This one suggests you might be able to also get the result without taking them into pain at all. I would assume you need to do a baseline test first to see what their initial limit is and then do retesting after a period of time to reset that goal of pain free walking distance/time.

Experimental model of pain-free treadmill training in patients with claudication.

Mika P, Spodaryk K, Cencora A, Unnithan VB, Mika A.

Department of Rehabilitation, Academy of Physical Education, Krakow, Poland.

OBJECTIVE: Treadmill training in claudication is often based on walking exercise to a pain threshold or longer to the maximum muscle pain of the lower limbs. This kind of exercise may cause an inflammatory response. The purpose of this study was to determine whether pain-free treadmill training using walking exercise to 85% of the distance to onset of claudication pain can significantly improve pain-free walking distance in patients with intermittent claudication and to evaluate whether this kind of program may induce an inflammatory response leading to the progression of atherosclerosis.

DESIGN: A total of 98 patients aged 50-70 yrs with stable intermittent claudication were randomized into a supervised treadmill training program or a comparison group. Patients in the treatment group participated in 12 wks of supervised treadmill training. We examined the effects of 12 wks of pain-free treadmill training on pain-free walking distance, total leukocyte count, neutrophil count, and microalbuminuria in patients with claudication.

RESULTS: A total of 80 participants completed the program. Exercise rehabilitation increased the time to onset of claudication pain by 119.2%, from 87.4 +/- 38 m to 191.6 +/- 94.8 m (P < 0.001). There was no increase in total leukocyte count, neutrophil count, or microalbuminuria after 12 wks of treadmill exercise (P > 0.05)

CONCLUSION: A pain-free training program can be used in the treatment of claudication as a low-risk program, increasing walking ability without potential harmful effects of ischemia-reperfusion injury.