Effect of Metabolic Syndrome on the Mobility Benefit of a Structured Physical Activity Intervention-The Lifestyle Interventions and Independence for Elders Randomized Clinical Trial

Abstract

Objectives: To test whether structured physical activity (PA) is associated with a greater reduction in major mobility disability (MMD) in older persons with metabolic syndrome (MetS) than in those without.

Design: Data from the Lifestyle Interventions and Independence for Elders (LIFE) Study, a multicenter randomized trial of 1,635 persons with assessments every 6 months (average 2.7 years).

Setting: Eight U.S. centers.

Participants: Sedentary men and women aged 70 to 89 with functional limitations (N = 1,535); 100 participants were excluded because of missing MetS data.

Intervention: Participants were randomized to a moderate-intensity PA program (n = 766) or a health education program (n = 769).

Measurements: MetS was defined according to the 2009 multiagency harmonized criteria. Outcomes included incident MMD (loss of ability to walk 400 m) and persistent MMD (two consecutive MMD diagnoses or one MMD diagnosis followed by death).

Results: Seven hundred sixty-three (49.7%) participants met criteria for MetS. PA reduced incident MMD more than health education did in participants with MetS (hazard ratio (HR) = 0.72, 95% confidence interval (CI) = 0.57-0.91, P = .007) but not in those without MetS (HR = 0.96, 95% CI = 0.73-1.25, P = .75); the test for statistical interaction was not significant (P = .13). PA reduced the risk of persistent MMD in participants with MetS (HR = 0.57, 95% CI = 0.41-0.79, P < .001) but not in those without MetS (HR = 0.97, 95% CI = 0.67-1.41, P = .87). The test for statistical interaction was significant (P = .04).

Conclusion: Moderate-intensity PA substantially reduces the risk of persistent MMD in older persons with functional limitations with MetS but not in those without MetS. Comparable results were observed for incident MMD. The LIFE PA program may be an effective strategy for reducing mobility disability in vulnerable older persons with MetS.

Keywords: Intervention trial; Metabolic syndrome; Mobility disability; Physical activity.

Figure 1

Effect of Physical Activity Intervention vs. Health Education on Incident Major Mobility Disability, According to Metabolic Syndrome Status. Abbreviations: HR-hazard ratio; MetS – metabolic syndrome; PA – physical activity; HE – health education The graph for incident MMD was truncated at 3.5 years; the non-MetS/HE subgroup had one additional MMD event and the MetS/HE subgroup had 2 additional MMD events between 3.5 and 3.6 years of follow-up. Number of events represents cumulative events and adjusted HRs and P values are from proportional hazards regression models adjusted for gender and clinical site, as described in the Statistical Analysis section.

Figure 2

Effect of Physical Activity Intervention vs. Health Education on Persistent Major Mobility Disability, According to Metabolic Syndrome Status. Abbreviations: HR-hazard ratio; MetS – metabolic syndrome; PA – physical activity; HE – health education The graph for persistent MMD was truncated at 3.5 years. No additional events were recorded between 3.5 and 3.6 years of follow-up. Number of events represents cumulative events and adjusted HRs and P values are from proportional hazards regression models adjusted for gender and clinical site, as defined in the Statistical Analysis section.