Tuesday, March 18, 2014

Should you do resistance exercise to failure?

Doing resistance exercise to failure is normally recommended for those who want to maximize strength and muscle mass gains from the exercise. Yet, going to failure tends to significantly increase the chances of injury, after which the ability to do resistance exercise is impaired – also impairing gains, in the long term.

From an evolutionary perspective, getting injured is clearly maladaptive. Prey animals that show signs of injury, for example, tend to be targeted by predators. There is also functional loss, which would be reflected in impaired hunting and gathering ability.

So, assuming that going to failure is at least somewhat unnatural, because of a higher likelihood of subsequent injuries, how can it be advisable in the context of resistance exercise?

The graph below is from a study by Izquierdo and colleagues (). They randomly assigned several athletes to two exercise conditions, namely resistance training to failure (RF) and not to failure (NRF). A control group of athletes did not do any resistance exercise. The athletes were tested at four points in time: before the initiation of training (T0), after 6 wk of training (T1), after 11 wk of training (T2), and after 16 wk of training (T3).

The graph above shows the gains in terms of weight lifted in two exercises, the bench press and squat. It is similar to other graphs from the study in that it clearly shows: (a) improvements in the amount of weight lifted over time for both the RF and NRF groups, which reflect gains in strength; and (b) no significant differences in the improvements for the RF and NRF groups.

When you look at the results of the study as a whole, it seems that RF and NRF are associated with slightly greater or lesser gains, depending on the type of exercise and the measure of gains employed. The differences are small, and one can reasonably conclude that no significant difference in overall gains exists between RF and NRF.

It is clear that going to failure leads to increased metabolic stress, and that increased metabolic stress is associated with greater secretion of anabolic hormones (). How can this be reconciled with the lack of a significant difference in gains in the RF and NRF groups?

The graph below provides a hint as to the answer to this question. It shows resting serum cortisol concentrations in the participants. As you can see, after 16 wk of training (T3) cortisol levels are higher in the RF group, which is particularly interesting because the NRF group had higher cortisol levels at baseline (T0). Cortisol is a catabolic hormone, which may in this case counter the effects of the anabolic hormones, even though going to failure is expected to lead to greater anabolic hormone secretion.

It seems that cortisol levels tend to go up over time for those who go to failure, and go down for those who do not. I am not sure if this is a strictly metabolic effect. There may be a psychological component to it, as strength and power gains over time tend to be increasingly more difficult to achieve (see schematic graph below); perhaps leading to some added mental stress as well, as one tries to continue increasing resistance (or weight) while regularly going to failure.

And, of course, it is also possible that the results of the study reviewed here are a statistical “mirage”. The authors explain how they controlled for various possible confounders by adjusting the actual measures. This approach is generally less advisable than controlling for the effects of confounders by including the confounders in a multivariate analysis model ().

Nevertheless, in light of the above I am not so sure that regularly doing resistant exercise to failure is such a good idea.


Stephan Raczak said...

Interesting review of the study. I personally started out with High Intensity Training (HIT) going to failure for 8 months but have dialed it back ever since. It's not necessary to keep growing.

Actually, this isn't a shameless plug - but I have just written an article on why it's not necessary to go to failure. It makes more sense to increase your overall work capacity by staying short of failure.


JamesSteeleII said...

Hi Ned,

I'd have to disagree with your concerns. There just isn't much data regarding long term training to momentary muscular failure (MMF) to indicate that it is a bad idea and more data to suggest that, at least for strength (http://www.medicinasportiva.pl/new/pliki/ms_2011_03_08_Fisher.pdf) and hypertrophy (http://www.medicinasportiva.pl/new/pliki/ms_2013_04_09_Fisher.pdf) it is likely to produce significantly greater adaptations.

Further, acute cortisol levels may actually be associated positively (albeit weakly) with lean mass gains (http://www.ncbi.nlm.nih.gov/pubmed/22105707).

Some of the 'bro-science' concerns regarding consistent training to MMF make the assumption that trainees are following high frequencies and volumes also. I;d like to see more data on longer term impacts of training to MMF when both are more moderate in comparison. I suspect the negative effect will be minimal if at all.

WilliamS said...

"I'd like to see more data on longer term impacts of training to MMF when both are more moderate in comparison. I suspect the negative effect will be minimal if at all."

I suspect James is right. Note that the training to failure was apparently *both* high-intensity and, by my lights, high-volume, i.e., 2x/week, multiple sets, 45–60 minutes per session. This was not Body By Science or RenEx style HIT. The to-failure protocol they used may have led to substantial overtraining, which you'd expect to be not the healthiest.

The to-failure training might also have led to higher strength gains if overtraining had been avoided.

I don't think this study says anything, really, about to-failure training in general, though it might possibly say something about the particular protocol they used. If anything I'd summarize the results as providing some very slight further evidence that it's not wise to overtrain.

john said...

Neither powerlifters nor weightlifters lift to failure, in the way that some bodybuilders do. The most effective strength workouts seem to be more sets, lower reps per set. Intensity would differ depending on level of athlete, with high intensity being tougher on elite lifters' bodies (sprinting is very similar in terms of training strategy).

Sometimes I do light singles or doubles up to a max set of 1-6, where I try to break a record, followed by a "backoff" set of -10% or so.

Other times I want more volume, doing several sets of 3 (for example), where I either repeat a weight a bit below of 3-rep max or increase weight in smaller intervals up to near my 3-rep max (in this case I still have the chance to break a record).

Ned Kock said...

Hi James. The association between cortisol and LMG in the study you linked was actually based on an unadjusted correlation, correct?

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JamesSteeleII said...

Hi Ned,

Yes that's correct. The full text is available via PubMedCentral through that link. I don't necessarily think that acute exercise induced cortisol elevations are causatively associated with muscular adaptations, though they might be in a hormetic manner.

I wonder on the real relevance of the cortisol data from Izquierdo et al. also. You noted that levels were higher in the NRF group at baseline. Both groups were alot higher than the controls strangely. Also the SD bars for the RF group are huge compared to the NRF group. It would be interesting to see some effect sizes as there was clearly far greater variability in response from the RF group.

On reading the article again I couldn't find any information on procedures for blood sampling, particularly timing, for any other time point than T0. The timing of further blood sampling relative to the training sessions could have impacted the results also.

JamesSteeleII said...
This comment has been removed by the author.
raphi said...

Until cortisol subfractions (recycling vs output vs sensitivity) are understood in terms of 'cortisol profiles' being conducive or not to certain metabolic states then it'll be hard to confidently link 'cortisol' levels to any aspect of mass gain...

See here (http://www.ketotic.org/2014/02/the-ketogenic-diets-effect-on-cortisol.html ) for how cortisol 'usage' and what can be inffered from measuring it signifies in terms of comparing someone in dietary ketosis vs someone burning sugar predominantly (for e.g.,..not to turn this in a fat vs carbs thing, just to illustrate the point about cortisols multidimensional character).

js290 said...

To add to James' points. Genetically gifted people who are prone to hypertrophy can probably do so with any stimulus: http://www.jappl.org/content/110/2/301.full

From my experience, the whole point of training to failure (HIT style, not crossfit style) is precisely for the metabolic effects. James and other HIT influenced people have talked about the notion of "there's no such thing as cardio."

When I started to understand the metabolic effects of exercise, I started to appreciate more the idea of how little exercise do you really need to confer the health benfits, not how much exercise you can tolerate.

"Cardio" like the lipid hypothesis will soon be understood to be a faith based proposition. A lot of what people call "exercise" may be better labeled as "recreation" which is fine to do unto itself, but may not have the metabolic conditioning effects that they're led to believe.

Richard said...

Thanks for the post on this, and all of your posts. My idea of the HIT is based on the research that I saw suggesting a few sets with 30 seconds between sets. Do the first set and all the sets to MMF. By the fifth set (the last one...) you can't do many reps. You can't do HIT like that for 40-60 minutes and, considering the research, I think it would be pointless. My background is that I am now 69 and many years ago I was a gymnast on still rings at the University of Michigan. I have been lifting weights and playing tennis for years. And for the last four years I have been on a very low carb, no wheat, diet, emphasizing higher saturated fats. And more cheese, along with supplementing D3 and K2, I'm 5'8" and 170, and very muscular, still. BP is 120 over 70. I don't take any medications. Proper HIT is the long term answer for strength and cardio, and although the program studied looks to me like serious over-training the strength increases seem very good over the 16 weeks.

Anonymous said...

My understanding is that the exercise science community claims that overtraining doesn't exist for reacreational lofter, and especially not for people who only do the bench press.

Ned Kock said...

Thanks for sharing your experience Richard!

Ned Kock said...

James, I checked the research that you have been doing on your site. Thanks for commenting and posting!

JamesSteeleII said...

Ned, no problem. I've not put much on the blog recently as I have been pretty busy. We've a number of papers under review at the moment though and I have just finished up analysing the data from some recent studies we've been involved in and am writing them up now. I'll update the blog once they are published.

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Anonymous said...

It's funny how my spouse can suggest for years on end that I should lessen the intensity of my strength training and I always dismissed the idea. After reading your article and turning 57, I'm ready for a change. I don't heal as quickly as I used to. After listing to failure for 25 years, it's surprisingly hard to do.

Anonymous said...

This is really interesting to me, as I have real problems with cortisol regulation - can't get a doctor to order tests, but I had elevated cortisol levels for many years and now I have low cortisol symptoms no matter what I do to raise my cortisol levels. High intentsity exercise has been recommended but I have trouble staying awake more than a few hours as it is, and I just can't face more exhaustion. I'm intrigued by recent research that people may develop cortisol resistance, much like insulin resistance in prediabetes. Since there's as yet no test for that, I figure my best bet is to treat it like insulin - of decreasing your need for insulin improves insulin sensitivity over time, then maybe decreasing my cortisol spikes will over time improve my sensitivity.

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