Discussion
mobility-related disability
To our knowledge, the REACT study is the largest translational trial delivered to date targeting long-term changes in lower-limb physical function in older adults with mobility-related disability. Older adults with mobility limitations who received the 12-month exercise intervention demonstrated significant improvements in lower limb function compared to age-matched controls at 6 and 12 months. Physical function appears to peak at 6 months (the most intensive part of the intervention - two sessions per week) and is sustained for an additional 6 months despite reducing to one supervised exercise session per week. Higher intervention effects within individual components of the SPPB were associated with increased attendance to the group-based exercise sessions. Changes in physical function include significantly greater lower-limb muscle strength and balance profiles (assessed using the SPPB test) at 6 and 12 months, which were supported by a higher SF-36 physical component score, MAT-SF score, and self-reported PA and adherence to muscle-strengthening exercise. The subgroup analyses suggested consistency of intervention effects across different subgroups of the population, including sex, people of different ages (over 65 years) and number of comorbidities. These results are consistent with the notion that the exercise intervention increased engagement in muscle strengthening, balance, and endurance activities that mediated the observed effects on physical functioning. Therefore, contrary to the belief that older age comes with an inevitable decline in physical functioning, the REACT study shows that this decline can be slowed or even prevented with modest lifestyle changes.At the completion of the intervention, significant differences were observed in two of the three components of the SPPB; muscle strength (stand to sit), and balancing tasks, not gait speed. As performing lower-limb strengthening and balance tasks were the cornerstone of the 12 month exercise intervention, the favourable improvements demonstrated in strength and balance are most likely a direct consequence of training specificity and applying the overload principle (progressive intensity of a similar movement pattern performed frequently). No change in gait speed score was a surprising finding given how frequently walking was promoted outside of the REACT sessions (an entire topic was dedicated to PA promotion during the behavioural element of the REACT programme). Whilst the SPPB is a well validated (Based on this scoring method, no significant differences were reported between intervention and control group at any time point during the intervention. One reason for this might be due to the ‘ceiling effect’. Baseline SPPB gait scores (mean 3.1) were highest of the three sub-domains suggesting the opportunity for group level increases were reduced relative to the lower scores demonstrated in balance (mean 2.9) and chair rise (mean 1.3). However, when expressed as a continual variable (seconds to walk 4 metres), significant difference were demonstrated at 6 months, but not at 12 months. Had the participant been instructed to “safely walk as briskly/fast as you can,” greater opportunity to identify changes in ambulatory function might have been possible. It is therefore likely that the significant differences demonstrated in physical function between the REACT intervention and control groups (as determined by total SPPB score) was underestimated in this study. However, results from accelerometer data (There are numerous studies, all using different approaches to multicomponent exercise intervention design, which have elicited favourable changes in mobility-disability and health in community dwelling older adults (Despite being a safe exercise intervention that demonstrates improvements in physical function, falls and fall-related injuries were not found to be significantly reduced by the REACT intervention. This finding is in line with both the LIFE (Resistance training is commonly performed using specialist equipment (i.e., free weights, resistance machines etc.) and international organisations, such as the American College of Sport Medicine [ACSM] (