Associations of cardiorespiratory fitness and body mass index with incident restrictive spirometry pattern

Restrictive spirometry pattern (RSP) suggests an impairment of lung function associated with a significantly increased risk of premature mortality. We evaluated the independent and joint associations of cardiorespiratory fitness (CRF) and body mass index with incident RSP.Data from the Aerobics Centre Longitudinal Study included 12 360 participants (18-82 years). CRF was assessed by maximal treadmill test and categorised into five groups. Body mass index was categorised into normal weight (<25.0 kg/m2), overweight (25.0-29.9 kg/m2) or obesity (≥30.0 kg/m2). RSP was defined as the simultaneous occurrence of forced expiratory volume in 1 s/force vital capacity ≥lower limit of normal and forced vital capacity