Here a patient is reported illustrating the value of using a simple 12 minute walk test. Key words: McArdle Disease; glycogen storage disease type V; second wind phenomenon; exercise test; 12 minute walk test. McArdle disease or glycogen storage disease type V muscle phosphorylase deficiency, glycogenosis Type V is a rare autosomal recessive metabolic myopathy with significant molecular heterogeneity caused by homozygous or compound heterozygous mutations in the muscle glycogen phosphorylase gene PYGM located at chromosome 11q13 1 , 2.
It is the most common glycogen storage disorder affecting muscle, with an estimated prevalence of ,, 3 , 4. The disorder is caused by deficiency of the enzyme muscle glycogen phosphorylase which catalyzes the degradation of glycogen into glucose subunits.
Second wind is a phenomenon in distance running, such as marathons or road running whereby an athlete who is out of breath and too tired to continue. Albums de Pierre Moerlen's Gong · Breakthrough () Wild child (). modifier · Consultez la documentation du modèle. Second wind est le 7e album.
Enzyme deficiency can be demonstrated in frozen muscle sections using enzyme histochemistry: muscle fibres show absent phosphorylase activity while the activity is preserved in smooth muscle in the walls of blood vessels due to the expression of the brain isoform, which is expressed by a different gene Figure 1. The inability to metabolise glycogen results in severe impairment of physical activity that is dependent on anaerobic glycolysis.
Consequently, people with this condition will experience exercise intolerance during the first minutes of physical activity, represented by fatigue, pain and weakness; and throughout more intense or isometric activity. A contracture, or severe muscle cramp causing rigidity, occurs due to the lack of muscle energy substrate during intense exercise and leads to muscle damage and myoglobinuria.
swivinloma.tk Figure 1. Illustrations of key pathological features. There is a marked increase in glycogen content within vacuoles on the PAS preparation B.
Muscle fibres show reduced phosphorylase activity C while the activity is preserved in smooth muscle in the walls of blood vessels arrows. Despite its rarity, it is important for doctors to be familiar with the condition because early diagnosis and the adoption of an appropriate lifestyle may help in improving quality of life and prevent severe life-threatening complications such as compartment syndrome, acute rhabdomyolysis and acute renal failure. Unfortunately, there is often a delay in diagnosing McArdle disease and affected individuals may be misdiagnosed with other disorders such as polymyositis and chronic fatigue syndrome 5 , 6.
The second wind phenomenon, as described in a 12 minute walking test and 15 minute cycle test, is known to be pathognomonic for McArdle disease and its identification in the clinic can aid diagnosis.
Here we present a case of a patient with a history of exercise intolerance with immediate increase in exercise capacity and illustration of the second wind phenomenon during a 12 minute walk test 12MWT. A 50 year-old-man was referred for neuromuscular evaluation some 20 years after being diagnosed with McArdle disease. From his medical history it was clear that he had problems with exercise since he was a child. He had never been able to run and symptoms such as myalgia and exercise intolerance had always been severe enough to disrupt any physical activity undertaken since the age of 4.
Muscle cramps in his legs were the most common feature. He was reprimanded by his schoolteachers in physical education classes and learnt to avoid sports such as football. He gave up swimming having almost drowned on two occasions. However, despite these early problems, he remained active choosing activities he could do at his own pace including a daily newspaper delivery round. He found that he could even complete day-long hikes and felt better at the end than at the beginning of activities. Many attempts at diagnosis were rebuffed by family doctors and local specialists.
He was diagnosed with gout at age 19, despite no obvious risk factors. Over the years he suffered several episodes of rhabdomyolysis but hospital admission resulted only in pain medication and no diagnostic investigation.
It was finally a rheumatologist treating his gout 10 years later who listened to his story and carried out a baseline serum creatine kinase CK test. He received little information about his condition and no follow up until he was referred by his GP to a specialized clinic at age On interview at 50 years of age, it was clear that whilst he had no knowledge of the second wind phenomenon he had in fact been using it since childhood.
During the 12MWT performed at clinic, an increase in his heart rate HR was associated with leg discomfort during the first minutes of activity, with improvement of both symptoms occurred at around minutes Table 1. Thereafter he was able to continue exercise with improvement in his symptoms. The clear demonstration of such second wind phenomenon during the 12 MWT, and a discussion of the timings and mechanisms involved, has enabled him to make more confident in his physical abilities using this phenomenon, thus improving his quality of life substantially.
Table 1. During the test, an increase in HR was associated with left leg thigh more than calf discomfort during the first 6 minutes of activity, which made him reduce his pace. The patient achieved the second wind following minutes of activity, when his symptoms and HR reduced without changing the walking speed.
A carefully taken history is essential to diagnose this condition. It is commonly associated with dyspnoea and tachycardia. Triggers for exercise intolerance include any kind of skeletal muscle activity, particularly anaerobic activity as this is dependent on muscle energy from glycogenolysis 8. There is an increased risk of myoglobinuria and rhabdomyolysis if activities are continued in the presence of these symptoms. Fixed weakness affecting the paraspinal and upper limb muscles may occur. Muscle hypertrophy can also be seen in a proportion of patients 4 , 6 , 9.
The finding of a raised serum CK in combination with exercise intolerance should raise suspicion of a metabolic myopathy. The second wind is a period of less painful and more effective exercise after the initial period of muscle cramps. This was first observed and reported by Pearson et al Once in the second wind , people with McArdle Disease can continue to exercise with amelioration of their symptoms.
The second wind phenomenon appears to represent the lag that exists in supplying sufficient energy for physical activity as a result of deficient glycolytic muscle metabolism and the time taken for the release of glucose from liver glycogen stores and fatty acid oxidation to provide the required energy. Consequently, identifying the second wind helps with the clinical assessment and diagnostic process. Although the second wind phenomenon is present in all cases of McArdle disease, some patients may have difficulty in recognizing and eliciting the phenomenon in themselves during everyday physical activity 4 , 6.
Consequently, they may not volunteer it in the clinical history even if it is specifically asked for. Performing an exercise test to reproduce the phenomenon in a clinic setting may not only help with the diagnostic process for McArdle disease but also be used to demonstrate the phenomenon to patients from a therapeutic perspective. There are two exercise tests that elicit the second wind phenomenon in McArdle disease, namely 12 minute walk test 12 MWT 6 and cycle test The 12 MWT is a simple, easy, non-invasive assessment that can be performed in any clinical setting 6.
Vulnerability Management. Network Computing Dark Reading. About Us.
Follow DR:. The Edge. App Sec. Threat Intelligence. Edge Articles. John Klossner Edge Features.
Email This. Building a Security Culture.
Al Delvecchio. Technical Specs. After some time the veins and capillaries dilate and cooling takes place more through the skin, so less heavy breathing is needed. Create a free personal account to access your subscriptions, sign up for alerts, and more. External Sites.
White Papers. Getting Started With Emerging Technologies. Rethinking Enterprise Data Defense.
I guess managment really is all in on the cloud solution. They are their biggest fans. Now that the merger of the cubicle farm with the wind farm is compelte I hear that there are plans to merge with the dairy farm. I regret skimming over the telework agreement. I believe they would be much more effective if installed in the executive suite. They were installed to replace the backup generator, forgetting the windows don't open.
My feet are so tired.