The HUNT3 Fitness Study

Fitness numbers and health – The HUNT3 Fitness Study

Physical fitness is very important for longevity and good health. The maximal oxygen uptake is the most precise measure of overall cardiovascular fitness. To investigate the distribution of maximal oxygen uptake across a healthy, adult population, we at the Cardiac Exercise Research Group tested more than 4,600 healthy Norwegians between 20 and 90 years of age.

The tests were performed between 2006 and 2008 as part of the third wave of the Nord-Trøndelag Health Study (HUNT3). We still use data from the HUNT3 Fitness Study in much of our research. From the same material we also made our popular Fitness Calculator, a non-exercise algorithm that estimates fitness accurately and preditcts future health, and our Maximum Heart Rate Calculator.

The fitness numbers

Average fitness numbers

The mean maximal oxygen uptake in women and men participating in the HUNT3 Fitness Study were 35 and 44 mL/kg/min, respectively. The results suggest a ~7% decline in maximal oxygen uptake with every 10 year age increase in both genders.

Mean maximal oxygen uptake across the age-groups

Age Women Men
20–29 years 43 54
30–39 years 40 49
40–49 years 38 47
50–59 years 34 42
60–69 years 31 39
Over 70 years 27 34

Active elderly persons are as fit as inactive young persons

  Age Inactive Active
Men 20–29 years 47 60
  50–59 years 38 47
Women 20–29 years 37 49
  50–59 years 31 37

Higher fitness, lower disease risk

Fewer cardiovascular risk factors

Women and men below the gender-specific mean were four to eight times more likely to have a cluster of at least three cardiovascular risk factors – called the metabolic syndrome – compared to the most fit quartile of subjects. We 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 uptake was associated with ~56% higher odds of having the metabolic syndrome.

Read the full research article:
Peak oxygen uptake and cardiovascular risk factors in 4631 healthy women and men

Fewer heart attacks

Moreover, high cardirespiratory fitness reveals the risk of heart attack in healthy persons. We found a strong link between higher fitness and reduced risk of a coronary event during the nine years following the HUNT3 Fitness Study. Only 147 participants had a heart attack or were diagnosed with angina pectoris during follow-up. The 25 % who measured the highest fitness levels had half the risk compared to those with the lowest fitness levels.

Read the full research article:
Peak oxygen uptake and incident coronary heart disease in a healthy population – The HUNT Fitness Study

Better lung function

We have also related higher cardiorespiratory fitness to better lung function. We studied the association between forced expiratory lung volume in one second (FEV1) and maximum oxygen uptake in 741 HUNT3 Fitness Study participants aged 20 to 79 years, and found a linear relationship between better lung function and higher fitness in men, women, young, elderly and non-smokers.

Infographic: Healthier lungs, higher fitness

Read the full research article:
The association between dynamic lung volume and peak oxygen uptake in a healthy general population: the HUNT study

Less inflammation

Furthermore, we found that the lower cardiorespiratory fitness, the higher levels of C-reactive protein (CRP) in blood. CRP levels indicate general inflammation, and high CRP is considered a risk factor for cardiovascular disease. The results might indicate that poor fitness contributes to increased inflammation, and that exercise to improve aerobic capacity could affect CRP levels positively. 1400 women and men from the HUNT3 Fitness Study was included in this study.

Infographic: Better fitness, less inflammation

Read the full research article:
Inflammation Is Strongly Associated With Cardiorespiratory Fitness, Sex, BMI, and the Metabolic Syndrome in a Self-reported Healthy Population: HUNT3 Fitness Study

Less headache

We have also found less headache in young adults with high fitness. Nearly 4000 of the HUNT3 Fitness Study participants also answered headache questions in HUNT3, and in those aged between 20 and 50 years there was significantly increasing prevalence of any headache, migraine and tension-type headache with lower fitness. Actually, the 20 % with the lowest fitness numbers had more than twice the odds of any headache and almost four-fold likelihood of migraine compared to the fittest 20 %.

Read the full research article:
Headache and peak oxygen uptake: The HUNT3 study

Blood markers of fitness

We have also used the HUNT3 FItness study to find markers in the blood that are associated with poor fitness. We compared the levels of 720 micro-RNAs in 12 participants with high maximum oxygen uptake with the levels in participants with low fitness. All participants were between 40 and 45 years old, and each person with high fitness was compared directly with a low-fit participants with similar levels of all other cardiovascular risk factors. Micro-RNAs are miniscule molecules that regulate the activity of our genes, and we identified three micro-RNAs that were indepentently associated with low fitness and could have potential as a biomarker of current and future health.

Read the full research article:
Circulating Micro-RNAs and Aerobic Fitness – The HUNT Study

Convenient fitness tests

We have also used the HUNT3 Fitness Study to create models that make it possible to estimate your own fitness number without expensive equipment. Our most popular prediction models are the non-exercise based Fitness Calculator and Maximum Heart Rate Calculator, which you can read more about by clicking the links.

However, we have also made accurate models based on maximum and submaximum performance tests. The models are inexpensive and uncomplicated, and are convenient options for both recreational athletes and in health care settings.

Peak exercise model

One of our models lets you calculate your maximum oxygen consumption by pushing yourself to exhaustion on a treadmill. Start at a moderate speed and inclination and increase the intensity every second minute until you reach exhaustion. Then calculate your fitness number by using the gender-dependent equation below. The correlation between the model and true fitness number is almost linear.

Men: VO2peak = 24.24 + (0.599 x treadmill inclination in %) + (3.197 x treadmill velocity in km/h)–(0.122 x body weight in kilos)–(0.126 x age in years)

Women: VO2peak = 17.21 + (0.582 x treadmill inclination in percent) + (3.317 x treadmill velocity in km/h)–(0.116 x body weight in kilos)–(0.099 x age in years) 

Submaximal exercise model

You could also estimate your fitness number accurately by exercising at moderate intensity and adding your treadmill inclination, speed, heart rate and body weight into the following equation.

Men: 35.25 + (1.276 x treadmill inclination in %) + (6.402 x velocity in km/h)–(0.196 x weight in kilos)–(27.615 x HRsubmax/(215.336–0.73 x age in years))

Women: 23.77 + (1.205 x treadmill inclination in %) + (6.051 x velocity in km/h)–(0.160 x weight in kilos)–(20.671 x HRsubmax/(212.497–0.702 x age in years))

Read the full research article:
Predicting VO2peak from Submaximal- and Peak Exercise Models: The HUNT3 Fitness Study, Norway

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