Scarlett McNally, a Consultant Orthopaedic surgeon, and her colleagues have spent 2 years analysing more than 200 separate pieces of research. The effect that regular exercise could have on our health is amazing. Exercise could:
- prevent type 2 diabetes
- reduce the risk of getting breast cancer by 25%
- decrease the risk of bowel cancer by 45%
- reduce the risk of having a stroke by 30%
- reduce the risk of developing dementia by 30%
- cut the risk of developing heart disease by over 40%
- as well as improvements to mental health
Exercise doesn’t have to be vigorous but it should be regular. Simply start by increasing your physical activity in whatever way you can: walk more, take the stairs, do some gardening, ride a bike…the possibilities are endless!
“We’re genetically programmed to respond favourably to movement and exercise,
there’s healing in motion.”
A lot of us know from experience that exercise is a great stress buster. Elizabeth Gould (Professor of Psychology at Princeton) and her associates have clarified the process. Their research was published in the March issue of the Journal of Neuroscience.
Their experiments were performed on mice. The mice were divided into 2 groups:
- Sedentary group: no running wheel
- Active group: free access to a running wheel (mice run about 4 km per day when given a running wheel!)
Six weeks later the mice were exposed to a stressor (cold water). The sedentary group showed an increase in ‘immediate early genes’ (short-lived genes that turn on rapidly when neurons fire). Whereas the active group showed no presence of these genes suggesting no neuronal excitation secondary to the stressor. In the active group, inhibitory neurons were more active and more gamma-aminobutyric acid (GABA) was released in the brain. GABA is a neurotransmitter that calms down neural excitement.
Gould concluded that “the results suggest that running improves anxiety regulation by engaging local inhibitory mechanisms in the ventral hippocampus”. In layman’s terms, this means that exercise prevents stress and anxiety by suppressing brain agitation.
A study by Arthur English and Nancy Thompson has found that exercise can promote the regeneration of peripheral nerve injuries. In both males and females, the effect requires the assistance of androgens such as testosterone.
Jens Bangsbo and Thomas Gunnarsson from the University of Copenhagen have published the results (Journal of Applied Physiology) of a fascinating study comparing the effects of interval training to regular endurance training. A group of moderately trained runners was split into 2 groups: over a 7-week period the control group continued their normal runs and the interval group replaced their usual runs with the 10-20-30 protocol.
The 10-20-30 protocol consisted of a 1km warm-up followed by 3-4 5 min blocks of interval training. Each block was followed by 2 min of recovery. The interval training was made of low, moderate and high-speed running (<30%, <60% and >90% of maximal intensity) for 30, 20 and 10 sec respectively.
Although the total training volume in the interval group was less than half that of the control group (14 km/week vs 30 km/week), it produced some amazing results. At the end of the study, the 10-20-30 group increased their VO2 max (maximal oxygen consumption) by 4% and improved their 1500 m and 5 km runs by 21 sec and 48 sec respectively. In addition to this, they significantly decreased their systolic blood pressure, total cholesterol and LDL cholesterol levels.
So despite a 50% reduction in training volume, 10-20-30 interval training improves the performance and health of trained runners.
Last month BBC Horizon ran a programme entitled “The Truth About Exercise”. In it Dr Michael Mosley travelled the country speaking to an assortment of Exercise Scientists. One of the first points made was that it takes a lot of exercise to burn calories. In fact, the example provided was that to burn off a cappuccino, a blueberry muffin and a banana, one would have to jog around a track for about 55 mins! Therefore, to stand any chance of losing weight, we must control what we eat.
Fortunately, exercise can have benefits even when no weight is lost. One of the benefits mentioned was the production of an enzyme that helps redistribute fat in the body and sends it to the muscles where it’s burned. This helps reduce the chance of getting atherosclerosis and possibly death from cardiovascular disease. Other health factors that can be improved are insulin sensitivity and the body’s maximum oxygen consumption (VO2 max). Insulin sensitivity is important because it means that blood glucose levels can decrease more rapidly thereby requiring less secretion of insulin by the pancreas. This reduces the likelihood of developing Type 2 diabetes. As for VO2 max, it’s been found to be a good marker of health and longevity.
Next, Dr Mosley met Jamie Timmons, professor of ageing biology at Birmingham University, and was told how training for 7 mins 3 times a week could deliver many of the health and fitness benefits of hours of conventional exercise! The training is called High Intensity Training (HIT) and resembles interval training. Interval training has been around for a long time and has been used by athletes to increase cardiovascular efficiency and increase tolerance to the build-up of lactic acid. The HIT protocol used on the programme was done on a static bike and consisted of: 2 mins warm-up, 20 secs full-out, 2 mins gentle, 20 secs full-out, 2 mins gentle and 20 secs full-out. This added up to a whopping 7 mins and was done 3 times a week for 4 weeks. It’s thought that this type of exercise can appeal to those that are time poor and need to get it done quickly or simply don’t enjoy it and so want to get it over and done with swiftly…hmmmmmm? It’s at this point that I became curious about exactly how many people fell into this category…so I did a little survey among some of my clients.
First I asked them whether they did any exercise or took part in any sports. Amazingly 95% of them did!
I then asked them how many times a week they exercised or took part in sports. Again I was surprised…an average of 3.6 times a week. I started wondering whether they were trying to please or impress me? Apparently 80% of the population doesn’t exercise regularly!
Finally, I asked them why they exercised? This was the last curveball…the most popular answer was because they enjoyed it…it made them feel good! Other popular reasons were for fitness, health (hypertension, diabetes, back pain) and weight loss.
So unfortunately there didn’t seem to be any takers for HIT. The claims are that HIT can give around 24% improvement in insulin sensitivity and 10% increase in VO2 max. After 4 weeks Dr Moseley did in fact improve his insulin sensitivity by exactly 24% but had no change in his VO2 max. His inability to improve his VO2 max was put down to genetics. According to Timmons, research has shown that 20% of the population doesn’t respond to endurance training.
What do I think about the HIT programme? Well, it paints exercising as a chore, but as the survey showed, most people get more from exercise or sports than just an improved insulin sensitivity…they enjoy it, it makes them feel good…possibly because of the endorphin release or a sense of achievement or accomplishment, maybe even because of social interactions? The HIT programme didn’t place much emphasis on fitness but other HIT protocols have. Gibala’s studies have shown benefits but his protocol was longer and a lot more gruelling…definetly not for everyone. There are many components to fitness: endurance, strength, flexibility, speed, agility, etc and I suppose people in the survey were happy to focus on particular aspects of this.
My main issue with the HIT protocol is its intensity. Pedalling “hell for leather” without a warm-up (not one that can be recognised as one anyway!) seems like a recipe for disaster. As a physiotherapist, I was a little uneasy watching Dr Moseley bounce around on his bike whilst pedalling as hard as he could for 20 secs…he should have known better after pulling a hamstring earlier in the programme when trying to sprint without any earlier warm-up…who knows, he may have felt comfortable doing it because he was surrounded by scientists? Surely this is not something that should be recommended to the sedentary masses?
The main drive of the HIT protocol seemed to be on health (primarily insulin sensitivity) and I think there are better, safer and more convenient ways of achieving this. New research published in the journal Diabetes Care has concluded that after meals, regular short bouts of light-intensity or moderate-intensity walking lower glucose and insulin levels. The subjects were asked to walk around for 2 mins every 20 mins. The light intensity walking decreased blood glucose and insulin levels by 24% compared to uninterrupted sitting. That figure is exactly the same as the one achieved by Dr Moseley after the HIT protocol.
If you enjoy exercise or sport and are happy with the fitness you’re achieving, keep it up! If you don’t enjoy exercise or sport and are mainly doing it for health or weight loss, you’re unlikely to keep going very long. My advice would be to focus on increasing your movement through activities of daily living…this was also talked about on Horizon but it seemed to get much less attention than HIT…in my opinion it’s where the real revolution lies…check in next week to find out more…
Blood pressure is the pressure exerted by the blood on the arteries and is measured in millimetres of mercury (mm Hg). There are two measures of blood pressure: the systolic blood pressure (SBP) is taken when the heart contracts and the diastolic blood pressure (DBP) is taken when the heart is relaxed. That’s why the systolic pressure is higher than the diastolic pressure. Blood pressure is considered high when it exceeds 140/90mm Hg and optimal blood pressure is 120/80mm Hg. High blood pressure or hypertension, as it’s also known, is a ‘silent killer’. ‘Silent’ because there are no signs unless it’s extremely high and ‘killer’ because it dramatically increases the risk of stroke, heart disease and kidney disease. Alarmingly, over 25% of adults in the UK have hypertension and that figure increases to more than 50% in those older than 60.
I was recently challenged by a client to provide evidence that exercise decreases high blood pressure. I think his exact words were…”where’s the evidence?” At first the question surprised me, but I soon realised he had a valid point. Why embark on a gruelling exercise programme without proof that it will actually fulfill the desired purpose?
So, here’s the evidence:
- Exercise decreases blood pressure in a staggering 75% of people with hypertension. On average, SBP decreases by 11mm Hg and DBP decreases by 8mm Hg. Now, if you’re thinking that those figures aren’t worth the effort…think again! The risks associated with hypertension are continuous. That means that with each 2mm Hg rise in SBP there’s an associated 7% increase in mortality from heart disease and 10% increase in mortality from stroke. So exercise alone can decrease your risks of dying from heart disease by just under 40% and decrease your risks of dying from stroke by 55%! Worth the effort?
- All guidelines (NHS, National Institute for Health and Clinical Excellence, American College of Sports Medicine, Canadian Hypertension Education Program, Mayo Clinic, etc) include exercise as a cornerstone in the prevention, treatment and management of hypertension.
Now that we know exercise works, here are some specific guidelines on how to go about it:
- Exercise should be undertaken on most days of the week and can include activities like gardening, household chores, walking, etc
- Perform primarily endurance exercise supplemented by some resistance work
- It should last 30mins a day (this can be continuous or accumulated over the day)
- The intensity should be 40-60% of reserve heart rate (low to moderate intensity exercise is as, if not more, beneficial as high intensity exercise)
What are you waiting for? Jump on that bike! Actually, before you jump on that bike, make sure you get permission from the owner and check with your GP as well. Next week, even more ways to help decrease blood pressure…
Aging, infections and diseases such as cancer, neurodegenerative disorders, inflammatory diseases and insulin resistance can all be caused by a buildup of waste products and debris within cells. It’s by a process called autophagy, an intracellular recycling system, that cells maintain their ideal environment. A group of researchers have found that exercise helps boost autophagy.
For a more in-depth analysis of the research, have a look at “Exercise as Housecleaning for the Body” in The New York Times.
A team of researchers have identified a new hormone named irisin. It’s produced by exercise and increases the metabolism and the sensitivity to blood sugar levels. This in turn may make us less susceptible to obesity and diabetes.
Yet more proof that exercise is beneficial…if we needed any more!
Researchers Art Kramer and Laura Chaddock, from the Beckman Institute at the University of Illinois, have found that children that are aerobically fitter perform better at memory tests than their less fit peers. The improvement in brain function is linked to an increased hippocampal volume. The hippocampus is a structure deep within the brain that is involved with learning and memory. This would suggest that exercise plays a crucial role in the brain development of children.
As we age, there is a natural decline in our mental function. However, studies have shown that this process can be slowed or even reversed! Dr Kirk Erickson conducted a 9 year follow-up study that demonstrated that increased exercise, in the form of walking, was associated with greater grey matter volume and less cognitive impairment. This can have dramatic effects on our ability to lead normal independent lives well into our old age.
The reason for the beneficial influence of exercise on brain growth and function may be due to a protein called Brain-Derived Neurotrophic Factor (BDNF). It supports the survival of existing nerve cells and promotes the growth of new ones and increases the levels of circulating BDNF.
These findings support the promotion of life-long exercise. I guess this sheds new light on the old Roman adage: “a healthy mind in a healthy body”!