Cellular health beyond body composition: phase angle suitability for breast cancer patients undergoing physical training: a randomised trial

Phase angle (PhA), a bioelectrical impedance-derived marker of cellular integrity, is reduced in breast cancer (BC) patients relative to normative values and often declines during treatment. Assessing the influence of different exercise modalities on PhA and its biological correlates. Thirty-seven BC women were assigned to a home-based exercise group (n = 20) or a hospital-based physiotherapist-supervised high-intensity training group (n = 17) that trained twice weekly for six months. Body composition was assessed by bioelectrical impedance analysis (TANITA MC-980) before chemotherapy (baseline), during treatment, and after chemotherapy. Blood parameters were analysed at baseline and after chemotherapy. No statistically significant differences between groups were observed for PhA (p = 0.8743) or other body composition parameters, and no significant exercise modality × treatment stage interactions were detected. Significant time effects were observed for PhA (p < 0.0001), BMI (p = 0.0377), fat mass (p = 0.0387), and muscle mass (p = 0.0449). Blood analyses revealed no consistent modality × treatment-stage interactions. Over time, white blood cell count (p = 0.0014), lymphocytes (p < 0.0001), eosinophils (p = 0.0020), HDL cholesterol (p = 0.0001), and FT4 (p = 0.0009) decreased. Most red blood cell indices decreased (all p < 0.0001), while liver enzymes increased (AST p = 0.0001; ALT p < 0.0001). PhA was not correlated with body composition in either group. However, in the home-based group, PhA correlated positively with monocytes (r = 0.5563, p = 0.0204) and FT3 (r = 0.5159, p = 0.0408), and negatively with MCHC (r = − 0.7189, p = 0.0011); no such associations were found in the supervised group. No statistically significant between-group differences were detected for PhA, body composition, or blood parameters. Changes were mainly treatment-dependent, while PhA appeared to reflect cellular and metabolic status independently, supporting the feasibility of structured home-based exercise in BC patients. Physical activity has a positive impact on patients health during chemotherapy. The study was registered in the clinicaltrials.gov registry (#NCT06190600) on 2024–01–05, retrospectively registered.