In an article published in The Age on 12th April 2022 by Gretchen Reynolds, Is 30 minutes of exercise a day enough? Reconfirms the latest guidelines by the American College of Sports Medicine (2018) that:
Adults should undertake:
- 150 minutes of moderate exercise per week OR
- 75 minutes of intense exercise per week
This level of physical activity lowers your overall risk of all-cause premature death and diseases such as stroke, heart attack, type 2 diabetes and many types of cancers (especially, breast, colon and prostate cancer).
But what does 150 minutes of exercise (30 minutes exercise a day) mean?
150 minutes can be broken up into small amounts during the week, but an easy way is 30 minutes, 5 times a week. However, this does not mean going for an easy stroll is effective. It does mean:
- You need to walk at a brisk rate, so that it is difficult to have a conversation with the person walking next to you. It doesn’t matter which activity you choose for your aerobic training, bike riding, walking, jogging or rowing, but the objective is the same, being somewhat puffed during the activity to gain the benefit
This level of exercise is enough to train your aerobic energy system, the long activity part of your cardiovascular system. The aerobic energy system is responsible for converting and maintaining energy within your muscles and heart for longer activities such as going for a run or hiking through the Dandenong Ranges. Any activity that sustained use of energy over time/
But what about strength training?
In the last 24 years of practice as a physiotherapist, the main reason people struggle with starting a new hobby or achieving a new physical goal is because they just aren’t strong enough. I often hear, “I’ve decided to take up running, so I started to just go for a run”. Although this sounds like a reasonable beginning, the most common limiting factor and cause of injury is a lack of strength.
A lack of strength means that the load on the joints and muscles is more than it should be and the task is just harder than it needs to be.
The beginning is strengthening the major postural muscle groups, especially around the back, hips and pelvis. These are the muscles such as:
- The gluteal muscle groups around the hips
- The small muscles around the lower back (multifidus muscle groups)
- The quadriceps muscle groups around the knees.
These muscles keep you up straight and are the also the muscles responsible for propulsion (moving you forward). Finally, these muscle groups protect the joints, by creating stability (control) around the joints and absorbing the shock of activity and reducing the direct load on the joints.
Why is running not enough to achieve this protection? Because, running is a low load, repetitive activity which means that you produce a slight increase in strength initially, but this plateaus very quickly. You need to strengthen these muscles to slightly more than they are comfortable doing to produce enough stimulus to grow and adapt.
What are the other health benefits of Strength exercise training?
More specifically, strength training has the following straightforward benefits (Thomson, 2020):
Protection against heart attack and stroke – Several studies have shown that, independent of aerobic training, strength training of 1 hour once a week (or ½ hour, 2 times a week) reduces the risk of heart attack and stroke by 70%.
Management of diabetes and glucose tolerance – Improving your muscle mass not only increases the number of receptors that pick up glucose and pull it away from the blood stream due to more muscle fibres, but the number and efficiency of these receptors improve, enhancing your glucose tolerance and helping manage diabetes.
Better overall cancer management – It has long been shown that people who are stronger and do regular strength training survive better if diagnosed with cancer. Strength training improves the survival rate, the recovery from any surgery, management during chemotherapy or radiotherapy and overall recurrence. This is particularly so for breast, colon and prostate cancers.
Better memory and brain function – People with higher grip strength (a proxy for overall body strength) performed higher in memory tests and reaction time. In a study, those who lifted weights at least once a week showed significant improvements in cognitive function such as attention. It seems to be because strength training releases several chemicals into the Osteocalcin from the bones. This improves the size and connectivity of the hippocampus, which has a major role in memory and learning.
In addition, strength training is linked with higher self-esteem and a feeling of being more capable in all stages of life. Our brain has an unconscious sense of health and state of our muscles and bones system, that makes us feel we “can or can’t do something”. As a result, strength training is a powerful tool against anxiety and depression. Sadly though, because of a more sedentary lifestyle, adults today are weaker than adults of the 1980’s, with further weakness in the up-coming generation.
So what is the ideal exercise amount per week?
For the best benefits from all types of exercise, the ideal combination is:
- Strength training, working on all the major muscle groups 2-3 x a week
- Aerobic exercise training of either:
- Brisk aerobic exercise (somewhat puffed) for 2.5 hours per week (30 minutes exercise a day) OR
- Intense aerobic exercise (Such as High-Intensity Interval training) for 1.25 hours per week
What about step count?
Unlike the activity guidelines, step-count does not account for intensity, just the number of steps that you take a day. Therefore, the health benefits of aerobic exercise (being somewhat puffed) are not the same just taking 10,000 steps a day compared to 30 minutes of brisk walking.
However, in a large-scale study published in The Lancet in March 2022, the optimal step count to reduce all-cause mortality:
- For people under 60: 8000 to 10,000 a day
- For people over 60: 6000 to 8000 a day
In interesting research on the Hadza hunter-gatherers of Tanzania (Pontzer, 2019) who rarely have heart disease or diabetes, the total energy expenditure from activity in this population is about the same as the Western population. How? Although they spend about 2 hours a day doing moderate to vigorous movement gathering food, there are larger amounts of rest in the other parts of the day, so the total energy expenditure is about the same. However, the active amount of steps is around 15,000 per day.
Additional recommendation – 1st May 2022 – 10,000 steps versus HIIT Training – Which is better?
Although in a recent large analysis of research
- 8,000 to 10,000 steps if you are under 60
- 6,000 to 8,000 steps if you are over 60
has been shown to reduce the risk all-mortality cause of death, this is really not enough to for an improvement in fitness
In a further recent study of 2000 participates from Boston University published in the European Health Journal, demonstrated that lower intensity forms of exercise, such as walking is not as effective in improving fitness as more intense forms of exercises, such as High Intensity Interval training (HIIT).
Not only was HIIT training more effective in improving fitness are higher levels of exertion, but it also improved the body’s ability to start and sustain activity at lower levels. This means that HIIT training is great at improving endurance and sustainability for walking, better than just walking itself.
These findings were consistent across different ages, genders and health status. Finally, the benefits of HIIT training on fitness was present no matter how much time is spent sedentary, such as sitting at work.
Adding HIIT training makes it easier to meet The American College of Sports Medicine’s recommended activity levels:
- 75 minutes of intense exercise a week
And translate into better fitness at both high and low exertion activities.
Andelane L (2022) Intense workouts ‘drastically’ more effective at improving fitness than walking 10,000 steps a day – study. NewsHub.co.na (28-4-22
Chodzko-Zajko, W. J., Proctor, D. N., Fiatarone Singh, M. A., Minson, C. T.,Nigg, C. R., Salem, G. J., & Skinner, J. S. (2009). Exercise and Physical Activity
for Older Adults. Medicine & Science In Sports & Exercise, 1510–1530.
Paluch A E et al (2022) Daily steps and all-cause mortality: a meta-analysis of 15 international cohorts. The Lancet, 7(3), e219-e228
Pontzer, H. (2019). Step on It. New Scientist, 34–37.
Reynolds, G (2022) Is 30 minutes of exercise a day enough?, The Age, 12th April 2022
Thomson, H. (2020). Discover your Inner Strength. New Scientist, 34-38.
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