Changes in objective and self-reported measures of physical capacity after an intervention in obese older women

The aim of this study was to determine if objective and self-reported measures of physical capacity are two equivalent methods to detect changes following an intervention in obese older women. 36 obese women aged between 55 and 75 years participated in a 3-month study with the aim of improving physical capacity by caloric restriction and/or resistance training. Physical capacity was measured objectively with 10 different tests and self-reported with the SF-36 physical functioning score (SF-36 PF score). Then the performance-to-objective tests were computed using quartiles to provide a baseline global physical capacity score. The mean percentage of change of the 10 tests as well as the SF-36 PF score were also calculated after the study. Body composition was measured by dual-energy X-ray (DXA) absorptiometry. The baseline global physical capacity score and the SF-36 PF score were significantly correlated at baseline (r = 0.43; P < 0.01). Eight out of the 10 objective tests of physical capacity improved after the intervention, while no improvement was observed for the SF-36 PF score. On average, percentage of change in physical capacity was 4.1 +/- 5.9% for the SF-36 PF score and 11.1 +/- 2.9% for the objective measures. However, no significant correlation was observed between percentage of changes between the two approaches after the intervention (r = 0.32; P = 0.07). Based on these results, the method used to quantify physical capacity after an intervention may have major implications on the outcomes. The methods used should be carefully analyzed in regard to the objective of the study.