Methodology
Based on data from the UK Biobank, the researchers conducted a longitudinal analysis to assess the relationship between changes in cardiorespiratory fitness over time and the risk of developing cardiovascular diseases and dying from them.
The scientists analyzed data from 11,530 adults (mean age: 56.5 years, 50.6% men) who underwent cardiorespiratory fitness assessment at the initial stage of the study and again after 4.3 years.
Cardiorespiratory endurance was assessed using a submaximal cycle ergometry protocol. The estimated maximum oxygen consumption (VO2max; ml/kg/min) was calculated based on heart rate during exercise using a validated estimation model. The outcomes were newly diagnosed cardiovascular diseases and cardiovascular disease mortality. The newly identified cardiovascular diseases were identified using the database of newly diagnosed diseases from the UK Biobank, and mortality from cardiovascular diseases was determined using data from the national death registry.
Participants were followed for an average of 14 years from the first visit until the first occurrence of the outcome of interest, death, withdrawal from the study, loss of contact with the participant, or administrative cessation of follow‑up, whichever occurred first.
Results
During the observation period, 921 participants developed cardiovascular diseases, and 119 died from cardiovascular causes.
An annual increase in VO2max of every 1 ml/kg/min led to a 15% reduction in the risk of cardiovascular diseases (risk ratio [RR] 0.85; 95% CI 0.75–0.96) and a 34% reduction in the risk of cardiovascular mortality (RR 0.66; 95% CI 0.51–0.87), regardless of baseline physical fitness, lifestyle factors, changes in BMI, and genetic predisposition.
A clear relationship was identified between the dose and the effect, with the risk of cardiovascular diseases gradually decreasing as cardiorespiratory fitness improved and increasing as physical fitness declined over time. A significant relationship in the same direction was also observed with respect to mortality from cardiovascular diseases.
Participants with the most pronounced decline in VO2max had a 33 % higher risk of developing cardiovascular diseases and a two‑fold higher risk of death from cardiovascular diseases, while participants with the greatest improvement in physical fitness had a 26 % lower risk of developing cardiovascular diseases and a 52 % lower risk of death from cardiovascular diseases.
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