Our Methodology

How we evaluate and grade exercise evidence using medical research standards

📊 Evidence-Based Grading

We use the same evidence hierarchy employed in medical research to evaluate exercises. This systematic approach ensures transparency about what the science actually shows—and where knowledge gaps exist.

Each exercise receives a grade from A (strongest evidence) to F (contradicted by research). A lower grade doesn't mean an exercise is ineffective—it may simply mean it hasn't been adequately studied yet.

Evidence Grade Definitions

A

Meta-Analysis / Systematic Review

What this means: Multiple randomized controlled trials (RCTs) have been pooled together in a systematic review or meta-analysis, providing the highest level of evidence.

Example: Cochrane reviews, systematic reviews in peer-reviewed journals

A-

Multiple RCTs

What this means: Two or more well-designed randomized controlled trials show consistent results supporting the exercise's effectiveness.

Example: Most established physical therapy interventions

B+

Single RCT

What this means: One well-designed randomized controlled trial supports effectiveness, but replication is needed.

Example: New exercise protocols with promising initial research

B

Cohort / Observational Studies

What this means: Large groups have been tracked over time showing benefits, but without randomization these results may be confounded.

Example: Epidemiological studies on exercise patterns

B-

Small Studies + Plausible Mechanism

What this means: Limited research exists, but the proposed mechanism is scientifically plausible based on anatomy, physiology, or related research.

Example: Most facial exercises, emerging therapeutic techniques

C+

Case Series

What this means: Multiple documented clinical cases show positive outcomes, but without control groups we can't rule out placebo or natural progression.

Example: Clinical observations reported in medical literature

C

Case Reports + Expert Opinion

What this means: Individual case reports and professional consensus exist, but systematic research is lacking.

Example: Emerging techniques with professional endorsement

C-

Expert Opinion Only

What this means: Healthcare professionals recommend this exercise based on clinical experience, but no formal studies exist.

Example: Traditional physical therapy exercises without formal research

D

Anecdotal + Plausible Mechanism

What this means: Internet claims and testimonials exist, and there's a logical basis for why it might work based on anatomy/physiology.

Example: Mewing for adults, some face yoga claims

D-

Anecdotal Only

What this means: Popular online but with no scientific verification. May still work, but we simply don't know.

Example: Most TikTok fitness trends, viral exercise claims

F

Contradicted / Potentially Unsafe

What this means: Research has shown this exercise doesn't work as claimed, or may cause harm. We include these to warn against common misconceptions.

Example: Spot reduction for fat loss, certain exercises with injury risk

🔍 Our Research Sources

We search the following databases when evaluating each exercise:

PubMed

Primary database for biomedical literature from the National Library of Medicine

Google Scholar

Broader search including conference papers and preprints

PEDro

Physiotherapy Evidence Database for rehabilitation research

Cochrane Library

Gold standard for systematic reviews

✅ Study Quality Checks

When evaluating individual studies, we consider:

  • Sample size: n>30 preferred for meaningful statistical power
  • Control group: Present and appropriately matched
  • Randomization: Method clearly described
  • Blinding: Single or double-blind when feasible
  • Follow-up duration: Adequate for measuring outcomes
  • Dropout rate: <20% preferred
  • Conflict of interest: Declared and considered
  • Peer review: Published in reputable journals

⚠️ Important Caveats

  • Low evidence ≠ ineffective: Many exercises simply haven't been studied. A "D" grade often means "unknown" rather than "doesn't work."
  • Cosmetic vs. health endpoints: Some exercises may have strong evidence for health outcomes (pain relief) but weak evidence for cosmetic claims.
  • Individual variation: Research shows average effects; your results may differ based on genetics, consistency, and other factors.
  • Evidence evolves: Our grades may change as new research is published. We update regularly.

Ready to explore our evidence-rated exercises?

Every exercise includes its evidence grade and supporting research.

Browse Exercises