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Øyvind Sandbakk, Guro Strøm Solli and Hans-Christer Holmberg

/Efficiency Work economy/efficiency is an important factor in all endurance disciplines, and differences in this respect may influence performance considerably. 30 However, findings on sex differences in exercise efficiency are contradictory and influenced by numerous factors including body composition

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Jane C. Golden, Kathleen F. Janz, William R. Clarke and Larry T. Mahoney

This paper demonstrates the reliability, validity, and practical applications of a unique protocol developed to obtain both submaximal steady-state and peak exercise responses in the same test in children and adolescents. The study examined exercise efficiency, cardiovascular fitness, and cardiovascular responses in 237 children, ages 7 to 17, during exercise stress on a cycle ergometer. The graded exercise test was continuous, consisting of three steady-state submaximal stages followed by 30-sec ramp stages to obtain peak values. Intraclass correlation coefficients ranged from r=0.69 to r=0.99, with no significant mean difference for any test parameter. Mean peak heart rate, peak VO2, and 84% of the respiratory exchange ratio (RER) values equal to or greater than 1.1 were comparable to other reported values. The validity for the protocol is substantiated by the results showing normal linear exercise responses, nonsignificant mean difference between the last two 30-sec periods, normal mean peak heart rate and VO2 values, and high mean peak RER values. The protocol is practical, as demonstrated by an optimal test duration and the ability to obtain valid submaximal and peak exercise data in the same test in subjects of varying ages and body size.

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Matthew W. Hoon, Andrew M. Jones, Nathan A. Johnson, Jamie R. Blackwell, Elizabeth M. Broad, Bronwen Lundy, Anthony J. Rice and Louise M. Burke

Context:

Beetroot juice is a naturally rich source of inorganic nitrate (NO3 ), a compound hypothesized to enhance endurance performance by improving exercise efficiency.

Purpose:

To investigate the effect of different doses of beetroot juice on 2000-m ergometer-rowing performance in highly trained athletes.

Methods:

Ten highly trained male rowers volunteered to participate in a placebo-controlled, double-blinded crossover study. Two hours before undertaking a 2000-m rowing-ergometer test, subjects consumed beetroot juice containing 0 mmol (placebo), 4.2 mmol (SINGLE), or 8.4 mmol (DOUBLE) NO3 . Blood samples were taken before supplement ingestion and immediately before the rowing test for analysis of plasma [NO3 ] and [nitrite (NO2 )].

Results:

The SINGLE dose demonstrated a trivial effect on time to complete 2000 m compared with placebo (mean difference: 0.2 ± 2.5 s). A possibly beneficial effect was found with DOUBLE compared with SINGLE (mean difference –1.8 ± 2.1 s) and with placebo (–1.6 ± 1.6 s). Plasma [NO2 ] and [NO3 ] demonstrated a dose-response effect, with greater amounts of ingested nitrate leading to substantially higher concentrations (DOUBLE > SINGLE > placebo). There was a moderate but insignificant correlation (r = –.593, P = .055) between change in plasma [NO2 ] and performance time.

Conclusion:

Compared with nitratedepleted beetroot juice, a high (8.4 mmol NO3 ) but not moderate (4.2 mmol NO3 ) dose of NO3 in beetroot juice, consumed 2 h before exercise, may improve 2000-m rowing performance in highly trained athletes.

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Ozcan Esen, Ceri Nicholas, Mike Morris and Stephen J. Bailey

− supplementation can improve performance in highly trained athletes in events where a large muscle mass is recruited, and the upper body musculature is heavily engaged, such as kayaking 6 and rowing. 7 Compared to leg exercise, exercise efficiency, vascular conductance, and muscle O 2 extraction are compromised

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Thomas A. Haugen, Paul A. Solberg, Carl Foster, Ricardo Morán-Navarro, Felix Breitschädel and Will G. Hopkins

observed for endurance events. While neuromuscular power production is paramount for performance in typical anaerobic disciplines, 9 , 10 , 15 – 17 maximal oxygen consumption (VO 2max ), fractional VO 2max utilization, and exercise efficiency/economy are the most crucial physiological factors for typical

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David M. Shaw, Fabrice Merien, Andrea Braakhuis, Daniel Plews, Paul Laursen and Deborah K. Dulson

could also change following exercise or ketone supplement ingestion ( Frayn, 1983 ). Exercise efficiency did not change following BD ingestion. There was no sustained difference in oxygen utilization during the SS exercise, reciprocating studies using racemic βHB salts ( Evans et al., 2018 ; O

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James R. Broatch, David J. Bishop and Shona Halson

attributed to a decreased transmural pressure (as a result of external compression) and a subsequent myogenic vasodilatory response of the arteries and arterioles. Such hemodynamic alterations may also explain why some studies have reported improvements in metabolic recovery, 21 exercise efficiency, 22 , 23

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Neil Armstrong

exercise test (that produced an unambiguous V ˙ O 2 -work rate plateau definitive for V ˙ O 2 max ) with the rapidly incremented or ramp testing protocol. Although this is more suitable for clinical and experimental investigations and enables measurement of the gas exchange threshold, exercise efficiency

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Brandon R. Rigby, Ronald W. Davis, Marco A. Avalos, Nicholas A. Levine, Kevin A. Becker and David L. Nichols

influences the cardiovascular system by increasing HR and decreasing exercise efficiency during submaximal exercise ( Moore et al., 2016 ). Other variables that could contribute to an added cardiovascular stress include a deconditioned state; posture and gait abnormalities; bradykinesia (especially

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Trent Stellingwerff, Ingvill Måkestad Bovim and Jamie Whitfield

due to early studies demonstrating improvements in exercise efficiency (decreased O 2 cost at the same absolute workload) and a reduction the VO 2 slow component (which reflects a loss in muscle efficiency during high-intensity exercise), following both acute and chronic supplementation (reviewed in