Introduction: The aging process can result in several physiological changes, such as the loss of muscle mass, muscle strength, and physical performance, collectively defined as sarcopenia. Sarcopenia is considered one of the primary health challenges among older adults. To prevent this condition and improve related health outcomes, regular physical exercise is the most recommended strategy, with multicomponent exercises being particularly effective for older individuals. Pilates is another potential form of physical exercise that has gained popularity among older adults seeking to improve muscle mass, strength, and physical performance. However, significant gaps remain in the literature, with a notable lack of studies evaluating the efficacy of Pilates in improving sarcopenic outcomes. Objective: To compare the efficacy of multicomponent training programs versus Pilates in improving muscle mass, muscle strength, and physical performance in older adults. Methods: A total of 100 older adults aged 60 to 80 years, of both sexes, will be randomized into two intervention groups: the Multicomponent Training Group (n=50) and the Pilates Group (n=50). Evaluations will be conducted at three time points: baseline (before the intervention), mid-treatment (3 months), and post-treatment (6 months). The following instruments will be used: Dual-energy X-ray absorptiometry (DXA) will be used to assess muscle mass. Muscle strength will be evaluated using an isokinetic dynamometer for the lower limbs and a handgrip dynamometer for the upper limbs. Physical performance will be assessed through the Brazilian version of the Short Physical Performance Battery (SPPB), the gait speed test, and the Timed Up and Go (TUG) test. The Feeling Scale will be applied to determine the affective valence of the exercise programs. The Shapiro-Wilk test will be performed to check the normality of the data, Student's t-test or Mann-Whitney U test will be used depending on whether the distribution is parametric or non-parametric, and ANCOVA will be used to compare the groups post-intervention, considering a 95% confidence interval (p<0.05). The data will be analyzed using SPSS 25.0 software.

The sample will consist of 100 elderly individuals of both sexes, aged between 60 and 80 years. The sample size calculation for this study was performed using the Bioestat 5.3 program, based on the values of whole-body DEXA (dual-energy X-ray absorptiometry) assessment, provided in a previous study (Seo et al., 2021). In this case, the post-intervention mean and standard deviation between the Resistance Training group (1566.75±189.47) and the Control group (maintaining routine habits) (1446.86 ± 206.42) were used, with a test power of 80%, an alpha value of 0.05, and a 15% error rate, which indicated the need for 50 participants in each group (Multicomponent Group and Pilates Group). Descriptive data analysis will be expressed as mean, standard deviation, and percentage delta of the difference. Normality will be assessed using the Shapiro-Wilk test. To verify if there are differences between the groups regarding baseline characteristics (age, weight, height, and BMI) at the pre-intervention stage, Student's t-test for independent samples or the Mann-Whitney U test will be used, depending on whether the data are parametric or non-parametric. To compare the groups post-intervention, ANCOVA will be used, with baseline data as covariates. If the data exhibit non-parametric characteristics, the Mann-Whitney U test will be applied to compare the groups based on the difference between pre- and post-intervention. A confidence interval of 95% (p<0.05) will be accepted. Data will be processed using SPSS 25.0 software. Effect sizes (Cohen's d) will be calculated and classified as small (0.20), medium (0.50), or large (0.80). For effect size calculations, the GPower 3.1 program will be used.

Inclusion Criteria:

• Not currently participating in a physical training program for at least six months;
• No medical restrictions for physical activity and physical tests;
• Achieve a score of 19 or higher on the Mini-Mental State Examination.

Exclusion Criteria:

• Individuals with severe/disabling musculoskeletal and/or neurological dysfunctions;
• Neurological disorders or cognitive impairment;
• Use of supplements for muscle mass increase;
• History of recent fractures or surgeries and severe cardiorespiratory diseases.

The sample randomization will be conducted secretly by a professional who is unaware of the study and the volunteers. This professional will perform the randomization using random numbers to assign the study sample into two groups: the Multicomponent Group (EM) (n=50) and the Pilates Group (EP) (n=50). The same professional will then place the assignments in opaque envelopes, which will be sealed and contain the group allocation inside. Participants will be informed that they may be allocated to either group during the recruitment and selection process. Moreover, both the participants and the researchers will only know which group each individual is assigned to at the moment of envelope delivery.

Assessments will be conducted before the intervention, during the treatment (3 months), and after its completion (6 months) by the same professional, who will be blinded to the identities of the volunteers.