Keeping it up! Do people continue to exercise after discharge from cardiac rehabilitation?

Les dette innlegget på norsk her!

It has been shown that a rehabilitation program that includes exercise training reduces mortality in subjects with coronary heart disease. To have a high cardiorespiratory fitness, that is a high maximum oxygen uptake (VO_2max), is strongly predicting survival in these subjects – as well as in the rest of us.¹ Therefore, it is smart to find out how to increase the VO_2max effectively by exercise training.

In CERG, we have done several studies showing that high intensity interval training (HIT) give larger improvements in VO_2max compared to moderate continuous exercise.^2,3 Our training studies typically last for three or four months, with a lot of supervision and good patient compliance. But is HIT something people can do on a regular basis during the rest of their life?

The fitness calculator in new version

During the last few months our fitness calculator has spread all around the world, and has been tested by more than 1.5 million people. When answering a few questions about physical activity and physiological measures, the calculator provides information about estimated VO2max, which is a well established measure of fitness. You also get to know you “fitness age” – meaning, your physical condition compared to the result of direct measurement of VO2max in a healthy population aged 20-90 years  (the HUNT study). In a previous blog post we have explained the background and how to understand the results in details.

One of the main purposes of our research group is to uncover how to treat and prevent major societal health problems, such as obesity and cardiovascular disease. We approach the issues from multiple angles, ranging from large epidemiological studies to studying the molecular mechanisms activated by physical training.

The fact that the fitness calculator has become so popular, gave us an idea: Why not collect this information in a database, in order to increase the knowledge of maximal oxygen uptake and cardiovascular health in a greater population than earlier?

Today we therefore launch our VO2max calculator in a new and extended version. After entering your data you will be asked for your consent to storing data for future research. It is 100 % anonymous, and no identifying information is required. However, you are totally able to decline, and use the calculator only for your own information as before.

Try out the new fitness calculator here!

Disputas 5.des – hjemmebasert versus veiledet trening for hjertesyke

I en bloggpost fra tidligere i år skrev stipendiat i CERG, Inger-Lise Aamot, om sin egen studie om rehabilitering etter hjertesykdom. Studien ble publisert i European Journal of Preventive Cardiology ogviste at intervalltrening i en klinisk sammenheng er både gjennomførbart og effektivt med tanke på å øke oksygenopptak. 90 pasienter trente etter intervallprinsippet, enten på sykehus eller hjemme. Intensiteten ble styrt ved hjelp av pulsklokker. Resultatene viste at frafallet var beskjedent og knyttet til ortopediske eller medisinske årsaker (83 av 90 fullførte 12 uker med intervalltrening 2 ganger i uka), alle pasientene trente på ønsket intensitet (gjennomsnittlig 90 % av maksimal hjertefrekvens) og oksygenopptaket økte med 10 % (tilsvarende 3,5 ml/kg/min) for hele gruppa sett under ett. Konklusjonen ble at intervalltrening er effektiv, vel tolerert og gjennomførbar i en klinisk sammenheng til stabile hjertepasienter.

Hjertepasient på tredemølle på treningslaben vår.

Hjemmetrening kan være et godt alternativ dersom man ikke ønsker eller har mulighet til å delta i et rehabiliteringsprogram på sykehus, men dette forutsetter oppfølging av kompetent helsepersonell og motivasjon for å trene. Faktisk fant Aamot at ved testing etter ett år hadde de som trente hjemme i den første treningsperioden på 12 uker, i større grad opprettholdt en aktiv livsstil enn de som hadde trent i klinikken.

Inger-Lise Aamot disputerer med avhandlingen Feasibility of high-intensity interval training in cardiac rehabilitation torsdag 5.desember. Praktiske detaljer rundt disputasen finner du her.

How to understand our fitness calculator

During the last few weeks, our fitness calculator has been spread all over the world, thanks to the NY Times blog post. We are happy to announce that the calculator now inow is available as an app for smartphones (currently only for Apple devices). It is called VO2cal and you can download it for free in AppStore.

The great media coverage has resulted in tons of questions from people all over the world, which we of course appreciate – nothing is better than transforming our research from statistics to useful tools for everyone, and, hopefully, promote a healthy lifestyle. However, it is not possible to answer individually, and in this blog post, we will explain the background of the calculator and answer frequently asked questions. Check out the FAQ section at our website as well.

The calculator uses maximal oxygen uptake as an indicator for fitness, and very many simply ask what this means. Briefly, maximal oxygen uptake is a measure involving several factors:

• how well the lungs are breathing
• how efficiently oxygen is transported into the blood
• how well the heart is pumping blood to the working muscles
• how well the blood vessels are transporting blood
• how good the muscles are to receive and utilize oxygen

…and this value has been shown to be the single best predictor of current and future cardiovascular health. Usually, the test is performed by running on a treadmill with a mask, through which the ventilation of oxygen and carbondioxide during high intensive exercise is measured. Much easier to perform at a calculator, isn’t it?

The calculator requires information such as gender, age, waistline measure and resting heart rate, as well as frequency, duration and intensity of ecercise. In a few seconds you get your estimated maximal oxygen uptake, and your fitness age – meaning, how old are you according to your fitness level, compared to other healthy subjects?

The basis and method behind the fitness calculator are described in details in the articles of Aspenes et al. (2011) and Nes et al. (2011), both former PhD candidates in Cardiac Exercise Research Group. Through participation in the Nord-Trøndelag Health Study (HUNT), more than 4600 healthy Norwegians between 20 and 90 years were tested on several parameters, among other maximal oxygen uptake.

The researchers discovered that the mean maximal oxygen uptake in women and men were 35 and 44 mL/kg/min, respectively. Further, they found a ~7% decline in maximal oxygen uptake with every 10 year raise in age in both genders. Women and men below the gender-specific mean were 4 to 8 times more likely to have a combination of more than three conventional cardiovascular risk factors (for instance, metabolic syndrome) compared to the most fit quartile of subjects. The researchers also observed that maximal oxygen uptake may represent a continuum from health to disease, and that a general 5 mL/kg/min lower maximal oxygen consumption was associated with ~56% higher odds of having the metabolic syndrome. This HUNT material is the historically largest and most robust of its kind with directly measured maximal oxygen uptake and more than 4600 subjects, and constitutes a stable reference for the fitness calculator.

How can I calculate my maximal oxygen uptake in liters?
If your body weight is 50 kg and you have a maximal oxygen uptake of 50 ml/kg/min you should multiply the two and convert VO2max from ml/min to L/min (i.e. 50kg x 50 ml/kg/min = 2500 ml/min =2.5 liters/min.)

In your test, is walking at a brisk pace considered exercising?

Yes, walking is considered exercise.

The questions you ask don’t accurately reflect my exercise or lifestyle.
We completely understand someone’s concern about this. However, if we are about to test 5000 people we have to be partly general in how to ask the questions. We have shown that it is reasonably accurate in more than 5000 persons, so in general, the questions can be considered reliable. We recommend to answer as best you can to describe a normal week for you – and we are confident that this will give an accurate estimate.

How can I improve my maximal oxygen uptake effectively?
We have made a 7-weeks exercise program that is presented at our homepage, where you can also watch a video about 4×4 intervals.

Why do you not use Body Mass Index (BMI) in the calculator?
Whether we used BMI or waist did not really matter for the outcome (we made several alternative calculators) but the chosen one was slightly better. Further, it has been shown that waist is a much better predictor of future cardiovascular disease risk compared to BMI in several large studies.

Why do you not include fitness ages above 75 and below 20?
There were too few subjects above the age of 75 to make a reference material that made sende for those older than 80 years of age – and we did not test individuals younger than 20 years of age.

Ulrik Wisløff, professor and leader of Cardiac Exercise Research Group.