Comparative Effect of Nonlinear and Linear Periodized Resistance Training on Thyroid Function and Quality of Life in Women with Hypothyroidism

Abstract

Background: Hypothyroidism is a prevalent endocrine condition linked to metabolic impairment, muscular weakness, and diminished quality of life. While pharmacological treatment remains the standard of care, resistance exercise may provide additional therapeutic benefits.
Objective: To compare the effects of non-linear versus linear periodized resistance training on serum thyroid stimulating hormone (TSH), thyroxin (T4), triglyceride-glucose index (TyG), handgrip strength, and quality of life (QoL) in women with hypothyroidism.
Subjects and methods: Seventy-five female subjects diagnosed with hypothyroidism, aged between 35 and 45 years, were randomly allocated into three equal groups (n=25 each): (Group A) non-linear periodized resistance training (NLPRT), (Group B) linear periodized resistance training (LPRT), and (Group C) the control group (CG). The training groups participated in the exercise three times each week for a period of 12 weeks. The results assessed before and after the intervention were blood TSH and T4 levels, triglyceride-glucose index, hand grip strength determined with a hand-held dynamometer, and quality of life evaluated by the SF-12 health survey.
Results: Following the 12-week intervention, the NLPRT group demonstrated significantly higher T4 levels and greater physical and mental quality-of-life scores than the LPRT group, while no significant between-group differences were observed in TSH, blood glucose, triglycerides and triglyceride glucose index (TyG) or handgrip strength. Compared with the CG, both NLPRT and LPRT demonstrated significantly higher T4 levels, hand grip strength, and physical and mental quality of life scores along with significantly lower TyG index values following the intervention, whereas significantly lower TSH, blood glucose, and triglyceride levels were observed only in the NLPRT group.
Conclusion: Both nonlinear and linear periodized resistance training were beneficial in enhancing thyroid function, handgrip strength, and both physical and mental dimensions of quality of life. Nonlinear periodization yielded superior advantages, especially with T4 levels and both the physical and psychological dimensions of quality of life.