Weekly Running Dose For Life Extension

The heart is mainly a muscle, but unlike a nice and round Gluteus Maximus, you cannot display a well-trained Heart on social media for personal gains. Well, maybe Hanuman was the only guy who managed to display his heart in order to impress his Boss and Boss’ Wife (Ram and Sita). He had eyes on the ‘Best Employee of the Ever Award’.

As with any muscle, the heart also adapts to training stress from exercise and eventually becomes more efficient at supporting the enhanced cardiovascular requirements of exercise. But all is not good in the domain of cardio because most of the protective cardiovascular benefits from cardiovascular exercises such as running and cycling, wane away after a certain point as per The Copenhagen City Heart Study (referred to as “the CCH Study” below).

In the year 2015 when the CCH Study was published, suddenly excessive and hard running was labelled dangerous for cardiac health, based on the exercise related findings in the CCH Study. Not wanting to lose out commercially, immediately Runner’s World published a very poorly written rebuttal, and then after 1 year they came out with a more nuanced article which admitted the relevance of the findings in the CCH Study. Competitor Running, in contrast, wrote a balanced article without any attempt to debunk the study and protect its customer base.

The CCH Study was launched in the year 1975 by Dr. Peter Schnohr, to understand physical activity and athleticism as tools for cardiovascular disease prevention, and it involved a starting sample population of 20,000 men and women. The Study grew over the years to include the effects of alcohol, education, smoking, diabetes, sleep etc. on coronary heart diseases and strokes in humans. Do note that Dr. Schnohr was amongst the top 10 runners in Denmark at that time and he initiated the entire study based on the unpleasant symptoms he experienced during his strenuous training and to understand whether excessive running could be unhealthy.

For the past several decades, it is common knowledge and obvious through medical evidence that our bodies need the effects of regular and vigorous exercise, and that physically active people have a significantly lower risk of death compared with inactive people. However, no upper threshold for physical activity has ever been recommended.[1]    

The CCH Study reported that both duration and intensity of walking, running and cycling were important factors in relation to coronary heart disease related mortality, with intensity of exercise playing a stronger role in increasing the chances of cardiovascular issues.

There appears to be a U-shaped association between all-cause mortality and dose of jogging as calibrated by pace, quantity, and frequency of jogging. As per Dr. Schnohr, light and moderate joggers have lower mortality than sedentary non-joggers, whereas strenuous joggers have a mortality rate which is not statistically different from that of the sedentary group.[2]

Long-term strenuous endurance exercise might induce pathological structural remodelling of the heart and large arteries. Current data suggests that long-term training and competing in extreme endurance events such as marathons, ultra-marathons, ironman distance triathlons, and very long distance bicycle races can cause physical abnormalities and malfunctions in the heart and elevate cardiac biomarker levels. Additionally, long-term excessive exercise may be associated with coronary artery calcification, diastolic dysfunction, and large artery wall stiffening.[3]

A similar finding[4] on cardiac dysfunction and injury from marathon training was reported in this study labelled “Myocardial Injury and Ventricular Dysfunction Related to Trailing Levels Among Nonelite Participants in the Boston Marathon”. The findings of this study are more relevant to the sensationalised stories we keep hearing about in the media about runners suffering heart attacks during or after a marathon, but which instances as per this study are mostly attributable to the lack of proper training in such runners i.e. low mileage in training for a long distance race.

Best Employee of the Ever

As per the jogging/running part of the CCH Study, the findings for the relationship between running and mortality when adjusted for various factors is as follows:

Note:

Hazard Ratio (HR) below represents the chance of an event occurring. A HR of 1 means that there is no difference in survival between the two groups. A hazard ratio of greater than one or less than one means that survival was better in one of the groups. So in the CCH Study a HR of 1 represents that the chance of death is certain. Therefore, the HR for understanding the numbers below is to be compared with a ‘sedentary nonjogger’ whose HR is 1 i.e. a ‘sedentary nonjogger’ will die (HR = 1), and anything less than 1 represents that the chance of mortality has decreased in the exercise group as compared to a ‘sedentary nonjogger’ group.

Quantity of Jogging (adjusted for age and sex):

Hours of jogging per week	HR (Hazard Ratio)	Remarks
Sedentary nonjogger	1	Certainty of mortality at a given point time.
Less than 1 hour per week	0.32	68% lowered risk of mortality (as compared to a sedentary nonjogger)
1 – 2.4 hours per week	0.18	82% lowered risk of mortality (as compared to a sedentary nonjogger)
2.5 – 4 hours per week	0.38	62% lowered risk of mortality (as compared to a sedentary nonjogger)
More than 4 hours per week	0.35	65% lowered risk of mortality (as compared to a sedentary nonjogger)

Quantity of Jogging (adjusted for age, sex, smoking, alcohol intake, education, and diabetes):

Hours of jogging per week	HR (Hazard Ratio)	Remarks
Sedentary nonjogger	1	Certainty of mortality at a given point time.
Less than 1 hour per week	0.47	53% lowered risk of mortality (as compared to a sedentary nonjogger)
1 – 2.4 hours per week	0.29	71% lowered risk of mortality (as compared to a sedentary nonjogger)
2.5 – 4 hours per week	0.65	35% lowered risk of mortality (as compared to a sedentary nonjogger)
More than 4 hours per week	0.60	40% lowered risk of mortality (as compared to a sedentary nonjogger)

Frequency of Jogging (adjusted for age and sex):

Frequency of jogging per week	HR (Hazard Ratio)	Remarks
Sedentary nonjogger	1	Certainty of mortality at a given point time.
Less than or equal to once per week	0.19	81% lowered risk of mortality (as compared to a sedentary nonjogger)
2 to 3 times per week	0.20	80% lowered risk of mortality (as compared to a sedentary nonjogger)
More than 3 times per week	0.48	52% lowered risk of mortality (as compared to a sedentary nonjogger)

 Frequency of Jogging (adjusted for age, sex, smoking, alcohol intake, education and diabetes):

Frequency of jogging per week	HR (Hazard Ratio)	Remarks
Sedentary nonjogger	1	Certainty of mortality at a given point time.
Less than or equal to once per week	0.29	71% lowered risk of mortality (as compared to a sedentary nonjogger)
2 to 3 times per week	0.32	68% lowered risk of mortality (as compared to a sedentary nonjogger)
More than 3 times per week	0.71	29% lowered risk of mortality (as compared to a sedentary nonjogger)

Jogging pace (adjusted for age and sex):

Jogging Pace	HR (Hazard Ratio)	Remarks
Sedentary nonjogger	1	Certainty of mortality
Slow (9.66 km/h to 11.27 km/hour)	0.34	66% lowered risk of mortality (as compared to a sedentary nonjogger)
Average (above 11.27 km/hour)	0.25	75% lowered risk of mortality (as compared to a sedentary nonjogger)
Fast (threshold workouts)	0.54	46% lowered risk of mortality (as compared to a sedentary nonjogger)

Jogging pace (adjusted for age, sex, smoking, alcohol intake, education and diabetes):

Jogging pace	HR (Hazard Ratio)	Remarks
Sedentary nonjogger	1	Certainty of mortality
Slow (9.66 km/h to 11.27 km/hour)	0.51	49% lowered risk of mortality (as compared to a sedentary nonjogger)
Average (above 11.27 km/h)	0.38	62% lowered risk of mortality (as compared to a sedentary nonjogger)
Fast (threshold workouts)	0.94	6% lowered risk of mortality (as compared to a sedentary nonjogger)

When the findings of the CCH Study appeared for the first time on various news outlets and health magazines, there was a general uproar in the running community since most of the avid runners did not want to acknowledge or believe that something which felt so good could also be bad for them. The U shaped graph (namely, the diminishing returns from running distance and intensity) was unbelievable to most since till the CCH Study, none of the previous studies had categorically stated that hard running may be detrimental to the human body to the extent that all the benefits may wane away after a certain peak. Moreover many of the news articles based on the CCH Study provided a very general analysis of jogging related findings of the CCH Study, which needless to say sounded quite ridiculous to runners who were training for races, and who, as human nature goes, obviously did not want to hear that training for races would be counterintuitive.

The CCH Study was not anti-running. It was a comprehensive long term study on the pros and cons of hard training on the human body. Dr. Schnohr and others have stated that “….to our knowledge, there has been no study of the longevity of marathon, half-marathon or triathlon participants, but such studies would clearly be informative…”

The simplistic interpretation of the jogging related findings in the CCH Study by news media and individuals was incorrect since if you carefully see the above tables from the CCH Study, the following points emerge which demonstrate that the CCH Study was pro-running:

• There are benefits from any duration, frequency and intensity of running since the HR (hazard ratio) declines for each category of runner as compared to a sedentary non-jogger.
• Notwithstanding the above, the benefits from running are maximized by slow jogging (9.66 km/h to 11.27 km/hour) when done for 1 to 2.4 hours per week and in less than 2 to 3 sessions per week, and if the runner does not smoke, consume alcohol or have diabetes.
• As compared to a sedentary nonjogger, a person who runs can reduce his mortality risk to almost 50% even if he/she trains hard i.e. for more than 4 hours per week at a fast pace and in several sessions. Hence, even hard running is beneficial, but it’s less beneficial than slow running.
• The risk of mortality is only 6% lesser in a runner as compared to a sedentary nonjogger when a runner, (i) runs for more than 4 hours per week; (ii) runs more than 3 times per week; (iii) runs at a fast pace; (iv) smokes and drinks; and (v) has diabetes.

Therefore, unless you have picked up a few vices (alcohol and tobacco) and maybe have diabetes too, as per the CCH Study, even if you keep training hard, your mortality risk will always be lower than a sedentary nonjogger’s.

Also note that the CCH Study is only limited to determining cardiovascular health, and it has not considered the mental benefits of excessive/hard/intense/prolonged exercise (howsoever you may want to describe it).

As science has shown and as you may have felt yourself, the mental benefits from “excessive running” especially in treating the general malaise/depression in contemporary society may most certainly cancel the higher cardiovascular risks associated with hard running (marathons, ultramarathons, triathlons etc.) if seen in terms of personal choice in improving lives. Quality of Life, over Quantity of Life?

What you can do with the aforesaid data and analysis is decide what you want from running and your running schedule. If you want to run only for longevity then run less per week and run slow (less than 2.4 hours per week and slower than 11.27 km/h) and spend a few hours every week on strength training since strength training can reduce mortality risks significantly and also reduce cancer cell growth. However, if you run long distances out of sheer passion and mental health then keep training hard but reduce alcohol and smoking to decrease your mortality risk which otherwise comes in close proximity to a sedentary nonjogger due to these vices.

Finally, the findings of the CCH Study fit like a glove with Professor Alexander Y. Bigazzi’s (Department of Civil Engineering, the University of British Columbia) recent findings[5] of the minimum dose speeds (MDS) for Walking, Running and Cycling at which the amount of inhalation of pollutants is the lowest. Move faster than these recommended speeds and you will expend dramatically more energy which in turn will increase your heart rate and respiration and therefore you will inhale exponentially higher amounts of air + pollution. I had written a blog on this last year since in highly polluted placed like Delhi, during the months ranging from November-March, the air quality is extremely poor and a slower exercise speed is necessary to reduce air pollution. So a combination of the findings of the CCH Study and MDS (minimum dose speed i.e. workout speeds) is a win-win formula for areas with polluted air.

- Aman Yadav

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[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4625209/

[2] https://www.ncbi.nlm.nih.gov/pubmed/25660917

[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4625209/

[4] http://circ.ahajournals.org/content/114/22/2325

[5] https://www.researchgate.net/publication/308535014_Determination_of_active_travel_speed_for_minimum_air_pollution_inhalation