Tag Archives: exercise

What Should Your Maximal Exercise Heart Rate Be?: The Importance Of Using The Right Age-Predicted HRmax Formula

A reader who runs 5Ks posted a question recently which indicated concern that his heart rate during intense exercise was much higher than his age-predicted heart rate.  He writes

I’m 65, exhaustion HRmax is 188, HRave for 5k is usually 152-154 and interval HRmax is usually 175-179 depending on how hard I push”

He wondered if he should be concerned about being a “high-beater.”

This prompted the skeptical cardiologist to examine the literature on age-predicted maximal heart rate which led to the shocking discovery that the wrong formula is being utilized by most exercise trainers and hospitals.

First , some background.

The peak heart rate achieved with maximal exertion or HRmax has long been known to decline with aging for reasons that are unclear.

The HR achieved with exercise divided by the HRmax x 100 (percentage HRmax) is widely used in clinical medicine and physiology as a basis for prescribing exercise intensity in cardiac rehab programs, disease prevention programs and fitness clinics.

During stress tests we seek to have patients exercise at least until  their heart rate gets to at 85% of HRmax.

The Traditional Formula For HRmax

The formula that is widely used for HRmax is

HRmax = 220-age

It appears to have originated from flawed studies in the early 1970s. These studies included subjects with cardiovascular disease, smokers and patients on cardiac medications.

The Improved HRmax Formula

Tanaka, et al in 2001 performed a meta-analysis of previous data on HRmax along with accumulating data in their own lab. This was the first study to examine healthy, unmedicated, nonsmokers. In addition each subject achieved a verified maximal level of effort as documented by metabolic stress testing.

Their analysis obtained the regression equation (which I term the Tanaka equation)

HRmax = 208-(0.7 x age) 

Below is the graph of the laboratory measurements from which the regression equation was obtained.

Relation between maximal heart rate (HRmax) and age obtained from the prospective, laboratory-based study.(Tanaka, et al)

This graph shows how  inaccurate the traditional equation is, especially in older  individuals like my reader:

Regression lines depicting the relation between maximal heart rate (HRmax) and age obtained from the results derived from our equation (208 − 0.7 × age) (solid linewith 95% confidence interval), as compared with the results derived from the traditional 220 − age equation (dashed line). Maximal heart rates predicted by traditional and current equations, as well as the differences between the two equations, are shown in the table format at the top.(from Tanaka, et al)

The traditional equation in comparison to the Tanaka equation  overestimates HRmaxin young adults, intersects with the present equation at age 40 years and then increasingly underestimates HRmaxwith further increases in age. For example, at age 70 years, the difference between the two equations is ∼10 beats/min. Considering the wide range of individual subject values around the regression line for HRmax(SD ∼10 beats/min), the underestimation of HRmaxcould be >20 beats/min for some older adults.

There are likely lots of perfectly healthy individuals in their sixties and seventies then who have heart rates at maximal exertion that exceed by 10 to 20 beats per minute the HR max predicted by the traditional formula.

This is due to a combination of the inaccuracy of the traditional formula and the wide variation in normal HR max at any given age (standard deviation (SD) of approximately 10 beats/min.)

Thus, my reader at age 65 would have a HRmax predicted by the Tanaka equation as

208-0.7 x 65=162

If we allow for a 10 BPM range of normality above and below 162 BPM we reach 172 BPM which gets close to  but doesn’t reach the reader’s 188 BPM.

If you examine the scatterplot of the Tanaka data you can see that several of the points for age 65 reach into the 180s so chances are my reader is still within normal limits

The Bottom Line on HRmax

The widely used traditional formula for predicting HR max is inaccurate.

Athletes, trainers, physicians and hospitals should switch to using the superior Tanaka HR max formula.

Individuals should keep in mind that there is a wide range of HR response to exercise in normals and variations of 10 BPM above and below the predicted response are common and of no concern.

Chronotropically Yours

-ACP

Addendum. The 220-age formula is so heavily etched into my brain that I used 220 instead of 208 when I initially calculated the predicted max HR for my reader. this has been corrected.Thanks to Chris Sivewright for pointing this out.

Exercise As Medicine: Preventing Age-Related Decline in Cardiac Stiffness

As we age our hearts and arteries become stiffer. This cardiovascular stiffening plays a key role in hypertension, atrial fibrillation, and heart failure in older individuals (1).

Age-related cardiac stiffening is worse in those who are sedentary compared to those who exercise regularly (2).

Recent studies strongly suggest that regular exercise can prevent or minimize these age-related changes, thereby hopefully reducing the high rate of heart failure, hypertension and atrial fibrillation in the elderly.

In my post on fitness as a vital sign I briefly mentioned a fascinating study from 2014 which looked at 102 healthy seniors (age>64 years) and stratified them into 1 of 4 groups based on their lifelong histories of endurance exercise training.

Consider which of these 4 categories you fall into:

Sedentary subject-exercised no more than once per week during the prior 25 years.

Casual exercisers-engaged in 2-3 sessions per week

Committed exercisers-performed 4-5 sessions per week

Competitive “Masters level” athletes-trained 6-7 times per week

Exercise sessions were defined as periods of “dynamic activity lasting at least 30 minutes.”

The participants had sophisticated measures of their exercise capacity (max VO2), the size and mass of their left ventricles (cardiac MRI) and the stiffness of their left ventricles (invasive pressure/volume curves to calculate LV compliance and distensibility.)

This graph shows the key finding of the study: a markedly different pressure/volume curve in the sedentary and casual exercisers (blue and red dots) versus the committed or master exercisers. The two curves on the left correspond to a very stiff heart, similar to curves found in patients with heart failure.

The far right curve of competitive exercisers resembles that of a young heart.

The black triangle curve of the committed exerciser is in between these extremes

F5.large-3

The study concludes:

“low doses of casual, lifelong exercise do not prevent the decreased compliance and distensibility observed with healthy, sedentary aging. In contrast, 4 to 5 exercise sessions/week throughout adulthood prevent most of these age-related changes”

It would appear we need at least 4-5 30 minute exercise session per week to forestall the age-related stiffening of the heart and lower our chances of getting heart failure, hypertension and atrial fibrillation.

Since this was an observational study there is always a chance that lack of exercise is not the causes of poor cardiac stiffness.  It is conceivable that those of us with stiffer hearts tend to be more sedentary because of the poor cardiac function.

Can You Reverse The Age-Related Changes In Cardiac Stiffness?

If you have already reached middle age there is still hope for you as these same investigators recently published a study showing that cardiac stiffness can be improved with exercise. These findings imply that lack of exercise is the cause of worsening cardiac stiffness with aging.

This study identified 61 sedentary men in their mid-fifties and randomly assigned them to either 2 years of exercise training or attention control (a combination of yoga, balance, and strength training 3 times per week for 2 years) and measured their LV stiffness and max VO2 before and after intervention.

Max VO2 increased by 18% and LV stiffness declined from .072 to .051 in the exercise group but did not change in the control group.

The exercise training arm of this study involved a mixture of continuous moderate-intensity aerobic exercise combined with high intensity training. The high intensity portion of the program involved exercising at 90-95% of HR maximum for 4 minutes followed by a 3 minute active recovery period, repeated 4 times.

Over a period of 6 months under the guidance of exercise physiologists the participants had their exercise levels gradually increased. After 6 months they were training 5-6 hours per week, including 2 of the “high intensity interval” session and 1 long (>/= 1 hour) and one 30-minute base pace session each week.

By the sixth month, participants were training 5 to 6 hours per week, including 2 interval sessions, and 1 long (at least an hour) and one 30-minute base pace session each week.

How Much Exercise Do We Need To Minimize Cardiac Aging?

This chart from recent European guidelines on lifestyle for prevention of disease describes different intensities of aerobic exercise:

 

screen-shot-2016-10-01-at-10-18-34-am

 

 

 

 

 

These guidelines suggest that if you engage in vigorous exercise such as running or jogging, cycling fast or singles tennis, you only need to achieve 75 minutes per week. Moderate exercise such as walking or elliptical work-outs requires at least  150 minutes/week.

Based on these recent studies on exercise and cardiac stiffness and the bulk of scientific literature on the overall health benefits of exercise I would advise for all individuals with or without heart disease

-If you are sedentary, become a committed exerciser.

-Committed exercise means some form of dynamic exercise 4-5 times per week

-If you are already a committed exerciser at moderate intensity levels consider adding to your routine one or two sessions of high intensity interval exercise.

-High intensity exercise will require you to get your heart rate up to 90-95% of your maximum 

-Predicted maximal HR=220 -age.  For a 60 year old this equals 160 BPM. 90% of 160 equals 144 BPM. 

Compliantly Yours,

-ACP

 

 

 

 

Should Fitness Be A Vital Sign?

The skeptical cardiologist routinely probes his patients’ activity and exercise levels and encourages them to engage in 150 minutes of moderate exercise weekly. However, I’m somewhat skeptical of the benefit of treating such assessments as a vital sign (like blood pressure or heart rate)  as a recent AHA scientific statement suggests.

I can only envision still another item  on a chart checklist that will have to be recorded in the EHR or already over-worked physicians will have their payments withheld.

The AHA statement suggests that ideally we should be measuring  our patients’ fitness by obtaining  maximal oxygen consumption (VO2 max) utilizing an expensive and rarely utilized cardiopulmonary exercise test. Failing that we should consider doing a treadmill stress test. Failing that, rather than utilizing my simple question to patients: “How active have you been?”,  the statement recommends doctors utilize some sort of formal questionnaire to estimate their patients’ cardiorespiratory fitness (CRF) such as the one at World Fitness Level.

I went online to take this CRF estimator (based on this paper) and I remain skeptical.

The online site and  a free smartphone app both ask the following questions:

  • Country and City
  • Ethnicity
  • Highest Level of Education
  • Gender/Age/Height/Weight
  • Resting and Maximal Pulse
  • How often do you exercise?
  • How long is your workout each time? (over/under 30 minutes)
  • How hard do you train? (I had to choose between “I go all out”or “Little hard breathing and sweating”)

 

screen-shot-2016-12-03-at-11-33-13-amWhen you have finished answering the questions you are given an estimate of your fitness age. When I did this online a few days ago and answered truthfully I got the result to the right: I had the fitness of a 41 year old with an estimated VO2 max of 49 ! (interestingly this estimate corresponds exactly with VO2 max derived from a recent stress test I completed.)

I used the app (which unlike the online version did not ask me my waistline measurement) and changed a few parameters:

  • I increased my resting heart rate or pulse  from 60 to 68 beats per minute (BPM)
  • I increased my maximal heart rate from what I know is 158 BPM to what the app calculated (173 BPM, which makes no sense)
  • I switched from exercising 2-3 times per week  and longer than 30 minutes  at “all out” level to the lowest level for all 3 questions.

The change was dramatic and depressing: I went from 39 years old to 67 years old in the bat of an eyelid!img_8073

 

 

 

The app and online site direct you to a non-profit site where you can get information on a 7 week program to increase your fitness level. I haven’t checked this out.

I’ll be trying out this CRF estimator on my patients: assessing whether it adds anything to my usual line of questioning on activity and fitness.

I encourage you to give the CRF estimator a try. Let me know in the comments how you feel it works for you. Does it motivate you to exercise more knowing that, for example, your fitness age is substantially higher than your chronological age?

Running For Longevity: From A-Punk to Aba Daba Honeymoon

About two years ago I wrote about a study that found that any amount of leisure-time running was associated with a lower risk of cardiovascular disease which  made me reconsider my usual advice to patients on exercise:

As part of a prospective longitudinal cohort study at the Cooper Clinic in Dallas, Texas, Lee, et al. looked at data from a group of 55,137 adults on whom they had information on running or jogging activity during the previous 3 months.
Those individuals who described themselves as having done any running in the last 3 months had a 30% lower risk of all-cause mortality and a 45% lower cardiovascular mortality.

Amazingly, it didn’t matter how much you ran.

Those who ran <51 minutes per week did just as well as those who ran >176 minutes per week.

At the time I felt the study was not definitive, but food for thought. Evidently, it got me thinking so much that I began running regularly (despite my previous dislike of running).

Music and the Tempo of Running

During my runs I listen to music on my iPhone, either through Apple Music or songs that I have purchased.

Today, after deciding Leonard Cohen’s Live in Dublin (although awesome, and one of the best live albums I’ve ever heard) was not motivating enough, I hit the first song on my iPhone: A-punk by Vampire Weekend.

A-Punk is one of my favorite songs released in the last decade. It’s very upbeat.. perfect for a running accompaniment. The opening guitar riff is simple, fast and catchy. It’s simple enough that I can play it on guitar but, so fast that my fingers fatigue quickly.  The bridge portion features a wonderfully fast and complicated bass line with punchy drums and an overlying synth flute melody. You can watch a video of it here:

As I ran I realized that the tempo of A-Punk was perfectly suited to my preferred running speed of 6.1 MPH. You’re probably wondering what the tempo of A-Punk is. It’s likely that the only time song tempo comes up in general conversation is when talking about CPR and the need to compress the sternum at 100 beats per minute, the alleged tempo of The Bee Gees Stayin’ Alive (it’s actually 104 BPM.)

A-Punk’s tempo turned out to be 175 BPM. If you are not inclined to count the actual beats in a minute to determine the tempo of a song, you can enter the song into this site to get the number or download a smart phone app for the purpose.

Oddly enough, the next song on my alphabetical listing of songs, Hoagy Carmichael’s version of Aba Daba Honeymoon, also had a screen-shot-2016-10-02-at-8-45-44-amtempo (174 BPM) perfectly suited to my running speed. (The song after that was my old band Whistling Cadaver attempting to play the medley at the end of Abbey Road at our 30 year high school reunion in 2002-not good for running to, but immensely entertaining).

Monetizing Music For Running

Having observed that the tempo of certain songs matched perfectly to my running tempo, I wondered if there were any advantages to selecting such songs. Would I run faster or longer or with less discomfort or less injuries?

The web site run2rhythm would certainly like me to believe that screen-shot-2016-10-02-at-9-45-42-amrunning to the right tempo song will improve my performance. This site claims that “the wrong musical playlists can be detrimental to your training as they will not provide any synchronization between the body, the music and the mind. The body is almost always out of sync with the music.”

screen-shot-2016-10-02-at-9-03-39-amRun2rhythm provides a chart of the BPM that corresponds to different running speeds and sells playlists starting at $3.99 corresponding to specific tempos. These are playlists by unknown artists created for run2rhythm and the samples were not inspiring to me.

Here’s an example:screen-shot-2016-10-02-at-9-05-39-am

 

 

Is Music a Legal Drug For Athletes?

It turns out that there is a body of scientific literature related to music and exercise, and the vast majority of it seems to come from one man,  Dr Costas Karageorghis at Brunel University in London, an expert on the effects of music on exercise.  In his 2010 book, Inside Sport Psychology, he claims that listening to music while running can boost performance by up to 15%.

In media articles on the topic he is often quoted as saying “Music is a legal drug for athletes.”

However, in a 2012 review article he is more circumspect, concluding:

Music is now rarely viewed in a manner akin to the ‘vitamin model’ described by Sloboda (2008) wherein one can ascribe immutable effects to a specific musical selection for all listeners and at all times. The beneficial consequences of music use stem from an interaction between elements of the musical stimulus itself and factors relating to the traits and experiences of the listener, and aspects of the exercise environment and task. In particular, the role of music is dependent on when it is introduced in relation to the task and the intensity of the exercise undertaken. In closing, the evidence presented in this review demonstrates that music has a consistent and measurable effect on the psychological state and behaviour of exercise participants

Creating Your Own Tempo Playlist

The research on music and exercise suggests that songs with inspirational themes (apparently, “Gonna Fly Now,” the Rocky theme, is the most popular workout song of all time) are more effective performance enhancers. Also, self-selection of songs works better.

For me, running while listening allows me to focus on nuances of instrumentation, timing  and lyrics that otherwise I would not pay attention to. It is essential, then, to have songs that are worthy of such close listening.

I wondered if anyone has compiled lists of songs of a certain BPM that were originals and good songs.  Sure enough, the folks at jog.fm have exactly such a function.  My search for songs with tempo of 175 BPM yielded A-Punk and hundreds of other songs, screen-shot-2016-10-02-at-10-10-58-amincluding some I like (thumbs down for Footloose and Wonderwall (which is really 1/2 of 175 BPM or  88 BPM), thumbs up for Dancing With Myself).

You will note that my preferred tempo of 175 BPM corresponds to a much faster running speed than my preferred 6.1 MPH. This may have to do with my short legs or my running style. It makes sense to count the number of steps you take per minute at your optimal speed rather than rely on charts or averages.

Achieving the Right Dose of Exercise

Whatever you listen to while running, walking, cycling or hopping, hopefully it will assist you to achieve the dose of exercise per week that results in improved cardiovascular outcomes.

This chart from recent European guidelines on lifestyle for prevention of disease describes different intensities of aerobic exercise:

screen-shot-2016-10-01-at-10-18-34-am
If you engage in vigorous exercise such as running or jogging, cycling fast or singles tennis, you only need to achieve 75 minutes per week. Moderate exercise such as walking or elliptical work-outs requires 150 minutes/week.

As a result of switching to running, I’ve cut down my total exercise time per week by half leaving me more time to create music!

Readers – feel free to share your favorite workout songs and let me know what tempo works best for you.

Synchronously Yours,

-ACP

Yikes! This is a silly video. I’m not sure I can run to the song anymore.

 

 

Is Exercise Impotent In Preventing Obesity?

What if all that exercise that authorities have been recommending  is not helping to stem the rising tide of obesity?

What if all calories don’t have the same ability to add fat?

These twin heresies fly in the face of the usual dogma on the cause of obesity: more calories in (gluttony) than calories out (sloth). The skeptical cardiologist has been pondering these possibilities for some time, since reading Gary Taubes book Good Calories, Bad Calories.

I have been advising my patients through this blog and during office visits that added sugar and  refined  carbohydrates are much more of a culprit in their  weight gain than fat, thus embracing the concept that there are good calories and bad calories

Exercise and Obesity

5Boro Bike Riders crossing the summit of the Queensboro aka 59th Street aka "Feelin Groovy" Bridge

But I also spend a lot of time during my office visits discussing activity levels and encouraging my patients to engage in moderate aerobic physical activity for at least 150 minutes per week.

I do this because there is good evidence that regular physical activity is associated with lower cardiovascular risk, cancer risk, mortality, and improved brain, muscle, and bone function. Exactly  what level and type of exercise is needed to reap these benefits is still up for debate.

I, personally, engage in regular moderate exercise and I think it helps maintain my weight where I want it.

Throwing Down the Gauntlet

A recent editorial in the British Journal of Sport Medicine stridently  makes the claim that exercise is not useful for weight loss as conventional wisdom teaches and that the food industry has been promoting exercise while simultaneously promoting junk food and sugar-sweetened beverages (The link I provided is no longer active because the journal has removed the editorial -“This paper has been temporarily removed following an expression of concern.”)

The authors wrote:

“members of the public are drowned by an unhelpful message about maintaining a healthy weight through calorie counting, and many still wrongly believe that obesity is entirely due to lack of exercise. This false perception is rooted in the Food Industry’s Public Relations machinery, which uses tactics chillingly similar to those of big tobacco. “

Root Causes of Obesity

It would appear that science cannot tell us with total certainty what the cause of our current obesity epidemic is.

After publishing a paper in 2014 that suggested Americans had become less active over the last 20 years, Ladabaum, et al admitted this:

“Although there is no clear answer at this time regarding the relative contribution of energy intake or physical activity (or other variables including dietary components, patterns of activity, and environmental factors, including the gut micro biome) to the public health problem of obesity, we believe that public health messages should continue to emphasize the importance of both a healthy diet and remaining physically active throughout life.”

Is Exercise Amount  A Cause or Effect?

In my own practice, I have observed a tendency for  those patients who regularly exercise or have very physically active jobs to stay thin whereas those who don’t exercise, especially if they have sedentary jobs or are retired, tend to be obese and gain weight.

But, I also note that those patients who take my recommendations on exercise to heart  are also listening to my advice in other areas, including diet and medications and are, in general, much more proactive about their health.

Therefore, I can’t say for sure whether it is the exercise  or the other aspects of a healthy lifestyle (including diet)  being followed in any individual patient that is keeping the pounds off. How much my patients move during the day when they are not specifically exercising may also be playing a role and is hard for me to assess.

There is also the mind-boggling possibility, as Gary Taubes has written about (here and in his book Why We Get Fat) that our genetics are driving both our activity levels and our food consumption:

Ultimately, the relationship between physical activity and fatness comes down to the question of cause and effect. Is Lance Armstrong excessively lean because he burns off a few thousand calories a day cycling, or is he driven to expend that energy because his body is constitutionally set against storing calories as fat? If his fat tissue is resistant to accumulating calories, his body has little choice but to burn them as quickly as possible: what Rony and his contemporaries called the “activity impulse”—a physiological drive, not a conscious one. His body is telling him to get on his bike and ride, not his mind. Those of us who run to fat would have the opposite problem. Our fat tissue wants to store calories, leaving our muscles with a relative dearth of energy to burn. It’s not willpower we lack, but fuel. “

I’m not ready to accept the heresy that exercise and activity have nothing to do with weight gain or loss. I, like most cardiologists, walk the walk and talk the talk of regular vigorous exercise for health benefits, extended longevity, cardiovascular fitness and for helping in weight control.

Exercise is not the be all and end all of weight control because increased consumption of bad or good calories can overcome the most prolonged and intense workouts but it is a useful adjunct.

Still exercising regularly,

-ACP

Does Any Amount of Leisure-Time Running Reduce Your Risk of Heart Attack?

1310552547_gumpThe skeptical cardiologist dislikes running. When I start running my whole body seems to be telling me I am making a serious mistake. After running, my knees hurt (worse than the normal level of pain) and if I do enough of it, my hips hurt too.

Despite this, I have incorporated running into my exercise routine over the last few years since I stopped playing tennis. I primarily get my aerobic exercise now by using elliptical type devices and I try to get at least 150 minutes of vigorous elliptical work per week. About once a week, I run a mile on a treadmill at 6 MPH.

My current patient exercise recommendation is for 150 minutes of moderate intensity aerobic exercise.  I have advised patients in the past, that walking at a moderate pace was adequate exercise, and I’ve felt, based on prior studies, that running was not necessary to achieve the cardiovascular benefits of exercise.

Any Running Associated With Lower Risk of Dying

A new study published recently in JACC has made me reconsider this advice.

As part of a prospective longitudinal cohort study at the Cooper Clinic in Dallas, Texas, Lee, et al. looked at data from a group of 55,137 adults on whom they had information on running or jogging activity during the previous 3 months.

To reduce confounding bias in the association between running and mortality, the total amount of other physical activities except running was adjusted in all multivariable regression models.

They obtained information on death from The National Death Index and over 15 years found 3,413 all-cause death and 1,217 deaths from cardiovascular disease.

Those individuals who described themselves as having done any running in the last 3 months had a 30% lower risk of all-cause mortality and a 45% lower cardiovascular mortality.

As you might expect, the non-runners were older, smoked more and were fatter. The investigators ran analyses that controlled for the differences in these factors. The protective effect of running, even a small amount, persisted, regardless of age, gender, body mass index, smoking or alcohol consumption.

Amazingly, it didn’t matter how much you ran.

This finding is quite remarkable.

Those who ran <51 minutes per week did just as well as those who ran >176 minutes per week.

Of the 20,67 that had two examinations, those who were runners at both examinations had the best outcomes with a 50% lower risk of CVD mortality.

These findings are not definitive. We need more studies in this area but they are food for thought.

Why Would Running Be A Better Form of Exercise For Your Heart

Some thoughts…

Perhaps the person who doesn’t want to run has a fundamentally different mindset about his/her health than the person who is willing to run just a little bit. Does this inclination to run mirror the person’s overall approach to their health? We can assess factors like cigarette smoking, obesity, diabetes and cholesterol but there are likely (so far) intangible factors that contribute to our health that tend to cluster with a pro-active health attitude.

Why do I run? After all, I don’t like it, it hurts my knees and I didn’t think it was contributing to my overall health. I did the mile run for a few reasons:

Running a mile in 10 minutes served as a milestone, a fixed goal if you will, for my cardiovascular fitness. I can get a very good idea of where I’m at by measuring my heart rate. I’m 60 years old and my predicted maximal heart rate (220 minus age) is 160. When I’m out of shape, my heart rate will get as high as 155 BPM during the mile, when in shape it is 10 BPM lower. 145 BPM is 91% of my predicted maximal HR.

My sense is  that a good goal for cardiovascular fitness is to get the heart rate up to 90% or so of your predicted maximal. It may be that running more reliably gets you to that threshold than other activities.

Also, as the significant other of the skeptical cardiologist points out, “you can’t cheat at running.” There’s a certain amount of effort you have to put into it and there’s no way to escape it as there is on a bicycle or an elliptical. With walking you could choose a speed ranging from the snail-like up to 4 MPH or so.

Those who don’t run may also have orthopedic limitations (plantar fasciitis, osteoarthritis, rheumatoid arthritis) or pulmonary problems (COPD, asthma) or undiagnosed heart problems (heart failure, valve defects, rhythm problems) that are not captured by the examinations the investigators performed.

These findings, the authors of the paper suggest, may make people more likely to run:

“Because time is one of the strongest barriers to participate in physical activity, this study may motivate more people to start running and continue to run as an attainable health goal for mortality benefits. Compared with moderate-intensity activity, vigorous-intensity activity, such as running, may be a better option for time efficiency, producing similar, if not greater, mortality benefits in 5 to 10 min/day in many healthy but sedentary individuals who may find 15 to 20 min/day of moderate-intensity activity too time consuming.”

Some Possible Mechanisms For The Benefits of Running

As I was putting the finishing touches on this post I notice that the Sept 23 issue of the Journal of the American College of Cardiology sitting in front of me has two articles that are directly relevant to this issue. I haven’t had time to analyze these in detail but the conclusions of the first study  are that

“low doses of casual, lifelong exercise do not prevent the decreased compliance and distensibility observed with healthy, sedentary aging. In contrast, 4 to 5 exercise sessions/week throughout adulthood prevent most of these age-related changes”

Thus, the mechanism through which running or more “committed” exercising improves survival could be mediated through improving the diastolic properties of the heart.

I spent most of my academic cardiology career studying diastolic function and it is an incredibly complicated and poorly understood area. Simply put, the heart has to contract to pump out blood (we call this systole) then it has to fill back up with blood (we call this diastole). With aging, the heart’s ability to contract doesn’t change but its ability to fill changes dramatically. Thus, diastolic properties become impaired with aging and this study suggests that dedicated regular exercise prevents that.

The other study showed that regular exercise helps to slow  age-related increase in blood pressure.  Lower blood pressure with aging could be a mechanism for preventing the age-related decline in diastolic performance of the heart.

Changing Exercise Prescription

From now on when I talk to my patients about exercise, I will inquire about running specifically and I’ll mention these studies which suggest a little running may go along way toward forestalling the aging process of the heart and lowering their risk of dying.

 

Urban Cycling Part I: Does Biking To Work Make You More or Less Likely to Die?

5Boro Bike Riders crossing the summit of the Queensboro aka 59th Street aka "Feelin Groovy" Bridge
5Boro Bike Riders crossing the summit of the Queensboro aka 59th Street aka “Feelin Groovy” Bridge. For some reason the significant other of the skeptical cardiologist (SOSC) has decided to stop here to look at her cell phone, thereby creating a traffic hazard.

The skeptical cardiologist recently participated in the 5 Boro New York City Bike Tour. It was quite cool.

This annual event allows 32,000 bike riders to stream from Manhattan to the Bronx to Queens, Brooklyn and Staten Island along 40 miles of traffic-free (except for thousands of cyclists) roads

Unlike my previous rides in Brooklyn and Manhattan (under the guidance of legendary Park Slope flaneur, NYC biking advocate, and old high school chum David Alquist) I was not in constant peril from automobile encounters because we cyclists had the mean streets of New York all to ourselves.

Take a look at this video to understand “why cyclists come from around the world for an experience of the Big Apple unlike any other”.

Urban Cycling as Transportation

The NYC event, and the fact that this is “bike to work week,” lead me to ponder aspects of urban bike riding, specifically, cycling as transportation.  Since cycling is physical exercise and there is scientific evidence (observational studies only) linking regular physical activity to a significant cardiovascular risk reduction, we might expect that it would help us live longer. 

A reasonable physical activity goal , endorsed by most authorities,  is to engage in moderate-intensity aerobic physical activity for a minimum of 30 min on 5 days each week or vigorous-intensity aerobic activity for a minimum of 20 min on 3 days each week. This level of exercise helps with weight control, fitness and is associated with lower mortality from cardiovascular disease .

METS:calories
METs and calories consumed per hour for various physical activities

The metabolic equivalent of task (MET) is a measure of the energy cost of physical activity. The chart to the left gives METs for various activities.  Individuals should be aiming for 500–1,000 MET min/week. Leisure cycling or cycling to work (15 km/hr) has a MET value of 4 and is characterized as a moderate activity  A person shifting from car to bicycle for a daily short distance of 7.5 km would meet the minimum recommendation (7.5 km at 15 km/hr = 30 min) for physical activity in 5 days (4 MET × 30 min × 5 days = 600 MET min/week).

 

Thus, cycling to work for many individuals would provide the daiy physical activity that is recommended for cardiovascular benefits. However, cycling in general, and urban cycling in particular, carries a significant risk of trauma and death from accidents and possibly greater exposure to urban pollutants.

bikversuscardeaths
from CBS (Statistics Netherlands) Traffic and Transport, 2008

This table shows the estimated numbers of traffic deaths per age category per billion passenger kilometers traveled by bicycle and by car (driver and passenger) in the Netherlands for 2008. These data suggest that there are about 5.5 times more traffic deaths per kilometer traveled by bicycle than by car for all ages. Interestingly, there is no increase in risk for individuals aged 15-30 years. On the other hand , those of us in the “baby-boomer” generation (?slowed reflexes, poor eyesight, impaired hearing) and older are at an 8 to 17 fold increase risk.

In the Netherlands, where a very large percentage of the population regularly rides bikes, there has been considerable scientific study of the overall health consequences of biking and we have reasonably good data on the question of relative safety of biking versus driving a car for short distances. You can watch the happy people of Groningen (“the world’s cycling city”, where 57% of the journeys in the city are made by bicycle) riding their bikes below.

Health Impact of Transition from Car to Bike for Short Trips

One study quantified the impact on all-cause mortality if 500,000  people made a  transition from car to bicycle for short trips on a daily basis in the Netherlands and concluded

For individuals who shift from car to bicycle, we estimated that beneficial effects of increased physical activity are substantially larger (3–14 months gained) than the potential mortality effect of increased inhaled air pollution doses (0.8–40 days lost) and the increase in traffic accidents (5–9 days lost). Societal benefits are even larger because of a modest reduction in air pollution and greenhouse gas emissions and traffic accidents.

Apart from the highest average distance cycled per person, the Netherlands is also one of the safest countries in terms of fatal traffic accidents so it’s reasonable to ask whether these data apply to other countries. This study concluded

 When  traffic accident calculations for the United Kingdom were utilized, where the risk of dying per 100 million km for a cyclist is about 2.5 times higher, the overall benefits of cycling were still 7 times larger than the risks.

If you decide to bike to work this week, braving the elements , the possible automobile collisions and the automobile exhaust you can rest comfortably with the thought that not only are you  prolonging your own life but by reducing greenhouse gas emissions and air pollution you are contributing to the health of everyone around you.