Research was conducted recently to determine if exercise limits can prevent post-exertional malaise in CFS patients. The theory was that the use of exercise limits prevents symptom increases and worsening of the patients health status following a walking exercise in people with Chronic Fatigue Syndrome.
The clinical trial (see full study report at this link) used walking exercise and exercise limits with 24 CFS patients:
Walking was chosen because it is a mode of exercise which is functionally relevant, easily applied in the clinical setting and frequently used in exercise therapy for people with chronic fatigue syndrome.
1,2 Prior to thewalking exercise, the patients were asked to indicate how long they would beable to walk on a flat surface without increasing symptoms, and whether theywere currently experiencing a good or a bad day. In order to account for
typical overestimations, the patient’s estimated exercise duration wasreduced with 25 of 50% in case of a good or a bad day respectively. This wasused to limit the walking duration. In addition, the exercise intensity waslimited using an upper heart rate limit corresponding to the RER=1.0 (derivedfrom the submaximal exercise stress test). Heart rate was monitored
continuously during exercise using a Polar Accurex Plus (Polar Electro OY,Kempele, Finland). The heart rate corresponding to RER=1.0 was entered in theheart rate monitor as the upper limit. The patients were asked to walk on aflat surface and in a straight line from one marking spot to another (the twomarking spots were placed at a 10 m distance). The patient was instructed towalk at a steady pace, not to talk or to stop walking during the exercise,
and to decrease the walking pace if the alarm went off (i.e. when the heartrate increased above the upper limit). The investigator recorded the walkingdistance and the number of times the alarm sounded.
The CFS study patients participated in a walking test with the two concurrent exercise limits. Each PWC walked at an intensity where the maximum heart rate was determined by heart rate corresponding to the respiratory exchange ratio=1.0 derived from a previous submaximal exercise test and for a duration calculated from how long each patient felt they were able to walk.
The fatigue increase observed immediately after exercising returned to pre-exercise levels 24 hours post-exercise. The increase in pain observed immediately after exercising was retained at 24 hours post-exercise. Fourteen of the 24 subjects experienced a clinically meaningful change in bodily pain; 6 indicated that the exercise bout had slightly worsened their health status, and 2 had a clinically meaningful decrease in vitality. There was no change in activity imitations/participation restrictions.
It was shown that the use of exercise limits (limiting both the intensity and duration of exercise) prevents important health status changes following a walking exercise in people with chronic fatigue syndrome, but was unable to prevent short-term symptom increases. [Note: additionally, the authors noted that The results for a minority of the subjects studied here support the notion that the exercise intensity necessary to cause a symptom increase can be quite mild that many subjects overestimated their exercise limits, and that study of other exercise limits to prevent worsening of ME/CFS symptoms & health status in response to exercise is warranted.]