The SWEFIT Study: A national survey of cardiorespiratory and muscular fitness in Swedish adolescents
Project Leader
- Gisela Nyberg
Department
- Department of Physical Activity and Health
Research Funders
- Skandias Stiftelse Idéer för livet
Abstract
Below you can read summaries about the project in English and/or Swedish. The information is taken from the publication database DiVA.
The SWEFIT study aims, for the first time, to measure cardiorespiratory fitness, muscular strength, and lifestyle factors in a nationally representative sample of approximately 4,000 adolescents aged 13–14 and 17–18 years. The study will establish Swedish reference values and investigate differences between sexes and socioeconomic groups. Results will also be compared with international studies and historical Swedish data, providing insight into long-term trends. In addition, the study will examine how fitness, strength, and lifestyle factors are associated with future disease risk.
Data collection will take place over two years, both in research facilities, schools, and using mobile testing units (buses), ensuring national coverage and participation from both urban and rural areas. Measurements include cardiorespiratory fitness (Ekblom-Bak test), handgrip strength, power of the lower limbs, upper-body strength, body weight, height, blood pressure, resting heart rate, and self-reported lifestyle behaviors. In the future, participants may be linked to national registers to allow long-term follow-up of cardiovascular and metabolic diseases, mental health diagnoses, and sickness absence. Inclusion of age groups previously examined in earlier studies (1987, 2001, 2007, 2019) and conscription register data enables analyses of long-term trends.
The results from the SWEFIT study will enable early identification of risk levels and provide an evidence base for preventive health initiatives. The study is led by researchers at the Swedish School of Sport and Health Sciences in collaboration with Karolinska Institutet, international researchers, clinicians, and strategic partners, ensuring high scientific quality, clinical relevance, and long-term societal benefit.
SWEFIT-studien syftar till att för första gången mäta kondition, muskelstyrka och levnadsvanor i ett nationellt representativt urval på omkring 4000 ungdomar i åldrarna 13–14 och 17–18 år. Studien ska etablera svenska referensvärden och undersöka skillnader mellan kön och socioekonomiska grupper. Resultaten ska också jämföras med internationella studier och historiska svenska data. Studien ger också kunskap om hur kondition, styrka och levnadsvanor samvarierar med risk för sjukdomar senare i livet.
Datainsamlingen sker under två år, både i forskningslokaler, i skolor och med mobila mätenheter (buss), vilket säkerställer nationell täckning och deltagande från både stad och landsbygd. Mätningarna omfattar kondition (Ekblom-Bak-test), handgreppstyrka, explosiv benstyrka, vikt, längd, blodtryck, vilopuls samt självrapporterade levnadsvanor. Deltagarna kopplas till nationella register för uppföljning senare i livet av hjärt-kärl- och metabola sjukdomar, psykiska diagnoser samt sjukfrånvaro. Inkludering av åldersgrupper som ingått i tidigare studier (1987, 2001, 2007, 2019) och värnpliktsregistret möjliggör analyser av långsiktiga trender.
Resultaten från SWEFIT-studien möjliggör tidig identifiering av risknivåer och underlag för hälsoinsatser. Studien leds av forskare vid Gymnastik- och idrottshögskolan i samarbete med Karolinska Institutet, internationella forskare, kliniker och strategiska partners, vilket säkerställer hög kvalitet, klinisk relevans och långsiktig nytta för samhället.
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About the project
There is growing concern that today’s adolescents have lower physical fitness and muscular strength than previous generations, and that cardiorespiratory fitness has declined. International studies show clear reductions, but in Sweden, there is a lack of national, representative data.
This is particularly important as research shows that cardiorespiratory fitness and muscular strength are strongly linked to both physical and mental health throughout life and are key indicators of overall health in young people. Low physical capacity in adolescence is associated with a higher risk of chronic disease, premature death, and impaired functioning later in life. There is also research indicating that poor fitness during adolescence may affect future capacity to manage physically and cognitively demanding occupations.
Previous Swedish studies have often been limited to boys, had small sample sizes, lacked socioeconomic representativeness, and paid little attention to geographical differences, such as those between urban and rural areas.
There is therefore a significant need for national, representative data on the fitness and muscular strength of young people in Sweden.
Study aim
The SWEFIT-study aims to measure cardiorespiratory fitness and muscular strength in a nationally representative sample of Swedish adolescents aged 13-14 and 17-18 years.
The study is based on the following research questions:
- What are the current levels and reference values for cardiorespiratory fitness and muscular strength among Swedish adolescents, and how do these vary by sex, socioeconomic background, and geographical region?
- How do these levels compare with previous Swedish data and with international levels?
- How are cardiovascular fitness and muscular strength related to mental health, blood pressure, and lifestyle habits?
Study phases
Recruitment – how schools are selected
To ensure that the study provides a representative picture of Swedish adolescents, a cluster sample of schools developed by Statistics Sweden (SCB) is used. The sample is designed to reflect the national variation among pupils in Sweden. This means that schools are selected so that, together, they reflect differences in governing body, school size, geographical distribution, including municipality type, and the socioeconomic background of legal guardians.
The selected schools receive a digital invitation by email. Once the school management has agreed to participate, study information is sent to pupils and guardians through the school’s regular communication channels, such as intranets, learning management systems (e.g. SchoolSoft), email, or letters. Participation in the study is voluntary. All pupils provide informed consent before taking part. For pupils under the age of 15, written consent from a legal guardian is also required.
The study plans to include 3,500-4,000 adolescents from Year 7 in compulsory school and Year 2 in upper secondary school, across Sweden. Data collection is carried out in groups together with each school class. Collection takes place either at universities in larger cities, at the participating schools, or in mobile testing units (buses) to ensure coverage across the whole country.
Has your school been invited to participate?
Information for participating schools
We are delighted that your school will take part in the SWEFIT study. The testing day may be held at a university near the school, or at the school itself if the distance is greater than 2-3 hours (the study covers transport). As a participating school, certain preparations are required ahead of the testing day:
- Designate a contact person, such as a form tutor for the participating class and/or a PE teacher, so that we can plan the testing day together.
- Ensure that information and consent forms are sent home to pupils and legal guardians.
- The contact person collects completed consent forms 1–2 weeks before the testing day.
- The contact person needs to confirm how many adolescents are participating.
Information for legal guardians and pupils
We are grateful for your help in carrying out this important study to better understand the physical and mental health of Swedish adolescents. As a participant, consent will be required from the adolescents, as well as the legal guardian if the participant is a minor.
Participants will take part in a testing day during which several measurements will be conducted. We understand some elements may feel uncomfortable, sensitive, or challenging for participants, and we will make adjustments to ensure all participants feel at ease. Tests will take place in small groups, and we will ensure that accommodations are made for pupils with particular needs.
We place great value on participants' experiences on the testing day and hope it is seen as an educational and positive experience.
To help understand potential differences across socioeconomic groups, information on guardians’ income and level of education is also used. This data is retrieved anonymously from national registers through Statistics Sweden (SCB) and cannot be linked to individual persons.
To gain a nuanced picture of adolescent health, all participants undergo several different types of measurement:
- Cardiorespiratory fitness is measured using the Ekblom-Bak test, a well-established sub-maximal bike test that estimates fitness level without requiring maximum effort from participants.
- Muscular strength is measured through several standardised exercises that assess different types of strength and explosiveness. Participants perform, for example, a handgrip test, a standing long jump test, and a bent arm hang test.
- Mental health and lifestyle habits are measured by having participants complete a digital questionnaire covering their well-being and lifestyle habits, including physical activity, screen time, and sleep.
In addition, several physiological measurements are recorded, including blood pressure, resting heart rate, weight and height.
Project time plan
- Spring 2026 – Preparations
During the Spring of 2026, all measurements are tested and adjusted during a pilot project. - Fall 2026 – Regional data collection
Data collection begins regionally in the Fall of 2026, including schools within 2-3 hours of travel from Stockholm and the Swedish School of Sport and Health Sciences. - 2027–2028 – National data collection
In 2027 and 2028, the national data collection will be conducted. During this period, schools from across Sweden participate.
Societal relevance
The results from the SWEFIT study will address a critical societal challenge, as Sweden lacks nationally representative data on cardiorespiratory fitness and muscular strength in adolescents. The project fills this knowledge gap and will provide results from the first nationally representative mapping of adolescents’ physical capacity in Sweden, with data broken down by age, sex, socioeconomic group and geographical region.
The results will enable:
- Identification of at-risk groups with low physical capacity (thus elevated risk of future ill health)
- Comparisons with older Swedish studies and international data.
- An evidence-based foundation for health-promoting and preventive interventions, with the potential to reduce future societal and healthcare costs.
- A national monitoring system for physical health in Swedish adolescents.
Do you want to know more?
Contact us through swefit@gih.se.
Co-researchers
- Örjan Ekblom, GIH, Department of Physical Activity and Health
- Karin Kjellenberg, GIH, Department of Physical Activity and Health
- Susanne Andermo, GIH, Department of Physical Activity and Health, Karolinska Institutet
Funding period
- 2026 - 2029
Project type
- Project grant
National Research Field
- Public Health, Global Health and Social Medicine
Contact
Professor, Director of Studies of hälsopromotionsprogrammet, Head of subject area Public Health ScienceGisela Nyberggisela.nyberg@gih.se+46 8-120 53 806