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Effects of Short-Term Phosphate Loading on Aerobic Capacity under Acute Hypoxia in Cyclists: A Randomized, Placebo-Controlled, Crossover Study.
Płoszczyca, K, Chalimoniuk, M, Przybylska, I, Czuba, M
Nutrients. 2022;(2)
Abstract
The aim of this study was to evaluate the effects of sodium phosphate (SP) supplementation on aerobic capacity in hypoxia. Twenty-four trained male cyclists received SP (50 mg·kg-1 of FFM/day) or placebo for six days in a randomized, crossover study, with a three-week washout period between supplementation phases. Before and after each supplementation phase, the subjects performed an incremental exercise test to exhaustion in hypoxia (FiO2 = 16%). Additionally, the levels of 2,3-diphosphoglycerate (2,3-DPG), hypoxia-inducible factor 1 alpha (HIF-1α), inorganic phosphate (Pi), calcium (Ca), parathyroid hormone (PTH) and acid-base balance were determined. The results showed that phosphate loading significantly increased the Pi level by 9.0%, whereas 2,3-DPG levels, hemoglobin oxygen affinity, buffering capacity and myocardial efficiency remained unchanged. The aerobic capacity in hypoxia was not improved following SP. Additionally, our data revealed high inter-individual variability in response to SP. Therefore, the participants were grouped as Responders and Non-Responders. In the Responders, a significant increase in aerobic performance in the range of 3-5% was observed. In conclusion, SP supplementation is not an ergogenic aid for aerobic capacity in hypoxia. However, in certain individuals, some benefits can be expected, but mainly in athletes with less training-induced central and/or peripheral adaptation.
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Distribution of concurrent training sessions does not impact endurance adaptation.
Kilen, A, Bay, J, Bejder, J, Breenfeldt Andersen, A, Bonne, T, Larsen, P, Carlsen, A, Egelund, J, Nybo, L, Vidiendal Olsen, N, et al
Journal of science and medicine in sport. 2021;(3):291-296
Abstract
OBJECTIVES Optimized concurrent training regimes are warranted in physical training of military-, law enforcement- and rescue-personnel. This study investigated if four 15-min endurance training sessions weekly improve aerobic capacity and performance more than one 60-min endurance session weekly during the initial phase of a Basic Military Training program. DESIGN A randomized training intervention study with functional and physiological tests before and after the intervention. METHODS Military conscripts (n=290) were randomly allocated to three groups completing 9 weeks training. Weekly training consisted of four endurance and four strength training sessions lasting 15min each ('Micro-training': MIC); one strength and one endurance session lasting 60min each ('Classical-training': CLA) or two 60min sessions of standard military training ('Control-training': CON). RESULTS Both 12-min (∼7-10%) and shuttle run performance (∼35-42%) improved (P≤0.001) similarly in all groups. Likewise, functional 2-min maximal repetition exercise capacity increased (P≤0.05) similarly in all groups (Lunges ∼17-24 %; PushUp ∼10-20%; AbdominalFlexions∼21-23%). Peak oxygen uptake changes depended on group (P≤0.05) with increases (P≤0.01) in MIC (7±7%, n=23) and CON (12±18%, n=17) and no changes in CLA. Maximal m. vastus lateralis citrate synthase activity decreased 14±26% (P≤0.001, n=18) in CLA. Likewise, maximal m. vastus lateralis 3-hydroxyacyl-CoA dehydrogenase activity decreased 8±17% in MIC (n=28) and 14±24% in CLA (n=18). CONCLUSIONS Four 15-min endurance training sessions weekly improves running performance and strength-endurance similarly to one 60min session. Peak oxygen uptake only increases with more than one endurance session weekly and leg muscle oxidative capacity appears reduced after basic military training.
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Exercise prescription improves exercise tolerance in young children with CHD: a randomised clinical trial.
Callaghan, S, Morrison, ML, McKeown, PP, Tennyson, C, Sands, AJ, McCrossan, B, Grant, B, Craig, BG, Casey, FA
Open heart. 2021;(1)
Abstract
OBJECTIVE The main objective of this study was to ascertain if a structured intervention programme can improve the biophysical health of young children with congenital heart disease (CHD). The primary end point was an increase in measureable physical activity levels following the intervention. METHODS Patients aged 5-10 years with CHD were identified and invited to participate. Participants completed a baseline biophysical assessment, including a formal exercise stress test and daily activity monitoring using an accelerometer. Following randomisation, the intervention group attended a 1 day education session and received an individual written exercise plan to be continued over the 4-month intervention period. The control group continued with their usual level of care. After 4 months, all participants were reassessed in the same manner as at baseline. RESULTS One hundred and sixty-three participants (mean age 8.4 years) were recruited, 100 of whom were male (61.3%). At baseline, the majority of the children were active with good exercise tolerance. The cyanotic palliated subgroup participants, however, were found to have lower levels of daily activity and significantly limited peak exercise performance compared with the other subgroups. One hundred and fifty-two participants (93.2%) attended for reassessment. Following the intervention, there was a significant improvement in peak exercise capacity in the intervention group. There was also a trend towards increased daily activity levels. CONCLUSION Overall physical activity levels are well preserved in the majority of young children with CHD. A structured intervention programme significantly increased peak exercise capacity and improved attitudes towards positive lifestyle changes.
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Association between vitamin D deficiency and exercise capacity in patients with CKD, a cross-sectional analysis.
Watson, EL, Wilkinson, TJ, O'Sullivan, TF, Baker, LA, Gould, DW, Xenophontos, S, Graham-Brown, M, Major, R, Jenkinson, C, Hewison, M, et al
The Journal of steroid biochemistry and molecular biology. 2021;:105861
Abstract
BACKGROUND Evidence is growing for a role of vitamin D in regulating skeletal muscle mass, strength and functional capacity. Given the role the kidneys play in activating total vitamin D, and the high prevalence of vitamin D deficiency in Chronic Kidney Disease (CKD), it is possible that deficiency contributes to the low levels of physical function and muscle mass in these patients. METHODS This is a secondary cross-sectional analysis of previously published interventional study, with in vitro follow up work. 34 CKD patients at stages G3b-5 (eGFR 25.5 ± 8.3 mL/min/1.73m2; age 61 ± 12 years) were recruited, with a sub-group (n = 20) also donating a muscle biopsy. Vitamin D and associated metabolites were analysed in plasma by liquid chromatography tandem-mass spectroscopy and correlated to a range of physiological tests of muscle size, function, exercise capacity and body composition. The effects of 1α,25(OH)2D3 supplementation on myogenesis and myotube size was investigated in primary skeletal muscle cells from vitamin D deficient donors. RESULTS In vivo, there was no association between total or active vitamin D and muscle size or strength, but a significant correlation with V̇O2Peak was seen with total vitamin D (25OHD). in vitro, 1α,25(OH)2D3 supplementation reduced IL-6 mRNA expression, but had no effect upon proliferation, differentiation or myotube diameter. CONCLUSIONS Vitamin D deficiency is not a prominent factor driving the loss of muscle mass in CKD, but may play a role in reduced exercise capacity.
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Cocoa-flavanols enhance moderate-intensity pulmonary [Formula: see text] kinetics but not exercise tolerance in sedentary middle-aged adults.
Sadler, DG, Draijer, R, Stewart, CE, Jones, H, Marwood, S, Thijssen, DHJ
European journal of applied physiology. 2021;(8):2285-2294
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Abstract
INTRODUCTION Cocoa flavanols (CF) may exert health benefits through their potent vasodilatory effects, which are perpetuated by elevations in nitric oxide (NO) bioavailability. These vasodilatory effects may contribute to improved delivery of blood and oxygen (O2) to exercising muscle. PURPOSE Therefore, the objective of this study was to examine how CF supplementation impacts pulmonary O2 uptake ([Formula: see text]) kinetics and exercise tolerance in sedentary middle-aged adults. METHODS We employed a double-blind cross-over, placebo-controlled design whereby 17 participants (11 male, 6 female; mean ± SD, 45 ± 6 years) randomly received either 7 days of daily CF (400 mg) or placebo (PL) supplementation. On day 7, participants completed a series of 'step' moderate- and severe-intensity exercise tests for the determination of [Formula: see text] kinetics. RESULTS During moderate-intensity exercise, the time constant of the phase II [Formula: see text] kinetics ([Formula: see text]) was decreased by 15% in CF as compared to PL (mean ± SD; PL 40 ± 12 s vs. CF 34 ± 9 s, P = 0.019), with no differences in the amplitude of [Formula: see text] (A[Formula: see text]; PL 0.77 ± 0.32 l min-1 vs. CF 0.79 ± 0.34 l min-1, P = 0.263). However, during severe-intensity exercise, [Formula: see text], the amplitude of the slow component ([Formula: see text]) and exercise tolerance (PL 435 ± 58 s vs. CF 424 ± 47 s, P = 0.480) were unchanged between conditions. CONCLUSION Our data show that acute CF supplementation enhanced [Formula: see text] kinetics during moderate-, but not severe-intensity exercise in middle-aged participants. These novel effects of CFs, in this demographic, may contribute to improved tolerance of moderate-activity physical activities, which appear commonly present in daily life. TRIAL REGISTRATION Registered under ClinicalTrials.gov Identifier no. NCT04370353, 30/04/20 retrospectively registered.
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Individual Participant Data Meta-Analysis Provides No Evidence of Intervention Response Variation in Individuals Supplementing With Beta-Alanine.
Esteves, GP, Swinton, P, Sale, C, James, RM, Artioli, GG, Roschel, H, Gualano, B, Saunders, B, Dolan, E
International journal of sport nutrition and exercise metabolism. 2021;(4):305-313
Abstract
Currently, little is known about the extent of interindividual variability in response to beta-alanine (BA) supplementation, nor what proportion of said variability can be attributed to external factors or to the intervention itself (intervention response). To investigate this, individual participant data on the effect of BA supplementation on a high-intensity cycling capacity test (CCT110%) were meta-analyzed. Changes in time to exhaustion (TTE) and muscle carnosine were the primary and secondary outcomes. Multilevel distributional Bayesian models were used to estimate the mean and SD of BA and placebo group change scores. The relative sizes of group SDs were used to infer whether observed variation in change scores were due to intervention or non-intervention-related effects. Six eligible studies were identified, and individual data were obtained from four of these. Analyses showed a group effect of BA supplementation on TTE (7.7, 95% credible interval [CrI] [1.3, 14.3] s) and muscle carnosine (18.1, 95% CrI [14.5, 21.9] mmol/kg DM). A large intervention response variation was identified for muscle carnosine (σIR = 5.8, 95% CrI [4.2, 7.4] mmol/kg DM) while equivalent change score SDs were shown for TTE in both the placebo (16.1, 95% CrI [13.0, 21.3] s) and BA (15.9, 95% CrI [13.0, 20.0] s) conditions, with the probability that SD was greater in placebo being 0.64. In conclusion, the similarity in observed change score SDs between groups for TTE indicates the source of variation is common to both groups, and therefore unrelated to the supplement itself, likely originating instead from external factors such as nutritional intake, sleep patterns, or training status.
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The effect of dietary nitrate on exercise capacity in chronic kidney disease: a randomized controlled pilot study.
Ramick, MG, Kirkman, DL, Stock, JM, Muth, BJ, Farquhar, WB, Chirinos, JA, Doulias, PT, Ischiropoulos, H, Edwards, DG
Nitric oxide : biology and chemistry. 2021;:17-23
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BACKGROUND Chronic Kidney Disease (CKD) patients exhibit a reduced exercise capacity that impacts quality of life. Dietary nitrate supplementation has been shown to have favorable effects on exercise capacity in disease populations by reducing the oxygen cost of exercise. This study investigated whether dietary nitrates would acutely improve exercise capacity in CKD patients. METHODS AND RESULTS In this randomized, double-blinded crossover study, 12 Stage 3-4 CKD patients (Mean ± SEM: Age, 60 ± 5yrs; eGFR, 50.3 ± 4.6 ml/min/1.73 m2) received an acute dose of 12.6 mmol of dietary nitrate in the form of concentrated beetroot juice (BRJ) and a nitrate depleted placebo (PLA). Skeletal muscle mitochondrial oxidative function was assessed using near-infrared spectroscopy. Cardiopulmonary exercise testing was performed on a cycle ergometer, with intensity increased by 25 W every 3 min until volitional fatigue. Plasma nitric oxide (NO) metabolites (NOm; nitrate, nitrite, low molecular weight S-nitrosothiols, and metal bound NO) were determined by gas-phase chemiluminescence. Plasma NOm values were significantly increased following BRJ (BRJ vs. PLA: 1074.4 ± 120.4 μM vs. 28.4 ± 6.6 μM, p < 0.001). Total work performed (44.4 ± 10.6 vs 39.6 ± 9.9 kJ, p = 0.03) and total exercise time (674 ± 85 vs 627 ± 86s, p = 0.04) were significantly greater following BRJ. Oxygen consumption at the ventilatory threshold was also improved by BRJ (0.90 ± 0.08 vs. 0.74 ± 0.06 L/min, p = 0.04). These changes occurred in the absence of improved skeletal muscle mitochondrial oxidative capacity (p = 0.52) and VO2peak (p = 0.35). CONCLUSIONS Our findings demonstrate that inorganic nitrate can acutely improve exercise capacity in CKD patients. The effects of chronic nitrate supplementation on CKD related exercise intolerance should be investigated in future studies.
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Short-Term Creatine Loading Improves Total Work and Repetitions to Failure but Not Load-Velocity Characteristics in Strength-Trained Men.
Feuerbacher, JF, von Schöning, V, Melcher, J, Notbohm, HL, Freitag, N, Schumann, M
Nutrients. 2021;(3)
Abstract
This study assessed the effects of a 7-day creatine (CRE) supplementation on the load-velocity profile and repeated sub-maximal bouts in the deep squat using mean propulsive velocity (MPV) and mean propulsive power (MPP). Eleven strength-trained men (31.4 ± 5.4 years) supplemented 0.3 g·kg-1·d-1 CRE or a placebo (PLA, maltodextrin) for seven days in a randomized order, separated by a 30-day washout period. Prior to and after the supplementation, the subjects performed an incremental maximal strength (1RM) test, as well as 3 × 10 repetitions and a repetitions-to-failure test (RFT), all at 70% 1RM. Maximal strength remained statistically unaltered in CRE (p = 0.107) and PLA (p = 0.568). No statistical main effect for time (p = 0.780) or interaction (p = 0.737) was observed for the load-velocity profile. The number of repetitions during RFT remained statistically unaltered in both conditions (CRE: +16.8 ± 32.8%, p = 0.112; PLA: +8.2 ± 47.2%, p = 0.370), but the effect size was larger in creatine compared to placebo (g = 0.51 vs. g = 0.01). The total work during RFT increased following creatine supplementation (+23.1 ± 35.9%, p = 0.043, g = 0.70) but remained statistically unaltered in the placebo condition (+15.0 ± 60.8%, p = 0.801, g = 0.08; between conditions: p = 0.410, g = 0.25). We showed that CRE loading over seven days did not affect load-velocity characteristics but may have increased total work and power output during submaximal deep squat protocols, as was indicated by moderate effect sizes.
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Nicotinamide mononucleotide supplementation enhances aerobic capacity in amateur runners: a randomized, double-blind study.
Liao, B, Zhao, Y, Wang, D, Zhang, X, Hao, X, Hu, M
Journal of the International Society of Sports Nutrition. 2021;(1):54
Abstract
BACKGROUND Recent studies in rodents indicate that a combination of exercise training and supplementation with nicotinamide adenine dinucleotide (NAD+) precursors has synergistic effects. However, there are currently no human clinical trials analyzing this. OBJECTIVE This study investigates the effects of a combination of exercise training and supplementation with nicotinamide mononucleotide (NMN), the immediate precursor of NAD+, on cardiovascular fitness in healthy amateur runners. METHODS A six-week randomized, double-blind, placebo-controlled, four-arm clinical trial including 48 young and middle-aged recreationally trained runners of the Guangzhou Pearl River running team was conducted. The participants were randomized into four groups: the low dosage group (300 mg/day NMN), the medium dosage group (600 mg/day NMN), the high dosage group (1200 mg/day NMN), and the control group (placebo). Each group consisted of ten male participants and two female participants. Each training session was 40-60 min, and the runners trained 5-6 times each week. Cardiopulmonary exercise testing was performed at baseline and after the intervention, at 6 weeks, to assess the aerobic capacity of the runners. RESULTS Analysis of covariance of the change from baseline over the 6 week treatment showed that the oxygen uptake (VO2), percentages of maximum oxygen uptake (VO2max), power at first ventilatory threshold, and power at second ventilatory threshold increased to a higher degree in the medium and high dosage groups compared with the control group. However, there was no difference in VO2max, O2-pulse, VO2 related to work rate, and peak power after the 6 week treatment from baseline in any of these groups. CONCLUSION NMN increases the aerobic capacity of humans during exercise training, and the improvement is likely the result of enhanced O2 utilization of the skeletal muscle. TRIAL REGISTRATION NUMBER ChiCTR2000035138 .
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Sacubitril/valsartan versus enalapril on exercise capacity in patients with heart failure with reduced ejection fraction: A randomized, double-blind, active-controlled study.
Dos Santos, MR, Alves, MNN, Jordão, CP, Pinto, CEN, Correa, KTS, de Souza, FR, da Fonseca, GWP, Tomaz Filho, J, Costa, M, Pereira, RMR, et al
American heart journal. 2021;:1-10
Abstract
UNLABELLED Sacubitril/valsartan reduces mortality in patients with heart failure with reduced ejection fraction (HFrEF) when compared with enalapril. However, it is unknown the effect of both treatments on exercise capacity. We compared sacubitril/valsartan versus enalapril in patients with HFrEF based on peak oxygen consumption (VO2) and 6-minute walk test (6-MWT). METHODS We included 52 participants with HFrEF with a left ventricular ejection fraction <40% to receive either sacubitril/valsartan (target dose of 400 mg daily) or enalapril (target dose of 40 mg daily). Peak VO2 was measured by using cardiopulmonary exercise testing. Six-minute walk test was also performed. RESULTS At 12 weeks, the sacubitril/valsartan (mean dose 382.6 ± 57.6 mg daily) group had increased peak VO2 of 13.1% (19.35 ± 0.99 to 21.89 ± 1.04 mL/kg/min) and enalapril (mean dose 34.4 ± 9.2 mg daily) 5.6% (18.58 ± 1.19 to 19.62 ± 1.25 mL/kg/min). However, no difference was found between groups (P = .332 interaction). At 24 weeks, peak VO2 increased 13.5% (19.35 ± 0.99 to 21.96 ± 0.98 mL/kg/min) and 12.0% (18.58 ± 1.19 to 20.82 ± 1.18 mL/kg/min) in sacubitril/valsartan (mean dose 400 ± 0 mg daily) and enalapril (mean dose 32.7 ± 11.0 mg daily), respectively. However, no differences were found between groups (P= .332 interaction). At 12 weeks, 6-MWT increased in both groups (sacubitril/valsartan: 459 ± 18 to 488 ± 17 meters [6.3%] and enalapril: 443 ± 22 to 477 ± 21 meters [7.7%]). At 24 weeks, sacubitril/valsartan increased 18.3% from baseline (543 ± 26 meters) and enalapril decreased slightly to 6.8% (473 ± 31 meters), but no differences existed between groups (P= .257 interaction). CONCLUSIONS Compared to enalapril, sacubitril/valsartan did not substantially improve peak VO2 or 6-MWT after 12 or 24 weeks in participants with HFrEF. (NEPRIExTol-HF Trial, ClinicalTrials.gov number, NCT03190304).