Cramp Training Induces a Long-Lasting Increase of the Cramp Threshold Frequency in Healthy Subjects

Effects of Neuromuscular Electrical Stimulation on the Frequency of Skeletal Muscle Cramps: A Prospective Controlled Clinical Trial

“…Male adults between the age of 20 and 80 years were included in the present study (Table ). Since the positive effects of the NMES protocol on the CTF in previous studies were observed in healthy men , we restricted the present study to cramp prone male adults to avoid any potential interference from sex differences in the response to the applied protocol. Using several articles in a local newspaper, 25 men with regularly occurring calf cramps (defined as at least one cramp per week) were recruited from April to August 2015.…”

Neuromuscular Electrical Stimulation Reduces Leg Cramps in Patients With Lumbar Degenerative Disorders: A Randomized Placebo-Controlled Trial

“…Due to different primary outcome measures and more heterogenous samples, the effects found in our previous studies ( 9 , 10 , 11 , 12 , 13 ) cannot be transferred one‐to‐one to the current investigation. However, based on the large effects seen in our previous studies, we assumed that we could achieve at least a medium effect (Partial eta 2 = 0.09; corresponding to an f‐value of 0.31) on the total number of reported leg cramps.…”

“…To determine the cramp threshold frequency (CTF), we used the same approach as described in our previous studies ( 9 , 10 , 11 , 12 , 13 ). Accordingly, a stimulation train of 5 sec was applied to the muscle belly every 55 sec, while participants were instructed to lay prone on an examination bench with their ankle joints flexed at ~120°.…”

“…A muscle cramp was defined by the following three criteria: 1) the subjective cramp sensation of the participant; 2) a sustained plantar flexion of the foot due to an involuntary contraction of the calf muscles after a stimulation train observed by the investigator; and 3) as the most objective criterium, an average EMG root mean square amplitude (aRMSA) within the 4‐sec interval following the stimulation trains that exceeded a value of 2x the standard deviation above the 2‐sec baseline aRMSA (preceding the first stimulation train). Except the longer EMG analysis periods used in the present and our previous studies ( 9 , 10 ), the used criteria have been applied in other trials to define the occurrence of an electrically induced muscle cramp ( 17 , 18 ).…”

Muscle Cramping During Exercise: Causes, Solutions, and Questions Remaining

“…The authors of this and other studies involving similar experimental designs should have reported whether the cramp intensity and cramp duration were different between the first and second exposures, and should perhaps also have habituated the subjects to the electrical stimulation process prior to the experimental trials. The importance of this is highlighted by a recent publication showing that repeated exposures to electrically-evoked cramps induce a long-lasting increase of the cramp TF in healthy subjects [67]. These authors induced EAMC in the gastrocnemius medialis of one leg twice a week, while the opposite leg served as the control leg; after four cramp training sessions, the cramp threshold frequency (CTF) increased in the intervention leg but not in the control leg.…”