SCIENCE FRIDAY FOR ATHLETES: PUSHUPS FOR LONGEVITY AS WELL AS STRENGTH

Firefighters tackling a blaze in Montreal Canada. Mtlfiredude [CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0)] https://commons.wikimedia.org/w/index.php?curid=53584345

PUSH-UP CAPACITY MAY MEASURE CARDIOVASCULAR RISK There are several exercise tests that have been proposed as methods of predicting longevity including hand grip strength, sit-to-rise, and 6-minute walk distance. Recently, Dr. Justin Yang of Harvard University’s T.H. Chan School of Public Health and colleagues from other institutions turned the spotlight on the ‘push-up test’
 
The group of scientists sought to determine whether a simple exercise test, not requiring specialized equipment or technology, in a medical office setting could be used to objectively “assess the association between fitness and cardiovascular disease risk”. 
 
They felt the most commonly used subjective assessments of cardiorespiratory fitness (CRF), based on self-reported accounts of physical activity and health and lifestyle questionnaires, weren’t accurate or adequate. It seems that the results of objective tests of aerobic fitness show that we aren’t as fit as our own estimates of physical activity would predict.
 
The results of their research, which studied 1104 male firefighters between the years 2000 and 2010, were released in a Journal of the American Medical Association Network publication (JAMAnetwork.com) in February 2019. The full article, “Association Between Push-up Exercise Capacity and Future Cardiovascular Events Among Active Adult Men” is available online, free of charge.
 
Data was collected from baseline and follow-up assessments of firefighters 18 years of age or older (mean age 39.6 years and body mass index 28.7) with no job restrictions. Information from a self-administered health and lifestyle questionnaire, complete physical examination, anthropometric measurements, lab analysis, and fitness testing (determination of exercise tolerance on a treadmill, plus push-up capacity) was gathered and analyzed, as well as occupational and clinical health outcomes.
 
Cardiovascular disease events tracked during the study period were defined as a diagnosis of coronary (heart) artery disease or a major cardiovascular disease event, like heart failure or sudden cardiac death.
 
To determine pushup capacity at the time of baseline and follow-up testing between 2000-2007, each “firefighter was instructed to begin push-ups in time with a metronome set at 80 beats per minute” until “the participant reach 80 or missed 3 beats of the metronome,“ or stopped voluntarily or because of medical symptoms noted by the clinical staff.
 
In the research analyses, 5 categories of 10 push-up number increments were created (0-10, 11-20, 21-30, 31-40, 41+).
 
Results:

• Firefighters who could perform a higher number of push-ups had correspondingly lower measures of independent cardiovascular disease (CVD) risk factors at baseline. They were younger, had a lower BMI, lower systolic and diastolic blood pressures, lower total and low-density lipoprotein cholesterol and triglycerides levels, lower blood glucose, and better smoking status).  Also, their greater pushup capacity correlated with better aerobic fitness as estimated from VO2max readings in an exercise tolerance test.
• The risk of cardiovascular disease events was lower in participants who had higher push-up capacity at baseline measurement.
• Greater pushup capacity was associated with a lower risk for CVD outcomes, even after accounting for age and BMI. Measurement of aerobic fitness by the treadmill test (VO2 max) was not similarly predictive.
• Among the study group of men aged 21 to 66 years old, those who could perform 11 push-ups at base line had a significantly reduced risk of CVD events compared with those who could complete less than 10 push-ups.
• Completion of 41 or more pushups was associated with the greatest degree of risk reduction (decrease of 96%) in CVD events compared with those who completed < 10.

 
Cautions:

• The lowered CVD risk might be explained by differences in recognized independent CVD risk factors at baseline.
• Study results “do not support pushup capacity is an independent predictor of CVD risk”
• Although the firefighter group of middle-aged occupationally-active men was representative of US firefighters, the “study results may not be generalizable to women, older, or non-active persons”.  

The take-home message of the article, from Earned Runs perspective, is that physical fitness which contributes to a long and healthy life may not be best measured by aerobic capacity and thus not solely attained through aerobic exercise. 
 
Workouts that build functional body strength may be equally or more important to cardiovascular health and longevity.  Adding years to life may be as uncomplicated as incorporating classic bodyweight strength moves like the pushup or its variations into our routines.  Resistance training is recommended to athletes by trainers and coaches to boost sport performance and prevent sidelining injuries. A third benefit may be that it protects against cardiovascular disease. 
 
Medical research may not produce results that apply to all populations, but guides thinking in new directions. The scientific ‘compass’ seems to be suggesting that functional strength is something we can work on to improve future health regardless of age or weight.
 
RUN & MOVE HAPPY!

NOTE: Why study firefighters?
 
On the surface it may seem that scientists randomly chose this Indiana-based group of public service workers because of convenience.  They were available to participate in and be studied by a research team for 10 years.  However, medical concern over firefighter wellness has been evident for a long time.  Firefighting is known to be a highly stressful job, and firefighters seem to be at increased risk for serious CVD events compared with persons in other occupations, especially during or shortly after firefighting activities. 
 
A 2017 study revealed that exposure to “extreme heat” at a time when peak physical exertion is required is may “trigger the formation of blood clots and impair blood vessel function”, which increases the risk of a heart attack. Dehydration combined with shunting of blood to the skin to help handle the higher body temperature (average of 2 degrees Fahrenheit) likely result in lowered blood pressure, an AHA heart.org article that highlights the research explains.
 
The article also states that approximately 45% of on-duty firefighter fatalities each year in the US are caused by CVD events.
 
Although the Harvard research study results may help motivate non-firefighting adults to improve muscle strength to improve longevity, the information may be of utmost importance to this particular highly-stressed population. Dr. Stephanos Kales, the senior and corresponding author on this ‘push-up capacity” paper has an established track record in investigating medical issues of firefighters and police officers. His comment was sought in the several articles I pulled off the internet about firefighter health risks.
 
“Dr. Kales’ primary research involves the health of firefighters and police officers, and he is an international clinical authority regarding cardiovascular disease among public safety personnel.” https://www.hsph.harvard.edu/stefanos-kales
 
Dr. Stephanos Kales directed Earned Runs to view the study's push-up protocol through this link: https://www.linkedin.com/feed/update/urn:li:activity:6504138764946939904/


https://www.shape.com/fitness/workouts/7-fitness-tests-gauge-your-life-expectancy
 
https://www.shape.com/fitness/tips/push-up-test-heart-disease-risk
by Rachel Schultz for SHAPE.com “The Number of Push-ups You Can Do May Predict Your Heart Disease Risk”
 
https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2724778

https://journals.lww.com/acsm-essr/fulltext/2016/07000/Cardiovascular_Strain_of_Firefighting_and_the_Risk.2.aspx

https://www.medicalnewstoday.com/articles/316707.php

https://www.reuters.com/article/us-health-firefighters-heart/heart-disease-common-among-firefighters-who-die-of-cardiac-arrest-idUSKCN1M822O

http://money.com/money/4167989/most-stressful-jobs/