More than 60 % of women experience hot-flashes during postmenopausal and 20 % have serious symptoms. Use of combined estrogen/progesterone therapy reduces hot-flashes effectively. In 2001, results from the randomized controlled WHI-study (Womens Health Initiative) showed increased risk for breast cancer and hearth-disease among users of combined estrogen/progesterone therapy. This reduced the use of combined estrogen/progesterone therapy. Many women seek alternative treatment for hot-flashes. They are often told that physical activity can reduce intensity and frequency of hot-flashes. The evidence for this advice is sparse.

The primary hypothesis tested in the WHAT-study will be: Increased physical activity reduce frequency and intensity of hot-flushes among sedentary postmenopausal women with bothersome hot-flushes.

The WHAT-study is designed as a pragmatic randomized controlled clinical trial. To answer the primary hypothesis we will need approximately 500 participants. The logistic in a pragmatic trial of a complex intervention are complicated and we decided to first run a pilot study with 50 participants as a feasibility study. The pilot gives us opportunity to gain experience with possible problems like withdrawals and injuries.

The WHAT study is a pragmatic randomized controlled trial with two parallel arms. The intervention is a 16 weeks individually tailored training programme with one hour physical activity 2-3 times per week. Women randomized to the control group are asked to keep physical activity at the same level as before the study.

Healthy postmenopausal women from Tromso will be recruited to the study by newspaper advertisements and media coverage. Interested women are asked to make a call. A staff member will ask about menopausal status, level of physical activity and diseases. Potential participants will receive a diary by mail and will be asked to record frequency and severity of hot-flashes, and duration of sleep at night for a period of 14 days. Women who return this diary will be asked to sign the informed consent and complete a questionnaire, before the fitness test. Baseline fitness is an important measure in this study. We will measure VO2-max (maximal oxygen consumption) as a proxy for fitness. Whether you are randomized to intervention or control group can influence the fitness test. The participants will therefore be randomized after the fitness test.

Randomization: Unit of Applied Clinical Research, Institute of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway, will develop and administrate a web-based randomization system for the WHAT pilot study. The data base will be located at a server at the Medical Faculty at Norwegian University of Science and Technology in Trondheim. The following staff are authorized to randomize people in WHAT pilot study: Sameline Grimsgaard, Merethe Kumle, Sissel Andersen , Jorid Degerstrøm, Svein Arne Pettersen

In this pilot 50 women will be randomized either to intervention group (25 women) or control group (25 women).

Elements in the intervention: A physiotherapist will based on interview and physical examination make a plan for the 16 weeks physical activity programme for each participant. The program will start with Pilates classes and low intensity aerobic training (2-4 weeks). After this period, classes with moderate to high intensity aerobic training will be introduced. The aim of the intervention is to increase aerobic capacity with 10 % from baseline.

Both the intervention group and the control group will receive questionnaires at baseline, 4 weeks, 8 weeks, 12 weeks, 16 weeks, 6 months and 1 year after inclusion. We will run the test for physical fitness at baseline and 16 weeks.

Inclusion Criteria:

• Postmenopausal
• Natural or induced menopause
• > 12 months since last menstruation
• Severe hot flushes (frequency and intensity)
• Sedentary life style
• Motivated to increase level of physical activity

Exclusion Criteria:

• Current use of estrogen/progesterone treatment.
• Physical active (mean activity last six months
• More than 30 min per regularly exercise sessions at least once a week.
• Regular exercise sessions are defined as any planned physical activity (e.g., brisk walking, aerobics, jogging, bicycling, swimming, rowing, etc.) performed to increase physical fitness. BMI > 35 kg/m2, disease of illness that can hamper regular training.
• Current use of HT (systemic or plaster) during last 8 weeks