Discussion
depression, cognitive decline, depressive, depressive symptoms
REGRESSION, SECONDARY
The ITT analyses of primary outcomes show that the COACH method, aimed at the promotion of low-to-moderate physical activity, increases the level of physical activity of healthy elderly. No significant effects of the intervention are seen on self-reported physical activity, physical fitness, and cognition. Although the indices of self-reported physical activity, physical fitness, and cognition in the intervention group improve over time, a similar trend is seen in the controls. Stratification by sex shows opposing effects of the intervention in gait speed for men (lower gait speed) and women (higher gait speed) relative to controls. The secondary outcomes show a decrease in the number of ADL limitations in the intervention group and a relative improvement in the mental health of those in the control group. The intervention did not affect serum levels or measures of frailty or depression.Additional responder analyses, focusing on the group that achieved the intended exposure of an increase in physical activity of  ≥ 35%, reveal that this group showed significant improvements in aerobic capacity and gait speed as well as verbal memory, executive functioning, and global cognition, compared to those who did not. The responder group did not show any significant improvements in the measures of balance, muscle strength, learning, frailty, mental health, serum levels, or depressive symptoms.The null results of the ITT analyses of the intervention effect on cognition are at odds with the results from several meta-analyses that indicate that physical activity interventions have modest positive effects on cognition [The improvement in mental health observed in the control condition cannot be attributed to group differences in mental health score at baseline and might therefore be speculatively interpreted as a beneficial effect of the stretching exercises. A review of previous trials investigating the effects of yoga, a combination between stretching exercises and regulation of respiration, on mental health, has reported similar improvements in perceived stress and mental health [The positive effects of the responder analyses on physical fitness and cognition suggest a threshold effect and substantiate the role of intensity and duration of physical activity behavior as important moderators of success. Based on the current findings, it remains unclear whether the effects of moderate-intensity aerobic exercise could also be achieved by equal energy expenditure during prolonged low-to-moderate physical activity. In addition, studies with a control condition with no contact or lifestyle education only more often resulted in significant intervention effects, whereas the presence of an active control or social group led to positive but no longer significant effects of the intervention, compared to controls [The significant increase in average number of steps per day following the intervention was not reflected in a significant change in the self-reported physical activity score. Previous comparisons have found moderate correlations between pedometer assessments and self-reported activity (Compared to controls and their male counterparts, the women in the intervention group show significantly more gain in average gait speed. This sex difference in the effect of the intervention on gait speed was not reported previously in the literature. Our finding could have been the result of regression to the mean or a higher compliance with the intervention in women. However, none of the other primary outcome measures suggested a difference in compliance between men and women. The relevance of this finding remains to be confirmed.Looking at effect modification by The increase in physical activity following the intervention did not lead to an increase in the level of circulating IGF-I or to a significant improvement in the biomarkers of the cardiovascular risk profile, the number of depressive symptoms, and levels of experienced frailty and mental health as expected based on the literature [The strength of our trial is the accessibility of the intervention for those vulnerable to accelerated cognitive decline. Dropout rates were under 25%. Comprehensive measurement led to the detection of modest changes in a wide range of functions. The effects of an improvement in physical activity of  ≥ 35% on cognition are small (Cohen’s 