Acute salivary antimicrobial peptide secretion response to different exercise intensities and durations.

Antimicrobial peptides, key players of innate mucosal immunity in the oral cavity, exert antibacterial and bacteriolytic effects. This study aimed to clarify the effects of acute exercise at different intensities and durations on salivary antimicrobial peptide levels. In a randomized crossover trial, 14 young healthy untrained men performed intensity trials (cycling at 35%, 55%, and 75% of maximal oxygen uptake [VO2max] for 30 min) and duration trials (cycling at 55% VO2max for 30, 60, and 90 min). Saliva samples were collected at baseline and 0 and 60 min after exercise. In intensity trials, the change in salivary Lactoferrin levels from baseline to 0 min after 30-min exercise was greater at 75% VO2max exercise intensity compared to that at 35% VO2max. Furthermore, the change in salivary human beta defensin-2 (HBD-2) levels was greater at 75% VO2max compared to that at 35% and 55% VO2max. Salivary Lysozyme levels increased after exercise, independent of exercise intensity. However, salivary LL-37 levels did not change after exercise at any intensity. Additionally, in duration trials, the change in salivary levels of LL-37 and HBD-2 from baseline to 0 min after exercise at 55% VO2max was greater after 60 min and 90 min of exercise compared to that after 30 min of exercise. However, salivary Lactoferrin and Lysozyme levels increased after exercise, independent of exercise duration. Our findings suggest that secretory responses to acute exercise with exercise intensity and duration differ among salivary antimicrobial peptides.

Acute effects of static stretching exercise-induced decrease in arterial stiffness on maximal aerobic capacity.

BACKGROUND: We recently have reported that individual day-to-day arterial stiffness variations are associated with maximal aerobic capacity. However, the evidence of this phenomenon was not provided sufficiently. The present study aimed to examine whether a decrease in arterial stiffness through static stretching exercise could enhance maximal aerobic capacity. METHODS: Twelve healthy young men (age 22±2 years, mean and standard deviation) participated in this study and underwent two separate sessions in a randomized controlled crossover design: a single session of a whole-body static stretching exercise protocol that involved the trunk, upper limb, and lower limb (stretch condition), and sedentary control where they rested in the exercise room. Brachial-ankle pulse wave velocity (baPWV) was measured as an index of systemic arterial stiffness before, immediately after and at 30 min after both conditions. Maximal oxygen uptake (V̇O2max) was assessed using a graded power test on an electronically braked cycle ergometer after these measurements. RESULTS: As we expected, there was a significant decrease in the baPWV at 30 min after the stretch trial compared to baseline values (P=0.01). The baPWV in the stretch condition was lower than that of the control condition, while V̇O2max in the stretch condition was higher than that of the control condition (P=0.03). CONCLUSIONS: Based on these findings, it can be inferred that an acute reduction in arterial stiffness may contribute to change in maximal aerobic capacity.

Effect of resistance training and chicken meat on muscle strength and mass and the gut microbiome of older women: A randomized controlled trial.

This study investigated the effects of white meat, such as chicken, intake combined with resistance training on muscle mass and strength in the elderly women, and whether the underlying mechanism involves changes in the gut microbiota. Ninety-three volunteers (age 59-79 years) were randomly allocated to sedentary control with placebo (Sed + PL) or chicken meat (Sed + HP) and resistance training with placebo (RT + PL) or chicken meat (RT + HP). Resistance training sessions were performed 3 d/week for 12 weeks using leg extensions and curls. Boiled chicken meat (110 g, containing 22.5 g protein) was ingested 3 d/week for 12 weeks. Maximal muscle strength and whole-body lean mass increased significantly in the RT + PL group compared to the Sed + HP group, and the RT + HP group showed a significantly greater increase than the Sed + HP and RT + PL groups. Additionally, the gut microbiota composition did not change before or after the interventions in any of the four groups. Moreover, the individual comparison of gut bacteria using false discovery rate-based statistical analysis showed no alterations before or after the interventions in the four groups. Resistance training combined with chicken meat intake may effective have increased muscle mass and strength without drastically modifying the gut microbiota composition in elderly women.

Effects of different exercise intensities or durations on salivary IgA secretion.

PURPOSE: This study aimed to examine changes in salivary immunoglobulin A (s-IgA) secretion at different intensities or durations of acute exercise. METHODS: Twelve healthy untrained young males were included in randomized crossover trials in Experiment 1 (cycling exercise for 30 min at a work rate equivalent to 35%, 55%, and 75% maximal oxygen uptake [ V ˙ O2max]) and Experiment 2 (cycling exercise at 55% V ˙ O2max intensity for 30, 60, and 90 min). Saliva samples were collected at baseline, immediately after, and 60 min after each exercise. RESULTS: Experiment 1: The percentage change in the s-IgA secretion rate in the 75% V ˙ O2max trial was significantly lower than that in the 55% V ˙ O2max trial immediately after exercise (- 45.7%). The percentage change in the salivary concentration of cortisol, an s-IgA regulating factor, immediately after exercise significantly increased compared to that at baseline in the 75% V ˙ O2max trial (+ 107.6%). A significant negative correlation was observed between the percentage changes in saliva flow rate and salivary cortisol concentration (r = - 0.52, P < 0.01). Experiment 2: The percentage change in the s-IgA secretion rate in the 90-min trial was significantly lower than that in the 30-min trial immediately after exercise (-37.0%). However, the percentage change in salivary cortisol concentration remained the same. CONCLUSION: Our findings suggest that a reduction in s-IgA secretion is induced by exercise intensity of greater than or equal to 75% V ˙ O2max for 30 min or exercise duration of greater than or equal to 90 min at 55% V ˙ O2max in healthy untrained young men.