The aim of the present study was to study differences in fitness (maximal aerobic power (VO(2max)), balance control, abdominal strength and endurance) and anthropometric data in Swedish women and men (20-65 years of age) between two national cross-sectional samples, studied in 1990/1991 and 2000/2001, respectively. The absolute and relative VO(2max) (aerobic fitness), estimated from a submaximal test, declined with increasing age in both genders. The submaximal test was validated against running VO(2max). Furthermore, the relative aerobic fitness (mL/min/kg) was lower in the 2000/2001 sample in men but not in women. Overall physical activity level was unchanged in both genders. An unexpected finding was that in both samples there were no major differences in relative VO(2max) between men and women of the same age. Combined overweight and obesity (body mass index> or =25) is becoming more prevalent in men, but not in women with prevalence in 2000/2001 of 61% and 38% for men and women, respectively. Balance control and abdominal strength and endurance decrease with increasing age with no differences between the two samples. Thus, the near future health situation for men may be worse, while for women it may be less or no differences compared with today.