A Review on Body Mass Index as an Indicator of Flexibility Among Young Adults

Research Article

Abstract

Background: Flexibility is a key component of physical fitness that supports joint mobility, muscular efficiency, and injury prevention. Among young adults, especially university students, unhealthy lifestyle patterns such as reduced physical activity and poor diet have led to increasing Body Mass Index (BMI), which may impact flexibility. BMI, although a simple anthropometric index, is widely used to assess weight status, but its influence on musculoskeletal function, particularly flexibility, remains underexplored.
Objective: To review body mass index as an indicator of flexibility among young adults and its effect on the body.
Methodology: A literature search was conducted using the keywords Body Mass Index, flexibility, young adults, and physical fitness in databases including PubMed, Google Scholar, ScienceDirect, and ResearchGate. The search included full-text, English-language articles from 2016 to 2024. Studies were screened based on inclusion and exclusion criteria and critically appraised using CASP tools. A total of 342 articles were identified; 12 high-quality studies were included in the final review.
Result: The findings reveal a non-linear, inverted U-shaped relationship between BMI and flexibility. Individuals with a normal BMI consistently demonstrated better flexibility (measured by sit-and-reach scores) compared to underweight or overweight/obese peers. Underweight individuals showed limited flexibility due to reduced muscle mass, while overweight individuals exhibited joint restrictions and increased muscle stiffness. Gender and activity level also influenced outcomes.
Conclusion: Maintaining a healthy BMI is essential for optimal flexibility and overall physical function in young adults. Both high and low BMI values can negatively impact musculoskeletal performance. These findings highlight the need for BMI monitoring and flexibility training as part of health and fitness programs for young adults.