None listed
Conditions
Brief summary
Females experience fluctuating steroid hormone profiles throughout their menstrual cycle. During the early follicular (EF) phase, characterised by the onset of bleeding, concentrations of both oestrogen and progesterone are low. Oestrogen increases, and then peaks in the late follicular (LF) phase just prior to ovulation before dropping and then increasing again during the mid-luteal (ML) phase (although not to the same concentrations as seen in the LF phase). Progesterone increases after ovulation, peaking during the ML phase and then decreasing prior to the next EF phase. There is some evidence that females tolerate gut ischemia (i.e. a lack of oxygen in the gut, often due to blood loss in circumstances such as trauma) better than males. It has been suggested that this is attributable to the protective effects of oestrogen. Interestingly, endurance exercise also causes reduced blood flow (and therefore oxygen) to the gut because blood is redistributed to the working muscles. After an hour of running at 70% of VO2 max blood flow has been shown to be reduced by 80% causing small intestinal injury similar to that induced by trauma. However, to date no study has looked at the menstrual cycle in humans in relation to changes in gut integrity in response to exercise. The aim of this study is to provide preliminary data on the potential sex dimorphism in susceptibility to intestinal damage during endurance exercise, and if this damage is menstrual cycle dependent. If differences are found, this may have implications for female athletes training and racing during different phases of their menstrual cycle.
Interventions
Intervention 1: Exercise. We will be exploring the effect of exercise (the intervention) on gut damage during the menstrual cycle.
There will be three groups of participants recruited:
1. Males
2. Females with a regular, natural menstrual cycle
3. Females with a regular cycle using a hormonal contraceptive
Participants will run on a treadmill in a climate controlled room (~21 deg c, 40% relative humidity) at the University of Tasmania Newnham Campus.
There will be 3 x 1 hour sessions for all p
Intervention 1: Exercise. We will be exploring the effect of exercise (the intervention) on gut damage during the menstrual cycle. There will be three groups of participants recruited: 1. Males 2. Females with a regular, natural menstrual cycle 3. Females with a regular cycle using a hormonal contraceptive Participants will run on a treadmill in a climate controlled room (~21 deg c, 40% relative humidity) at the University of Tasmania Newnham Campus. There will be 3 x 1 hour sessions for all participants. They will run at a continuous effort of 70% of VO2max. Sessions for males will be 1 x per week on the same day at the same time each week. Sessions for females will be in accordance with their menstrual cycle, but approximately on days 1-4 (early follicular), day 11-14 (late follicular) and day 21-25 (mid luteal). Each trial for females will be at the same time of day. Only one participant will be tested at a time. Intervention 2: Sugar solution. Participants will ingest a sugar solution that will be used to identify gut permeability during exercise (intervention 1). 5 g lactulose and 5 g L-rhamnose will be dissolved in 150 ml tap water and ingested by the participant 5 minutes prior to the start of each exercise trial. The interventions will be delivered by the research team, all of whom are university researchers and exercise professionals.
Sponsors
University of Tasmania
Study design
Allocation
Non-randomised trial
Intervention model
Single group
Primary purpose
Prevention
Eligibility
Sex/Gender
All
Age
18 Years to 50 Years
Healthy volunteers
Yes
Inclusion criteria
• Trained (recreational athletes), currently training a minimum of 5 hours a week (female and male) • Self-reported regular menstrual cycles with no history of dysfunction (females only) • BMI within healthy range (female and male) • Able to run on a treadmill for an hour (female and male) • Natural cycle: have not taken hormonal contraceptives for at least 6 months and self-reported menstrual cycle is regular (24-35 days) (females only) OR • hormonal contraceptive: : have consistently taken a hormonal contraceptive for at least 6 months (females only)
Exclusion criteria
Prior to data collection • Amenorrhea or irregular cycles • HC used to manage menstrual dysfunction • History of gastrointestinal disease/injury • BMI below 18 Post-collection of data • Anovulation • Hormone levels not meeting appropriate reference levels
Outcome results
None listed