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How much exercise do you need to stay healthy? – Expert Reaction

The World Health Organisation has updated its decade-old advice on how much exercise is needed to stay healthy.

The WHO says adults should break a moderate sweat for 150-300 minutes a week, or engage in vigorous activity for 75-100 minutes a week. It also now suggests all people limit the amount of time they spend seated.

The SMC asked experts to comment on the new guidelines. 

Professor Grant Schofield, Director of the Human Potential Centre, AUT, comments:

“It’s fantastic the WHO has updated the physical activity guidelines. It’s been obvious for a few decades now that being active and the physical fitness that comes from that is one of the most important things we can do to stay healthy, and/or sort most of the health conditions that affect us in modern society.

“This update helps emphasise some of the more important nuances around strength training and more vigorous activity. It also helps emphasise that at any age and any health condition getting active is probably going to be very good for you.

“What we haven’t seen in New Zealand is any substantial commitment from government in the previous decade or so around physical activity and health. Sport New Zealand lost the mandate to engage in this as their core business and have narrowed their focus to a subset of just sport and recreation. It’s clear that we need government mandated leadership, and funding from the very top. That means the Minister of Sport to fund and support a mandate to have Sport New Zealand once again take world-class leadership in this space.

“New Zealanders historically have enjoyed the benefits of a highly active lifestyle. Now we are midway in the OECD rankings.”

Conflict of interest statement: Grant Schofield receives funding to conduct research around physical activity and health. He is also the chief science officer for Prekure, a social enterprise which promotes education for health coaches. This includes physical activity and health.

Dr Wendy O’Brien, Assistant Lecturer, School of Sport, Exercise and Nutrition, Massey University, comments:

“I am delighted to see these new guidelines communicating the importance of all physical activity, and that they address key populations for the first time, applying to all individuals, regardless of age or ability. The fact that any physical activity is better than none at all is highlighted by the removal of the recommendation for physical activity to be accumulated in bouts of 10 min or more and in suggestions to replace sedentary behaviour with any activity, even if only of light intensity. It is just so important that people are moving, because the benefits of physical activity and limited sedentary time relate not only to physical health, but also to mental health and cognition.

“While evidence for the benefits of physical activity continues to accumulate, it is a shame that there is still insufficient evidence to quantify recommendations for sedentary time. Many people seem to think that, as long as they meet the guidelines, it does not matter how much time they spend being sedentary. But this is not the case; we must aim to be physically active and reduce sedentary time in order to counteract the negative consequences of sedentary behaviour.”

No conflict of interest.

Dr Meredith Peddie, Post Doctoral Fellow, Department of Human Nutrition, University of Otago; and Associate Professor Elaine Hargreaves, School of Physical Education, Sport and Exercise Sciences, University of Otago, comment:

“One of the key updates to the new WHO guidelines is the addition of messages around limiting time spent sitting and replacing it with activity of any intensity. This brings the WHO guidelines in line with country specific guidelines (including New Zealand) that already include messages that we need to reduce the time we spend sitting. This might look like countries like New Zealand are ahead of the game, but WHO last updated their guidelines 10 years ago.

“These guidelines stop short of suggesting a time limit on the amount of sitting we should be doing – but this reflects where the research is in this area – we know that a lot of sitting is associated with increased risk of diseases like diabetes and cardiovascular disease, but we don’t really know where the threshold of effect lies. Canada’s new guidelines suggested we should be limiting sedentary behaviours to less than 8 hours and have received criticism for jumping ahead of the literature.

“The WHO guidelines now identify that any amount of physical activity is important for health, not just continuous activity of 10 minutes or more. A quick 2-minute walk will still contribute to reducing risk! For New Zealand, these WHO guidelines are not telling us anything new, health promotion messages are already written with this information front and centre. Given that time is a frequently reported barrier to being physically active – maybe the message that any movement is better than nothing will encourage us to do small things, like take the stairs, or park at the far end of the parking lot, rather than trying, and failing, to fit that walk in before or after work.

“The new optimal ranges for duration of activity are interesting given that the much of the population worldwide struggles to reach the minimum target rather than doing too much. They could also be a little confusing given that the recommendations also state that more benefit can be achieved if you exceed this range. If people want to do more and feel benefits of doing more then go for it we say!

“Another important change is that for older adults, they now emphasise the benefits of exercise targeting strength and balance improvements for everyone, not just those at risk of falls or poor functional ability. This reflects evidence that suggests that improving strength and balance is an important component of preventing a decline of functional ability which could lead to a fall – and falls in the over 65 age group are a costly business – just ask ACC.

“These new guidelines provide clear evidence-based messages that physical activity is good for hearts, bodies and minds and that any amount of physical activity is better than none, and more is better. However, we know that physical activity guidelines alone do not motivate people to be physically active or reduce the amount of time spent sitting. They need to be combined with specific community-based initiatives that will support and encourage people to overcome the many barriers that exist to getting enough activity in the day. This is especially important in underserved or economically disadvantaged communities.”

No conflict of interest.

Associate Professor Melody Smith, Co-Associate Head (Research | Rangahau) of the School of Nursing, University of Auckland, comments:

“We know that being active is essential for our physical, social, and psychological health. The added benefits of physical activity are wide and varied – more people out and about leads to a sense of safety as well as social cohesion; children being active in nature can encourage environmental stewardship; people walking or cycling rather than driving improves safety and reduces emissions – the list goes on. On the other hand, sitting for too long is damaging to our health – physically and psychologically.

“Despite considerable research and practice in this area, for the most part physical activity rates have remained low and sitting time high globally. Clear inequities in meeting current activity recommendations exist across socio-economic status, geography, age, disability, and gender.

“These new guidelines are a timely call to action – providing updated high quality evidence for the benefits of physical activity across a range of socio-demographic groups. The guidelines have been developed from a large body of evidence which has undergone rigorous review. A systematic and cautious approach has been undertaken to produce updated recommendations, alongside evidence for the strength of evidence for each recommendation.”

What’s new?

“Key changes from the 2010 guidelines include:

  1. Removing the recommendation to accumulate activity in 10 minute bouts – this change aligns with a key message of the guidelines that any movement is better than none. While from a population health perspective this is helpful and potentially motivating (8 minutes still counts!), it will cause major upheavals from a research perspective, with much of our recent survey research focusing on this 10 minute bout metric. 2.  Guidelines now recommend recommend upper time limits for physical activity. These upper thresholds are interesting in that they are based on where exercise reduces major health risks the most. From a communications perspective this adds complexity to an already detailed set of guidelines and it is unclear how helpful this is – perhaps more useful maximum thresholds would have been where health risk from the exercise itself becomes apparent.
  2. There is an additional recommendation for aerobic, muscle strengthening, and balancing activities for all older adults rather than just those with poor mobility. Not only are these types of exercises important preventative activities (particularly to reduce falls risk), many activities that fit this remit (e.g., dancing) are also fun and can promote social connections.
  3. The original guideline for children and adolescents to accumulate 60 minutes of moderate-to-vigorous physical activity daily has been shifted to accumulating an average of 60 minutes per day. This change is simply based on the evidence presented (which was predominantly based on average values), rather than a suggestion that one is better than the other.
  4. A new recommendation that sedentary time should be limited across all groups, which is an important addition, although the lack of evidence has limited clear and helpful recommendations beyond this statement. This is a challenge of creating such a rigorous evidence piece like this – the need to ensure caution with messaging can result in missing important opportunities to provide practical recommendations regarding sedentariness.”

What’s missing? 

“Physical activity and sedentary behaviour research is fraught with challenges. For example, it is possible to simultaneously be physically active and participate in a “sedentary” behaviour, such as when active gaming. It is also possible to accumulate high levels of sedentary time as well as high levels of physical activity independently (e.g., sitting at a work desk for 8 hours then going for a run after work daily). These complexities have led to important shifts away from considering behaviours in isolation, instead looking to understanding patterns of activity and sedentary time, as well as sleep. Recognising this shift, the updated 2016 guidelines for rangatahi and tamariki in Aotearoa (and some other countries) recommend sitting less, moving more, and sleeping well. They also take into account the importance of outdoor time (where this is possible). While the new guidelines are beneficial in that they now consider sedentariness, the lack of consideration of sleep time and the way they consider physical activity means we are still only working in one corner of the puzzle.

“The compromise with taking such a robust and stringent approach at a global level in these new guidelines is that we miss context and nuances in activity patterns that are health promoting and miss opportunities to highlight pragmatic, context specific, relevant, and common-sense approaches that are still evidence-based. Indeed, the guideline authors recognise the need to consider national context in adopting these guidelines. My hope for Aotearoa is that we use these guidelines as a starting point, and support diverse communities to develop health promoting messages that are evidence-based, appropriate, relevant, useful, and meaningful for them. Reducing inequity is fundamental to supporting people to be active across their lifespan. It is essential that the wider context of people’s lives is acknowledged when further developing these recommendations.”

No conflict of interest.

Professor Erica Hinckson, Head of School of Sport and Recreation, AUT, comments:

“I support the addition of the recommendation to limit sitting for all groups for several reasons. The recommendation is cautious as it does not specify any thresholds. I agree with that decision for now as there is not enough evidence and consensus on what thresholds should be used for the different age groups. In New Zealand, for youth for example, we had taken a 24-hour holistic approach, and along with physical activity and sleep recommendations, we had recommended that youth should be engaged in no more than 2 hours per day of recreational screen time and for the remainder of the day, sitting less and moving more, breaking up sitting time and participating in structured and unstructured light physical activities. Nevertheless, this recommendation will potentially raise awareness to limit sitting, and signals sedentary behaviour (sitting time) as a distinct behaviour from physical activity.

“Sedentary behaviour is a common behaviour in adults, and increasingly prevalent in youth characterised by sitting for several hours per day. Some evidence shows that long periods of inactivity, through sitting, have detrimental health effects. In adults, an association has been reported between sitting time and a number of causes of death, as well as cardiovascular disease, and higher risk for obesity and type 2 diabetes. Factors that may influence sitting behaviour are age, attitudes, body mass index, depressive symptoms, quality of life, education, employment status, gender, income, moderate to vigorous physical activity and smoking status.

“Globally, physical activity in youth is declining and sitting time is increasing. The 2018 Report Card on Physical Activity for Children and Youth awarded a D grade on sitting time for youth in New Zealand. Only a fifth or less of children and adolescents in New Zealand had no more than 2 hours of screen time out of school hours per day.

“Researchers with interest in physical activity have been working hard over the years here in New Zealand and overseas to investigate the effects, impacts and associations of sitting time on health in different populations. A forum dedicated to this issue was formed in 2011, The Sedentary Behaviour Research Network, an international network that provides the platform for researchers and health professionals to focus specifically on the health impact of sedentary behaviour.

“I personally never agreed with the previous recommendation that physical activity should be accumulated in 10 min bouts, so it is good to see it removed from the WHO guidelines. ANY activity is better than none. We were meant to move throughout the day. Human beings have been designed for movement through the action of skeletal muscles that make up a good proportion of our biological system. We have had the evidence to support the new recommendation for decades, but the evidence is now stronger than ever.

“The upper limits of 300 min per week for moderate physical activity and 150 min for vigorous activity per week are also a good addition. This is supported by evidence that exercise beyond this limit does not substantially decrease the risk of major health outcomes. It’s important to note that these guidelines are for maintaining good health and mitigating health risks.

“I very much agree with the recommendation for balance and strength training for all over-65s (it was previously only recommended for those with poor mobility). It is vitally important to maintain functionality throughout life as substantiated by evidence. Having a more inclusive recommendation and not limiting it to those with poor mobility was a sensible and necessary change.

“Overall I am supportive of these recommendations, and the process that was undertaken to make the changes. There had been wide consultation and as researchers we have had the opportunity to contribute before the recommendations were finalised. The question though is, how are we going to work together across sectors (health, education, recreation, transport, urban planning) to provide supportive environments for all New Zealanders to meet these recommendations?”

No conflict of interest declared.