A recent study published in the British Journal of Sports Medicine assessed the association between cardiorespiratory fitness (CRF) and some site-specific cancers in healthy young men.
Studies have shown that CRF is associated with a reduction in the risk of developing certain types of cancers. However, large-scale studies of the link between CRF and multiple cancer sites have been sparse.
In the present study, researchers demonstrated a linear association between CRF and a reduced risk of developing most types of cancers investigated. This includes certain types of cancers that have not been previously linked to CRF or physical activity. These results emphasize the need for interventions to increase physical activity and CRF in youth.
The study cohort comprised young Swedish men enlisted in the military between 1968 and 2005. Participants diagnosed with cancer before or within five years of military conscription and those who died or emigrated within five years after military conscription were excluded from the study. None of the study participants had any underlying health conditions or injuries.
The height, weight, and body mass index of the participants were measured; those who weighed <18.5 kg/m2 were categorized as underweight, between 18.5 and 24.9 kg/m2 as normal weight, between 25 and 29.9 kg/m2 as overweight, and ≥30 kg/m2 as obese. Information regarding the level of parental education was obtained from Statistics Sweden and grouped according to the highest level of education of either parent.
CRF was estimated using the maximal aerobic workload cycle test during conscription. The researchers used Cox regression models to assess linear relationships and included factors such as age, body mass index, CRF, year and site of conscription, and parental education level. For easier interpretation, CRF was categorized into low, moderate, and high, and the results comparing individuals with low and high CRF were reported.
A total of 1,078,000 men were included in the primary analyses, among whom 84,117 (7%) developed cancer in at least one site over a 33-year follow-up period. Participants in the low, moderate, and high CRF groups showed similarities in blood pressure and age at conscription.
However, those in the low CRF group were found to be more likely to be obese compared to those in the high CRF group. Additionally, individuals in the low CRF group had a higher likelihood of reporting alcohol and substance abuse and lower parental education compared to those with greater CRF.