Type 1 polysaccharide storage myopathy caused by genetic mutation in the glycogen synthase 1 gene is present in many breeds including the Noriker and Haflinger horses. In humans, EMG has already been used to document changes in the muscle activity patterns of patients affected by human glycogen storage disorders. Therefore, the aim of the present study was to describe gluteus muscle activity with surface electromyography (sEMG) in Haflinger and Noriker horses with known GYS1 mutation status during walk and trot. Thirty-two horses (11 Haflinger and 21 Noriker horses) with homozygous non-affected (GG), heterozygous affected (GA) and homozygous affected (AA) status of GYS1 mutation without overt clinical signs of any myopathy were selected for the current study. Using surface electromyography gluteus medius muscle activity at walk and at trot was measured, and muscle activity was described in relation to the maximum observed value at the same sensor and the same gait. In order to further describe the signals in detail comprising both frequencies and amplitudes, the crossings through the baseline and the 25, 50 and 75 percentile lines were determined. The result of the relative muscle activity did not show a consistent difference between affected and non-affected horses. Genetically affected (GA and AA) horses showed significantly less density of muscle activity for both gaits and horse breeds except for the crossings per second at the baseline and 75 percentile at walk in the Haflinger horses and 75 percentile at trot in the Noriker horses. The medians of all calculated density values were significantly lower in the GA Haflingers compared to the GG Haflingers (p = 0.012) and also in the AA Norikers compared to the GG Norikers (p = 0.011). Results indicate that the GYS1 mutation reduces the number of functional muscle fibres detected by sEMG measurements even in the absence of overt clinical signs.

中文翻译：

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多糖贮积性肌病 Haflinger 和 Noriker 马臀中肌活动的比较

由糖原合酶 1 基因的基因突变引起的 1 型多糖贮积性肌病存在于包括 Noriker 和 Haflinger 马在内的许多品种中。在人类中，EMG 已被用于记录受人类糖原贮积症影响的患者肌肉活动模式的变化。因此，本研究的目的是用表面肌电图 (sEMG) 描述 Haflinger 和 Noriker 马在行走和小跑期间已知 GYS1 突变状态的臀肌活动。选择了 32 匹马（11 匹 Haflinger 和 21 匹 Noriker 马），它们具有 GYS1 突变的纯合未受影响 (GG)、杂合受影响 (GA) 和纯合受影响 (AA) 状态，没有任何肌病的明显临床症状。使用表面肌电图测量臀中肌在步行和小跑时的肌肉活动，并根据相同传感器和相同步态下的最大观察值描述肌肉活动。为了进一步详细描述包括频率和幅度的信号，确定了穿过基线和 25、50 和 75 个百分位线的交叉点。相对肌肉活动的结果没有显示受影响和未受影响的马之间的一致差异。遗传影响（GA 和 AA）马的步态和马品种的肌肉活动密度显着降低，除了基线时的每秒穿越次数和 Haflinger 马的步行时 75% 和 Noriker 马的小跑时的 75%。p  = 0.012) AA Norikers 与 GG Norikers ( p  = 0.011) 相比也是如此。结果表明，即使在没有明显临床症状的情况下，GYS1 突变也会减少通过 sEMG 测量检测到的功能性肌纤维的数量。