Table 1 The Oxford 2011 Levels of Evidence
From: Physical activity induced alterations of gut microbiota in humans: a systematic review
Evidence level (treatment benefits) |
|---|
Level 1: Systematic review of randomized trials or n-of-1 trials |
Level 2: Randomized trial or observational study with dramatic effect |
Level 3: Non-randomized controlled cohort/follow-up study |
Level 4: Case-series, case control study, or historically controlled study |
Level 5: Mechanism-based reasoning |