Leprosy is a chronic infectious contagious disease that is caused by mycobacterium leprae, a bacillus with affinity for cutaneous cells and peripheral nerves (sensory, motor, and/or autonomic) which has the respiratory tract as the main route of contamination ^1,2 . As a consequence, diagnosed individuals present skin lesions with altered sensitivity and peripheral nerve thickening, as well as positive smear microscopy for Hansen's bacillus ^1,3 .

Although the incidence of leprosy declined from 2006 to 2015, the disease control is stillpoor ⁴ . In Brazil, its prevalence is high, we have the second highest incidence of leprosy in the world, losing only to India. The largest case detection is in the Brazilian northeast, where the states presented a prevalence coefficient above the national average ⁵ . Particularly in Petrolina, a city located in PE state and border with BA, according to the Municipal Health Department, about 70 new cases of the disease per 100,000 inhabitants were diagnosed in 2018, making it a hyperendemic region.

Multidrug therapy is a first-line and effective treatment for individuals with leprosy ¹ . However, when undiagnosed and inadequately treated, the patient's clinical condition can be aggravated, resulting in neuromotor impairments. In the peripheral nervous system, Schwann cells have basal lamina receptors that recognize mycobacterium lepraeantigen, which allows the binding or invasion of these cells, which can lead to neural damage ⁶ . As a result, patients may develop deficiencies and physical deformities, functional disabilities, responsible for the high morbidity of leprosy, which may reduce the walking performance, muscle strength, physical activity levels and quality of life of these patients ^7,8,9 .

Physical activity is related to maintenance or improvement of mobility and functional capacity in patients with different comorbidities ¹⁰ . Nonetheless, the extent to which these disease-associated impairments caused by leprosy affect functional performance and physical activity levels is poorly understood ^8,11 . Apparently, both the presence and degree of severity of the disease, caused by the injury of the peripheral nerves, negatively influence the functional capacity, especially the walking capacity and palmar grip strength in these patients.. On the other hand, the results observed in relation to physical activity levels are still controversial ^7,8,11 . In this line, understanding the changes in these outcomes when compared to healthy controls could provide information to help design more appropriate physical activity and functional rehabilitation programs for this sub-group. Therefore, the aim of our study was to compare the functional performance and physical activity levels between individuals with and without leprosy in Petrolina-PE. We also analyzed how these outcomes differ by degree of disability according to the World Health Organization (WHO) ¹² .

Normality was checked using the Shapiro Wilk test. Differences between groups (leprosy vs. age-matched healthy controls; individuals with vs. without disability) were analyzed with an independent t-test. The effect size (ES) was calculated to verify the magnitude of the differences by Cohen’s d ¹⁹ . In this study, we did not perform a prior sample size calculation, however, the computed achieved power was 0.05, 0.05, 0.31, 0.98, 0.82, 0.99 and 0.89 for MVPA, handgrip right/left hand, SPBB, TUG, 6MWT and gait speed, respectively. Data were analyzed using the Statistical Package for the Social Sciences (SPSS Version 22.0 for Windows).

Table 1 shows the main characteristics of the study participants. There was similarity in age, body mass, and stature between groups, however, individuals with leprosy presented higher body mass index values.

Table 1 Table 1 Main characteristics of the participants Fonte: Autores.

Table 2 presents the comparisons of functional performance and physical activity measures between groups. The leprosy group demonstrated lower values in the SPPB, TUG, 6MWT, and gait speed when compared to the control group. The effect sizes varied from moderate to large (0.76-1.19). On the other hand, no significant differences were observed for handgrip strength or MVPA (p> 0.05).

Table 2 Table 2 Comparison of functional performance and physical activity levels between individuals with and without leprosy Note:

SPPB-Short Physical Performance Battery; MVPA- Moderate-to-vigorous physical activity; TUG-timed up and go; 6MWT-Six-minute walk test; ES- Effect size.

Of the total of 30 individuals with leprosy, 23% (n= 7) presented a degree of disability of 1, and 10% (n= 3) were classified as grade 2. In order to compare the degrees of disability, according to the WHO, the leprosy group was divided into two groups: with vs. without disability (Table 3). The disability group presented lower values for SPPB, handgrip strength (left hand), 6MWT, and gait speed when compared to the group without disability (p <0.01), and the magnitudes of effect sizes were large (1.01-1.55). No significant differences between groups were observed for handgrip strength (right hand), TUG, or MVPA (p> 0.05).

Table 3 Table 3 Comparison of functional performance and physical activity levels between degrees of disability according to the WHO in individuals with leprosy Note:

SPPB- Short Physical Performance Battery; MVPA- Moderate-to-vigorous physical activity; TUG- timed up and go; 6MWT- Six-minute walk test; ES- Effect size.

This cross-sectional study showed that individuals with leprosy presented marked functional impairment when compared to healthy people and that this functional impairment is amplified as the disease worsens. In contrast, physical activity levels were similar between individuals with and without the disease.

Leprosy affects the peripheral nerves and, if not properly diagnosed and treated, may worsen the patient's clinical condition, causing neuromotor damage, such as physical and functional impairments ¹ . Herein, we confirmed that individuals diagnosed with leprosy demonstrated marked functional impairment and the presence of disability exacerbated these limitations. In fact, a previous study. showed that leprosy patients with disability (grade 1-2) presented poor performance during the 6MWT when compared to patients without disability, and lower muscle strength during dorsiflexion, with low electromyographic activity of the anterior tibial when compared to healthy people ⁸ . This suggests that the progression of the disease may cause alterations in the areas enervated by peripheral nerves and, therefore, the action potentials generated for muscle contraction of the lower limbs may undergo negative changes that impact functional activity performance.

In addition, the literature highlights the importance of drug treatment for patients with leprosy. Even though the muscle mass and functional capacity of these patients is lower than their healthy peers, those who adhered to multidrug treatment presented better scores in these variables when compared to those who did not adhere to the use of medication ²⁰ . However, all patients evaluated in the present study were undergoing drug treatment at the local Basic Health Units and yet, nevertheless, showed lower scores in functional performance tests.

Interestingly, our results demonstrate that the time spent in moderate to vigorous physical activity was similar between individuals with and without leprosy. Although there are a limited number of studies quantifying the physical activity levels of individuals with leprosy, Do Prado et al. ¹¹ observed no correlation between the degree of disability and physical activity levels in 97 patients with leprosy. On the other hand, Cheng et al.. assessed the physical activity level and associated factors among 248 older adults (aged 75 yrs) institutionalized and diagnosed with leprosy (degree of disability 1). The results showed that the older adults with leprosy were less physically active when compared to the reference values of the older people without the disease. Although this study evaluated a large number of patients, the author did not compare the physical activity levels between individuals with leprosy and a healthy age-matched control group. In addition, both studies used questionnaires to measure physical activity. Thus, future studies should explore potential differences between individuals with and without leprosy and the degree of disability, using objective measurement techniques.

In summary, individuals with leprosy present functional impairment when compared with healthy controls, and this impairment is amplified as the disease worsens. No differences were observed in physical activity levels between participants. The clinical interpretation is that patients with leprosy who have poor functional performance may be prime candidates to improve this outcome through an exercise-targeted rehabilitation intervention.