DMD and exercise

Question 1

When was the fist description of mdx mouse?

Answer 1

1984

Question 2

Pros and cons seen with dmd and exercise

Answer 2

• Exercise proposed as palliative therapy to maintain strength and prevent
contractures
• Remains controversial as training benefits may be counteracted by muscle
overuse/damage

Question 3

No use disuse study

Answer 3

Gold standrad
• Intervention consisted of assisted bicycle training 30 min/d, 5 d/wk, 24 wks
• Participants cycled with both their arms and legs using mobility trainer
• Primary outcome measures were Motor Function Measure and Assisted
6 min Cycling Test

Question 4

Individual differences in Motor Function Measure scores b/w intervention of exercise and control

Answer 4

after 24 wk intervention most boys showed improvements in. motor function

Question 5

Does exercise training maintain motor function over time?

Answer 5

Yes

Question 6

Which patients with DMD is exercise safe for?

Answer 6

boys who are in late ambulatory or powerchair dependent

Question 7

What do these results contradict?

Answer 7

Results contradict opinion that exercise training accelerates disease progression

Question 8

What does future work have to examine?

Answer 8

Future work must examine mechanisms underlying training-induced preservation of function

Question 9

Take home from study

Answer 9

If exercise is preformed correctly than function is preserved (type, intensity) safe and mostly affective or delaying progression

Question 10

12-week (3X/week) in-home, remotely supervised, bi-lateral isometric leg
training at 50% MVC for 6 weeks, then 60% of new MVC for 6 weeks, n = 8 in ambulatory DMD boys shows

Answer 10

No signs of damage via serum CK, muscle MRI, or subjective pain after 12 weeks of exercise training!

Question 11

How many boys completed the training?

Answer 11

7/8

Question 12

What were the strength and function outcomes?

Answer 12

• Post-training (PT) participants showed significant increases in strength of
knee extensors (KE) and knee flexors (KF) compared to baseline (BL)
• Training also improved function: time to ascend/descend stairs was reduced

Question 13

in BMD PATEINTS: Short-term (12 wks, n = 11) and long-term (12 mo, n = 6) exercise training program consisting of cycle ergometer 3-5 times/wk at heart rate corresponding to 65% VO2 (endurance training)

Answer 13

12 wks increased BMD VO2max & Wmax by 50-80% (% improvement 3-fold higher vs controls)

endurance training improves fitness in BMD patients

Question 14

How does endurance training affect strength?

Answer 14

• Significant increases in strength were observed in muscles required for
cycling exercise
• Training-induced increases in fitness and strength in BMD patients paralleled
by self-reported improvements in endurance, strength & walking distance
after 12-week intervention

Question 15

Does exercise training compromise muscle structure?

Answer 15

No

Question 16

Is there a change in fiber type composition, capilary density, central nuclie, necrotic cells, nMHC, plamsa creatine kinase, ?

Answer 16

no (no signs of muscle damage)

Question 17

What does the muscle morphology data demonstrate?

Answer 17

Muscle morphology data demonstrated no signs of increased satellite cell activation,
suggesting exercise does not contribute to exhaustion of regenerative pool

Question 18

After 12 weeks voluntary wheel running in mdx mice, what happened to utrophin levels is dystrophic muscle?

Answer 18

• Chronic exercise increased utrophin protein expression in quads, tended to increase in soleus
• Muscle fiber size variability and level of inflammatory infiltrate not affected by running
• Exercise may increase utrophin content in patients with DMD & BMD