Physical exercise is a tool to prevent and treat some of the chronic diseases affecting the world’s population. A mechanism through which exercise could exert beneficial effects in the body is by provoking alterations to the gut microbiota, an environmental factor that in recent years has been associated with numerous chronic diseases. Here we show that physical exercise performed by women to at least the degree recommended by the World Health Organization can modify the composition of gut microbiota. Using high-throughput sequencing of the 16s rRNA gene, eleven genera were found to be significantly different between active and sedentary women. Quantitative PCR analysis revealed higher abundance of health-promoting bacterial species in active women, including Faecalibacterium prausnitzii, Roseburia hominis and Akkermansia muciniphila. Moreover, body fat percentage, muscular mass and physical activity significantly correlated with several bacterial populations. In summary, we provide the first demonstration of interdependence between some bacterial genera and sedentary behavior parameters, and show that not only does the dose and type of exercise influence the composition of gut microbiota, but also the breaking of sedentary behavior.

Regular physical exercise provides many health benefits, protecting against the development of chronic diseases, and improving quality of life. Some of the mechanisms by which exercise provides these effects are the promotion of an anti-inflammatory state, reinforcement of the neuromuscular function, and activation of the hypothalamic–pituitary–adrenal axis. Recently, it has been proposed that physical exercise is able to modify gut microbiota, and thus this could be another factor by which exercise promotes well-being, since gut microbiota appears to be closely related to health and disease. The purpose of this paper is to review the recent findings on gut microbiota modification by exercise, proposing several mechanisms by which physical exercise might cause changes in gut microbiota.

LUCÍA, A., J. HOYOS, M. PÉREZ, and J. L. CHICHARRO. Heart rate and performance parameters in elite cyclists: a longitudinal study. Med. Sci. Sports Exerc., Vol. 32, No. 10, pp. 1777–1782, 2000. Purpose This study was designed to evaluate the stability of target heart rate (HR) values corresponding to performance markers such as lactate threshold (LT) and the first and second ventilatory thresholds (VT₁, VT₂) in a group of 13 professional road cyclists (V̇O_2max ∼ 75.0 mL·kg⁻1·min⁻1) during the course of a complete sports season. Methods Each subject performed a progressive exercise test on a bicycle ergometer (ramp protocol with workload increases of 25 W·min⁻1) three times during the season corresponding to the “active” rest (fall: November), precompetition (winter: January), and competition periods (spring: May) to determine HR values at LT, VT₁, and VT₂. Results Despite a significant improvement in performance throughout the training season (i.e., increases in the power output eliciting LT, VT₁, or VT₂), target HR values were overall stable (HR at LT: 154 ± 3, 152 ± 3, and 154 ± 2 beats·min⁻1; HR at VT₁: 155 ± 3, 156 ± 3, and 159 ± 3 beats·min⁻1; and at VT₂: 178 ± 2, 173 ± 3, and 176 ± 2 beats·min ⁻¹ during rest, precompetition, and competition periods, respectively). Conclusion A single laboratory testing session at the beginning of the season might be sufficient to adequately prescribe training loads based on HR data in elite endurance athletes such as professional cyclists. This would simplify the testing schedule generally used for this type of athlete.

Despite their young age, limited training history, and lack of running tradition compared with other East African endurance athletes (e.g., Kenyans and Ethiopians), male endurance runners from Eritrea have recently attained important running successes. The purposes of our study were (i) to document the main physical and physiological characteristics of elite black Eritrean distance runners (n = 7; age: 22 ± 3 years) and (ii) to compare them with those of their elite white Spanish counterparts. For this second purpose we selected a control group of elite Spanish runners (n = 9; 24 ± 2 years), owing to the traditionally high success of Spanish athletes in long-distance running compared with other white runners, especially in cross-country competitions. The subjects’ main anthropometric characteristics were determined, together with their maximum oxygen uptake (VO_{2 max}) and VO₂(mL·kg^–1·min^–1), blood lactate, and ammonia concentrations while running at 17, 19, or 21 km·h^–1. The body mass index (18.9 ± 1.5 kg·m^–2) and maximal calf circumference (30.9 ± 1.5 cm) was lower in Eritreans than in Spaniards (20.5 ± 1.7 kg·m^–2and 33.9 ± 2.0 cm, respectively) (p < 0.05 and p < 0.01, respectively) and their lower leg (shank) length was longer (44.1 ± 3.0 cm vs. 40.6 ± 2.7 cm, respectively) (p < 0.05). VO_{2 max}did not differ significantly between Eritreans and Spaniards (73.8 ± 5.6 mL·kg^–1·min^–1vs. 77.8 ± 5.7 mL·kg^–1·min^–1, respectively), whereas the VO₂cost of running was lower (p < 0.01) in the former (e.g., 65.9 ± 6.8 mL·kg^–1·min^–1vs. 74.8 ± 5.0 mL·kg^–1·min^–1when running at 21 km·h^–1). Our data suggest that the excellent running economy of Eritreans is associated, at least partly, with anthropometric variables. Comparison of their submaximal running cost with other published data suggests that superior running economy, rather than enhanced aerobic capacity, may be the common denominator in the success of black endurance runners of East African origin.