Phase Angle and Body Composition, Inflammatory and Oxidative Stress Biomarkers.

Modifications to Phase Angle After Resistance Training Are Associated With Changes in Body Composition, Inflammatory and Oxidative Stress Biomarkers in Older Women

The main purpose of the present study was to investigate the effects of 12 weeks of resistance training (RT) on phase angle (PhA), body composition, inflammatory and oxidative stress biomarkers, in older women and to evaluate whether RT induced adaptations on body composition, inflammatory and oxidative stress biomarkers are related to healthy adaptations in PhA.

The investigation was carried out over a period of 16 weeks, with 12 weeks dedicated to the RT program and 4 weeks allocated for measurements. Anthropometric, body composition, and blood samples measurements were performed at weeks 1-2, and 15-16. A supervised progressive RT was performed between weeks 3-14. The CG did not perform any type of physical exercise during this period.

Recruitment was carried out through newspaper and radio advertisings, and home delivery of leaflets in the central area and residential neighborhoods. All participants completed health history and physical activity questionnaires and met the following inclusion criteria: 60 years old or more, physically independent, free from cardiac or orthopedic dysfunction, not receiving hormonal replacement therapy, and not performing any regular physical exercise more than once a week over the six months preceding the beginning of the investigation. After individual interviews, 59 volunteers were dismissed as potential candidates because they did not meet the inclusion criteria for the investigation. The remaining 51 older women were randomly divided into one of two groups: a training group that performed the RT program or a control group that did not perform any type of physical exercise. Anthropometric, body composition (DXA), phase angle, total body water (intra and extracellular water compartments; Xitron 4200 Bioimpedance Spectrum Analyzer), muscular strength (1RM), and blood sample measurements were performed pre- and post-training. Two-way analysis of variance for repeated measures was applied for intra- and inter-group comparisons. When an F-ratio was significant, Fisher's post hoc test was employed to identify mean differences. The statistical power was determined to verify the statistical power of the analysis. Pearson's correlation was used to evaluate the correlation between delta percent changes in body composition, and muscular strength, inflammatory and oxidative stress biomarkers (independent variables) with the percentage change in PhA (dependent variables). Subsequently, linear regression (bivariate analyses) was performed for all variables that presented P<0.05 in the Pearson's correlation analyses. For the multiple comparison the multivariate regression model was performed. For all statistical analyses, significance was accepted at P<0.05.

Inclusion Criteria:

• 60 years old or more, physically independent, free from cardiac or orthopedic dysfunction, not receiving hormonal replacement therapy, and not performing any regular physical exercise more than once a week in the six months preceding the beginning of the investigation.
• Participants passed a diagnostic graded exercise stress test with a 12-lead electrocardiogram, reviewed by a cardiologist, and were released with no restrictions for participation in this investigation.

Exclusion Criteria:

• All subjects not participating in 85% of the total sessions of training or withdrawl