a 2-3 month hiatus from running to work on strength as a focus. Of course, that can be great for many other goals, but if the goal is to be a faster runner, that simply is not a good decision.
In addition to this, as was mentioned above, maintaining your endurance training will also blunt the muscle-building effects of strength training. In theory, this means you have increased odds of getting the boost in economy without the increase in mass.
Practical Applications:
This all conveniently brings us back to the recommendations from the previous articles:
– Do the real stuff in the offseason (low rep, heavier weights that hit key running muscles – squats, lunges, deadlifts).
– Complete your strength plan for 10-16 weeks (enough to see the benefits, not a super obvious risk of building bulk or taking away from your endurance training)
– Do not completely stop running- V02max will drop very quickly, and the odds of bulking up goes up.
If the goal is to be the best runner possible:
– More or less maintain your volume, drop a little if needed
– Maintain your frequency of quality days, but drop how hard they are
– Do this for a few months, and then stop and focus on sharpening your running without the fatiguing impact of strength training taking away from that focus.
So, is there a downside?
As always, the answer is: it depends. The two major possible areas of negative impact include:
– Having the strength sessions take away from your running training too much for too long. Ask yourself if you have the time and energy for this!
– Building too much mass and taking away from your power-to-weight ratio
The exact balance that avoids these detrimental outcomes while reaping the benefits will be custom to you. For instance:
– Masters and female athletes will have a harder time building mass – and have more wiggle room with how much resistance training they do.
– Your body type/physiology – you probably know if you’re the type to put on muscle quickly or if you could lift weights for months without seeing a change in mass.
Other considerations when looking at this risk include your goals and where you are with your training.
For instance:
– If your goal is to be a faster 5K runner, and you’re only running 20K/week, any ounce of energy you have should be spent on running more.
– If you have been running high mileage for many months or years and you’re looking to get faster, it’s almost a no brainer to look at a 10-16 week heavy strength block in your offseason.
– If your goal is to be able to run a decent 5K, but also be a better hockey player, skier etc., well then of course adding strength to the slight detriment of your running is a good idea.
At the end of the day, as always, it’s a multifactorial decision. So yes, there is the chance of some downsides to adding strength, but the presence and magnitude of those negatives depend on so many factors – including your physiology, goals and training history.
Hopefully, this series gave you some ammunition to make an educated attempt at doing the right thing with your strength training and endurance sports performance!
