Undernutrition occurs in 900 million individuals globally, so it is a very important health problem because it contributes to high mortality rates, especially in children. In addition, undernutrition has consequences for children's growth and development, including increased susceptibility to 1) Experiencing fat accumulation, especially in the central part of the body; 2) Experiencing changes in body metabolism, especially fat, decreased oxidation; 3) Experiencing a decrease in resting energy expenditure and postprandial energy expenditure; 4) Insulin resistance in adulthood which results in hypertension and dyslipidemia, 5) Decreased capacity to do manual work that requires physical strength. 6) Changes occur in the function of the autonomic nervous system (Matrins et al., 2011). Loss of muscle mass and function causes muscle weakness. Handgrip strength has been used as a tool to measure muscle strength and functionality and can measure low individual mobility because handgrip strength is positively correlated with daily activity (Whiting et al., 2016). Hand grip strength or handgrip strength is used as a predictor of undernutrition in adult patients with cancer who are hospitalized (Bauer et al., 2015), and is stated as a predictor of nutritional status and changes in nutritional status (Flood et al., 2014). Other research also shows that there is a positive correlation between BMI percentile and hand grip strength (Kotecha and Desai, 2022). In studies on elderly populations, handgrip strength is positively correlated with nutritional status (Akbar and Setiati, 2018), while in populations of children at risk of malnutrition (using the Paediatric Yorkhill Malnutrition Score-PYM), it shows handgrip strength based on age (HGS z-score). and based on height is lower than children who have a lower risk of malnutrition. The HGS z-score can also be used as a predictor of fat free mass (FFM) for sick children compared to healthy children and is also related to plasma CRP (Mckirdy et al., 2021).

Based on the explanation above, this research was conducted to know the differences in hand grip strength, muscle mass, and blood pressure in undernourished children aged 8-10 years compared to normal children.

An experimental study with an analytic cross-sectional design examines muscle mass, hand grip strength, and blood pressure in children with undernutrition compared to normal. The subjects are elementary school children aged 8-10 years with undernutrition and overnutrition. Undernutrition was determined after measuring body weight and height, then weight/age, height/age, and weight/height z-scores were determined using the WHO Anthroplus software. If < -2 SD, then grouped into undernutrition, but if 0 to -2 SD then grouped into normal. Homogeneity and normality tests were carried out on the variables age, weight, height, anthropometry, arm and waist circumference, hand grip strength, muscle mass, and blood pressure. Data is presented in descriptive form (x + SD). A paired sample t-test (or Mann-Whitney test) was performed on these variables, dividing the subjects into 2: undernutrition vs. normal, with significance >0.05. Relationships between variables were analyzed using Pearson's or Spearman's correlation.

1. After obtaining permission and approval from the school, the researcher conducted an initial screening by measuring height and weight, as well as the age of the prospective subject/
2. Determination of nutritional status using WHO Anthroplus to determine undernourished and normal nutritional subjects
3. Furthermore, the researchers reported the findings to the school for socialization and the signing of informed consent by parents
4. Researchers re-measurement of weight, height, waist circumference, blood pressure and handgrip strength in subjects who are willing to take part in the study.

Inclusion Criteria:

• Children aged 8 years until 10 years
• Study in Primary School in Surabaya
• Healthy
• Volunteer to participate in this study (the parents sign the informed consent we sent)

Exclusion Criteria:

• Had autoimmune disease, congenital disorders, or other chronical disease
• Retire during the observational periods
• Consumed steroids, antibiotics or hormone therapy

Subjects are elementary school children aged 8-10 years with undernutrition and overnutrition. Undernutrition was determined after measuring body weight and height, then weight/age, height/age and weight/height z-scores were determined using the WHO anthroplus software. If < -2 SD, then grouped into undernutrition, but if 0 to -2 SD then grouped into normal.

The data will be shared in Airlangga Repository