Break points and Thresholds in Health and Fitness
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In studying and learning principles of nutrition and physical fitness, you’re bound to bump into research and data regarding diseases, risks, and outcomes. You’re also going to rub shoulders (is that the expression?) with stats. There’s plenty of overlap, and it’s helpful to know where some of these other concepts apply to the gains you’re after.
Most things are linearly related. Generally, you eat more, and you’ll gain some weight. Likewise, if you eat less, you’ll lose weight. The magnitude of movement in either direction is proportionally associated with the magnitude of energy consumed or restricted.
For example, if you stop eating, let’s say, for three days (not recommended or advised), you’ll lose the most weight you can and do so the quickest in that amount of time compared to other protocols. If you eat about half of what you usually do, you’ll lose about half of what is maximally possible for you (also not recommended or advised). If you eat just a little less, you’ll lose a little bit of weight (which is the advised strategy), and it will be a slower process.
If you overeat a little bit throughout the year, you’ll slowly put on weight. If you go to a buffet and try to put them out of business in a single sitting, you’ll store most of that energy as additional weight (fat/adipose) over the next few days—a lot of fat tissue deposited very quickly.
This relationship is linear, thankfully—although sometimes it certainly doesn’t feel like it, which is part of the problem with weight loss.
However, there are many areas in health and fitness that do not have linear relationships, which is where it’s helpful to know about breakpoints and thresholds.
Sometimes it may happen that the relationship between the response and some explanatory variables is non-linear, showing a few values where the effect on the response changes abruptly. These values are called break-points, change-points, transition-points or switch-points; the word ‘threshold’ is also used, but some authors use it just when there is no effect on the response before of such a value. [1]
That is, there may be no observable effect or a very weak one until, for some reason, a threshold is reached, and then something manifests exponentially, something skyrockets, like it reaches escape velocity, and it just takes off. In physics and engineering, even business, this threshold might not be met without a critical mass—the minimum amount of something needed to get the system going. And once it’s going, it’s really going.
One paper—A Pooled Analysis of Waist Circumference and Mortality in 650,000 Adults [2]—looked at, obviously, the associations of waist circumference and all-cause mortality. Most of us can intuit this association. More is not better in this case. “Waist circumference was strongly and positively associated with all-cause mortality for both men and women.” Also, and unsurprisingly, larger waists are associated with higher BMI (body mass index), and these associations track pretty well irrespective if a person is a smoker or not.
For women, the relationship appears to be linear. Smaller circumferences have the lowest associations with all-cause mortality, and the numbers trend up in step with growing waistlines. Fortunately, there doesn’t appear to be a break-point or threshold. “Women with a waist circumference of 95 cm [about 37.5 inches] or greater had 80% greater mortality risk compared with those with a waist circumference less than 70 cm [about 27.5 inches].”
With guys, though, unfortunately, there is a break-point. There seems to be a small hazard ratio with waist circumference and mortality up to a point. When that point/threshold is met, the hazard ratio breaks out and spikes. This study found that the break-point waist circumference for men is 38 inches (about 96.5 cm). Then, a small increase catapults the risk: “Men with a waist circumference of 110 cm [about 43 inches] or greater had 52% greater mortality risk compared with those with a waist circumference less than 90 cm [about 35.5 inches].
Since people are not homogenized in height and body composition—the ratio of body fat to fat-free mass—a 38-inch waist sits differently on each person, so a common heuristic I hear in this space is that guys should focus on getting their waist circumference to be under half of their height. If you’re 70 inches tall, try to keep your waist circumference under 35 or thereabouts. With women, a smaller circumference is generally better.
With food and nutrition, again, most risk factors are linear, which in my view is a good thing. It makes things easy to know, see, and control. The more we lean into unhealthy foods and behaviors, the more we can expect negative outcomes (non-communicable and metabolic diseases and major adverse cardiovascular events), and we can expect them sooner.
Example: the more that sodium in your diet increases so too does your risk of mortality [3]. Interestingly, but not surprisingly, this is also the case for processed meats, which likely has a lot to do with the amount of sodium. A single serving (two ounces/a couple of slices) of Oscar Mayer ham has 500 mgs of sodium, almost a quarter of a single day’s recommended intake. (I grew up on deli meat, so I’m not hating for hate’s sake.) Imagine having a couple of servings at each meal of this or something similar, and then doing so over a long enough period—years even.
Knowing little things like these associations can do wonders for our health. We can be armed with the knowledge of what to look for. If we find ourselves in a situation where we’re choosing some of these foods, or even have few options, we can at least mitigate some of the risk by keeping our intake low.
On the fitness side of things, fortunately, there are no break-points. In fact, exercising more does not necessarily result in a linear increase in fitness gains. Ironically, as a newbie embarks on any fitness regimen, they can get some robust results by doing very little, which lends itself to being a problem because they often want to do more than they need to; they think they’re not doing enough, and more must be better.
In weightlifting and resistance training, Dr. Patroklos Androulakis-Korakakis (Dr. Pak) did his PhD. research on what’s called the minimum effective dose, as one of his papers—a systematic review and meta-analysis [4]—seeks an answer to: “What is the minimum one needs to do to increase 1-repetition maximum (1RM) strength?” He and his coauthors concluded that
Performing a single set of 6–12 repetitions with loads ranging from approximately 70–85% 1RM [one repetition maximum] 2–3 times per week with high intensity of effort (reaching volitional or momentary failure) for 8–12 weeks can produce suboptimal, yet significant increases in SQ [squat] and BP [bench press] 1RM strength in resistance-trained men.
Yes, even in trained men, a single work set done with high effort and performed as little as twice a week can still result in strength gains. That’s nothing. If any coach or trainer worth their weight in whey protein were to see a workout program with a single set done twice a week, they’d say, “Aw. That’s cute.” If well-trained men can get away with doing so little and still see increases in strength, what do newbies need? Almost nothing. Seriously.
As a trainee becomes adapted to doing more work, their work capacity increases, but just because work capacity increases, it doesn’t necessarily mean more work is better or that more work will result in more or better results. As work volume is one of the primary drivers of muscle growth, we tend to think that if we do more, we’ll see more results, but that’s simply not the case.
“It is important to emphasize that the relationship between volume and muscle growth is unlikely to be linear. That is; continual increases in training volume would inevitably lead to a plateau in the development of muscle mass” [5]. And you can continue adding more work, but the plateau is likely to continue, and then there’s a point of diminishing returns, or even regressions. This point is different for everyone and depends on your training status and other contextual factors.
And this doesn’t just apply to weightlifting and resistance training. It holds true for cardiovascular adaptations as well. You don’t need to do full-out sprints multiple times a day and multiple times a week to increase your cardiorespiratory fitness. I don’t know what the minimum effective dose is here, but I’d wager it’s similar to Dr. Pak’s finding for strength gains.
The idea here is that there’s no break-point for exercise. We don’t reach some threshold or critical mass, and then our results skyrocket. We just have to do enough, which is not a lot, to create the adaptation stimulus; then, we give ourselves time to recover and physiologically adapt with adequate nutrition and rest, including sleep. Repeat a couple of times a week and that’ll get us the majority of our benefits. So, when it comes to not having time to exercise—it’s possible but not likely.
Becoming and staying healthy and fit is much easier than a lot of people make it out to be. It comes down to a series of small decisions and actions, each seeming to be not very significant or have much effect on its own, but those actions and decisions add up and can be captured in one of my favorite lines of all of literature, from David Mitchell’s Cloud Atlas: “What is an ocean but a multitude of drops?”
