Can high intensity exercise reduce period pain? A pilot feasibility study.

BRIEF NAME: High intensity exercise - "F45" PROCEDURE: Participants will be asked to attend four F45 classes per week based on their own personal schedule. These classes will be provided free of charge as part of this study. Two of the four classes attended will have a cardiovascular focus and the other two a strength training focus. All classes will be the standard 45 minutes (as per F45 structured training protocols). For the purpose of this study, 'high intensity' has been defined according to the guide provided by F45, which is 75% of heart rate maximum (calculated by 206.3-[0.711 x age]). This is constantly measured by a heart rate monitor that is worn throughout the 45 minute class. Participants will attend general F45 classes that will also be attended by members of the public. These classes are not designed specifically for this trial, but instead for a general F45 population. Class sizes differ based on the number and difficulty of exercises, as well as the equipment required. Class sizes range from a maximum of 27-36 per class; however, class sizes may be smaller depending on attendance numbers. The exercises in each class vary, but the classes use a format of approximate 30-40 seconds of work and 10-20 seconds of rest for all exercises. Examples of exercises in the 'cardiovascular' classes include: burpees, skipping, and stationary cycling. Examples of exercises in the 'strength' classes include: dead lifts, dumb bell bench press, and pull ups. The classes are structured sessions which are designed by exercise scientists. The exercises in each class are projected onto television screens throughout the gym. Certified fitness instructors supervise participants to ensure fidelity to the set exercises. Adherence to the exercise program will be done in two ways: first, an attendance checklist will be taken by F45 and provided to the research team; and second, participants will be phoned weekly and asked to provide their attendance rate. Participants in the exercise group will perform the exercise intervention for 45 sessions over 12 weeks in total. A ‘ramp up’ process will be used, where women are asked to do two sessions for the first week, then three for the second week before moving to the 4/week for the remainder of the 10 weeks (total 45 sessions).