Gjør tryggere omgivelser oss mer aktive?

Tidligere denne måneden la helse- og omsorgsminister Jonas Gahr Støre frem “Folkehelsemeldingen: God helse – felles ansvar”. Det er gått ti år siden forrige melding – “Resept for et sunnere Norge” i 2003. Meldingen ble den gang møtt med kritikk fra mange hold fordi en mente at den i for stor grad la ansvaret for god helse på enkeltindividet. Årets melding ser derimot ut til å i større grad vektlegge hva samfunnet og myndighetene kan og bør gjøre for å fremme folkehelsen. Blant annet er viktigheten av et helsefremmende samfunn viet et helt kapittel i meldingen, med spesielt fokus på helsevennlig transport og nærhet til friarealer der en kan bedrive fysisk aktivitet.

Det sier seg selv at et slik satsning vil kreve en utstrakt grad av tverrfaglig samarbeid, og her virker det faktisk som om myndighetene har gjort jobben sin. Nasjonal Transportplan 2014 – 2023, ble lagt frem tidligere i år, og presenterte klare strategier for tilrettelegging for mer miljøvennlig og helsefremmende transport. Målet er ambisiøst: sykkeltrafikken i Norge skal kun utgjøre 8 % av alle reiser innen 2023. Dette innebærer at sykling minst må dobles i omfang, og at 80 % av barn og unge går eller sykler til skolen.

strandMålsetninger er vel og bra – om tiltakene virkelig blir gjennomført, gjenstår å se. Et annet spørsmål som er verdt å stille seg, er om de vil ha den tilsiktede virkningen. Vil barn sykle til skolen bare det er trygg sykkelvei helt frem? Vil inaktive voksne begynne å løpe hvis de får tursti rett ved huset?

Forskning viser at nivået av fysisk aktivitet trolig henger sammen med en rekke faktorer, der fysisk tilrettelegging bare er en del av svaret. For eksempel viser en nylig publisert artikkel i PloS One fra Nederland at bedret trafikksikkerhet i nærmiljøet økte andelen fysisk aktive, når en sammenlignet aktivitetsnivå ved to ulike tidspunkt. Når det er sagt, var økningen relativt beskjeden. Dessuten viste det seg at antall timer fysisk aktivitet ikke økte med økende trafikksikkerhet blant dem som allerede var litt aktive ved første måling. Evalueringen av trafikksikkerhet var videre svært objektiv – deltakerne ble bedt om å gradere hvor enig de var, fra 1-5, i påstanden “Jeg synes trafikksikkerheten i mitt nabolag er god”. Tendensen til økt fysisk aktivitet var dessuten sterkest blant kvinner, personer i alderen 35-60 år, og folk med høy sosioøkonomisk status. 

Denne undersøkelsen henvendte seg til voksne, men hvordan er situasjonen for barn? En review av 23 studier fra 2003 om sammenhengen mellom aktivitetsnivå blant barn og fysiske forhold i nærmiljøet. Med tanke på infrastruktur var resultatene klare: barn i områder med godt oppbygd nettverk for gåing og sykling var mer aktive enn i områder med dårligere tilrettelegging. Det viktigste tiltaket var fravær av trafikkfarlige situasjoner, som kryssing av veier, uoversiktlige veikryss, høye fartsgrenser, og så videre. Derimot var ikke tilgang til arealer for  utøvelse av fysisk aktivitet så viktig. Når det gjaldt trygge omgivelser, viste faktisk flertallet at den subjektive oppfatningen av et trygt nabolag ikke gjorde barn mer aktive. Fra et objektivt perspektiv var imidlertid saken litt annerledes: der det var mye kriminalitet, samt i områder med mye løshunder, var barna i større grad inaktive enn andre steder. Som en liten kuriositet (som forhåpentligvis er representativt her i Norge også) hadde ikke dårlig vær noen betydning for aktivitetsnivået.

Å løfte frem fysisk aktivitet i alle lag av samfunnet er en komplisert prosess som krever en innsats på flere områder. Vi vil derfor i tiden fremover fokusere på flere aspekter ved Folkehelsemeldingen her på CERG-bloggen.

Maria Henningsen, CERG.

Exercise minimalism – this little is needed

It is a commonly held misconception that getting and staying in shape requires hard work and hours upon hours of training. In today’s society many of us feel the burden of all the requirements and expectations and the constant feeling of too little time. Not seldomly, this goes beyond regular exercise routines – and training adds to the list of things you should have done, but that simply are dropped in favor of other, more urgent tasks. But does it really need to be this way? Is it possible to get both worlds – overcome enough training to achieve health benefit from it, without sacrificing other stuff?

AtefeNew research shows that just one hour of exercise a week for a period of two weeks is enough to observe improvements. The key to training effect on health is not duration, but the intensity of the workout. You don’t have to train long, but once you do, go hard. In our laboratory we advise people to train with 4×4 interval training as a starting point. However, we have even observed that interval workouts with shorter duration are almost as effective in increasing maximal oxygen uptake as longer sessions. These short sessions consists of only one 4-minute interval of 90-95% of maximum heart rate. Maximal oxygen uptake is known as a key factor related to the risk of cardiovascular morbidity and mortality.

But there are also other options for shorter training sessions with high intensity. Dr. Martin Gibala of McMaster University in Canada is a world leader in the science of training with high intensity training, and has in recent years tested several different protocols in terms of health effects. According to Gibala, it is surprising how little training volume required to elicit a positive response. He recommends 60 second intervals at 90% of maximum heart rate followed by 60 seconds of rest, a total of 10 repetitions (1×10). Gibala’s research group found that just 60 minutes of high intensity exercise per week (amounting to three 1×10 workouts per week) improved glucose handling and insulin sensitivity remarkably among sedentary men and women.

So our clear call is: Lack of time is no excuse to skip exercise! Anyone can set aside at least four minutes of their precious time three times per week and invest in their health. Who knows how much time is lost in the future if you do not?

Nina Zisko, research fellow at CERG

High-intensity exercise – a tool for improved public health?

Physical inactivity is the fourth leading risk factor for global mortality. Recent reports from England and the United States indicate that physical inactivity is the most common risk factor for chronic disease given that 95% of the adult population does not comply with their national recommendations of physical activity. 

D-eldre1Population-based strategies, aimed at reducing general risk factor levels through lifestyle and environmental changes, are considered to be the most cost-effective and sustainable approaches for reducing the rates of mortality and morbidity. The rationale is that a moderate lowering of risk across a large number of people will have a bigger public health impact than large risk reductions among the few at high risk. However, one of the lessons from previous large community health interventions is that when you try to do too much with too many people, the focus of the program may be lost, the dose per person is low, and the outcomes are often disappointing. The majority of projects have shown only modest impacts on the prevalence non-communicable diseases (NCDs) and its risk factors at the community level.

There is massive evidence that physical activity is associated with reduced risk of NCDs such as cardiovascular disease, diabetes, high blood pressure, many different types of cancer, asthma, arthritis, osteoporosis and Alzheimer’s disease, to mention some. Individuals with at least average cardiorespiratory fitness (CRF) live longer than those with lower fitness, and even small changes in fitness can provide significantly increased life expectancy. Results from the HUNT survey including over 56 000 men and women showed that one vigorous workout a week was associated with a 39% reduction in mortality for men and 51% reduction in mortality for women. In another study involving 416 175 individuals, physical activity for 15 min a day or 90 min a week provided a reduction in all-cause and all-cancer mortality and extended an individual’s lifespan for an average of 3 years. This minimum amount of exercise was found to be applicable to men and women of all ages, even those with cardiovascular diseases or lifestyle risks.

Research also point to that high intensity training, such as interval training, is superior to that of training with low and moderate intensity with respect to its preventive effect, both in health and disease. Actually, in patients with heart failure, an improvement of the hearts pump function has only been found after high-intensity exercise training. Interestingly, it seems that most of the effect of aerobic training is attained when the high-intensity threshold is passed for only a few minutes, and with only one exercise bout. Thus, interval training can be an effective way to implement high exercise intensity in the general population, and we believe there is sufficient empirical support to use high intensity exercise to promote health in a coordinated population-based intervention to maximize cardiorespiratory fitness. In line with this, WHOs report on global recommendations on physical activity for health emphasizes the central role of high intensity exercise.

In a recent review article, we argue that the high prevalence of chronic diseases, increasing obesity and inactivity, rising health expenditure and the increasing proportion of elderly people in our society represent a set of developments that cannot be considered sustainable, and will have dire long-term consequences. Increased physical activity has a beneficial effect on all risk factors for NCDs and premature death. A coordinated population-based intervention program for improved health through increased physical activity in the entire population urgently needs to be implemented. High intensity exercise should be emphasized as the health benefits seem to be larger with high intensity training, specifically forms of interval training.

Tommy A. Rehn

Tommy A. Rehn

The question is how a sufficient level of high intensity physical activity can be attained in all strata of the population. In contrast to most previous large-scale population-based intervention programs, we believe that introducing a single focus, namely increased physical activity with high exercise intensity, will improve the chance of a successful intervention. It is crucial that the intervention has an effect on the inactive individuals, regardless of age, and that there is a strong focus to intervene from childhood as this would have the greatest potential in a long perspective. Such a coordinated population-based intervention could demonstrate positive effects of increased physical activity on public health by reducing the prevalence of NCDs, reducing medical expenses and mortality, as well as increasing work capacity in the population, which in turn would reduce socioeconomic costs. This could form the basis for national and international implementation of health policies.

Tommy Aune Rehn, general practitioner at Levanger Legesenter, PhD in cardiology and exercise physiology.