Interrelationships Between Body Composition, Physical Functioning, and Quality of Life in Adults with Cystic Fibrosis Open Access

Crain, Benjamin (Spring 2020)

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Background and Objectives: Maintaining lean mass, a higher level of physical activity, and peripheral muscle strength are associated with more favorable outcomes and increased lifespans for individuals with Cystic Fibrosis (CF). This study aimed to compare physical activity, muscle strength, and muscle quality in individuals with CF compared to healthy controls. We also assessed the relationships between body composition, peripheral muscle strength, muscle quality, and physical activity with quality of life.

Study design and Methods: This was an observational, cross sectional study design in adults (ages 18 - 50) with CF (n = 27) and age-matched healthy controls (n = 25). Body composition was assessed with dual energy X-ray absorptiometry, physical activity by a self-reported questionnaire, peripheral strength by handgrip dynamometry, and quality of life by the Cystic Fibrosis Quality of Life-Revised (CFQ-R) questionnaire. Muscle quality was determined by handgrip strength divided by arm lean mass. Statistical analyses included t-tests and Pearson’s or Spearman’s correlations.

Results: Demographics, body composition, handgrip strength, and muscle quality were similar between individuals with CF and healthy controls. Among adults with CF, hand grip strength was positively, significantly associated with lean mass and bone mineral density. Higher levels of physical activity were positively associated with higher quality of life scores, and more total body fat and body fat percent were associated with lower quality of life scores.

Discussion: This study provides further evidence of the need to maintain lean mass and engage in physical activity for increased quality of life among individuals with CF. Results also indicated that hand grip strength may be a clinically useful surrogate for body composition. Future studies should determine if exercise interventions to increase lean mass and fitness levels can improve quality of life for individuals with CF.

Table of Contents

Introduction. 1

1.1 CF Pathophysiology. 1

Figure 1: The Pathophysiology of the Delta F508 Mutation on the CFTR Protein. 3

Figure 2: Effects of CF on the airway. 3

1.2 CF Screening. 5

1.3 Treatments for CF. 5

1.4 Physical Activity. 6

1.5 Body Composition. 7

1.6 Peripheral Muscle Strength. 8

1.7 Muscle Quality. 10

1.8 CF Quality of Life. 10

1.9 Sex-Based Differences. 13

1.10 Objective and Specific Aims. 13

Materials and Methods 15

2.1 Subjects and Study Design. 15

2.2 Lung Function. 16

2.3 Body Composition. 16

2.4 Quality of Life. 16

2.5 Hand Grip Strength and Muscle Quality. 17

2.6 Physical Activity. 17

2.7 Statistical Analysis. 17

Results 18

3.1 Demographic and Clinical Characteristics. 18

Table 1: Clinical Characteristics and Demographics of Healthy Controls and Individuals with Cystic Fibrosis. 19

Table 2: Peripheral Muscle Strength and Physical Activity in Healthy Controls and Individuals with Cystic Fibrosis. 19

Table 3: Healthy Control and CF Patients Clinical Characteristics and Demographics Stratified by Sex. 21

3.2 CFQ-R Results. 22

Table 4: CFQ-R Results. 22

3.3 Correlations of Physical Activity and Lung Function vs. Muscle Function and Quality. 23

Table 5: Correlations of Physical Activity vs. Body Composition and Physical Functioning among Adults with CF.. 24

3.4 Correlations of Body Composition and Muscle Quality to Physical Activity and Hand Grip Strength. 25

Figure 3. Associations between Hand Grip Strength and Body Composition. 26

3.5 Relationships between Quality of Life and Body Composition/Physical Outcomes. 27

Table 6: CFQ-R Correlations with Physical Activity, HG Strength, and Muscle Quality. 28

Table 7: CFQ-R Correlations with Body Composition Measures. 30

Discussion. 31

4.1 Body Composition, Muscle Strength and Quality in Adults with CF Compared to Healthy Controls. 31

4.2 Muscle Strength and Quality, Body Composition, and Physical Activity Correlations. 32

4.3 Correlations with the Self-Reported Cystic Fibrosis Questionnaire. 34

4.4 Study Strengths. 35

4.5 Limitations and Future Directions. 35

4.6 Conclusion 36

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