BackgroundEdit

What is Myotonic Dystrophy?Edit

Myotonic Dystrophy is an autosomal dominant neuromuscular disorder [1]. This means in order for a newborn to inherit it, they only need the abnormal gene from just one parent [2]. There are two different types of Myotonic Dystrophies; pathological methods identify dystrophy type 1 by an unstable triplet cytosine thymine guanidine repeat on chromosome nineteen and dystrophy 2 by a tretranucleotide repeat of cytosine-cystosine-thymine-guanine (CCTG) on chromosome 3 [3][4]

Who does it affect?Edit

Myotonic Dystrophy type 1 is most commonly diagnosed during early adulthood, however incidences have occurred where newborns who show no immediate signs of neuromuscular abnormalities are diagnosed later in childhood [5]. Weakness in facial and neck muscles, poor suckling ability, problems with swallowing and speech are indicative of any potential cases of muscular dystrophy [6]. Key clinical features of Myotonic Dystrophy in adults are wasting of the sternocleidomastoid and temporal muscles, decrease in finger flexor strength, weak facial muscles and ptosis [6]. A muscular impairment rating scale has been developed to measure the progression of the severity of muscular weakness, wasting and myotonia [7].

Myotonic muscular dystrophy can also greatly impact the functioning of the ocular, cardiovascular, respiratory, digestive, metabolic and endocrine systems as well as the central nervous systems [7]. Due to the restrictions in physical activity, individuals with myotonic muscular dystrophy have a higher risk of developing secondary chronic illnesses [7]. Cardiovascular disease, diabetes and obesity are all sedentary lifestyle associated diseases that have higher incidence rates for progressive neuromuscular diseases [7].

PreventionEdit

There is no immediate cure available for Myotonic Muscular Dystrophy [7]. The identification and intervention for those with functional limitations warrants the initiation of preventative exercise programs to better the quality of life in sufferers [7].

Exercises used for prevention are:

  • Resistance training
  • Endurance training
  • Aerobic exercise
  • Proprioceptive Neuromuscular Facilitation
  • Inspiratory muscle training

It is recommended the prevention physical exercises be kept at moderate intensities due to the nature of the disease [8]. The lack of protein synthesis means the muscles can be damaged and fatigued if the load is excessive [9].

Exercise LoadsEdit

Resistance training has been recommended to be at 60-80% of 1RM, at 8 reps of 3 sets [10]. Benefits include; increases size and strength of muscle fibres and improves membrane permeability of serum myoglobin in the muscle cells [11].'

Endurance exercise training to be performed at body weight 30-40% 12 reps of 2 sets [12]. Benefits include; maintains activation of the neuromuscular junction which often deteriorates in a sedentary lifestyle as well as functionality [12].

Aerobic exercises such as fast walking 25-30 mins and light running 15-20 mins can be highly beneficial [13]. Muscles become conditioned and slight hypertrophy occurs, this will delay the onset of muscle degeneration [14].

Inspiratory muscle training is effectively resistance training for the lungs by blowing against a resistance [9]. This trains the lungs so that degeneration is delayed [9].

  1. Larkin, K & Fardaei, M, 2001. Myotonic Dystrophy - A multi-gene disorder. Brain Research Bulletin, 56/3, 389-395
  2. Medline Plus. 2014. Autosomal dominant. [ONLINE] Available at: http://www.nlm.nih.gov/medlineplus/ency/article/002049.html
  3. Ha, A, Tarnopolsky, M, Bergstra, T, Nair, G, Al-Qubbany, A, & Healey, J 2012, 'predictors of atrio-ventricular conduction disease, long-term outcomes in patients with myotonic dystrophy types i and ii', pacing & clinical electrophysiology, 35, 10, pp. 1262-1269
  4. Antonini, G, Soscia, F, Giubilei, F, De Carolis, A, Gragnani, F, Morino, S, Ruberto, A, & Tatarelli, R, 2006, 'health-related quality of life in myotonic dystrophy type 1 and its relationship with cognitive and emotional functioning', journal of rehabilitation medicine (taylor & francis ltd), 38, 3, pp. 181-185
  5. Lindeman, E, Leffers, P, Reulen, J, Spaans, F, & Drukker, J 1998, 'Quadriceps strength and timed motor performances in myotonic dystrophy, Charcot-Marie-Tooth disease, and healthy subjects', Clinical Rehabilitation, 12, 2, pp. 127-135
  6. a b Schara, U., Benedikt, G.H., Schoser, M.D, 2014. myotonic dystrophies type 1 and type 2: a summary on current aspects. Pediatric Neurology, 1, 71-80. Invalid <ref> tag; name "Schara" defined multiple times with different content
  7. a b c d e f Kierkegaard, M, Harms-Ringdahl, K, Holmqvist, L, & Tollbäck, A 2011, 'Functioning and disability in adults with myotonic dystrophy type 1', Disability & Rehabilitation, 33, 19/20, pp. 1826-1836
  8. Hammarén, E, Ohlsson, J, Lindberg, C, & Kjellby-Wendt, G 2012, 'Reliability of static and dynamic balance tests in subjects with myotonic dystrophy type 1', Advances In Physiotherapy, 14, 2, pp. 48-62
  9. a b c Mccool, F.D & Tzelepis, G.E, 1995. Inspiratory Nuscle training in the patient with neuromuscular disease. Physical Therapy, 75/11, 1006-1014
  10. Jamnik, V.K., Warburton, D., Markarski, J., Mckenzie, D.C., Shephard, R., Stone, J., Charlesworth, S & Gledhill, N, 2011. Enhancing the effectiveness of clearance for physical activity participation: background and overall process. Applied Physiology of Nutrition Metabolics, 36, 3-13
  11. Jamnik, V.K., Warburton, D., Markarski, J., Mckenzie, D.C., Shephard, R., Stone, J., Charlesworth, S & Gledhill, N, 2011. Enhancing the effectiveness of clearance for physical activity participation: background and overall process. Applied Physiology of Nutrition Metabolics, 36, 3-13
  12. a b Ansved, TT 2001, 'Muscle training in muscular dystrophies', Acta Physiologica Scandinavica, 171, 3, pp. 359-366
  13. Lindeman, E, Leffers, P, Reulen, J, Spaans, F, Drukker, J, Reulen, J., Kerckhoffs & Koke, A, 1995. Strength training in patients with Myotonic Dystrophy and Hereditary Motor and sensory neuropathy: a randomised clinical trial. American Academy of Physical Medicine and rehabilitation, 76, 389-395
  14. Lindeman, E, Leffers, P, Reulen, J, Spaans, F, Drukker, J, Reulen, J., Kerckhoffs & Koke, A, 1995. Strength training in patients with Myotonic Dystrophy and Hereditary Motor and sensory neuropathy: a randomised clinical trial. American Academy of Physical Medicine and rehabilitation, 76, 389-395