Sarcopenia is one of the main issues associated with the process of aging. Characterized by muscle mass loss, it is triggered by several conditions, including sedentary habits and negative net protein balance. According to World Health Organization, it is expected a 38% increase in older individuals by 2025. Therefore, it is noteworthy to establish recommendations to prevent sarcopenia and several events and comorbidities associated with this health issue condition. In this review, we discuss the role of these factors, prevention strategies, and recommendations, with a focus on protein intake and exercise.

Nutrient consumption and body mass index (BMI) are closely related to the gut microbiota, and exercise effects on gut bacteria composition may be related to those variables. Thus, we aimed to investigate the effect of 10-week moderate aerobic exercise on the cardiorespiratory fitness and gut bacteria composition of non-obese men with the same nutritional profile. Twenty-four previously sedentary men (age 25.18 [SD 4.66] years, BMI 24.5 [SD 3.72] kg/m²) were randomly assigned into Control (CG; n = 12) or Exercise Groups (EG; n = 12). Body composition, cardiorespiratory parameters, blood markers, dietary habits and gut bacteria composition were evaluated. EG performed 150 min per week of supervised moderate (60–65% of VO₂peak) aerobic exercise, while CG maintained their daily routine. The V4 16S rRNA gene was sequenced and treated using QIIME software. Only EG demonstrated marked improvements in cardiorespiratory fitness (VO₂peak, p < 0.05; Effect Size = 0.971) without changes in other gut bacteria-affecting variables. Exercise did not promote clustering based on diversity indices (p > 0.05), although significant variations in an unclassified genus from Clostridiales order and in Streptococcus genus were observed (p < 0.05). Moreover, α-diversity was correlated with VO₂peak (Pearson’s R: 0.47; R² 0.23: 95%CI: 0.09 to 0.74, p = 0.02) and BMI (Pearson’s R: −0.50; R² 0.25: 95%CI: −0.75 to −0.12, p = 0.01). Roseburia, Sutterella and Odoribacter genera were associated with VO₂peak, while Desulfovibrio and Faecalibacterium genera were associated with body composition (p < 0.05). Our study indicates that aerobic exercise at moderate intensity improved VO₂peak and affected gut bacteria composition of non-obese men who maintained a balanced consumption of nutrients.

The use of probiotics in sports has been growing in the past years focusing on the attenuation of upper respiratory tract (URS) and gastrointestinal (GI) symptoms commonly present in endurance athletes. Researches shown different results and this may related to the probiotic strain, dose, period consumption or even the form of administration (capsules, sachets or fermented milk). These four factors directly influence in the probiotic's outcome and this question still remains unclear. Thus, the goal of this review is to clarify how these factors may influence the outcomes, approaching the major differences among studies, mechanisms by which the probiotic may contribute in sports field and applied conclusions. It was used 'probiotics', 'athletes', 'sports', 'exercise', 'athletes performance', 'immune response', 'intestinal symptoms' as keywords and its combinations and 20 original articles were selected for our purpose. All the articles were performed in healthy physically active people and/or athletes. Putting together, it was observed that athletes may benefit from probiotics consumption. It seems that multi strain ingested via sachet or fermented food and a larger period of consumption may shown better results at minimizing URS and GI symptoms. Also, specific species appears to have a role in exercise recovery. Therefore, the beneficial effect of probiotics in sports field is strictly dependent on the four factors abovementioned. The molecular mechanisms behind the probiotics effectiveness have not yet been elucidated and perhaps the biological assessments performed in the studies as well the few number of studies published did not answer the question yet.