scholarly journals Can too many cooks spoil the broth? Coordination costs, fatigue, and performance in high‐intensity tasks

2021 ◽  
Author(s):  
Bastian Kordyaka ◽  
Mario Lackner ◽  
Hendrik Sonnabend
Keyword(s):  
High Intensity ◽  
Coordination Costs ◽  
And Performance

A Systematic Review of CrossFit® Workouts and Dietary and Supplementation Interventions to Guide Nutritional Strategies and Future Research in CrossFit®

2020 ◽  
pp. 1-19
Author(s):  
Ricardo Augusto Silva de Souza ◽  
André Guedes da Silva ◽  
Magda Ferreira de Souza ◽  
Liliana Kataryne Ferreira Souza ◽  
Hamilton Roschel ◽  
...  
Keyword(s):  
Systematic Review ◽  
Muscle Fatigue ◽  
High Intensity ◽  
Scientific Evidence ◽  
Metabolic Stress ◽  
Optimal Recovery ◽  
Future Research ◽  
Nutritional Recommendations ◽  
And Performance ◽  
Nutritional Strategies

CrossFit® is a high-intensity functional training method consisting of daily workouts called “workouts of the day.” No nutritional recommendations exist for CrossFit® that are supported by scientific evidence regarding the energetic demands of this type of activity or dietary and supplement interventions. This systematic review performed in accordance with PRISMA guidelines aimed to identify studies that determined (a) the physiological and metabolic demands of CrossFit® and (b) the effects of nutritional strategies on CrossFit® performance to guide nutritional recommendations for optimal recovery, adaptations, and performance for CrossFit® athletes and direct future research in this emerging area. Three databases were searched for studies that investigated physiological responses to CrossFit® and dietary or supplementation interventions on CrossFit® performance. Various physiological measures revealed the intense nature of all CrossFit® workouts of the day, reflected in substantial muscle fatigue and damage. Dietary and supplementation studies provided an unclear insight into effective strategies to improve performance and enhance adaptations and recovery due to methodological shortcomings across studies. This systematic review showed that CrossFit® is a high-intensity sport with fairly homogenous anaerobic and aerobic characteristics, resulting in substantial metabolic stress, leading to metabolite accumulation (e.g., lactate and hydrogen ions) and increased markers of muscle damage and muscle fatigue. Limited interventional data exist on dietary and supplementation strategies to optimize CrossFit® performance, and most are moderate to very low quality with some critical methodological limitations, precluding solid conclusions on their efficacy. High-quality work is needed to confirm the ideal dietary and supplemental strategies for optimal performance and recovery for CrossFit® athletes and is an exciting avenue for further research.

scholarly journals Supplements and Nutritional Interventions to Augment High-Intensity Interval Training Physiological and Performance Adaptations—A Narrative Review

Nutrients ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 390 ◽  
Author(s):  
Scott C. Forbes ◽  
Darren G. Candow ◽  
Abbie E. Smith-Ryan ◽  
Katie R. Hirsch ◽  
Michael D. Roberts ◽  
...  
Keyword(s):  
Sex Differences ◽  
Sodium Bicarbonate ◽  
High Intensity ◽  
Interval Training ◽  
Narrative Review ◽  
High Intensity Interval Training ◽  
Beta Alanine ◽  
And Performance ◽  
High Intensity Interval ◽  
Nutritional Strategies

High-intensity interval training (HIIT) involves short bursts of intense activity interspersed by periods of low-intensity exercise or rest. HIIT is a viable alternative to traditional continuous moderate-intensity endurance training to enhance maximal oxygen uptake and endurance performance. Combining nutritional strategies with HIIT may result in more favorable outcomes. The purpose of this narrative review is to highlight key dietary interventions that may augment adaptations to HIIT, including creatine monohydrate, caffeine, nitrate, sodium bicarbonate, beta-alanine, protein, and essential amino acids, as well as manipulating carbohydrate availability. Nutrient timing and potential sex differences are also discussed. Overall, sodium bicarbonate and nitrates show promise for enhancing HIIT adaptations and performance. Beta-alanine has the potential to increase training volume and intensity and improve HIIT adaptations. Caffeine and creatine have potential benefits, however, longer-term studies are lacking. Presently, there is a lack of evidence supporting high protein diets to augment HIIT. Low carbohydrate training enhances the upregulation of mitochondrial enzymes, however, there does not seem to be a performance advantage, and a periodized approach may be warranted. Lastly, potential sex differences suggest the need for future research to examine sex-specific nutritional strategies in response to HIIT.

scholarly journals The Spatiotemporal Characteristics of 0–24-Goal Polo

Animals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 446 ◽  
Author(s):  
Russ Best ◽  
Regan Standing
Keyword(s):  
High Intensity ◽  
Average Distance ◽  
Interval Training ◽  
Linear Increase ◽  
Positioning Systems ◽  
Spatiotemporal Characteristics ◽  
Physiological Demands ◽  
And Performance ◽  
High Intensity Interval ◽  
Mean Differences

Global positioning systems (GPS) have recently been shown to reliably quantify the spatiotemporal characteristics of Polo, with the physiological demands of Polo play at low- and high-goal levels also investigated. This study aims to describe the spatiotemporal demands of Polo across 0–24 goal levels. A player-worn GPS unit was used to quantify distance, speed and high-intensity activities performed. Data were divided into chukkas and five equine-based speed zones, grouped per cumulative player handicap and assessed using standardized mean differences. Average distance and speed per chukka increased in accordance with cumulative player handicap, with the magnitude of differences being trivial–large and trivial–very large, respectively. Differences between time spent in high-intensity speed zones (zones 4 and 5) show a linear increase in magnitude, when comparing 0 goal Polo to all other levels of play (Small–Very Large; 6–24 goals, respectively). High-intensity activities predominantly shared this trend, displaying trivial–large differences between levels. These findings highlight increased cardiovascular, anaerobic and speed based physiological demands on Polo ponies as playing level increases. Strategies such as high-intensity interval training, maximal speed work and aerobic conditioning may be warranted to facilitate this development and improve pony welfare and performance.

scholarly journals Metabolism and performance during extended high-intensity intermittent exercise after consumption of low- and high-glycaemic index pre-exercise meals

2012 ◽  
Vol 108 (S1) ◽  
pp. S81-S90 ◽  
Author(s):  
Christine B. Bennett ◽  
Philip D. Chilibeck ◽  
Trevor Barss ◽  
Hassanali Vatanparast ◽  
Albert Vandenberg ◽  
...  
Keyword(s):  
Blood Glucose ◽  
High Intensity ◽  
Intermittent Exercise ◽  
Glycaemic Index ◽  
Treadmill Running ◽  
Postprandial Blood Glucose ◽  
Exercise Session ◽  
Performance Improvements ◽  
And Performance

The metabolic and performance benefits of prior consumption of low-glycaemic index (GI) meals v. high-GI meals were determined in extended high-intensity intermittent exercise. Participants (ten males and four females, aged 25·8 (sd 7·3) years) completed two testing days (each consisting of back-to-back 90-min intermittent high-intensity treadmill running protocols separated by 3 h) spaced by at least 7 d. Using a randomised counterbalanced cross-over design, low-GI, lentil-based meals (GI about 42) or high-GI, potato-based meals (GI about 78) matched for energy value were consumed 2 h before, and within 1 h after, the first exercise session. Performance was measured by the distance covered during five 1-min sprints (separated by 2·5 min walking) at the end of each exercise session. Peak postprandial blood glucose was higher by 30·8 % in the high-GI trial compared with the low-GI trial, as was insulin (P = 0·039 and P = 0·003, respectively). Carbohydrate oxidation was lower by 5·5 % during the low-GI trials compared with the high-GI trials at the start of the first exercise session (P < 0·05). Blood lactate was significantly higher (6·1 v. 2·6 mmol/l; P = 0·019) and blood glucose significantly lower (4·8 v. 5·4 mmol/l; P = 0·039) at the end of the second exercise session during the high-GI trial compared with the low-GI trial. Sprint distance was not significantly different between conditions. A low-GI meal improved the metabolic profile before and during extended high-intensity intermittent exercise, but did not affect performance. Improvements in metabolic responses when consuming low-GI meals before exercise may be beneficial to the long-term health of athletes.

X-ray monochromator combining high resolution with high intensity

2002 ◽  
Vol 35 (1) ◽  
pp. 41-48 ◽  
Author(s):  
M. Servidori
Keyword(s):  
High Resolution ◽  
High Intensity ◽  
Asymmetry Factor ◽  
Photon Flux ◽  
Wavelength Band ◽  
Germanium Crystal ◽  
X Ray ◽  
Band Pass ◽  
And Performance ◽  
Exit Beam

A two-germanium-crystal four-220-reflection (+ - - \,+) monochromator, combining high intensity with high resolution, is proposed in this work. The main characteristic is that only the first reflection is asymmetric. The asymmetry factor was chosen so as to allow mixing of asymmetric and symmetric reflections in a monolithic channel-cut crystal without the need for rotation of the two monolith components to correct for the different refraction-induced angular shifts of the reflection pair. It is demonstrated that the exit-beam divergence in the diffraction plane and the fractional wavelength band-pass are smaller by 40% than those of the widely used germanium 220 Bartels monochromator, while the photon flux collected from the source is larger by a factor of five. The optical features and performance of the monochromator are discussed and compared with those of other (+ - - \,+) monochromators reported in the literature.

The Effects of Low– and High–Glycemic Index Foods on High-Intensity Intermittent Exercise

2009 ◽  
Vol 4 (3) ◽  
pp. 367-380 ◽  
Author(s):  
Jonathan P. Little ◽  
Philip D. Chilibeck ◽  
Dawn Ciona ◽  
Albert Vandenberg ◽  
Gordon A. Zello
Keyword(s):  
Glycemic Index ◽  
High Intensity ◽  
Intermittent Exercise ◽  
Fat Oxidation ◽  
Mean Difference ◽  
Treadmill Running ◽  
Repeated Sprint ◽  
The Mean ◽  
Improved Performance ◽  
And Performance

The glycemic index (GI) of a pre exercise meal may affect substrate utilization and performance during continuous exercise.Purpose:To examine the effects of low- and high-GI foods on metabolism and performance during high-intensity, intermittent exercise.Methods:Seven male athletes participated in three experimental trials (low-GI, high-GI, and fasted control) separated by ~7 days. Foods were consumed 3 h before (~1.3 g·kg−1 carbohydrate) and halfway through (~0.2 g·kg−1 carbohydrate) 90 min of intermittent treadmill running designed to simulate the activity pattern of soccer. Expired gas was collected during exercise to estimate substrate oxidation. Performance was assessed by the distance covered on fve 1-min sprints during the last 15 min of exercise.Results:Respiratory exchange ratio was higher and fat oxidation lower during exercise in the high-GI condition compared with fasting (P < .05). The mean difference in total distance covered on the repeated sprint test between low GI and fasting (247 m; 90% confidence limits ±352 m) represented an 81% (likely, probable) chance that the low-GI condition improved performance over fasting. The mean difference between high GI and fasted control (223 m; ±385 m) represented a 76% (likely, probable) chance of improved performance. There were no differences between low and high GI.Conclusions:When compared with fasting, both low- and high-GI foods consumed 3 h before and halfway through prolonged, high-intensity intermittent exercise improved repeated sprint performance. High-GI foods impaired fat oxidation during exercise but the GI did not appear to influence high-intensity, intermittent exercise performance.

A Carbohydrate Ingestion Intervention in an Elite Athlete Who Follows a Low-Carbohydrate High-Fat Diet

2018 ◽  
Vol 13 (7) ◽  
pp. 957-960 ◽  
Author(s):  
Christopher C. Webster ◽  
Jeroen Swart ◽  
Timothy D. Noakes ◽  
James A. Smith
Keyword(s):  
High Intensity ◽  
Time Trial ◽  
Endurance Performance ◽  
High Fat ◽  
Carbohydrate Ingestion ◽  
High Intensity Training ◽  
Low Carbohydrate ◽  
Elite Level ◽  
And Performance ◽  
Intensity Training

This case study documents the performance of an elite-level, exceptionally well-fat-adapted endurance athlete as he reintroduced carbohydrate (CHO) ingestion during high-intensity training. He had followed a strict low-CHO high-fat (LCHF) diet for 2 y, during which he ate approximately 80 g of CHO per day and trained and raced while ingesting only water. While following this diet, he earned numerous podium finishes in triathlons of various distances. However, he approached the authors to test whether CHO supplementation during exercise would further increase his high-intensity performance without affecting his fat adaptation. This 7-wk n = 1 investigation included a 4-wk habitual LCHF diet phase during which he drank only water during training and performance trials and a 3-wk habitual diet plus CHO ingestion phase (LCHF + CHO) during which he followed his usual LCHF diet but ingested 60 g/h CHO during 8 high-intensity training sessions and performance trials. After each phase, rates of fat oxidation and 30-s sprint, 4-min sprint, 20-km time trial (TT), and 100-km TT performances were measured. Compared with LCHF, 20-km TT time improved by 2.8% after LCHF + CHO, which would be a large difference in competition. There was no change in 30-s sprint power, a small improvement in 4-min sprint power (1.6%), and a small reduction in 100-km TT time (1.1%). The authors conclude that CHO ingestion during exercise was likely beneficial for this fat-adapted athlete during high-intensity endurance-type exercise (4–30 min) but likely did not benefit his short-sprint or prolonged endurance performance.

Physiological and performance responses to high-intensity interval training in female inline speed skaters

2017 ◽  
Vol 52 (196) ◽  
pp. 131-138 ◽  
Author(s):  
Sara Fereshtian ◽  
Mohsen Sheykhlouvand ◽  
Scott Forbes ◽  
Hamid Agha-Alinejad ◽  
Mohammadali Gharaat
Keyword(s):  
High Intensity ◽  
Interval Training ◽  
High Intensity Interval Training ◽  
And Performance ◽  
High Intensity Interval

Effect of Low- and High-Glycemic-Index Meals on Metabolism and Performance During High-Intensity, Intermittent Exercise

2010 ◽  
Vol 20 (6) ◽  
pp. 447-456 ◽  
Author(s):  
Jonathan P. Little ◽  
Philip D. Chilibeck ◽  
Dawn Ciona ◽  
Scott Forbes ◽  
Huw Rees ◽  
...  
Keyword(s):  
Glycemic Index ◽  
Muscle Glycogen ◽  
High Intensity ◽  
Perceived Exertion ◽  
Intermittent Exercise ◽  
Random Order ◽  
Rating Of Perceived Exertion ◽  
Repeated Sprint ◽  
High Glycemic Index ◽  
And Performance

Consuming carbohydrate-rich meals before continuous endurance exercise improves performance, yet few studies have evaluated the ideal preexercise meal for high-intensity intermittent exercise, which is characteristic of many team sports. The authors’ purpose was to investigate the effects of low- and high-glycemic-index (GI) meals on metabolism and performance during high-intensity, intermittent exercise. Sixteen male participants completed three 90-min high-intensity intermittent running trials in a single-blinded random order, separated by ~7 d, while fasted (control) and 2 hr after ingesting an isoenergetic low-GI (lentil), or high-GI (potato and egg white) preexercise meal. Serum free fatty acids were higher and insulin lower throughout exercise in the fasted condition (p < .05), but there were no differences in blood glucose during exercise between conditions. Distance covered on a repeated-sprint test at the end of exercise was significantly greater in the low-GI and high-GI conditions than in the control (p < .05). Rating of perceived exertion was lower in the low-GI condition than in the control (p = .01). In a subsample of 5 participants, muscle glycogen availability was greater in the low- and high-GI conditions versus fasted control before the repeated-sprint test (p < .05), with no differences between low and high GI. When exogenous carbohydrates are not provided during exercise both low- and high-GI preexercise meals improve high-intensity, intermittent exercise performance, probably by increasing the availability of muscle glycogen. However, the GI does not influence markers of substrate oxidation during high-intensity, intermittent exercise.

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