By David Tuller, DrPH
A journal under the Lancet umbrella, eClinicalMedicine, recently published a study from China called “Effects of therapeutic interventions on long COVID: a meta-analysis of randomized controlled trials.” (I wrote about it here.)
The authors themselves determined that most of the research they included was, to be charitable, on the crappy side. Nonetheless, they claimed “high-certainty evidence” for the effectiveness of exercise interventions—a claim then disseminated without qualification by some of the usual members of the biopsychosocial ideological brigades. Same old, same old. The amplification of nonsense.
I have submitted the following letter to eClinicalMedicine.
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To the Editor:
A recent article, “Effects of therapeutic interventions on long COVID: a meta-analysis of randomized controlled trials,” reported “high-certainty evidence” that exercise training can improve health and “should be prioritized” [1]. However, this meta-analysis is deeply flawed, and any such conclusions cannot be taken seriously.
First, the dozens of trials in the meta-analysis feature wildly divergent definitions of Long COVID. In some cases, it appears that trial participants did not even have Long COVID. As just one example, a Brazilian study included “subjects with coronavirus disease 2019 in the acute phase” [2]. Lumping together trials with extremely heterogeneous populations, including some without Long COVID, makes it challenging, if not impossible, to interpret the meta-analysis results.
Second, the authors themselves determined that the data used in the meta-analysis are of questionable value. They found that, according to Cochrane’s Risk of Bias Tool, only three of the included trials were at “low risk” of bias, with 33–the majority–at “high risk” of bias. Their analysis of quality of evidence for the many outcomes, per the Grading of Recommendations Assessment, Development and Evaluation (GRADE) framework [3], was equally dismal, with “27% of the evidence…rated as very low, 57% as low, 11% as moderate, and 5% as high.”
Given these acknowledged limitations, the confident assertion that exercise training is effective and “should be prioritized” is perplexing and unwarranted. And the statement that these findings constitute “high-certainty evidence” is preposterous.
David Tuller
Center for Global Public Health
School of Public Health
University of California, Berkeley
1.Tan C, Meng J, Dai X, et al. Effects of therapeutic interventions on long COVID: a meta-analysis of randomized controlled trials. eClinicalMedicine. 2025;87:103412
2. Rodríguez-Blanco C, Bernal-Utrera C, Anarte-Lazo E, et al. Breathing exercises versus strength exercises through telerehabilitation in coronavirus disease 2019 patients in the acute phase: A randomized controlled trial. Clin Rehabil. 2022;Apr;36(4):486-497.
3. Guyatt GH, Oxman AD, Vist GE, et al. GRADE: an emerging consensus on rating quality of evidence and strength of recommendations. BMJ. 2008;336(7650):924-926.