Neuromuscular Characteristics of Strict Vegetarians and Non-Vegetarians Women

A strict vegetarian diet includes only foods of plant-based origin and, despite being able to meet the nutritional needs of individuals of different ages, when correctly planned, it commonly offers a lower protein intake than a non-vegetarian diet. Daily protein intake directly influences the turnover of body proteins (synthesis vs. degradation rates), being important for the maintenance of skeletal muscle mass, tissue that performs metabolic functions in the body and enables the performance of tasks of daily living. In addition, the practice of strength training (ST) interferes in muscle mass increasing rates, also exerting an influence in muscle quality, strength and power increase, which are associated with better physical fitness, quality of life and health. To make these increases possible, especially in relation to morphological aspects, a higher protein intake than recommended for the general population is necessary (1.2 to 1.6 g/kg/day), which requires careful dietary planning, especially when the consumption of meat, eggs and dairy products, which are important sources of this nutrient, is excluded. Thus, the present study has two main objectives: to compare the neuromuscular characteristics of strict vegetarians (VE) and non-vegetarians (NV) (Phase 1 - cross-sectional) and the neuromuscular adaptations induced by 16 weeks of ST (Phase 2 - longitudinal).

A strict vegetarian diet includes only foods of plant-based origin and, despite being able to meet the nutritional needs of individuals of different ages, when correctly planned, it commonly offers a lower protein intake than a non-vegetarian diet. Daily protein intake directly influences the turnover of body proteins (synthesis vs. degradation rates), being important for the maintenance of skeletal muscle mass, tissue that performs metabolic functions in the body and enables the performance of tasks of daily living. In addition, the practice of strength training (ST) interferes in muscle mass increasing rates, also exerting an influence in muscle quality, strength and power increase, which are associated with better physical fitness, quality of life and health. To make these increases possible, especially in relation to morphological aspects, a higher protein intake than recommended for the general population is necessary (1.2 to 1.6 g/kg/day), which requires careful dietary planning, especially when the consumption of meat, eggs and dairy products, which are important sources of this nutrient, is excluded. Thus, the present study has two main objectives: to compare the neuromuscular characteristics of strict vegetarians (VE) and non-vegetarians (NV) (Phase 1 - cross-sectional) and the neuromuscular adaptations induced by 16 weeks of ST (Phase 2 - longitudinal). For Phase 1, 140 healthy adults of both sexes (70 VE and 70 NV) will be recruited, who have been strength-untrained and who have adhered to the respective dietary pattern, both for at least 6 months. Participants will be instructed to perform the 3-day food record and count the number of steps for 5 days. Subsequently, they will undergo assessments of body composition, physical activity level and neuromuscular tests of the lower limbs (maximum strength, jumping power and muscle thickness of the quadriceps femoris, hamstring and gastrocnemius muscles). Comparisons of means between groups will be performed by the T test - independent. Results will be expressed as mean and standard deviation and the accepted significance level will be 5%. For Phase 2, 33 VE and 33 NV will be recruited (66 participants in total), who, in addition to meeting the eligibility criteria set out in Phase 1, are also available to participate in the strength training period. Participants will undergo the same assessments provided for in Phase 1 and must maintain their respective eating habits and patterns. At the 4th, 8th, 12th, and 16th weeks of ST, all participants will complete a new 3-day food record and perform step counts. In the 17th week, the initial evaluations will be repeated. Comparisons will be performed through two-way analysis of variance with repeated measures, considering the factors group (2 stratifications), time (2 stratifications) and group x time interaction. Results will be expressed as mean and standard deviation and the accepted significance level will be 5%.

Eligibility Criteria:
Inclusion Criteria:

* Body mass index until 30kg/m²
* Be a strict vegetarian or non-vegetarian for at least 6 months
* Not performing regular physical exercise for at least 6 months

Exclusion Criteria:

* Having chronic diseases, such as systemic arterial hypertension, diabetes mellitus, cardiomyopathy
* Present physical limitations or musculoskeletal problems, which contraindicate the performance of strength exercises
* Make use of a protein or amino acid food supplement, caffeine or other thermogenic substances