Sunday, November 30, 2008

Does Cardio Interfere with Strength Training? How 'bout "no."

A question that strength trainees ask at some point:
doesn't endurance (cardio) training interfere with strength training?

Great Question: Initially, starting in 1980 with Hickson, continuing through the 90's, as described in this super review by Andrew Burne, the answer was pretty much "yes."

Even more recent literature still seems to show that there is some interference effect, depending on volume/intensity of the types of training. More recently (2006) there has been a super article that says, ok, based on the findings that more consistently than not show an impact on explosive resistance training, let's consider what the molecular mechanisms are that may be involved to better tune training.

There's a couple new studies, however, lead by Davis [1][2] that revisits this issue of assumed "interference." These studies are interesting on their own, but are particularly useful for reviewing the key ideas around when and how interference happens, if it happens, and why keeping that VO2max KB work in with the strength program is a Good Thing - though there's some other mixes that may have awesome results, too.

Davis is the researcher who in Jan 2008 showed that the effect on delayed onset muscle soreness (DOMS) can be mitigated by doing some cardio between sets (consider accelerated fast and loose) rather than just resting. He and his group seem to be applying similar protocols to strength training. That is, in the first Davis study, he had a group do serial concurrent exercise protocols (CE = strength and endurance) and what he defines as "integrated." Serial means that the group did their resistance training, then they did their aerobic stuff. The participants rested between sets of their lifts. Pretty standard prescription.
In the "integrated" version, participants did their aerobic work *during* their lifts, effectively between sets. Their heart rates were significantly higher across the complete period of their resistance trainng than their serial colleagues. This is not standard. How many times have you heard "leave your cardio till after your workout; you'll tire yourself out and won't be able to lift"

Here's the kicker: the results. First, the cool thing is we're talking well conditioned participants, not newbies (what i don't know is if they're new to resistance though), but second, the results will surprise you: the mean lower body strength of the serial group went up 17.2%. Not bad at all. The mean lower body strength of the integrated group, however, went up 23.3%. Intriguingly, gains in UPPER body strength were higher in the Serial group than the integrated. As for Endurance, both groups made big improvements; the integrated made more. As for body composition, not surprisingly perhaps, the integrated group was significantly better: 3.3% for integrated, vs 1.8% for serial.

The main take away, according to the authors, is that when compared to single mode training for strength, the concurrent exercise, both serial and integrated, made as good or better gains than single mode. So take that, interference ideas. Also, that by going "integrated" the gains across every marker (but upper body strength), were better in integrated practice.

A cool thing also shown is that there seems to be considerable benefit to strength by adding a Range of Motion cool down, rather than just strength work alone (if you don't have ROM work, consider some zhealth (overview of Z)).

The overview of interference by the authors:
  • Many studies have postulated that training frequency is a variable as to whether or not interference occurs. There's nothing conclusive: "Evidence for the training frequency hypothesis is therefore suggestive but equivocal."
  • Poor (untrained) physical condition of participants in studies has also been suggested as a factor for interference (or not) "Most studies cited here that report interference from CE used untrained or sedentary subjects, whereas most studies cited here that report absence of interference or synergy used well-trained subjects. Studies reporting absence of interference or synergy in medium- to high-frequency concurrent training protocols invariably used well-conditioned subjects" Most of these studies looked at effects on endurance athletes, it seems, not the other way around, and that's where the money is for most strength athletes like hard style kettlebellers.
  • The usual hypothesis that timing of aerobic vs resistance work is a key factor, eg aerobics before, after or during resistance, isn't well established either. "The few studies that have evaluated exercise timing and sequence during concurrent training therefore suggest a possible effect, but its nature and prerequisites are unclear."
The authors suggest that their study adds credence to the hypotheses that more benefit accrues to the better trained athlete when adding endurance to strength work rather than strength work alone, and that frequency and sequencing of training are factors.

Ok, i'll go along with the study showed that there were benefits of adding vigorous cardio (and ROM cool down) to strength. Great. It's also pretty clear that keeping your heart rate up (not resting between sets) is also a benefit to strength. This approach well supports and advances what Pavel's written about not sitting down between sets but keeping your heart up (see Enter The Kettlebell (review) as an example with its discussion of what to do between sets), though the rationale there was not particularly because it *improved* strength gains or reduced DOMS (as far as i recall, anyway).

What i don't quite see tested, and so not supported in the article is the critical issue of frequency. The authors claim that their work is "consistent" with other research on frequency. Which? the work that has shown that negative impacts with more days a week vs fewer days a week? or work that showed even low doses were troubling? The authors picked a nice middle-of-the-road protocol of 3 days a week for training and ONLY three days a week and got nice results.

We do know, that for whatever the myriad of factors, total density of training is a factor in any training plan, balancing recovery and effort, as Kenneth Jay keeps telling me, more an art than a strict science. It's not hard to believe, therefore, that tagging on additional effort to an already loaded program, could have a negative impact, whether resistance or cardio.

So why might the "integrated" approach be a goodie? Davis et al don't know. They have a really neat hypothesis, though, related to their earlier work on "cardioaccleration" and DOMS (remember, they found doing cardio between sets reduced DOMS).
[T]he time course of DOMS reduction and elimination in both men and women trained in the integrated CE protocol is similar to the known time course of skeletal muscle angiogenesis, which may increase muscle perfusion during resistance exercise in the integrated CE group. The same mechanism could account for the apparent synergy of strength and endurance training in the integrated CE group. DOMS signifies contraction-induced muscle damage and consequent reduced capacity to generate muscular power for up to 72 hours (60), implying reduced responsiveness to strength training even in low-frequency (2 days per week) training protocols, whereas enhanced muscle perfusion increases muscle performance by up to 20% (44). The elimination of DOMS and consequent faster muscle recovery combined with enhanced muscle perfusion in the integrated CE protocol could therefore increase training adaptations compared with the serial CE protocol, as found in the present study, perhaps through the mechanism of enhanced postactivation potentiation of muscle responses to resistance exercises (11,12).
In other words, their integrated approach is reducing DOMS which means faster recovery, which means accelerated growth/performance.

When the DOMS article first came out, colleagues said they wouldn't want to sacrifice performance just to reduce DOMS - in other words the cardio during resistance would take away from the effort they could put in - they hypothesized. This latest study shows the reverse seems to be the case.

What does this CE result mean for our training?
Enhanced training adaptations from integrated CE, combined with the potentially related elimination of DOMS (15) and consequent faster muscle recovery (21), therefore have the potential to improve training and clinical outcomes in exercise programs at all levels.
It's worth looking at the article for exactly what intensity is being described in the CE protocol. Saying that, one of the big takeaways from the study is that, if the frequency is right (don't overdo your training. duh), and if you're already well conditioned, intense cardio + resistance are better for strength than strength work alone. If you want to take these benefits further, and enhance recovery, there's an opportunity to "integrate" resistance and "vigorous" / intense cardio.

So for folks who have been mixing up or integrating strength and intense cardio already (see the end of the Cardio/VO2Max article for examples of such protocols), this research just seems to add more support for the value of the approach for strength. What this result means for the rest of us? Well balanced CE programs are better for strength than strength training alone.


Jason said...


What another great post. You seem to be on a roll at the moment. Cardio/V02 rest periods etc. Followed the link to DD what a thread. eccentric/concentric VM breathing pattens, rowing vs snatching all manner of stuff.


dr. m.c. said...

Hi Jason,
thanks for stopping by and saying hello.
Interesting topic how all these systems connect and how, eh?

As kenneth also reminds me, there's so much we don't know about how we work - that's a plus for those of us trying just to get a handle and make sense of what is known. :)

drop by anytime.


Mike T Nelson said...

Good stuff! There is renewed interest in this topic again. Dr. Coffey presented some cool data on this topic at ACSM this past year where he took a group of highly trained endurance folks and a group of highly trained strength athletes and had them switch and they showed that the body will adapt (cardio bunnies gained strength and strength power athletes gained CRF). They are working on some similar studies to what you mentioned where strength and endurance are now mixed.

I tend to agree in that adding some "cardio" will improve overall performance to a degree. Specialization though always has a cost and mixing extremes will not result increased performance though (most top level body builders will not win marathons).

Keep up the great work
Mike N


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