Do Obese People With Heart Disease Benefit Less From Cardiac Rehab?

Few events are likely to command your attention as urgently as a sudden interruption of blood flow to your heart muscle.

Fortunately, thanks to the miracle of modern cardiac revascularization, you may well find yourself amongst the many, who today survive this “heart-wrenching” event – a situation which often precipitates remarkably intense longings for lifestyle change.

Indeed, at no time (other than January 1), would you meet anyone more determined to swear off their cigarettes, convert to the solemn teachings of Canada’s Food Guide and embrace the rejuvenating powers of exercise – an only fitting response to celebrate this new lease on life.

This is why many modern health systems dedicate a significant amount of personnel and resources to the exploitation of this life-changing moment with the laudable goal of “re-habilitating” the fortunate survivor to a life of healthier habits.

But, you may ask, is even such a dramatic event enough to prompt lasting betterment in the victims? And, will those, who have brought this upon themselves through their supposedly unholy practice of gluttony and sloth, really manage to turn things around?

This burning question has now been thoroughly examined by Billie-Jean Martin (a former Obesity Network Bootcamper) and colleagues from the University of Calgary, in a paper published in OBESITY.

Happily enough, almost 4,000 participants, studied one year after their participation in a 12-week rehabilitation program (which invoked the dedicated services of exercise physiologists, nurses, registered dieticians, social workers and clinical psychologists), did indeed experience a small but measurable improvement in aerobic fitness – a parameter known to forecast survival.

Sadly, however, not everyone benefitted equally. Despite enthusiastic participation in the program, obese patients (who also happened to start off on a poorer footing in terms of exercise capacity) showed a lesser sustained improvement in peak estimated metabolic equivalents (a sciency measure of aerobic fitness) than their less corpulent counterparts.

Prejudiced readers should, however, not jump to the conclusion that the obese participants were perhaps less enthusiastic or committed to this enterprise.

Indeed, during the 12 week intervention, the obese group increased their weekly mins at the prescribed exercise heart rate by 40 mins (from 123 to 163), whereas their leaner peers merely managed to add a measly 10 mins to their routine (from 153 to 164). Clearly, the obese participants were not shying away from the extra effort – if anything, they were working substantially harder (relatively speaking) than their leaner colleagues.

Notably, at one year, BOTH groups had regressed in their enthusiasm to slightly BELOW their baseline weekly mins of exercise heart rates; the obese group fell back to 121 mins, while the normal weight group fell back to 150 mins.

Thus, to be fair, NEITHER group managed to sustain the recommended 160+ mins of weekly exercise heart rate at 12 months.

It would seem that neither the “life-changing” occurrence of clogged coronaries nor 12 weeks of the dedicated services of an inter-disciplinary team of healthcare professionals, appears to be all that life-changing after all.

Would a 16 week program, a 24 week program, or perhaps even a 52 week program have lead to better results?

My gut tells me that any “time-limited” behavioural-change program will always produce “time-limited” behavioural change.

Apparently, the situation for cardiac rehab appears no better than the story for weight loss – when “treatment” stops, the lifestyle/weight comes back.

Incidentally, the Albertan actors in this story are no better or worse than the rest of Canada.

According to a recent report from Statistics Canada, three in four smokers with respiratory disease do not quit smoking; most people with diabetes or heart disease will not become more physically active and virtually no one diagnosed with cancer, heart disease, diabetes or stroke will increase their intake of fruit and vegetables.

Nonetheless, I am told, cardiac rehab efforts have demonstrated benefits in a host of modifiable cardiovascular risk factors, at least during and perhaps for a few months following the intervention.

However, the durability of these efforts certainly leave substantial room for improvement across the full spectrum of body shapes and sizes.

Edmonton, AB

ResearchBlogging.orgMartin BJ, Aggarwal SG, Stone JA, Hauer T, Austford LD, Knudtson M, & Arena R (2012). Obesity negatively impacts aerobic capacity improvements both acutely and 1-year following cardiac rehabilitation. Obesity (Silver Spring, Md.), 20 (12), 2377-83 PMID: 22627915