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Nitrate Supplement Benefits Contractile Forces in Fatigued but Not Unfatigued Muscle
- Source :
- Medicine and science in sports and exercise. 50(10)
- Publication Year :
- 2018
-
Abstract
- Evidence suggests dietary nitrate supplementation enhances low-frequency (≤20 Hz) involuntary, but not voluntary, forces in unfatigued human muscle. We investigated the hypotheses that nitrate supplementation would also attenuate low-frequency fatigue and the loss of explosive voluntary forces in fatigued conditions.In a counterbalanced double-blinded order, 17 male participants completed two experimental trials after 7 d of dietary supplementation with either nitrate-rich (NIT) or nitrate-depleted (PLA) beetroot juice. Each trial consisted of measuring isometric knee extension forces during a series of explosive maximal voluntary contractions (MVC) and involuntary tetanic contractions (at 10, 20 50, and 100 Hz) in unfatigued conditions, followed by a fatigue protocol of 60 MVC and a repeat of the tetanic contractions immediately after the 60 MVC.In unfatigued conditions, there was no effect of NIT on any of the measured dependent variables, including maximal voluntary force, explosive impulse, and tetanic peak forces or peak rate of force developments at any frequency. In contrast, the percentage decline in explosive voluntary impulse from the first to the last 6 MVC in the fatigue protocol was lower in NIT (51.1% ± 13.9%) than in PLA (57.3% ± 12.4%; P = 0.039; d = 0.51). Furthermore, low-frequency fatigue determined via the percentage decline in the 20/50-Hz ratio was attenuated in NIT for tetanic peak force (NIT: 12.3% ± 12.0% vs PLA: 17.0% ± 10.1%; P = 0.110; d = 0.46) and tetanic peak rate force development (NIT: 12.3% ± 10.4% vs PLA: 20.3% ± 9.5%; P = 0.011; d = 0.83).Nitrate supplementation reduced the decline in explosive voluntary forces during a fatiguing protocol and attenuated low-frequency fatigue, likely due to reduced disruption of excitation-contraction coupling. However, contrary to previous findings, nitrate supplementation had no effect on contractile performance in unfatigued conditions.
- Subjects :
- Adult
Male
medicine.medical_specialty
Physical Therapy, Sports Therapy and Rehabilitation
Electromyography
030204 cardiovascular system & hematology
03 medical and health sciences
chemistry.chemical_compound
Young Adult
0302 clinical medicine
Nitrate
Human muscle
Double-Blind Method
Internal medicine
Dietary Nitrate
medicine
Humans
Orthopedics and Sports Medicine
Muscle, Skeletal
Nitrites
Nitrates
Muscle fatigue
medicine.diagnostic_test
business.industry
Excitation–contraction coupling
Explosive strength
030229 sport sciences
Sports Nutritional Physiological Phenomena
Endocrinology
chemistry
Dietary Supplements
Muscle Fatigue
medicine.symptom
business
Muscle contraction
Muscle Contraction
Subjects
Details
- ISSN :
- 15300315
- Volume :
- 50
- Issue :
- 10
- Database :
- OpenAIRE
- Journal :
- Medicine and science in sports and exercise
- Accession number :
- edsair.doi.dedup.....bb9338782b83ff898290f337c372f3b1