Perhaps the most established factor that contributes to our health and longevity is physical activity. It is a relatively inexpensive way that can contribute massively to our quality of life. I hope that this article and the nicer weather can motivate many of you to get out and be more physically active.
Exercising can prevent many health conditions, the most obvious perhaps being cardiovascular disease. However, research in the past five years shows that physical activity has benefits that extend well beyond cardiovascular health. Even a single bout of physical activity can reduce blood pressure, enhance insulin sensitivity and improve our capacity to make decisions, plan and problem-solve. Physical activity can also help reduce depression and anxiety symptoms and increase our sense of quality of life. When we are physically active, life is good!
If a single bout of exercise leads to all these benefits, what happens if we exercise regularly? The benefits as you probably guessed are even more astonishing (if not jaw-dropping!). Many studies find that regular exercise reduces the risk of cardiovascular, metabolic and obesity-related conditions, dementia, diabetes, depression and anxiety disorders, osteoarthritis, and even various types of cancer such as colon, breast and endometrial cancers. Even in those already suffering from a disease, exercise can help to slow down its progression. A major study with data from 1.44 million people from the US and Europe, extended these findings and found that exercise decreased the risk for 13 types of cancer, and in most cases, this effect persisted in those who were overweight and those who smoked.
Does physical activity improve sleep? As you guessed, the answer is yes! Those who exercise enjoy longer sleep, better sleep quality, greater sleep depth, greater ease at falling asleep at night, fewer difficulties such as insomnia, and greater alertness in the morning. Those with poorer sleep and older adults benefit the most.
Interestingly, there seems to be a bidirectional relationship between sleep and exercise. Exercise helps us sleep better but not sleeping sufficiently, makes it less likely for us to exercise the next day. Those who are sleep-deprived are less motivated to exercise, so lack of sleep may prevent us from enjoying the benefits of physical activity. Perhaps you can remember an occasion when this happened, where you stayed up late to work or catch up on your favourite show and didn’t feel energized to go to the gym or go out for your walk the next day.
If we think of the different activities on a spectrum, those that are the least physically demanding such as sitting, reclining or lying down, fall under the umbrella of sedentary behaviours. Depending on what we do for a living (sitting at a desk, commuting to work etc), we may spend many hours each day in sedentary behaviours which may increase even more, if our leisure activities (watching tv, playing video games, reading, etc) are also sedentary. The more time we spend in sedentary behaviours, the greater the cost to our health, with increases in the risk for all-cause mortality, shorter and poorer sleep, cardiovascular disease, diabetes, and increased risk of cancers such as colon, endometrial, etc.
So if exercising is the way to go, which type of exercise is best? The evidence is both consistent and convincing. When it comes to physical activity, moderate-to-vigorous physical activity (MVPA) yields the strongest benefits in all the areas mentioned above, hands down. The advice on the NHS website on ‘Physical Activity Guidelines for Adults Aged 19 to 64’ recommends at least 150min per week of moderate physical activity (brisk walking, dancing, biking, etc.) or 75 min of vigorous exercise per week (running, swimming, martial arts, etc.) spread across each day of the week, if possible. A combination of moderate and vigorous types of activities may be the best way to meet the appropriate level of activity. In comparing MVPA and light-intensity physical activities (household chores, cooking, walking, gardening etc) and sedentary behaviours, light-intensity physical activities lower the risk for all-cause mortality compared to sedentary behaviours but do not lead to any other considerable benefits.
The current trend is to move away from thinking of exercise in isolation and to consider the whole 24-hour activity cycle, and the time we spend in the different types of activities, altogether. The activities to consider are light physical activity, MVPA, sedentary behaviour and sleep. This shift in viewing all of these types of activities in a 24h-period is more informative. It can help us create a more accurate profile of ourselves, and to better estimate health risks. More importantly though, it can help us create a more personalized program for intervention to improve our health given our personal circumstances, i.e. type of work, level of MVPA, sedentary behaviours, sleep, etc.
Reallocating time that we spend in sedentary behaviours to one of the other categories, will help to start reshaping our profile. Even if we reallocate half an hour away from our sedentary activities towards sleep, was found to be beneficial. So perhaps we would be ‘killing two birds with one stone’, if we extended our sleep by stealing time away from our sedentary activities, such as lying down on the couch watching TV. The most benefits, however, emerge when we take time away from sedentary activities and invest it in MVPA. Can we reallocate a precious 30-minute slot to physical activity or sleep per day? This is certainly challenging but perhaps setting the 24h day on a piece of paper will help us understand better how we spend our time, and where and how much time can be reallocated to a healthier activity at the expense of a sedentary one. When it comes to physical activity, more is more.
To help you out, I am providing a 24-hour timeline where you can fill in the number of hours you spend each day on a given type of activity. At the bottom, try to create your target time allocation, considering optimal activity levels and sleep for you. I highlighted 8 hours of sleep to get you started. Good luck!
Rosenberger ME, Fulton JE, Buman MP, Troiano RP, Grandner MA, Buchner DM, Haskell WL. The 24-Hour Activity Cycle: A New Paradigm for Physical Activity. Med Sci Sports Exerc. 2019 Mar;51(3):454-464. doi: 10.1249/MSS.0000000000001811
Posted in sleep on May 01, 2023