Positives

• Modified protocols emphasize symptom-contingent intensity (rather than fixed weekly increments), recumbent or supine starting positions, daily HRV/symptom tracking to detect overshoot before PEM hits, and immediate de-escalation after any worsening PMC.
  
  

Negatives

• Multiple patient surveys of unmodified or aggressive GET show 74-81% of patients with PEM report symptom worsening or no change, with some patients deteriorating from being able to work and walk to entirely housebound or bedbound after months of GET RTHM.
  
  

Hurdles & Side Effects

• The Patient-Led Research Collaborative’s clinician pacing guide explicitly distinguishes pacing/symptom-titrated exercise from GET: pacing balances rest with activity to prevent PEM, while GET aims for steady weekly increases regardless of symptom response Patient-Led Research Collaborative.
  
  
• Heart-rate-cap pacing (typically 60-70% of age-predicted max, or anaerobic threshold from CPET) plus heart-rate-variability monitoring is the safest framework for patients attempting modified exercise; underloading is far less harmful than overloading in this population Long COVID Physio.