OBJECTIVE: Investigate whether high physical work demands increase risk of ischemic heart disease (IHD) mortality among men of low social class with low physical fitness.

METHOD: Thirty-year follow-up in the Copenhagen Male Study of 5249 men aged 40 to 59 years without cardiovascular disease. Physical fitness was estimated using the Åstrand cycling test, and physical work demands determined by two self-reported questions.

RESULTS: Among 2707 low social class men, multiple-adjusted Cox proportional hazard ratios showed an almost threefold increased risk of IHD mortality among men with high physical work demands and low physical fitness, but not among men with a high physical fitness, referencing men with low physical work demands.

CONCLUSION: These findings among low social class men support that high physical work demands increases the risk of IHD mortality among those with low physical fitness.