Limited effects of dietary nitrate supplementation with resistance training on skeletal muscle and vascular outcomes in middle-aged and older adults.

Muscle nitrate/nitrite (NOx) values did not significantly change in either group following 12 weeks of intervention.

• BRJ group showed a +15.4% increase in muscle NOx (P = 0.073), which did not reach statistical significance.
• PLA group showed a +7.8% increase in muscle NOx (P = 0.514), also non-significant.
• No significant group × time interaction was observed for muscle NOx values.
• BRJ provided 140 mL daily containing 800 mg NO3-; placebo was NO3--depleted BRJ.

Both groups significantly improved measures related to muscle hypertrophy following 12 weeks of resistance training.

• Improvements in whole body lean mass and mid-thigh muscle cross-sectional area were observed in both groups.
• No significant group × time interactions were found for whole body lean mass or mid-thigh muscle cross-sectional area.
• Participants were assessed via whole body dual-energy X-ray absorptiometry and right mid-thigh ultrasonography.
• Participants were apparently healthy, untrained men and women aged 56 ± 7 years with BMI 29.1 ± 5.3 kg/m2.

Both groups significantly improved strength outcomes, but BRJ supplementation did not provide additional benefits over placebo.

• Strength improvements were observed in both BRJ and PLA groups following 12 weeks of supervised full-body resistance training.
• No significant group × time interaction was observed for strength measures.
• Resistance training was performed twice per week for 12 weeks as a supervised full-body program.
• Sample consisted of 28 participants (n=14 BRJ with 7 men/7 women; n=14 PLA with 7 men/7 women).

Both groups significantly improved popliteal artery flow-mediated dilation (FMD), but no group × time interaction was observed.

• FMD was assessed in the right leg popliteal artery before and after the 12-week intervention.
• No significant group × time interactions were observed for popliteal artery FMD outcomes.
• Both BRJ and PLA groups showed significant improvements in FMD over the intervention period.
• These findings suggest resistance training alone was sufficient to improve vascular endothelial function.

No significant group × time interactions were observed for histological or molecular markers of skeletal muscle angiogenesis.

• Biopsy analyses included immunoblotting for proteins involved in angiogenesis and immunohistochemistry to quantify fiber type-specific capillaries and cross-sectional areas.
• A NOx fluorometric assay was also performed on biopsy samples.
• Biopsies were taken from the right mid-thigh vastus lateralis before and after the intervention.
• No significant differences between BRJ and PLA groups were detected for any histological or molecular angiogenesis markers.

The authors characterize the study as preliminary data on a limited number of participants, acknowledging sample size as a potential limitation.

• Total sample size was 28 participants completing the 12-week intervention.
• The abstract explicitly states 'these preliminary data on a limited number of participants indicate that BRJ supplementation does not enhance RT adaptations in middle-aged and older adults.'
• Participants were described as 'apparently healthy, untrained men and women' aged 56 ± 7 years.
• The study notes it is unknown whether chronic NO3- supplementation can enhance resistance training adaptations specifically in middle-aged and older individuals.