Development and Validation of a Telephone Coaching Program to increase Physical Activity among Community-Dwelling Older Individuals

Problem: Exercise rehabilitation is essential for reducing morbidity and mortality in older individuals, particularly after a fall. This pilot tudy evaluated whether a home-based exercise program combined with telephone coaching increases physical activity (PA) among community-dwelling older individuals.
Methods: Participants were randomized to either an intervention group (IG), receiving the “Vivifrail” home-based exercise program and weekly motivational telephone coaching, or a control group (CG), receiving general PA recommendations. PA (via accelerometer) and physical function (via Short Physical Performance Battery, SPPB) were assessed at baseline and after 12 weeks.
Results: Thirty individuals (15 IG, 15 CG; mean age±SD: 76.2±6.1 years; 87% female) completed the study. There was little evidence for between-group differences in pre-to-post changes for accelerometer-derived outcomes (β (95 % CI)), including daily steps (734.6 (-737.5, 2206.7) p=0.315) and daily walking time in minutes (7.72 (-8.72, 24.15) p=0.344). However, physical function improved significantly (t(26)=2.96, p=0.006) in the IG compared to the CG. 
Discussion: A short-term home-based exercise program with weekly telephone coaching did not increase objective PA in community-dwelling older individuals. This lack of effect might be influenced by high sample heterogeneity or unaddressed environmental barriers.
Conclusion: While the intervention failed to increase immediate daily physical activity, it significantly enhanced physical function. These functional gains may serve as a crucial precursor to promote long-term engagement in PA.

Key Words: Gerontology, Accelerometry, Home-Based Exercises, Fall Risk, Fall Prevention

This randomized controlled trial examined the effects of an individualized low-threshold home-based exercise program combined with telephone coaching using established BCTs on PA among community-dwelling older individuals.

Although accelerometer-derived PA did not differ significantly between groups, the IG showed clinically meaningful improvements in physical function, as evidenced by increased SPPB scores. While the IG did show improvements in daily steps and moderate-to-vigorous PA levels, these differences did not reach statistical significance when compared to the CG.

This lack of statistically significant PA effects may be partly attributed to the inherent challenges of assessing PA in older populations. As Brach et al. recently highlighted, several confounding factors must be considered when interpreting PA data in older adults (2). In particular, high intra-individual heterogeneity can easily mask potential intervention effects. In our study, the sample size calculation was based on a cohort with a mean age of 42 years. Even though we assumed a conservative effect size, we did not account for the substantially higher heterogeneity in our older sample compared to that of Fischer et al. Future trials must therefore factor this greater intra-individual variability into their power calculations (10). Additionally, environmental barriers, such as stairs, inadequate walkways, or poor public transportation, were not addressed by our home-based program. These factors may have continued to restrict participants‘ outdoor PA, even after their physical capacity had improved.

In contrast to the PA outcomes, physical function, measured via the SPPB, showed significant intervention effects. These findings align with previous research demonstrating that individualized exercise regimens enhance physical function in older adults. Similar functional gains have been documented for the „Vivifrail“ program across various populations, supporting its efficacy in maintaining or restoring functional capacity even without supplementary telephone coaching (5, 18, 26). For instance, Casas-Herrero et al. reported a 1.41-point SPPB improvement after a three-month “Vivifrail” intervention in a significantly older cohort (mean age: 84 years) (5), while Li et al. observed a 1.03-point increase after 12 weeks (18). Our study yielded an SPPB improvement of 0.8 points in the IG. However, our participants had higher baseline functional scores than those in previous trials, suggesting they were starting from a higher level of fitness. This likely explains the slightly more moderate functional adaptations observed here.

Given the discrepancy between improved physical function and unchanged PA levels, we hypothesize that in this specific cohort, functional improvements may occur as a necessary precursor before tangible changes in habitual, daily PA can be observed.
Beyond the clinical benefits, low-threshold PA interventions are also of particular relevance from a health-economic perspective given the substantial healthcare costs associated with physical inactivity in older individuals. Findings from the NAKO study indicate that insufficiently active adults aged 60 years and older generate considerably higher healthcare costs per year than their physically active counterparts, with the difference increasing further when indirect costs are considered (13).

Accordingly, low-threshold, cost-efficient interventions are becoming increasingly relevant. Previous health-economic studies suggest that telephone-based coaching can achieve comparable health outcomes at lower costs than conventional face-to-face rehabilitation by reducing transportation requirements and in-person visits (20). In addition, telephone-based approaches require only minimal technical skills, making them particularly accessible for older individuals. Furthermore, they may improve access to rehabilitation, especially for individuals with limited mobility or for those living in rural or underserved areas. In the long-term, they may also help expand treatment capacity by enabling appropriately trained non-physiotherapeutic staff to provide coaching interventions.

Several limitations should be considered when interpreting the findings of this pilot trail. First of all, participants were community-dwelling older adults with relatively high functional capacity at baseline. This may have limited the potential for further improvement. Comparable interventions may therefore yield larger effects in frailer populations such as patients after hip fracture. Second, the small sample size and predominance of female participants limit the statistical power and generalizability of the findings, particularly to older men. Furthermore, the effectiveness of the telephone coaching may have been influenced by the coaches’ limited practical experience with motivational interviewing. Although all coaches received structured training, motivational interviewing is a complex communication technique that requires extensive practical experience for optimal implementation (12). Moreover, PA was objectively measured using accelerometry. While the objective assessment eliminated self-report bias and therefore represents a strength of this study, the accuracy of wrist-worn accelerometers may vary between devices. Höchsmann et al. demonstrated systematic differences in recorded step counts across different devices despite identical wearing positions (15). Finally, due to the nature of the intervention, neither the participants nor the examiners could be fully blinded. 

In summary, future research should evaluate whether longer intervention and follow-up periods translate functional improvements into long-term increases in everyday PA. Additionally, the effectiveness of this approach should be investigated in more vulnerable populations including frail older adults and patients after hip fracture. Finally, further health-economic evaluations are required to determine the cost-effectiveness and feasibility of implementing telephone-based coaching within routine clinical practice.

Conflict of Interest
The authors have no conflict of interest.

Funding
This study was supported by internal funding from the University of Applied Sciences Niederrhein (to LS).

Ethical Approval and Informed Consent
This study was approved by the Ethics Committee of the German Sport University Cologne (number: 169/2025). Oral and written informed consent were obtained from all participants before the study onset.

Data Availability
Study data are available from corresponding author on reasonable request. AI was not used for scientific content.

Author Contributions / Statement of Author Contributions
All authors have completed the ICMJE Uniform Disclosure Form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organization for the submitted work (instead of the declared internal funding). 

This randomized controlled trial demonstrated that an individualized, home-based exercise program involving telephone coaching improved physical function in older adults, despite there being no statistically significant difference in physical activity (PA) levels compared to the control group. The lack of significant PA effects may be explained by the high degree of heterogeneity within older populations and unaddressed environmental barriers. It is also notable that, since the participants started with higher baseline fitness than cohorts in previous “Vivifrail” studies, their functional gains were slightly more moderate. These findings suggest that a home-based exercise intervention combined with telephone coaching can improve physical function in the short term. Further research is needed to establish whether long-term PA improvements are a consequence of higher physical function in older adults.