Elicitability of muscle cramps in different leg and foot muscles

Abstract

To explore the efficacy of muscle motor point stimulation in eliciting muscle cramps, 11 subjects underwent eight sessions of electrical stimulation of the following muscles bilaterally: abductor hallucis flexor hallucis brevis, and both heads of the gastrocnemius muscles. Bursts of 150 square wave stimuli (duration: 152 micros; current intensity: 30% supramaximal) were applied. The stimulation frequency was increased from 4 pulses per second (pps) at increments of 2 pps until a cramp was induced. The number of cramps that could be elicited was smaller in flexor hallucis brevis than in abductor hallucis (16 vs. 22 out of 22 trials each; P < 0.05) and in the lateral gastrocnemius than in the medial gastrocnemius (5 vs. 20 out of 22 trials each; P < 0.0001). We show that leg and foot muscles have different cramp susceptibility, and the intermuscle variability in the elicitability profile for electrically induced cramps supports the use of the proposed method for cramp research.

Mechanisms of cramp contractions: peripheral or central generation?

“…Consistently, the above‐threshold stimulation allows the elicitation of involuntary contractions that present intensity and duration comparable to those of voluntarily‐ or spontaneously‐induced cramps. Moreover, in the case of electrically elicited cramps of foot and leg muscles (Minetto & Botter, 2009), the pain associated with the contraction and the delayed onset muscle soreness following the resolution of the cramp are also comparable to those in naturally occurring cramps. Another limitation of the study is that the investigator who determined the cramp threshold was not blinded to the subject's condition (intact vs .…”

“…Cramps were elicited in the abductor hallucis muscle of the dominant foot with electrical stimulation of the muscle motor point, as described previously (Minetto et al . 2008; Minetto & Botter, 2009). The subject was seated comfortably on a chair with the ankle in a neutral position and the foot resting on a padded support.…”

Neural Mechanisms of Muscle Cramp

“…Therefore, electrical stimulation is often applied directly to the muscle motor point. This produces less pain, and has been developed as an alternative to peripheral nerve stimulation and has been utilized (Minetto and Botter 2009;Minetto et al 2008Minetto et al , 2009aMinetto et al , b, 2011. A study with the motor point stimulation demonstrated that the threshold frequency and pain in intrinsic foot muscle were lower than those in leg muscle.…”

“…A study with the motor point stimulation demonstrated that the threshold frequency and pain in intrinsic foot muscle were lower than those in leg muscle. The authors concluded that the intrinsic foot muscle is the most suitable for the study of muscle cramps (Minetto and Botter 2009). It has been found that the high frequency magnetic stimulation to peripheral nerve can provoke muscle cramps, which are less painful than those produced by electrical stimulation (Caress et al 2000).…”

Restless legs syndrome and nocturnal leg cramps: review and guide to diagnosis and treatment

“…Studies aimed at answering this question have used several methods to illicit cramps, such as direct electrical stimulation of nerves, which has demonstrated a lower threshold of intensity necessary to trigger cramps in cramp -prone individuals compared with those with no history of cramps. [70][71][72][73] This suggests that there may be a physiological predisposition to cramps. Fasciculations, a classic "lower motor neuron" sign, may be seen during a cramp discharge, supporting a peripheral origin of cramps.…”