Fitness, strength and severity of COVID-19: a prospective register study of 1 559 187 Swedish conscripts

• Published in: BMJ open Vol. 11; no. 7; p. e051316
• Main Authors: af Geijerstam, Agnes, Mehlig, Kirsten, Börjesson, Mats, Robertson, Josefina, Nyberg, Jenny, Adiels, Martin, Rosengren, Annika, Åberg, Maria, Lissner, Lauren
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group LTD 05-07-2021; BMJ Publishing Group
• Series: Original research
• Subjects: Adolescent; Adult; Blood pressure; Body Mass Index; cardiovascular; Cohort Studies; Coronaviruses; COVID-19; Cross country running; Disease; Education; Epidemics; Epidemiology; fitness; Folkhälsovetenskap, global hälsa, socialmedicin och epidemiologi; General & Internal Medicine; Hospitals; Humans; Hypertension; Intensive care; long-term risk; Male; Measurement techniques; Military service; Muscle Strength; Obesity; overweight; Pandemics; Physical Fitness; Population; Public health; Public Health, Global Health, Social Medicine and Epidemiology; Risk Factors; SARS-CoV-2; Severe acute respiratory syndrome coronavirus 2; Sweden - epidemiology; Teenagers; Sweden; COVID-19; epidemiology; public health
• ISSN: 2044-6055; 2044-6055
• DOI: 10.1136/bmjopen-2021-051316

ObjectiveTo investigate the possible connection between cardiorespiratory fitness (CRF) and muscle strength in early adulthood and severity of COVID-19 later in life.DesignProspective registry-based cohort study.Participants1 559 187 Swedish men, undergoing military conscription between 1968 and 2005 at a mean age of 18.3 (SD 0.73) years.Main outcome measuresHospitalisation, intensive care or death due to COVID-19 from March to September 2020, in relation to CRF and muscle strength.ResultsHigh CRF in late adolescence and early adulthood had a protective association with severe COVID-19 later in life with OR (95% CI) 0.76 (0.67 to 0.85) for hospitalisation (n=2 006), 0.61 (0.48 to 0.78) for intensive care (n=445) and 0.56 (0.37 to 0.85) for mortality (n=149), compared with the lowest category of CRF. The association remains unchanged when controlled for body mass index (BMI), blood pressure, chronic diseases and parental education level at baseline, and incident cardiovascular disease before 2020. Moreover, lower muscle strength in late adolescence showed a linear association with a higher risk of all three outcomes when controlled for BMI and height.ConclusionsPhysical fitness at a young age is associated with severity of COVID-19 many years later. This underscores the necessity to increase the general physical fitness of the population to offer protection against future viral pandemics.