Mastering aging (Part 2): The cardiovascular system
In my last column I discussed some of the physiological changes that inevitably occur as we age. It’s amazing to me that there is actually no universally accepted theory of aging; believe it or not, whilst we can observe the effects of aging on our tissues and organ systems, we don’t actually know what the underlying cause is. There are several theories, the most widely proposed of which suggests that the progressive accumulation of DNA damage and the consequent effects on our organs, along with repeated micro-trauma to our tissues leads directly to the effects seen as we age. Our blood vessels stiffen, our skin and connective tissues lose their elasticity, injuries accumulate and we see lots of cardiovascular, musculoskeletal and hormonal changes as discussed in my column a few weeks ago.
Fortunately there are things we can do to combat these effects. It is possible to reverse or slow down some of these processes.
In this column we’ll look at the cardiovascular system – our heart and blood vessels. As we age, we see declines in VO2max and maximal heart rate. Cardiac output (how much blood the heart pumps out with each beat) and our total blood volume declines. Our blood vessels stiffen and narrow, leading to rises in blood pressure and such disasters as heart attacks and stroke. Fortunately studies have shown that lifelong exercisers seem to avoid many of these negative cardiovascular consequences.
A study in the UK looked at 125 amateur cyclists aged between 55 and 79. They were all lifelong exercisers, and were able top perform at a pretty good level. The men in the study were eligible if they could ride 100km in under 6.5 hours, and the women in the study could ride 60km in 5.5 hours. These people were fit but certainly not superhuman. They were compared to a similar group of non-exercisers. They all underwent a variety of laboratory based tests. Not surprisingly, the exercising group had better muscle mass and strength, less body fat, and lower cholesterol. The males had higher testosterone levels. Additionally, the regular exercise cohort was found to have better immune function, with higher levels of T cells, a key immune indicator. They were less prone to infection, as well as having improved cardiac risk factors.
So firstly, in very general terms, we should adopt an active lifestyle, and we should try to maintain this as we age. I don’t think this will come as much of a surprise to anyone reading this.
What may be a little more surprising, however, is that we should probably be exercising more vigorously as we age. I don’t think this is well known, and perhaps not that intuitive. As we get older, we tend to gravitate towards longer, less intense activities, but this may not offer the same benefits as HIIT. High Intensity Interval Training (HIIT) involves repeated short bouts of intense exercise – anything from 30 seconds to a couple of minutes of hard effort – interspersed with much less intense ‘rest periods’. The intense bouts are repeated over and over, but because each ‘interval’ is short, it’s relatively easy to recover and do more of them. Each session need only last 15 to 30 minutes but certainly seems to pack a punch in terms of the potential health benefits, especially for older subjects.
One example of a HIIT workout would be to warm up for 5 to 10 minutes on a bike or stationary trainer. Then pedal hard and fast for 20 seconds, pedal easy for 40 seconds. Repeat the hard, easy intervals for a total 10 minutes then spin easy to cool down. Another example would be to walk briskly for 3 minutes, then walk easily for 3 minutes. Repeat the fast/slow walks for half an hour. Research has shown some impressive benefits if these workouts are performed 3 times per week, and the older subjects see bigger gains than younger athletes performing these same workouts. The message here is that it’s never too late to start! Cardiovascular fitness (VO2max), strength, lean muscle mass, and insulin sensitivity all improve markedly with these workouts, and we believe that these workouts ‘switch’ on genes, that can slow down the aging process.
Of course it’s never a bad idea to check with your family doctor if you have pre-existing health problems, or if you are new to an exercise program. And in between sessions, which should be spaced through the week, ensure that you don’t push too hard. Ensure adequate sleep and light activity on rest days. These are fun workouts that can help us to combat the effects of aging.
In my next column we’ll look at preserving muscle strength and mass.