Supervised Treadmill Walking, Calf Muscle Capillarization and Walking Distance

Effects of supervised treadmill walking training on calf muscle capillarization in patients with intermittent claudication. Angiology. 2009 Feb-Mar;60(1):36-41. Wang J, Zhou S, Bronks R, Graham J, Myers S.


The aim of this study was to evaluate the effects of supervised treadmill walking training on the calf muscle capillarization in patients with intermittent claudication. The first 12-week period was a non-exercise, within-subject control stage, and the second 12-week period was an exercise training stage. Calf muscle biopsy and functional capacity measurement were performed at baseline, preexercise and postexercise training. In all, 11 subjects completed all procedures. Their average age was (mean +/- standard deviation) 73.9 +/- 5.5 years and resting ankle-to-brachial systolic blood pressure index was 0.57 +/- 0.11. After exercise training, the difference between the pretraining and posttraining capillaries in contact with type IIx and IIa muscle fibers for each subject was significantly correlated with an improved pain-free walking time, r = 0.69 and r = 0.62 (both P < .05), respectively. This finding suggests that the change in calf muscle capillarization might contribute to the improved walking capacity following supervised treadmill walking training in patients with intermittent claudication.

My comments:

The protocol in this paper was as follows;

  • Start on treadmill at 3.2 kph (2 mph) with incline individualized to get ⅘ (moderate) claudication pain after 5 minutes
  • Sit and rest after pain reaches ⅘ and begin walking again after pain fully subsides
  • Increase incline 0.5 % if patient is able to walk 7 minutes continuously
  • Start increasing speed 0.5 kph after patient works to 5% grade
  • 1 hour per day, 3 times per week for 12 weeks

5 point pain scale slightly different than 4 point scale of other researchers (why everyone can’t just use regular 10 point scale I’ll never know)

  1. no pain
  2. onset of pain
  3. mild pain
  4. moderate pain
  5. max claudication (pain)

This study found capillaries in contact with each muscle fiber increased significantly for type II (fast, anaerobic) muscle fibers but not type 1 (slow, aerobic) fibers to total muscle fibers. Absolute capillary contact number did increase for all fibers, just not significantly, but I expect it would have if there were a greater number of study subjects. Percent increase in capillary contact was 9.7% for type 1 muscle fibers, 9.2% for type IIa fibers, and 15% for type IIx fibers.

Pain free walking distance (PFWD) improved from 130 m to 348 m (168%), while maximal walking distance (MWD) improved from 323 m to 714 m (120%). In an effort to compare apples to apples I’m going to take these percentages per week and percentages per workout. So for this study that works out to:

  • PFWD/week = 14%
  • MWD/week = 10%
  • PFWD/workout (60 minutes) = 4.67%
  • MWD/workout (60 minutes) = 3.33%

I think the goal should be to find the protocol the most improvement in the least time with the least pain. This protocol is what I started my 1st claudication patient on. He reported it felt pretty good, in that he could stop when it hurt but then he could go at it again when he felt better. At the beginning of his hour he lasted almost exactly 5 minutes but he worked up to 7 minutes by the end of the hour, which he thought was pretty encouraging. The protocol above is also very similar to the TASC II program. The main difference is that intensity is increased after one is able to walk 7 minutes continuously rather than 10 minutes in the TASK II program, but I would be surprised if it made much difference either way.  Improvements per week and per workout were not as good as the interval protocol with active rest, however.  

As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.

Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.

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