Peripheral muscle strength and functional capacity in patients with moderate to severe asthma

The adequate control of asthma includes the absence of nocturnal symptoms, minimal use of medication, normal or nearly normal lung function and no limitations to physical activity. The choice of a more sedentary lifestyle can lead to physical de-conditioning, thereby aggravating asthma symptoms and increasing the risk of obesity.

This study aimed at performing a battery of function-related assessments in patients with asthma and comparing them to a healthy control group. A prospective, transversal and case-control study was designed. It was set up at Santa Casa de Misericórdia Hospital -Sao Paulo and Nove de Julho University on a population of outpatients. Subjects of the study were patients affected by moderate to severe asthma. A case-control study was carried out involving 20 patients with moderate to severe asthma and 15 healthy individuals (control group). All participants underwent body composition analysis (BMI and BIA) and a controlled walk test (Shuttle test), resistance muscle test (1RM) and answered a physical activity questionnaire (IPAQ). The group with asthma also answered a questionnaire addressing the clinical control of the illness (ACQ).

In comparison to the control group (unpaired Student's t-test), the patients with asthma had a significantly higher BMI (31.09 ± 5.98 vs. 26.68 ± 7.56 kg/m(2)) and percentage of body fat (38.40 ± 6.75 vs. 33.28 ± 8.23%) as well as significantly lower values regarding distance traveled on the walk test (369 ± 110 vs. 494 ± 85 meters) and metabolic equivalents (3.74 ± 0.87 vs. 4.72 ± 0.60). A strong correlation was found between the distance completed and peripheral muscle strength (r: 0.57, p < 0.05) and METs (Metabolic equivalents - minutes/week) and peripheral muscle strength of 1RM (r: 0.61, p = 0.009).

The individuals with asthma had lower functional capacity and levels of physical activity as well as a higher percentage of body fat compared to healthy individuals. This suggests that such patients have a reduced physical performance stemming from a sedentary lifestyle. Despite the existence of few studies reporting moderate to severe asthmatic patients and functional capacity assessment, it is clear that the assessment presented in the current study is a valid and accessible tool in clinical practice.