Effect of dietary nitrate supplementation on swimming time-trial performance and neuromuscular function

Nitrate (NO3-) supplementation and its ergogenic effects has received considerable interest in the last two decades. Recent evidence has suggested that the potential effects of NO3- supplementation are more evident under hypoxic conditions and activities. The aims of this thesis were to investigate the ergogenic effect of NO3- supplementation on swimming time-trial performances in trained swimmers and to provide novel insight into its potential effects on motor unit activities during brief isometric muscle contractions, a sustained ischemic muscle contraction and recovery in recreationally active people. The specific objectives of this thesis were to (1) undertake a systematic review and meta-analysis of the randomised control trials (RCTs) on inorganic NO3- supplementation and quantify its effect on muscle contractility in healthy adults; (2) investigate the effects of NO3- supplementation on swimming time-trial performances in trained swimmers; and (3) investigate the effects of short-term NO3- supplementation on neuromuscular functions (e.g., motor unit [MU] potential [MUP] size, firing rates [MUFR] and stability of neuromuscular transmission [jiggle]), during brief isometric contractions and sustained ischemic contraction, and after brief recovery in healthy active adults. The participants underwent various supplementation regimens, invasive and non-invasive physiological measurements, and numerous exercise tests to assess the influence of NO3- supplementation on enhancing performance, attenuating fatigue and improving recovery. Chapter 3 showed that NO3- supplementation may have potential to enhance muscle contractility during a short-duration high-intensity dynamic exercise. Chapter 4 demonstrated that NO3- supplementation elevated plasma NO2- concentration and lowered BP but did not enhance short- (100-m) or middle-distance (200-m) swimming performance in moderately-trained swimmers. Chapter 5 illustrated that NO3- supplementation resulted in shorter MUP duration, but had no effect on MUP area, MUFR and near fibre (NF) jiggle, during brief isometric contractions and a sustained contraction with BFR. Likewise, Chapter 6 showed that NO3- supplementation provided shorter MUP duration but had no effect on other MU properties (MUP area, MUFR and II NF jiggle) after brief recoveries with and without BFR following a sustained ischemic contraction. Chapter 5 also reported lowered BP at rest and during muscle contraction in response to increased plasma NO2- concentration. In conclusion, the work presented in this thesis indicates that NO3- supplementation may have potential to enhance power output during short duration (< 10 s) dynamic exercise but has no ergogenic effect on swimming performance during short- and middle-distance activities in moderately-trained swimmers. NO3- supplementation may also influence the some of the properties of a MU population, such as lowering MUP duration during isometric submaximal muscle contractions. Lastly, NO3- supplementation may confer benefits in reducing blood pressure in healthy, active, young adults. Therefore, NO3- supplementation might be considered as an ergogenic aid for exercise where rapid, short, and explosive movements are performed while it also can be recommended as a means for improving cardiovascular health

One-Week L-Arginine Supplementation Had No Effect on 200m Freestyle Swimming Time Trial in Moderately-Trained Male Swimmers

Research on the effect of L-arginine supplementation on exercise performance is still inconsistent and its influence on single-bout swimming performance has not been investigated. Therefore, the aim of this study was to assess if one-week L-arginine supplementation would enhance 200-m freestyle swimming performance in trained/developmental (regularly training ∼3 times per week with a purpose to compete) male swimmers. In a randomized, cross-over, double-blind design, 8 trained/developmental male swimmers (age 25 ± 5 years; mean ± SD) completed 200-m freestyle swimming time-trial on 3 separate occasions: a control trial; and after 2 separate 7-d supplementation periods, with a daily dose of either 8 g/d of L-arginine or placebo trials. Blood lactate concentration was measured immediately post time-trial swimming. Completion time of the 200-m freestyle swimming time-trial did not differ significantly (F = 4.55; P = 0.060; ŋp2 = 0.394) between control (149.40 ± 9.88 s), L-arginine (146.02 ± 10.34 s) and placebo trials (147.58 ± 10.86 s). There was no statistically significant difference in post time-trial swimming blood lactate concentration between trials (control: 11.2 ± 2.7; L-arginine: 13.1 ± 1.8; Placebo: 12.2 ± 2.7, F = 3.52; P = 0.058; ŋp2 = 0.335). One-week of supplementation with 8 g/d of L-arginine, had no ergogenic effect on middle-distance (200-m), freestyle swimming performance in trained/developmental male swimmers

Acute Beetroot Juice Supplementation Enhances Intermittent Running Performance but Does Not Reduce Oxygen Cost of Exercise among Recreational Adults

Nitrate (NO3−) supplementation has been reported to enhance intermittent exercise performance; however, its impact on oxygen (O2) cost during intermittent running exercise is unclear. The aim of this study was to assess if acute NO3− supplementation would elicit performance benefits in recreationally active individuals during the Yo–Yo intermittent recovery level 1 (Yo-Yo IR1) test, with its potential benefit on O2 consumption (VO2), in a double-blind, randomized, crossover study, 12 recreational males consumed NO3−-rich (NIT; ~12.8 mmol), and NO3−-depleted (PLA; 0.04 mmol) concentrated beetroot juice 3 h before completing the Yo-Yo IR1 test. VO2 was measured at 160, 280 and 440 m (sub-maximal) and when the test was terminated (peak). Performance in the Yo–Yo IR1 was greater with NIT (990 ± 442.25 m) compared to PLA (870 ± 357.4 m, p = 0.007). The VO2 was not significantly different at 160 m (1.92 ± 0.99 vs. 2.1 ± 0.88 L·min−1), 280 m (2.62 ± 0.94 vs. 2.83 ± 0.94 L·min−1), 440 m (3.26 ± 1.04 vs. 3.46 ± 0.98 L·min−1) and peak (4.71 ± 1.01 vs. 4.92 ± 1.17 L·min−1) between NIT and PLA trials (all p > 0.05). The present study has indicated that acute supplementation of NO3− enhanced intermittent running performance but had no effect on VO2 during the Yo–Yo IR1 test in recreational young adults

Effects of a 12% carbohydrate beverage on tackling technique and running performance during rugby league activity: a randomised, placebo-controlled trial

The purpose of this study was to investigate the effects of a 12% carbohydrate (CHO) beverage on tackling technique and running performance during rugby league activity. Using a double-blind, placebo-controlled, randomised, crossover design, 15 academy rugby league players ingested a 250 ml bolus of a 12% CHO solution (30 g maltodextrin and 30 g sucrose in 500 ml) 15 minutes before two bouts of rugby activity. The rugby league match simulation for interchange players was used to standardise the movement patterns of activity and provide reliable outcome measures, whilst also reflecting the duration of a typical field-based conditioning session. Measures of tackling technique, external responses (e.g., fatigue index from sprint data) and rating of perceived exertion (RPE) were recorded throughout. Gut discomfort was measured before each bout. The interaction effect was largely compatible with the hypothesis for relative distance (P<0.001, η2 = 0.217) and fairly compatible for tackling technique (P = 0.068, η2 = 0.0640). The time effect for tackling technique, relative and high-intensity distance, sprint, and sprint to contact velocity, time at high metabolic power, PlayerLoad™, and RPE (all P<0.05; η2 = 0.131–0.701) was compatible with the hypothesis. Data for tackling technique, relative and high-intensity distance, sprint, and sprint to contact velocity, sprint, and sprint to contact fatigue index (all P<0.05; η2 = 0.189–0.612) was compatible with a supplement effect overall despite few differences in the pattern of change (interaction). Minimal gut discomfort was reported for the CHO (bout 1 = 27 ± 17; bout 2 = 23 ± 17 AU) and placebo (bout 1 = 23 ± 18 AU; bout 2 = 24 ± 13) trials. This study shows that a 12% CHO beverage before two bouts of standardised rugby activity is a practical and effective strategy for retaining tackling technique, increasing external responses, and reducing RPE without compromising gut comfort

High-Dose Nitrate Supplementation Attenuates the Increased Blood Pressure Responses to Isometric Blood Flow Restriction Exercise in Healthy Males

The effect of nitrate (NO3−) supplementation on blood pressure (BP) responses during large muscle mass isometric and ischaemic exercise in healthy young adults is unclear. The aim of the present study was to assess the effect of 5-day supplementation of NO3− on BP responses during a short isometric contraction and a sustained ischaemic contraction. In a randomised, double-blinded, crossover design, 14 healthy active young adults underwent BP measurements after 5 days of either NO3− (NIT) or placebo (PLA) supplementation. Beat-by-beat BP was measured at pre- and post-exercise rest, and during a short (20 s) isometric contraction at 25% maximal strength and throughout a sustained ischaemic contraction. Plasma nitrite (NO2−) concentration increased significantly after NO3− supplementation compared to placebo (475 ± 93 nmol·L−1 vs. 198 ± 46 nmol·L−1, p 0.05). Five days of NO3− supplementation elevated plasma NO2− concentration and reduced BP during a short isometric contraction and a sustained ischaemic contraction in healthy adults. These observations indicate that multiple-day nitrate supplementation can decrease BP at rest and attenuate the increased BP response during isometric exercise. These findings support that NO3− supplementation is an effective nutritional intervention in reducing SBP and MAP in healthy young males during submaximal exercise

The effects of IgM-enriched immunoglobulin preparations in patients with severe sepsis [ISRCTN28863830]

INTRODUCTION: In this prospective, randomized controlled study, we aimed to evaluate the effect of IgM-enriched immunoglobulin treatment on progression of organ failure and septic shock in patients with severe sepsis. MATERIALS AND METHODS: Forty-two patients with severe sepsis were enrolled in the study. Patients in the study group (n = 21) received an intravenous immunoglobulin preparation (Pentaglobin(®)) in addition to standard therapy. Pentaglobin(®) therapy was commenced on the day of diagnosis of severe sepsis: 5 ml/kg per day Pentaglobin(®) (38 g/l IgG, 6 g/l IgM, and 6 g/l IgA) was infused over 6 hours and repeated for 3 consecutive days. Patients in the control group (n = 18) received standard sepsis therapy, but no immunoglobulin administration. Blood samples for procalcitonin (PCT) measurements were taken daily for 8 days. Severity of critical illness and development of organ failure were assessed by obtaining daily acute physiological and chronic health evaluation (APACHE) II and sequential organ failure assessment (SOFA) scores. RESULTS AND DISCUSSION: Procalcitonin levels showed a statistically significant decrease in the Pentaglobin(®) group (P < 0.001); however, an improvement in SOFA scores could not be demonstrated. Procalcitonin levels and SOFA scores did not change significantly in the control group. Septic shock incidence (38% versus 57%) and 28-day mortality rate (23.8% versus 33.3%) were found to be similar between the Pentaglobin(®) and control groups. The evaluation of serial APACHE II scores did not demonstrate a difference between Pentaglobin(®) and control groups either. CONCLUSION: Present data could not demonstrate any beneficial effects of polyclonal immunoglobulin preparation Pentaglobin(®) on organ morbidity, septic shock incidence and mortality rate in patients with severe sepsis

Practical Nutrition Strategies to Support Basketball Performance during International Short-Term Tournaments: A Narrative Review

A short-term (e.g., 6 days) basketball tournament is a shorter version of international tournaments, and qualification in it enables participation in international tournaments such as the Olympics and World championships or preparation before major tournaments. Time for recovery between matches is shorter compared with major tournaments, resulting in an accentuated load on players, which can be repeated up to four times within the 6-day competition period. Therefore, nutritional strategies need to focus on faster and adequate recovery after each match as well as optimum fuelling and hydration before and during matches. Travelling can also create additional challenges when preparing and/or applying those nutritional strategies. There are some particular evidence-based sport foods and ergogenic aids that can improve intermittent activity and/or the execution of motor skills, which may facilitate basketball players’ recovery and performance. The present review provides practical nutritional strategies to support short-term basketball tournaments based on players’ physiological needs and current sport nutrition guidelines

Effect of nitrate supplementation on skeletal muscle motor unit activity during isometric blood flow restriction exercise

Background Nitrate (NO3-) supplementation has been reported to lower motor unit (MU) firing rate (MUFR) during dynamic resistance exercise, however its impact on MU activity during isometric and ischemic exercise is unknown. Purpose To assess the effect of NO3- supplementation on knee extensor MU activities during brief isometric contractions and a 3-min sustained contraction with blood flow restriction (BFR). Methods Sixteen healthy active young adults (six females) completed two trials in a randomized, double-blind, crossover design. Trials were preceded by 5 days of either NO3- (NIT) or placebo (PLA) supplementation. Intramuscular electromyography was used to determine the m.vastus lateralis MU potential (MUP) size, MUFR and near fibre (NF) jiggle (a measure of neuromuscular stability) during brief (20 s) isometric contractions at 25% maximal strength and throughout a 3 min sustained BFR isometric contraction. Results Plasma nitrite (NO2-) concentration was elevated after NIT compared to PLA (475±93 vs.198±46 nmol·L-1, p0.05), MUP duration was shorter with NIT compared to PLA during brief isometric contractions and the sustained ischemic contraction (p<0.01). Additionally, mean MUP duration, MUP area and NF jiggle increased, and MUFR decreased over the 3 min sustained BFR isometric contraction for both conditions (all p<0.05). Conclusion These findings provide insight into the effect of NO3- supplementation on MUP properties and reveal shorter MUP duration after short-term NO3- supplementation which may have potential positive implications for skeletal muscle contractile performance