An RCT on 12 weeks of cognitive, motor or combined cognitive-motor exercise to improve dual-task walking in older adults: The role of baseline cognitive and motor fitness

Background Cognitive-motor dual-tasking, essential for daily activities like walking in busy spaces, declines with age. Research suggests that cognitive (cogT), motor (motT), and cognitive-motor dual-task training (DTT) can improve dual-task performance in older adults, yet studies report heterogeneous effects. This RCT examined whether baseline cognitive (cf) and motor fitness (mf) moderates training effects of these interventions on cognitive-motor dual-task performance in older adults. Methods Participants ( N  = 97, aged 65–75) completed 12-week interventions in cogT, motT, or DTT. A battery of cognitive and motor tests was conducted at pre-test to create composite scores of cf and mf. Cognitive-motor performance was assessed at pre- and post-test using a Serial Threes task (S3), a Stroop task (STR), and a walking task. For the cognitive domain, outcomes included correct responses (S3) and inverted RT inhibition costs expressed as percentage (STR); for the motor domain, step variability (inverted to step stability) was used. Outcomes were assessed under single-task (ST) and dual-task (DT) conditions. Results In summary, linear mixed model results indicated that for both S3 as STR, cogT and DTT led to greater increases in cognitive performance than in motor performance across both ST and DT conditions, while the motT showed greater increases in motor performance than in cognitive performance (S3: cogT vs. motT: t = -2.25, DTT vs. motT: t = -2.69; STR: cogT vs. motT: t = -2.41, DTT vs. motT: t = -2.08). The results also showed that mf and the interaction between cf and mf did not moderate pre-post changes in cognitive or motor performance. However, cf did play a significant moderating role for the S3. When comparing the groups, in particular, cogT and motT showed opposing effects ( t  = 5.35). For individuals with higher cf, motor performance increased more in the cogT than in the motT. However, their cognitive performance increased more in the cogT than in the motT. Conclusions The results emphasize the complex relationship between cognitive and motor outcomes in cognitive-motor interventions and the key role of baseline fitness in moderating intervention effects. Trial registration This trial was retrospectively registered at German Clinical Trials Register (DRKS00022407).