Oronzo Chialà, Ercole Vellone, Leonie Klompstra, Giorgio Alberto Ortali, Anna Strömberg, Tiny Jaarsma
Department of Biomedicine and Prevention, University of Rome Tor Vergata, 00143 Rome, Italy
DOI: 10.2340/16501977-2574

Objectives: To describe the relationships among 3 measures of physical fitness (exercise capacity, muscle function and functional capacity) in patients with heart failure, and to determine whether these measures are influenced by impairment of movement.
Methods: Secondary analysis of baseline data from the Italian subsample (n = 96) of patients with heart failure enrolled in a randomized controlled trial, the HF-Wii study. Exercise capacity was measured with the 6-min walk test, muscle function was measured with the unilateral isotonic heel-lift, bilateral isometric shoulder abduction and unilateral isotonic shoulder flexion, and functional capacity was measured with the Duke Activity Status Index. Principal component analysis was used to detect covariance of the data.
Results: Exercise capacity correlated with all of the tests related to muscle function (r = 0. 691–0. 423, p < 0. 001) and functional capacity (r = 0. 531). Moreover, functional capacity correlated with muscle func-tion (r = 0. 482–0. 393). Principal component analysis revealed the bidimensional structure of these 3 measures, thus accounting for 58% of the total variance in the variables measured.
Conclusion: Despite the correlations among exercise capacity, muscle function and functional capacity, these measures loaded on 2 different factors. The use of a wider range of tests will help clinicians to perform a more tailored assessment of physical fitness, especially in those patients with heart failure who have impairment of movement.

Physical fitness is a complex concept, and is particularly affected in patients with heart failure, especially in those with impairment of movement. Physical fitness is often assessed by examining only some of the factors involved, mainly based on physical endurance or strength. This study explored the relationship among 3 different measures of physical fitness: exercise capacity, muscle function and functional capacity. Moreover, the study showed how these 3 measures, despite their good correlation, can be used to assess 2 different factors related to physical fitness. These results should encourage clinicians to choose a tailored strategy to assess physical fitness in patients with heart failure, paying particular attention to patients with impairment of movement.