Most participants recalled being awoken from sleep by cramps and cramps occurring at irregular times or in the middle of sleeping time. These findings suggest that night-time muscle cramping may profoundly affect quality of sleep. Most participants also reported experiencing calf-muscle soreness in the days following cramp. There are anecdotal reports in the literature of discomfort persisting for hours following night-time muscle cramp . This is the first study to demonstrate the prevalence and lengthy duration of ongoing pain.
Mean usual pain intensity of night-time calf cramp was 66 mm on a 100 mm visual analogue scale and most participants also experienced night-time muscle cramping of other muscles and day time muscle cramping. The severity and high frequency of cramps reported by participants are despite current therapies. As most participants reported experiencing some help from treatment, it is expected that frequency and severity of cramp would be higher if current treatments were withdrawn.
Median reported age of first cramp (50 years) in this sample was younger than previous reports in the literature. Of 86 respondents to a United Kingdom (UK) postal survey who reported suffering from rest cramps, the mean age of cramp onset was 60 years (95%CI: 57 to 63) . This result is reflected by a second UK survey of 182 people over 65 years of age who experienced leg muscle cramp. 80% of participants reported cramp onset after 55 years of age . The younger age of cramp onset in the present sample might reflect the inclusion of adults of all ages or differences in exposure to cramp precipitants (e.g. climate) between the UK and Australia. Indeed one participant stated that cramps 'started when I moved from England at 67 [years of age]', although this could be coincidental.
Advice-seeking behaviour in our sample was more common than in previous reports in the literature. In a UK survey of 182 people over 65 years of age who experienced leg muscle cramp, only 40% sought advice from their General Practitioner about their cramp (contrast to 63% in our sample) . This is similar to the results of a similar survey in England of people randomly selected from a General Practitioner's Register . Interestingly, of all participants who had not reported cramp to a General Practitioner, 31% described their cramps as being very distressing or a major nuisance . Despite the present finding of more common advice seeking, only two participants reported achieving cramp prevention with treatments recommended. Both reports related to quinine, which doctors in Australia are now discouraged from prescribing for muscle cramps.
The most commonly reported treatment used to prevent recurrent cramp was magnesium supplementation (used by 58% of participants). Most participants perceived the magnesium supplements as being 'useless' or only 'a little help'. This is consistent with randomised trials that found that, while magnesium supplementation might benefit women experiencing leg cramps during pregnancy , it is no more effective than placebo for night-time cramp  or chronic persistent leg cramp . The effectiveness of magnesium for skeletal muscle cramps is currently being reviewed under the Cochrane Neuromuscular Disease Group .
Interestingly, in the trial of magnesium citrate for chronic persistent leg cramps , 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 placebo effect accounts for some, if not all, of the perceived effectiveness of some interventions.
Interpretation of some findings is constrained by limitations of the survey. For example, people who reported stretching the calf muscles were not asked to demonstrate 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 ratings for calf stretching in this survey, it clearly demonstrates 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 nominating 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 literature as a potential treatment to prevent recurrent cramp [23–26]. Suggestions include using pillows [25, 27] or a foot board  to resist ankle plantarflexion, and sleeping prone with feet overhanging the end of the bed . None of these approaches have been evaluated in clinical trials and some might not be practical due to propensity to reposition during sleep . Use of a dorsiflexion night-splint would offer a more controlled and sustained dorsiflexion, yet this has not been evaluated or even suggested, to our knowledge.