Hey there!
I think I'm really going to enjoy answering this question, because it's going to require me to incorporate my training as an Epidemiologist to give you a thorough answer. I'm going to assume that when you say "low level" you are referring to the frequency and perhaps the intensity of the aerobic exercise. I'm also going to assume that by "aerobic" you mean cardiovascular exercise (cardio).
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I'd like to first state that in the world health, it is incredibly difficult to directly link one variable as the cause of some disease or mortality (at least with chronic disease). Many factors come into play when talking about different diseases and health outcomes (such as age, height, ethnicity, diet, pre-existing conditions, etc.), and it's the interplay between these factors that become important as they increase the chances of a certain outcome. I really like how you used the word "associated", and I'll go over what I found after a quick look through some of the literature currently available.
One thing I tried to do was find systematic reviews on the topic. If you're not sure on what a systematic review is, it's simply a literature review which gathers many high-quality studies related to one another in answering a specific study question, and then uses the results of these studies to come to a conclusion on the research question posed.
One piece of literature that I found was a systematic review on the association of physical activity with cardiovascular and all-cause mortality [1]. The review was conducted in Germany and published in the European Journal of Preventive Cardiology. The researchers systematically searched MEDLINE in 2007 and included cohort studies (longitudinal studies that follow people with a similar trait who do not have a disease over long periods time and compare them to another group of people) that looked at the primary preventive impact that physical activity had on all-cause and cardiovascular mortality and included a total of 33 studies which all together included 883,372 participants. Risk reduction was determined by comparing two subgroups of individuals (least active and most active), with the least active subgroup being used as the reference group (the group that all other groups in a study are compared to). Follow up of participants ranged anywhere from 4-20+ years, and the majority of the 33 studies included reported a significant risk reduction of cardiovascular and all-cause mortality. Physical activity was associated with a 35% reduction in cardiovascular mortality with a 95% confidence level that the true value for cardiovascular mortality reduction due to physical activty was somwhere between 30-40%. For all-cause mortality, there was a 33% reduction due to physical activity with a 95% confidence level that the true reduction level value was somewhere between 28-37%.
But your question wasn't so much about general physical activity as it was about cardio and its association between mortality. So I tried to find literature that talked about that specifically. There were two studies that I came across that seemed relevant and were interesting. The first study selectively bred two different groups of lab rats based on treadmill running capability (ones with higher aerobic treadmill running ability and ones with lower treadmill running aerobic ability) to determine if there was a difference in survivability between these groups [2]. The researchers found that the median lifespan for rats bred for low aerobic capacity was 28-45% shorter than rats bred for high aerobic capacity, and that the degredation of the cardiovascular system from childhood to adulthood was more pronounced in rats bred for lower aerobic capacity. The researchers concluded that increased aerobic capacity may be significantly linked to longevity and prolonged prevention of mortality.
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Another study I looked at was another literature review that observed the longevity and mortality rates of "elite athletes' compared to the generatl population [3]. The researchers wanted to see if those who engaged in long-term vigorous exercise training had better survival rates than the general population. A total of 14 epidemiological studies were used and separated based on type of sport (exclusively aerobic and mixed aerobic/anaerobic). Using life expectancy, standarized mortality ratio, standarized proportionate mortality ratio, mortality rate, and mortality odds ratio for all causes of death, the researchers found that aerobic athletes and mixed aerobic/anaerboic athletes survived longer than the general population (as referenced over the 14 studies used). They concluded that long-term vigorous cardiovascular exercise may be associated with greater longevity and survival rates (at least in those types of athletes observed in the 14 studies) when compared to the general population.
So for the most part, a lot of the high quality research that I found indicated that increased aerobic activity played at least some kind of role in increased lifespan, longevity, and a decrease in mortality. Not all studies that I looked at came to this conclusion though [4], and as stated above it is important to consider many things when trying to prolong and improve your life. Many different factors in one's life and lifestyle come into play when it comes to age longevity such as smoking, gender, diet, pre-existing conditions, heredity, genetics, etc. However, having a sound cardiovascular routine is definitely not a bad idea when it comes to living a healthy life in my opinion. So go ahead and build up your cardiovascular endurance! Your body will most likely reward you for it!
Source: easierliving.com
Hope that helps!
-Jtrain
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*Have a question about natural bodybuilding / fitness / nutrition / stress? Need some advice? Email me at jtrainfitness@gmail.com and I will answer it on this blog! Be sure to enter your email to receive alerts for when the next blog post has come out, and be sure to tell your friends about this blog! Follow me on twitter @jtrainfitness and tell your friends to do the same!*
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Citations
[1] Nocon, Marc, Theresa Hiemann, Falk Müller-Riemenschneider, Frank Thalau, Stephanie Roll, and Stefan N. Willich. "Association of Physical Activity with All-cause and Cardiovascular Mortality: A Systematic Review and Meta-analysis." European Journal of Cardiovascular Prevention & Rehabilitation 15.3 (2008): 239-46. Print.
[2]Koch, LG, OJ Kemi, SX Leng, P. Bijma, LJ Gilligan, JE Wilkinson, H. Wisloff, MA Hoydal, N. Rolim, PM Abadir, EM Van Grevenhof, GL Smith, CF Burant, O. Ellingsen, SL Britton, and U. Wisloff. "Intrinsic Aerobic Capacity Sets a Divide for Aging and Longevity." Circulation Research 109.10 (2011): 1162-172. Print.
[3]Teramoto, Masaru, and Timothy J. Bungum. "Mortality and Longevity of Elite Athletes." Journal of Science and Medicine in Sport (2009): n. pag. Print.
[4]Semlitsch, Thomas, Klaus Jeitler, Lars G. Hemkens, Karl Horvath, Eva Nagele, Christoph Schuermann, Nicole Pignitter, Kristen H. Herrmann, Siw Waffenschmidt, and Andrea Siebenhofer. "Result Filters." National Center for Biotechnology Information. U.S. National Library of Medicine, June 2013. Web. 30 July 2013.
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