Fitness Testing for Chronic Fatigue Syndrome

PEM is the hallmark feature of CFS/ME and the primary concern with exercise testing:

• What is PEM? Worsening of all symptoms following exertion (physical, cognitive, emotional, or sensory). Not simple fatigue-a systemic crash
• Delayed Onset: PEM typically occurs 12 to 48 hours after exertion, sometimes longer
• Duration: Can last days, weeks, or months. May cause permanent worsening in severe cases
• Unpredictable: What is tolerable one day may cause severe PEM on another day
• Risk with Maximal Testing: Standard VO₂ max testing pushes to maximum exertion. This is a significant PEM trigger risk

This is why testing requires extremely careful consideration and may not be appropriate for many CFS/ME patients.

Testing may have value in limited circumstances:

• Research Participation: Some CFS/ME research studies use exercise testing to document objective impairment or study PEM mechanisms. Two-day CPET (cardiopulmonary exercise testing) shows abnormal response in CFS/ME
• Disability Documentation: Objective demonstration of reduced exercise capacity may support disability claims
• Baseline for Very Mild Cases: Some individuals with very mild CFS/ME (still working, minimal PEM) may tolerate submaximal testing to establish baseline
• Long-Term Monitoring: For those who have significantly improved, testing might track recovery progress

However, the risk of triggering severe PEM must be weighed against potential benefits. Many CFS/ME specialists advise against exercise testing due to PEM risk.

Testing is likely NOT appropriate if you have:

• Moderate to severe CFS/ME with significant PEM
• History of severe crashes from minimal exertion
• Currently in a symptom flare or crash
• Severe orthostatic intolerance (POTS, orthostatic hypotension)
• Primarily housebound or bedbound
• Significant cognitive impairment making consent difficult
• Recent worsening of symptoms

If you fall into any of these categories, discuss alternatives with your physician. Observation-based functional assessments may be safer.

If testing is deemed appropriate, we can offer modifications:

• Submaximal Test: Stop at predetermined heart rate (e.g., 70 to 80% predicted max) rather than pushing to exhaustion. Provides some data with less PEM risk
• Very Gradual Progression: Smallest possible workload increments with extended time at each stage
• Patient-Controlled: You determine stopping point based on symptoms. No pressure to continue
• Extended Recovery Monitoring: Stay 30 to 60 minutes post-test to assess immediate response
• Follow-Up Communication: Report any delayed PEM symptoms days after testing

Important: Even submaximal testing carries PEM risk. There are no guarantees of avoiding symptom flares.

If you and your physician decide to proceed:

• Clear Schedule: No activities, appointments, or obligations for 3 to 7 days after testing. Plan for potential crash
• Good Baseline: Wait until you are at your typical baseline, not in a flare. Avoid testing if recently crashed
• Support Person: Bring someone to drive you home and assist if needed
• Energy Envelope: Note your current activity limits to inform safe stopping points
• Physician Plan: Discuss with doctor what to do if severe PEM occurs (medications, urgent care triggers)
• Written Clearance: Bring explicit physician approval for testing acknowledging PEM risks

If PEM occurs post-testing:

• Complete Rest: Physical and cognitive rest for as long as needed
• Symptom Management: Use strategies that typically help your symptoms (medications, positioning, quiet environment)
• Pacing: Return to activity extremely gradually as symptoms permit
• Medical Support: Contact your CFS/ME specialist if crash is severe or prolonged
• Document: Track symptom changes for disability documentation if applicable

Unfortunately, there is no way to predict how severe or how long PEM will last if triggered by testing.

Safer alternatives to exercise testing for CFS/ME:

• Activity Logs: Detailed tracking of activities and symptoms over weeks
• Actigraphy: Wearable devices that objectively measure activity levels
• Heart Rate Monitoring: Track resting heart rate, heart rate variability, orthostatic heart rate changes without exertion testing
• Functional Questionnaires: SF-36, DePaul Symptom Questionnaire, validated CFS/ME scales
• Tilt Table Test: If orthostatic intolerance suspected (less PEM risk than exercise test)

Research on CFS/ME and exercise testing shows:

• Many CFS/ME patients have reduced VO₂ max (20 to 50% below predicted)
• Two-day CPET testing shows abnormal response-VO₂ max decreases on day two (not seen in healthy people or depression)
• Some show chronotropic incompetence (blunted heart rate response)
• Ventilatory inefficiency common
• Early anaerobic threshold shift

Single-day testing may not capture these abnormalities. Research-grade two-day testing is more diagnostic but even higher PEM risk.

Understanding CFS/ME exercise intolerance:

• CFS/ME is not deconditioning-exercise does not cure it and can worsen it
• Graded Exercise Therapy (GET) is controversial and potentially harmful for many patients
• Pacing (energy envelope theory) is currently recommended management approach
• The goal is staying within energy limits, not pushing through

VO₂ Max Test (standard or modified): $250

Given the risks and considerations, we recommend thorough discussion with your CFS/ME specialist before booking. We will not proceed without explicit physician clearance acknowledging PEM risks.

Fit Evaluations
311 Soquel Ave
Santa Cruz, CA 95062

Behind Hindquarter restaurant (second entrance off Dakota St.)

Phone: 831-400-9227
Email: info@fitevals.com

Call to discuss your CFS/ME status and physician recommendations thoroughly before any decision about testing.