Interference Effects and Crossover Effects in Training

Can one form of training hurt or help another? This is an intriguing question to say the least. Let’s dive in.

Context is king. It really matters. We always have to consider the organism in question (you, me, the athletic beast), the current or long-term goal, and a multitude of other factors. “Yes, no, maybe, and it depends” are all valid answers. And despite what some say, you are allowed to say “it depends” as long as you explain the pertinent context.

An interference effect is essentially a negative impact of one form of training on the potential outcome of another. We’re looking for the answer to this question: “Will doing such and such training impair or inhibit the adaptations I’m gunning for with this other type of training?”

A crossover effect is basically an additive one in which the doing of one kind of training enhances or supports the gains achieved with another form of training. 

In order for this discussion to have some clarity and not be overly nuanced, let’s just arbitrarily lay out some simple terms in training and athleticism.

Strength and HypertrophyResistance (R)
SpeedSprinting (S)
Power (force-velocity relationship)High Intensity Intervals/Reps (HIT)
EnduranceLow Intensity Steady State (LIST)
Agility (mobility/stability/fluidity/reactivity)Agility (A)

The table above presents very basic and broad areas which define athleticism and the type of training which develops those capacities. There is plenty of room for interpretation and ways of subdividing each category. Our greatest challenge as Lifetime Athletes and healthy humans is to find the balance of training that gives us no glaring weaknesses in any capacity while at the very same time allowing us to maximize our abilities in one or several of those components. 

Here are some of the usual concerns:

  • A powerlifter’s primary goal is strength. No one would disagree. But how much of the other capacities do lifters need for their sport? And how little training in areas other than resistance can they get away with for long term health?
  • Marathoners need lots of endurance to go in a relatively straight line. Do they even need agility?
  • Team sport athletes (court, field, ice, etc.) need blends of all 5 of the major capacities. But how does this vary from sport to sport?
  • Swimmers exist in horizontal positions in a gravity-reduced environment. What is the value of “dry-land” training for aquatic specialists?

There are lots more examples than those above, but you can see how one might start thinking “What’s the best training for my sport and is that the same or different than the mixology of exercise I might want for longevity?”

Let’s look at one of the most common questions related to exercise interference and provide a brief answer.

Does cardio kill my gains? This is the classic question regarding aerobic exercise, primarily LIST, and how it impacts muscle size and strength. The answer is decidedly “No and Yes.” Doing a moderate (sometimes I hate that word) amount of walking, and low-impact exercise, per the Physical Activity Guidelines for Americans, will have no deleterious effect on the development of strength and hypertrophy. This will improve cardiorespiratory health and fitness and actually allow the strength athlete to train more effectively through greater workout endurance and recovery mechanisms.

However, have that athlete do a crap-ton (you can define this as you like) of jogging and other cardio work, including long-burn intensity classes, and gains will be inhibited. That kind of training drives hormonal signaling that is in opposition to muscle gains. Muscle is heavy and metabolically expensive, and more than moderate cardio strongly cues the body to emphasize endurance over strength and minimize muscle mass to the bare minimum to get the job done. A little cardio for a lifter is great but more is decidedly not better.

Now, on the flip-flop, here is a very frequently-asked question (VFQA) from runners.

Does cross-training have any value for me as a runner? I’ve got to start this response with some definitions. Cross-training (XT) is alternative mode aerobic conditioning and for a runner it might look like cycling, rowing, swimming, or other modalities. XT is technically not supplemental conditioning which might include supportive training such as stretching and lifting weights. Now for the answer and in true flip-flop fashion…it’s “Yes and No.” 

Running performance is highly dependent upon aerobic fitness which we’ll call metabolic economy. It’s also significantly related to neuromuscular skill which we can phrase as mechanical efficiency. Both matter but here’s where XT really helps the runner. We have a limiting factor which I term maximum absorbable workload. It’s fairly self-explanatory but it’s intensity x duration in a workout, and over longer periods such as weeks or months we look at frequency and ultimately volume. For most runners this is weekly mileage and we assume (although not always correctly) that they are doing similar workouts in a training cycle. This max absorbable workload is also termed max recoverable volume. I like workload better as a term because volume alone suggests only amount and not the quality of training. Whatever.

Any given runner at any given time period will have a max amount of training, performed as running, from which they can adapt and not break down. But if that amount is insufficient for full development of the aerobic system, XT will have a beneficial effect. Applied artfully (as all training should be), XT can get the runner the conditioning benefits of, say, another 10-15 miles per week without all the pounding and injury risk. 

However, once we’ve maxed out the aerobic system (or at least gotten close), the only way a runner gets faster is by more running. Specificity of training rules here, and we have to stimulate the neuromuscular system to develop the highest level of efficiency in the running stride. No amount of elliptical training will get those remaining percentage points. 

So, in summary (this turned out to be more of a ramble than I originally anticipated), a judicious amount of XT can be beneficial for most runners in pursuit of max aerobic development with reduced injury risk. But to truly run to your fastest potential, there are times when most of your training needs to be just running. 

I hope you enjoyed today’s discussion. My main goal was just to get you thinking about some of these terms. Maybe you’ll ask yourself things like “Am I getting all I can out of my training…are my workouts right for ME and my goals…can I change things up to get less interference and more crossover?” These are things I ask myself often. They are also the questions I help my coaching clients to answer on the way to better results in performance and health.

Share a comment or question!

This site uses Akismet to reduce spam. Learn how your comment data is processed.