PurposePhysical inactivity is associated with reduced physical fitness (PF) in older women with impaired cardiometabolic health. Although exercise has been shown to improve PF, interindividual variability in response and adaptation changes over time remain unclear. This study evaluated the effects of eight weeks of resistance training (RT) and high-intensity interval training (HIIT) on body composition, isometric strength, and the 6-minute walk test (6MWT) in older women with impaired cardiometabolic health. Additionally, the study explored the reduction of non-responders (NRs) and adaptation changes over time.MethodsThis randomized clinical trial involved 36 older women (64 +/- 8.4 years; BMI: 31.8 +/- 5.5) with impaired cardiometabolic health, divided into RT-G (n = 12; 62 +/- 7 years; BMI: 32.2 +/- 4.1), HIIT-G (n = 12; 66 +/- 10 years; BMI: 31.2 +/- 4.1), and CG (n = 12; 64 +/- 9 years; BMI: 31.8 +/- 6) groups. RT-G performed elastic band exercises, and HIIT-G performed cycle ergometer intervals. BMI, body fat, lean mass, isometric strength, and 6MWT were measured at baseline and at four and eight weeks. The Student's t-test was applied for normally distributed variables and the Mann-Whitney U test for non-normal variables. Intra- and inter-group differences were analyzed using a two-way repeated measures ANOVA, considering group, time, and their interaction. Post-hoc comparisons were conducted using the Bonferroni test. Individual responses (IR) were calculated using the equation proposed by Hopkins: SDIR = root(SDExp2 - SDCon2). The prevalence of responders (Rs) and non-responders (NRs) was expressed as a percentage, and percentage changes from baseline to weeks four and eight were used to evaluate adaptations dynamics.ResultsBy week eight, isometric strength in RT-G significantly improved from 21.3 +/- 4.4 to 24.37 +/- 3.99 kg (p = 0.027; 95% CI: 1.8, 4.3 kg; Cohen's d = 0.731) and 6MWT distance in HIIT-G increased from 441.0 +/- 48.9 to 480.0 +/- 53.0 m. (p = 0.002; 95% CI: 22, 55 m; Cohen's d = 0.757). Both protocols reduced NRs for body fat, lean mass, and 6MWT. Responders showed greater adaptations in the first four weeks, stabilizing by week eight.ConclusionRT and HIIT improved PF in older women with impaired cardiometabolic health, reducing NRs in terms of body composition and 6MWT over eight weeks, with similar adaptation changes over time among the responders. These findings highlight the importance of individualized exercise interventions to maximize health benefits.Trial registrationThis study was part of a trial registered at ClinicalTrials.gov (ID: NCT06201273). Date: 22/12/2023.