Cardiovascular diseases (CVDs) are the leading cause of death around the world and lead to enormous disease burden on public health systems [1]. Ischemic heart disease (IHD), associated with a reduction of blood supply to the heart, accounts for about 50 % of all cardiovascular deaths [2].

Physical activity (PA) is a health-relevant lifestyle factor, which is generally considered to have various benefits on both physical and mental health. Strong evidence supports that PA is one of the modifiable risk factors tightly associated with CVD outcomes [3]. PA can affect cardiovascular system through skeletal muscle growth, vascular remodeling and favorable influence on metabolism, and can also cause structural changes of myocardium to prevent ischemic injury [4]. It was reported that around 7–11 % of disability-adjusted life years (DALYs) and deaths caused by IHD can be attributable to physical inactivity among the middle-aged and elderly population [5]. A meta-analysis showed that compared those with no exercise, those with 150 min of moderate intensity aerobic PA each week can reduce the incidence rate and mortality of cardiovascular diseases by 17 % and 23 %, respectively, and the risk of IHD by about 25 % [6].

Sarcopenia is a disease characterized by progressive and generalized loss of skeletal muscle mass and strength [7]. It was estimated that the global prevalence of the disease among individuals aged 60 and above, both men and women, was approximately 10 % [8], and this rate among the people needed long-term care will increase up to 33 % [9]. Growing evidence suggests that sarcopenia is strongly associated with various adverse health outcomes, including falls, frailty, mortality, and several measures of age-related functional decline [10], particularly CVDs, such as myocardial infarction and heart failure [11,12]. A longitudinal study found association between sarcopenia and increasing risk of CVDs among middle-aged and older adults [13]. Another recent study reported that among 2432 middle-aged and elderly people, sarcopenia is positively correlated with an increased risk of carotid atherosclerosis, myocardial infarction and atrial fibrillation [14].

As deleterious conditions that occur with ageing, lack of PA and sarcopenia are both closely associated with IHD, especially among the middle-aged and elderly people. However, previous studies mostly concentrated on the individual effect of PA or sarcopenia on IHD, few studies explored the potential interaction of PA and sarcopenia. A large longitudinal study reported that low aerobic fitness level and low muscle strength at the age of 18 had a significantly elevated risk of developing IHD in adulthood, but no multiplicative or additive interaction was found [15]. However, the fitness and strength of participants were measured at young age in this study, which limited the applicability of the findings to health guidance for the elderly. As far as we know, no study has investigated potential additive or multiplicative interaction of PA and sarcopenia in middle-aged and elderly adults.

We thus conducted the current study to explore the associations of PA and sarcopenia with incident IHD as well as its subtypes, and dose-response association between the volume of self-reported PA and incident IHD. Findings of our study may provide further insights into aetiologic pathways for IHD and offer health guidance to susceptible subgroups.