Leg cramps are painful sensations of tightening in the muscles of the legs, that are often associated with secondary insomnia. They are common especially at an older age. There is no evidence that any method of prevention of nocturnal leg cramps would be both safe and effective. There are no previous trials concerning cramp prevention by using compression stockings. The objective of this study is to assess in a prospective randomised controlled trial whether leg cramps can be prevented by daily use of knee-length compression stockings or magnesium supplements.

Leg cramps are painful sensations of tightening in the muscles of the legs that commonly appear during the night and are often associated with secondary insomnia. They are common especially in older age. There is no evidence that any method of prevention of nocturnal leg cramps is both safe and effective. There are no previous trials concerning cramp prevention by using compression stockings. The objective of this study is to assess in a prospective randomised controlled trial whether leg cramps can be prevented by the daily use of knee-length compression stockings or magnesium supplements.

Methods The study will be set in Finland, and 50-84-year-old volunteers will be recruited through Google Ads, the Finnish Health Library and Finnish primary health care centres. The participants must have a minimum of two episodes of leg cramps per week for the past four weeks to be included in the study. The participants (n = 225) will be allocated to three equal groups: the compression stocking arm, the magnesium supplement arm and the placebo arm. The participants will go through four weeks of follow-up without intervention, and then another four weeks of follow-up with the assigned intervention. The material for the study will be collected through electronic questionnaires.

Discussion This protocol describes a study that compares compression stockings, magnesium supplements and placebo for the prevention of leg cramps. The results of this study can significantly improve knowledge on the methods of preventing leg cramps.

Inclusion Criteria:

• Minimum of two leg cramps per week in the past four weeks.
• Age from 50 to 84 years.

Exclusion Criteria:

• Peripheral artery disease (confirmed or suspected).
• Peripheral artery bypass surgery.
• Grave peripheral neuropathy or any sensory disorder.
• Allergy to the material of the compression stockings.
• Grave renal failure (GFR under 30 ml/min).
• The use of a magnesium carbonate product (e.g. Rennie® or Berocca®).
• Cardiac failure with pulmonary oedema or massive lower limb swelling.
• Lower limb soft tissue problems, including skin transplant, thinned skin, varicose ulcer, necrosis and any infection.
• Lower limb deformity or atypical shape or size that could prevent the usage of compression stockings.
• Continuous usage of compression stockings for any other reason than leg cramps.

The full protocol will be available in open access format. The datasets generated and analysed during this trial will be available from the corresponding author on reasonable request.

The participants assigned to the two tablet groups will be blinded to the intervention. The magnesium and placebo tablets that are used in the trial will be identical in terms of packaging and appearance. The compression stocking group cannot be blinded, but the participants will not know their allotted intervention until they have received it by mail delivery. The statisticians will be blinded to the group allocation by using codes to label the three groups and will randomly assign outcome assessors to the follow-up. The allocation sequence will be concealed until the end of the study. The allocation code will be stored in a separate file.