My interest in this, as an aging lifelong endurance athlete with PC, is the question of how much cardiovascular exercise is optimal (not just minimal) to maintain my fundamental fitness? Is there an upper limit at which it becomes detrimental?
I am using longevity studies to be a proxy for indicating the best level of fitness conferred by increasing volumes and intensities of exercise. "Cardiovascular fitness" is a measure of how much energy (Calories/Kg/min) we are able to sustain in exercise. Or alternatively, how much Oxygen we can utilize (VO2max) at our maximal intensity of exercise.
This measure gives a very good estimation of our efficiency and fitness at lower intensities of exercise. It is formally measured in a maximal exercise test on a treadmill or exercise bike. (Sometimes supplemented with blood lactate and exhaled respiratory gas measurements.)
We can do one of several simple tests that can give a rough estimate of VO2 max to assess our current CV fitness status. Perhaps the easiest of these is the Rockport Walking test. It simply requires walking a level measured mile at your fast but sustainable pace and noting the time it takes, and your heart rate immediately at the end. Here is a link and calculator:
whyiexercise.com/rockport-w...
Exercise "intensity" is often expressed in terms of "Mets", Metabolic equivalents. One Met is the amount of energy spent per kilogram of body weight per minute at rest. (Or entirely equivalent to Oxygen burned per kilogram per minute), when we are essentially at rest.
"Moderately" intensity exercise is a term applied to activities in the vicinity of 3.5 Mets. This is like somewhat brisk walking on level ground. Heart rate may go above 100, but we hardly notice it and breathing may be only mildly increased. No lactate buildup so it is enjoyable and we can talk easily. The American Heart Association and many other organizations recommend 150 minutes per week at this level as a desirable minimum.
"Vigorous" intensity exercises are those in the vicinity of 6.5 Mets or higher. The AHA and others suggest 75 min/week as an alternative minimum. These feel strenuous but not unsustainable. Breathing is much deeper and rapid. Heart rates may be 75 to 85 % of our maximum. Talking comes in short phrases. Here are links to an overview, with a link to a comprehensive listing, of activities and sports and estimates of their Mets.
whyiexercise.com/metabolic-...
So now that we can measure our own current fitness level and our distribution of moderate and vigorous exercise habits. What is optimal for fitness and longevity? The following prospective cohort study looked at over 200,000 Australians, ages 45-70. Followed for exercise habits (volume in minutes per week). Plus the proportion of that exercise that was "vigorous". These were compared with mortality rates.
Rates of mortality continued to decline with increasing volumes of exercise, up to and beyond 300 minutes per week. And additionally, mortality rates were further lowered when a higher percentages the exercise was done at "vigorous" levels, up to 30% of the total volume.
Effect of Moderate to Vigorous Physical Activity on All-Cause Mortality in Middle-aged and Older Australians
jamanetwork.com/journals/ja...
Results: During 1,444,927 person-years of follow-up, 7435 deaths were registered. Compared with those who reported no MVPA (crude death rate, 8.34%), the adjusted hazard ratios for all-cause mortality were 0.66 (95% CI, 0.61-0.71; crude death rate, 4.81%), 0.53 (95% CI, 0.48-0.57; crude death rate, 3.17%), and 0.46 (95% CI, 0.43-0.49; crude death rate, 2.64%) for reporting 10 through 149, 150 through 299, and 300 min/wk or more of activity, respectively. Among those who reported any MVPA, the proportion of vigorous activity revealed an inverse dose-response relationship with all-cause mortality: compared with those reporting no vigorous activity (crude death rate, 3.84%) the fully adjusted hazard ratio was 0.91 (95% CI, 0.84-0.98; crude death rate, 2.35%) in those who reported some vigorous activity (but <30% of total activity) and 0.87 (95% CI, 0.81-0.93; crude death rate, 2.08%) among those who reported 30% or more of activity as vigorous. These associations were consistent in men and women, across categories of body mass index and volume of MVPA, and in those with and without existing cardiovascular disease or diabetes mellitus."Conclusions and relevance: Among people reporting any activity, there was an inverse dose-response relationship between proportion of vigorous activity and mortality. Our findings suggest that vigorous activities should be endorsed in clinical and public health activity guidelines to maximize the population benefits of physical activity."Another study that was a meta-analysis of prospective cohort studies to estimate a "dose-response" relationship between volume of exercise and mortality. It included 661,137 men and women (116,686 deaths); median age 62 (range 21–98) years.It showed further reductions in mortality occurred at increased levels of exercise up to 3 to 5 times the recommended minimum. That would be 450 to 750 minutes per week (7.5 to 12.5 hours)! This is reassuring for me as that corresponds to my own usual minimum of 1.5 -2 hours most days. Furthermore they found no detriment (though also no additional mortality benefit) of up to 10 times the minimum of 150 minutes. 25 hours per week!
A couple of related links:
"Cardiorespiratory Fitness and Adiposity as Mortality Predictors in Older Adults" jamanetwork.com/journals/ja...
Leisure Time Physical Activity and Mortality: A Detailed Pooled Analysis of the Dose-Response Relationship ncbi.nlm.nih.gov/pmc/articl...
Fighting Prostate Cancer with Exercise and Diet (Part 1)
