Is the number of push-ups a person can do a good risk estimate for heart attacks?

Question

According to this article below, people who can do more than 40 push-ups have lower risk of heart attack. Is this a valid claim?

https://www.sciencealert.com/what-new-science-says-about-men-who-can-do-over-40-push-ups

EDIT:

Actual journal article: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2724778

Answer 1

Yes, or at least, that's what this article in a reputable medical journal says and there is no reason to be more skeptical of it than the normal skepticism that any isolated article deserves.

The 10 year IRR they find is 0.04 (95% CI 0.01-0.36), after adjusting for age and BMI, which is a pretty strong effect. The article is not claiming this is the best or most predictive way to estimate risk, they are just pointing out that this might be a simple, no-cost method of assessing physical health (and note that they only tested men, and all of the men are firefighters).

Note that the study does not claim nor should be interpreted as causal: that is, it is unlikely that training to do more push ups has a substantial cardiovascular benefit. Instead, people who can do a large number of push ups for their age are probably among the most physically fit in other ways, too.

I think you can restate the claim to be "physically fit men have lower risk of heart attack than non-physically fit men of the same age and weight, and # of push ups is a decent estimator of physical fitness" and stated that way it doesn't sound all that controversial, and that's pretty much how the Science Alert article you linked to describes the results.

Answer 2

Limitations of the study:(3)

• First, the study assessed the association between push-ups and CVD events. The results do not support push-up capacity as an independent predictor of CVD risk. 

• Second, because the study cohort consisted of middle-aged, occupationally active men, the study results may not be generalizable to women, older or nonactive persons, other occupational groups, or unemployed persons.

Previous studies and research(3)

• Cross-sectional studies have incorporated push-ups in the assessment of muscular fitness and its correlation with cardiometabolic risk markers.In those studies, the authors found that a higher level of muscular strength was associated with lower cardiometabolic risk independent of cardiorespiratory fitness in the cohorts observed.

• Muscular strength has been shown to have an independent protective effect for all-cause mortality and hypertension in healthy males and is inversely associated with metabolic syndrome incidence and prevalence.

However, most of those studies were either cross-sectional or conducted with adolescent participants.

Hands down, this article and the research conducted is exceptional and one of it's kind. But one may fail to recognise that Heart attack itself is multifactorial disease and that's mentioned in the research paper-

The results do not support push-up capacity as an independent predictor of CVD risk. (1):

• Although complex disorders often cluster in families, they do not have a clear-cut pattern of inheritance. This makes it difficult to determine a person’s risk of inheriting or passing on these disorders.

• Secondly the other risk factors, just a few mentioned;

  • Hemoglobin A1c

  • Blood Pressure

  • Low‐Density Lipoprotein

  • Type 2 Diabetes Mellitus:

Are quite well established(traditional risk factors)

In 2016, the American Heart Association released a scientific statement concluding that “CRF should be measured in clinical practice… Indeed, decades of research have produced unequivocal evidence that CRF provides independent and additive morbidity and mortality data that when added to traditional risk factors significantly improves CVD risk prediction.(2)(5)

So alternatively physical fitness will help to keep the traditional risk factors within the range or in control,

let's see an example:

• In men, Cardiorespiratory fitness was indirectly associated with all CHD risk factors among men without CHD.

• Triglycerides and HDL demonstrated significant higher-order associations with fitness(2)

Let's look at another example:

Let's say there's an athlete (here)with familial hypercholesterolemia

• Now think, won't the athlete be able to do 40 or may be far more than that.

• Let's say there's another non-athlete with no history of hypercholesterolemia of same age and sex; he is not able to do even 5 pushups.

• But now it's quite tricky to think who will have a higher risk, but here it's also important to realize that this shows how and why multifactorial disease are difficult to screen and treat.

The example above may be rare, but they do form a part of medicine. In no way I want to prove that this article is far from truth, it's merely the part of a big big story.

This research,

• Paves a way for new ways of screening just as- self examination of breast in breast cancer is.

• May also be used in assessing risk in clinics provided keeping in mind the other risk factors.

• The problem with typical CRF testing is that it’s typically expensive, time-consuming, and requires special personnel this research may help in this aspect.

• Lastly a greater data is needed and this has to compared to the well established risk factors.

Conclusion: As a risk factor this has strong association but this may be true for one individual (or patient) and may be not for other, as case may be that even a healthy and fit, able to do 40 pushups easily have an heart attack (here)

References:

1:https://ghr.nlm.nih.gov/primer/mutationsanddisorders/complexdisorders

2:https://www.ahajournals.org/doi/full/10.1161/01.CIR.102.14.1623

3:https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2724778

4:https://www.heart.org/en/health-topics/cholesterol/causes-of-high-cholesterol/familial-hypercholesterolemia-fh

5:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1884475/

6:https://www.google.com/amp/s/tonic.vice.com/amp/en_us/article/jpnea7/how-does-someone-as-fit-as-bob-harper-have-a-heart-attack