Exercise Training Decreases Nitrite Concentration in the Heart and Locomotory Muscles of Rats Without Changing the Muscle Nitrate Content

Eight weeks of high-intensity interval training alters the tongue microbiome and impacts nitrate and nitrite levels in previously sedentary men

Nitric oxide (∗NO) is a key signalling molecule, produced enzymatically via ∗NO synthases (NOS) or following the stepwise reduction of nitrate to nitrite via oral bacteria. Exercise training upregulates NOS expression and improves systemic health, but its effect on oral health, and more particularly the oral microbiome, has not been investigated. We used an exercise training study design to investigate changes in the tongue dorsum microbiome, and in nitrate and nitrite levels in the saliva, plasma and muscle, before, during and after an exercise training period. Eleven untrained males (age 25 ± 5 years, mass 64.0 ± 11.2 kg, stature 171 ± 6 cm, V˙ O2peak 2.25 ± 0.42 l min-1) underwent 8-weeks of high-intensity interval training (HIIT), followed by 12-weeks of detraining. The tongue dorsum microbiome was examined using Pac-Bio long-read 16S rRNA sequencing. Nitrate and nitrite levels were quantified with high-performance liquid chromatography. Grouped nitrite-producing species did not change between any timepoints. However, HIIT led to changes in the microbiome composition, increasing the relative abundance of some, but not all, nitrite-producing species. These changes included a decrease in the relative abundance of nitrite-producing Rothia and a decrease in Neisseria, alongside changes in 6 other bacteria at the genus level (all p ≤ 0.05). At the species level, the abundance of 9 bacteria increased post-training (all p ≤ 0.05), 5 of which have nitrite-producing capacity, including Rothia mucilaginosa and Streptococcus salivarius. Post-detraining, 6 nitrite-producing species remained elevated relative to baseline. Nitrate increased in plasma (p = 0.03) following training. Nitrite increased in the saliva after training (p = 0.02) but decreased in plasma (p = 0.03) and muscle (p = 0.002). High-intensity exercise training increased the abundance of several nitrite-producing bacteria and altered nitrate and nitrite levels in saliva, plasma, and muscle. Post-detraining, several nitrite-producing bacteria remained elevated relative to baseline, but no significant differences were detected in nitrate or nitrite levels. Switching from a sedentary to an active lifestyle alters both the microbiome of the tongue and the bioavailability of nitrate and nitrite, with potential implications for oral and systemic health.

Physical activity reverses the aging induced decline in angiogenic potential in the fast locomotory muscles of mice

Fast locomotory muscles, which are responsible for generating the highest power outputs, are more vulnerable to aging than slow muscles. In this study, we aimed to evaluate the impact of middle age and voluntary physical activity on capillarization and angiogenic potential in fast locomotory muscles. Middle-aged (M-group) and young (Y-group) wild-type FVB female mice were randomly assigned to either the sedentary or trained group undergoing 8-week spontaneous wheel running (8-sWR). Capillary density (assessed via immunohistochemical capillary staining and Western immunoblotting) of the fast locomotory muscles in the M-group (15-months old) was not significantly different compared to the Y-group (4-months old). Nevertheless, the expression of key pro-angiogenic genes in the fast muscle of the M-group was lower than that in the fast muscle of Y-group. 8-sWR had no impact on muscle capillarization; however, it increased fast muscle Vegfa expression in both the M and Y groups. We concluded that although fast muscle capillarization is still preserved in middle age, nevertheless the angiogenic potential (at least at the level of gene expression) is significantly reduced at this stage of aging. Moderate-intensity voluntary physical activity had no effect on capillary density, but it increased the angiogenic potential of the fast muscle.

Effects of dietary inorganic nitrate on blood pressure during and post-exercise recovery: A systematic review and meta-analysis of randomized placebo-controlled trials

OBJECTIVES

A systematic review with meta-analysis was completed to study the effects of dietary inorganic nitrate (NO3-) oral ingestion from vegetables and salts on blood pressure responses during and following exercise.

BACKGROUND

NO3- is a hypotensive agent with the potential to reduce blood pressure peaks during exercise and amplify exercise-induced hypotensive effects. Several randomized and controlled trials have investigated the effects of NO3- on hemodynamic responses to physical exercise, however this still has yet to be studied systematically.

METHODS

The searches were conducted on EMBASE, Medline, and SPORTSDiscus databases. The study included masked randomized controlled trials (RCTs) with participants ≥18 years old. The NO3-intervention group received at least 50 mg NO3-/day with similar sources amid NO3- and placebo conditions. Included studies reported systolic blood pressure (SBP) or diastolic blood pressure (DBP) values during or following exercise performance.

RESULTS

1903 studies were identified, and twenty-six achieved the inclusion criteria. NO3- daily dosages ranged from 90 to 800 mg/day. Throughout exercise, SBP had smaller increases in the NO3- group (-2.81 mmHg (95%CI: -5.20 to -0.41), p=0.02. DBP demonstrated lower values in the NO3- group (-2.41 mmHg (95%CI: -4.02 to -0.79), p=0.003. In the post-exercise group, the NO3- group presented lower SBP values (-3.53 mmHg (95%CI: -5.65 to 1.41), p=0.001, while no changes were identified in DBP values between NO3- and placebo groups (p=0.31). Subgroup meta-analysis revealed that SBP baseline values, exercise type, duration of NO3- ingestion, and its dosages mediated blood pressure responses during and following exercise.

CONCLUSIONS

NO3- ingestion prior to exercise attenuated the increases in SBP and DBP during exercise, and increased the decline in SBP after exercise. These results are dependent on factors that moderate the blood pressure responses (e.g., health status, type of exercise, resting blood pressure values).