Menstrual Cycle Phase Based Training

The primary purpose of this study is to employ state-of-the-art methods to fill current knowledge gaps on the effects of the menstrual cycle on resistance exercise training adaptations. This work will reduce the sex gap present in exercise physiology, improving women's health information by yielding a deeper understanding of the effect of female physiology on exercise adaptations and subsequent health benefits.

Employing a unilateral training design, participant's will have their legs randomized to one of four groups: non-exercise control (CON), exercise control (EX), Follicular based training (FOL), Luteal based training (LUT)

Researchers will compare these conditions to see if there are greater benefits to prioritizing resistance training around phases of the menstrual cycle,

Participants will be required to track their menstrual cycle (MC) for a total of four MC's. MC tracking will be done via self-reported menstrual onset and ovulation strips. During the first tracking cycle participants will be asked to come in at three time points for blood draws to confirm hormone concentrations and familiarize them with the strength testing protocol. Following the tracking month participant legs will then be blocked randomized based on leg skeletal muscle mass and strength into one of four groups: non-exercise control (CON), exercise control (EX), follicular based training (FOL) and luteal based training (LUT). Participants will then be asked to come in \~2x per week (4-6x/menstrual cycle phase) for resistance training under direct supervision. Participants will be trained in unilateral leg extension and unilateral leg press. For legs randomized to the FOL and LUT group, training volume will be manipulated by changing the number of sets completed. The FOL group will train high volume (\~20+ sets per week) in their follicular phase and low volume (\~5 sets/week) in their luteal phase, the opposite will be true for the LUT group. Muscle biopsies will be taken both prior to and after training to assess changes in fiber cross-sectional area (CSA) and capillarization. Segmental body composition will be assessed both prior and post training using bioelectrical impedance analysis (BIA), dual x-ray absorptiometry (DXA), and vastus lateralis cross-sectional area and thickness. Muscle strength will also be assessed pre and post training using the isokinetic dynamometer, unilateral one-repetition maximum (1RM) leg extension and unilateral 1RM leg press.

Eligibility Criteria:
Inclusion Criteria:

* Women, between the ages of 18 - 30 years (inclusive)
* Have a body mass index (BMI) between 18-35 kg·m2 (inclusive)
* Be in general good health as assessed by a general health questionnaire
* Non-smoking
* Regular menstrual cycle (21-35 days, inclusive)
* Not using hormonal contraceptives
* Willing and able to provide informed consent

Exclusion Criteria:

* Use of tobacco or related products.
* Ineligible to participate in physical activity based on get active questionnaire (GAQ)
* Any concurrent medical, orthopedic, or psychiatric condition that, in the opinion of the Investigator, would compromise his/her ability to comply with the study requirements.
* Current illnesses which could interfere with the study (e.g. prolonged severe diarrhea, regurgitation, difficulty swallowing)
* Use of hormonal contraceptives
* Currently pregnant
* Training more than 3x/week for the past 6 months.
* Have any electronic medical or metal implants
* A history of neuromuscular disorders or muscle/bone wasting diseases
* The use of any medications known to affect protein metabolism (glucocorticoids, non-steroidal anti-inflammatory medication, or prescription strength acne medication, etc.)
* A (family) history of thrombosis
* The use of anticoagulant medications
* Excessive alcohol consumption (\>21 units/wk)
* History of bleeding diathesis, platelet or coagulation disorders, or antiplatelet/anticoagulation therapy