might benefit women experiencing leg cramps during pregnancy [20], it is no more effective than placebo for night-time cramp [21] or chronic persistent leg cramp [17]. The effectiveness of magnesium for skeletal muscle cramps is currently being reviewed under the Cochrane Neuromuscular Disease Group [22].
Interestingly, in the trial of magnesium citrate for chronic persistent leg cramps [17], about half of people allocated to the placebo group perceived that placebo had helped. For all interventions reported in the present study, it is not possible to disentangle any placebo effect from true intervention effects. It is possible that the pla- cebo effect accounts for some, if not all, of the perceived effectiveness of some interventions.
Interpretation of some findings is constrained by lim- itations of the survey. For example, people who reported stretching the calf muscles were not asked to demon- strate how they performed the stretch. On discussion with some participants, it became clear that some stretching techniques were inappropriate, for example, actively plantarflexing the foot to stretch the calf muscle. While this limits the interpretability of effectiveness rat- ings for calf stretching in this survey, it clearly demon- strates the need for health practitioners to carefully demonstrate and check stretching techniques when advising their patients to stretch. A second limitation of the survey is the potential for recall bias when nominat- ing interventions used now and in the past. Participants were asked to list all interventions that they had used for night-time muscle cramp. In addition, participants were specifically asked whether they had used certain interventions. These are marked with asterisks in Table 3. Direct questioning may have improved recall and led to an increased response rate for these interventions.
The most commonly suggested cause of cramp was sleeping position and movements from this position. Participants who identified the particular movements that induced cramp described plantarflexion of the ankle joint as the trigger. To prevent calf cramp, one participant described sleeping with a foot board at the base of their bed to prevent ankle joint plantarflexion and others described actively dorsiflexing the ankle joint when the early symptoms of cramp appeared. Avoidance of ankle plantarflexion has been described in the litera- ture as a potential treatment to prevent recurrent cramp [23-26]. Suggestions include using pillows [25,27] or a foot board [24] to resist ankle plantarflexion, and sleep- ing prone with feet overhanging the end of the bed [24]. None of these approaches have been evaluated in clini- cal trials and some might not be practical due to pro- pensity to reposition during sleep [27]. Use of a dorsiflexion night-splint would offer a more controlled and sustained dorsiflexion, yet this has not been evalu- ated or even suggested, to our knowledge.