Sanal-Hayes, Nilihan Em, Hayes, Lawrence D, Mair, Jacqueline L et al. · Nature communications · 2026 · DOI
Researchers tested whether a smartphone app called 'Pace Me' combined with an activity tracker could help people with long COVID manage their energy better and reduce post-exertional malaise (the worsening of symptoms after activity). Over 6 months, some participants used the app with the tracker and received helpful messages when they approached their daily activity limit, while others used a basic version of the app. Both groups improved slightly, but there was no meaningful difference between them.
Energy management is central to long COVID and ME/CFS treatment approaches, yet evidence-based digital tools remain limited. This study tests whether real-time activity tracking and adaptive messaging—scalable interventions that could reach many patients—actually reduce post-exertional malaise, a key outcome for these conditions.
This study does not prove that energy management approaches are ineffective; rather, it suggests the specific app-and-tracker combination tested here did not outperform a basic control app in long COVID. The authors acknowledge that natural recovery in long COVID may have masked true intervention effects, meaning the results may not generalise to ME/CFS or other non-recovering populations. The study also does not address whether energy management itself is beneficial versus the delivery mechanism.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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