Miller Kevin C, Long Blaine C, Edwards Jeffrey E
Central Michigan University, School of Rehabilitation and Medical Sciences, 1208 Health Professions Building, Mount Pleasant, Michigan, USA.
School of Health Sciences, Mount Pleasant, Michigan, USA.
Muscle Nerve. 2017 Dec;56(6):E95-E99. doi: 10.1002/mus.25562. Epub 2017 Apr 5.
Muscle cramping may increase peripheral nervous system excitability. It is unknown if, and how long, cramp susceptibility is affected by previous cramping. We tested whether volitionally induced muscle cramps (VIMCs) lowered cramp threshold frequency (TF ) and how long TF was affected post-VIMC.
Fifteen cramp-prone participants volitionally induced a flexor hallucis brevis (FHB) cramp on 4 separate days. FHB TF was measured before VIMC (i.e., baseline) and 5, 30, and 60 min post-VIMC. VIMC electromyography (EMG) amplitude, VIMC duration, and perceived VIMC intensity were measured to ensure consistency of VIMC between days.
VIMC EMG amplitude, duration, and perceived intensity were similar between days (P > 0.05). VIMC lowered TF ; baseline TF (18 ± 6 Hz) was higher than 5-min (14 ± 6 Hz), 30-min (14 ± 5 Hz), and 60-min TF (14 ± 5 Hz; P < 0.05).
Acute VIMCs increase cramp susceptibility. Clinicians should apply treatments for at least 60 min postcramp to decrease the probability of cramp recurrence. Muscle Nerve 56: E95-E99, 2017.
肌肉痉挛可能会增加外周神经系统的兴奋性。之前的痉挛是否会影响痉挛易感性以及影响时长尚不清楚。我们测试了自主诱发的肌肉痉挛（VIMC）是否会降低痉挛阈值频率（TF）以及VIMC后TF受影响的时长。
15名易痉挛参与者在4个不同日期自主诱发了拇短屈肌（FHB）痉挛。在VIMC之前（即基线）以及VIMC后5、30和60分钟测量FHB的TF。测量VIMC的肌电图（EMG）振幅、VIMC持续时间和主观感受到的VIMC强度，以确保不同日期VIMC的一致性。
不同日期之间VIMC的EMG振幅、持续时间和主观感受强度相似（P>0.05）。VIMC降低了TF；基线TF（18±6Hz）高于5分钟时的TF（14±6Hz）、30分钟时的TF（14±5Hz）和60分钟时的TF（14±5Hz；P<0.05）。
急性VIMC会增加痉挛易感性。临床医生应在痉挛后至少60分钟进行治疗，以降低痉挛复发的可能性。《肌肉与神经》56: E95-E99, 2017。
