This article was posted last year, and I'm doing it again at New Years Resolution time. Let's all get off the couch. Physical exercise is important for everyone's general health -- but in Huntington's which is known to cause muscle abnormalities and weakness -- it is especially important for maintaining muscle strength and function.
There are studies in Huntington's people showing that physical activity programs give functional benefit, raise motor scores, and prevent falls. And recently a new study gives evidence that a more active lifestyle may slow progression of disease before symptom onset. For those with premanifest Huntington's, higher levels of physical activity correlated with delay in predicted onset of symptoms for as much as 4 years .
The Mouse: Might mouse models predict benefit in people? Mouse model study shows that environmental enrichment that includes physical exercise on a running wheel delays onset [van Dellen A 2008], improves motor and cognitive ability [Pang TY 2006], and rescues levels of protective chemicals including BDNF [Spires TL 2004]. The magnitude of benefit seen in the mouse that occurs with voluntary exercise is similar to that reported in mouse studies of creatine.
Recent studies show that physical activity improves strength and function in Huntington's and likely slows progression of the disease.
What about People? In a recent study England, Busse and colleagues [Busse ME 2008] have shown that baseline muscle strength in Huntington's is greatly (50%) reduced compared to age-matched individuals. Muscle weakness is most prominent in proximal (hip and thigh) leg muscles, as has been shown for Parkinson's even in early stage [Inkster LM 2003]. However the good news is that studies in both diseases suggest that physical activity, either endurance and/or resistance training results in gains in strength and function:
2006: In a report of 40 early to mid stage HD patients who received 3 weeks of intensive in-patient rehabilitation that included physical therapy had improved scores on Physical Performance Testing (PPT). The PPT test is a 9 item measure of motor function and balance. Eleven participants who completed 6 sessions over 2 years showed stabilization of motor function for the entire 2 year period [Zinzi P 2007].
2008: In another unpublished case-report presented at the Lisbon meeting of EHDN, a twice weekly exercise program utilizing strength, balance and aerobic training in a patient with mid-stage disease resulted in increased strength, improved balance and motor function at 7 weeks (Busse 2008).
Though these combined studies are small and not conclusive, they suggest that physical activity, whether endurance or strengthening can stabilize and improve function using measures recently shown to be valid measures of disease progression [Rao AK 2009].
Lifestyle Activity and Age of Onset in Huntington's Disease: In this study of 154 individuals presented at the 2008 HSG symposium, it was reported that physical activity level (as did the CAG count) correlated as an independent factor in age of onset -- those who were less active had earlier onset of disease symptoms, and those with greater activity levels had later onset (Trembath 2008). This appeared to be significant -- those at the low end of physical activity had onset more than 4 years earlier than those at the high end of physical activity.
Though not proved by this study, it is likely be that physical activity delays symptom onset and disease progression -- as has been shown in mouse models.
Exercise is a Good Prescription for Huntington's: Based on these studies, the degree of physical activity benefit is high at all stages of Huntington's. But it is greatly under prescribed and used in the HD community -- even in Centers of Excellence. My advice? Get off the couch, get a physical therapy referral that includes requests for aerobic exercises (via a recumbent bicycle for those with gait instability) and aerobic strengthening exercises for upper and lower body, and balance training.
Of course, any physical activity program works only if we use it safely and long term. Take what you have learned home or to a local gym. Stay with the program for long-term results -- that may well include slowing of disease progression.
van Dellen A, Cordery PM, Spires TL, Blakemore C, Hannan AJ. Wheel running from a juvenile age delays onset of specific motor deficits but does not alter protein aggregate density in a mouse model of Huntington's disease. BMC Neurosci. 2008 Apr 1;9:34. doi: 10.1186/1471-2202-9-34. PubMed abstract
Pang TY, Stam NC, Nithianantharajah J, Howard ML, Hannan AJ. Differential effects of voluntary physical exercise on behavioral and brain-derived neurotrophic factor expression deficits in Huntington's disease transgenic mice. Neuroscience. 2006 Aug 25;141(2):569-84. Epub 2006 May 22. PubMed abstract
Spires TL, Grote HE, Varshney NK, Cordery PM, van Dellen A, Blakemore C, Hannan AJ. Environmental enrichment rescues protein deficits in a mouse model of Huntington's disease, indicating a possible disease mechanism. J Neurosci. 2004 Mar 3;24(9):2270-6. PubMed abstract
Busse ME, Hughes G, Wiles CM, Rosser AE. Use of hand-held dynamometry in the evaluation of lower limb muscle strength in people with Huntington's disease. J Neurol. 2008 Oct;255(10):1534-40. doi: 10.1007/s00415-008-0964-x. Epub 2008 Aug 2. PubMed abstract
Inkster LM, Eng JJ, MacIntyre DL, Stoessl AJ. Leg muscle strength is reduced in Parkinson's disease and relates to the ability to rise from a chair. Mov Disord. 2003 Feb;18(2):157-62. PubMed abstract
Zinzi P, Salmaso D, De Grandis R, Graziani G, Maceroni S, Bentivoglio A, Zappata P, Frontali M, Jacopini G. Effects of an intensive rehabilitation programme on patients with Huntington's disease: a pilot study. Clin Rehabil. 2007 Jul;21(7):603-13. PubMed abstract
Hirsch MA, Toole T, Maitland CG, Rider RA. The effects of balance training and high-intensity resistance training on persons with idiopathic Parkinson's disease. Arch Phys Med Rehabil. 2003 Aug;84(8):1109-17. PubMed abstract
Schenkman M, Hall D, Kumar R, Kohrt WM. Endurance exercise training to improve economy of movement of people with Parkinson disease: three case reports. Phys Ther. 2008 Jan;88(1):63-76. Epub 2007 Oct 16. PubMed abstract
Rao AK, Muratori L, Louis ED, Moskowitz CB, Marder KS. Clinical measurement of mobility and balance impairments in Huntington's disease: validity and responsiveness. Gait Posture. 2009 Apr;29(3):433-6. doi: 10.1016/j.gaitpost.2008.11.002. Epub 2008 Dec 25. PubMed abstract