This is a prospective, comparative, double-blind, randomized, monocentric study.

The objective of this project is to evaluate the effects on health of probiotic supplementation (PS) with or without physical activity (PA). Participants who meet the study criteria will be randomized into 4 groups: probiotic and physical activity group (A+), probiotic and non-physical activity group (A-), placebo and physical activity group (T+), placebo and non-physical activity group (T-).

The probiotics used are Lactibiane® Reference provided by Pileje Laboratory. The study population are healthy women (university students) who do not practice sports. A total of 120 participants will participate.

At inclusion, each participant will undergo a medical examination, collect microbiota and salivary samples and perform different tests (questionnaires, assessments of strength and endurance). Then, a follow up phase will last 6 weeks. Each participant will receive a pillbox containing capsules (probiotic or placebo in a double-blind manner). Participants which randomized in the PA groups (A+ and A-) will perform 2 physical activity sessions per week for 6 weeks. At the end of this follow up phase, tests conducting during inclusion will be performed again.

Rationale: Nowadays, the intestinal microbiota is recognized as a significant factor in the health of the host organism. It has an impact on the immune system, the hypothalamo-hypophyseal adrenal axis, the overall state of the individual such as body composition and muscle activity. The intestinal microbiota has also an impact on digestion and associated problems. However, its balance is fragile and can be easily disrupted by a diet rich in proteins or carbohydrates, medications, contraceptive use or lack of physical activity (PA).To restore this balance, subjects may modify their diet, take probiotic supplements (PS) or engage in physical activity. Currently, studies remain limited, particularly regarding effects of physical activity and/or probiotic have never been explored especially in women. The objective of this project is therefore to explore effects of PS and/or PA on the mental and physical health of the holobiont.

Method: Each participant will, during an initial visit, undergo a medical examination (ECG, anthropometric measurements) to ensure there are no contraindications to engaging in physical activity or taking probiotics. Then, we will conduct the first collections of intestinal microbiota and salivary cortisol, initial evaluations of anxiety, depression, and self-esteem (indicators of mental health with questionnaires), as well as assessments of strength and endurance (indicators of physical health), body composition, and nutritional parameters. Following this, participants will be assigned to experimental groups, and we will distribute pillboxes containing capsules (probiotic or placebo in a double-blind manner). Participants in the PA groups (A+ and A-) will perform two 45-minute physical activity sessions per week for 6 weeks, consisting of muscle strengthening and endurance exercises. Participants in the sedentary groups (T+ and T-) will be contacted by phone once a week to ensure proper protocol adherence. At the end of the 6 weeks, we will repeat the tests conducted during the initial visit.

Probiotics: The probiotics used are Lactibiane® Reference, composed of 4 probiotic strains (Bifidobacterium longum LA101, Lactobacillus helveticus LA102, Lactobacillus lactis LA103, Streptococcus thermophilus LA104) dosed at 10 billion per capsule provided by Pileje laboratory. Placebos are also provided by Pileje laboratory.

Statistics: Having no proven hypothesis on the effect of physical activity and/or probiotic supplementation on the population, we started with inclusion of 120 participants in total. This will allow to highlight a moderate effect size (0.25) for the primary endpoint, under the hypothesis of an alpha risk of 0.05, with a power of 80%. and representing 20% lost to follow-up.

Inclusion Criteria:

1. Being female
2. Age ≥ 18 years old
3. Have a BMI between 18.5 and 30 kg/m2
4. Be registered as a student at the University of Orléans
5. Be non-athletic
6. Have no contraindication to the practice of physical activity
7. All participants must sign informed consent before the start of the study

Exclusion Criteria:

1. Smokers >10 cigarettes per day
2. Having treatment for a pathology at the time of inclusion
3. Taking a probiotic supplement during the last month prior to inclusion
4. Practice physical activity regularly (150 minutes/week of moderate physical activity according to the WHO)
5. Participant under guardianship or curators
6. Pregnant or breastfeeding women
7. Menopausal women
8. Allergy to any excipient known to be present in the probiotic or placebo formulation

Open label for physical activity or no-physical activity (A versus T groups). Double-blind for placebo/probiotic supplementation (+ versus - groups)