Healthy Living: December 3, 2019
We have seen many studies over the years showing the cardiovascular benefits of vigorous exercise over a sedentary lifestyle. Lowered incidence of heart ischemia (angina), heart failure, and sudden death attributed to cardiac causes have all been seen among those who exercise regularly. Now, there are well-known exceptions such as the marathon runner Jim Fixx who died at age 52 of multi-vessel heart disease, as well as concerns that the research may have some inherent bias because those who exercise in the first place may already be healthier than those who cannot. Still, the broad consensus from multiple studies is that pursuing some form of vigorous activity (brisk walking, jogging, swimming, biking, etc.) averaging at least 150 minutes per week, will reduce one's symptomatic coronary artery disease about 20-40%.
What about brain health? Here there are fewer long-term studies, but just last month researchers in Sweden announced the result of a large study that looked at the risk of three neurodegenerative conditions: Parkinson's Disease, vascular dementia from strokes, and Alzheimer's Disease among cross-country skiers compared to their more sedentary compatriots. They tracked down 190,000 people who participated in a well-known cross-country race known as the Vasaloppet in the 1990s, and identified age-matched controls in the general population with similar baseline health characteristics. Two decades after participation in the race they determined how many were presently suffering from any of these brain diseases and compared these rates with 190 thousand non-racing Swedes.
Their findings, published in the journal "Alzheimer's Research & Therapy"*, showed a significant decrease by 50% in the rates of vascular dementia, and a 28% decrease in Parkinson's among the competitive skiers compared to the non-skiers. Curiously, however, they did not find a significant difference in the rates of Alzheimer's between the two groups. The authors of the study conjectured that the drop in vascular dementia occurred because exercise prevented or slowed circulation problems. However, Alzheimer's Disease is not caused by changes in brain circulation. Instead it is thought to be from the accumulation of inflammatory proteins that interfere with neuron function, and as such is not likely to be prevented with measures that address circulatory health.
The research had an additional level of analysis that served as a clever design check on the overall findings. They further stratified the skiers into three groups: those with below average racing times, those with average times, and those with very fast times. Upon analysis of these three groups, they found that there was a consistent trend showing that the 'better' skiers, who presumably had higher levels of cardiovascular fitness, also showed lower incidence of vascular dementia. However, they all had the same risks for developing Alzheimer's disease. The authors felt that this strongly supported the overall study results, that we should not falsely assume that exercise will help prevent Alzheimer's type dementia, but can indeed decrease the risks for vascular types of dementia.
So, what is the take home message of this research? For me, it is one more reason why we should not make excuses for exercise, even if its cold outside. Luckily, I enjoy cross-country skiing, but I would encourage those who may not be as experienced to consider snow-shoeing or even just getting out to walk during our winter months. I know that concerns about falling on ice, or access to good cold-weather gear will be problems for some people, but don't forget: Santa Claus will be coming in less than a month. Now is the time to make sure that list includes good boots, and perhaps some shiny new snowshoes for your winter exercise plan!
*Oskar Hansson, et al: Alzheimer's Research & Therapy, 2019; 11 (1) DOI: 10.1186/s13195-019-0538-4