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1.
The effect of foot orthoses and insoles on running economy and performance in distance runners: A systematic review and meta-analysis.
Crago, D, Bishop, C, Arnold, JB
Journal of sports sciences. 2019;(22):2613-2624
Abstract
Foot orthoses and insoles are prescribed to runners, however their impact on running economy and performance is uncertain. The aim of this systematic review and meta-analysis was to determine the effect of foot orthoses and insoles on running economy and performance in distance runners. Seven electronic databases were searched from inception until June 2018. Eligible studies investigated the effect of foot orthoses or insoles on running economy (using indirect calorimetry) or running performance. Standardised mean differences (SMDs) were computed and meta-analyses were conducted using random effects models. Methodological quality was assessed using the Quality Index. Nine studies met the criteria and were included: five studies investigated the effect of foot orthoses on running economy and four investigated insoles. Foot orthoses were associated with small negative effects on running economy compared to no orthoses (SMD 0.42 [95% CI 0.17,0.72] p = 0.007). Shock absorbing insoles were also associated with negative effects on running economy, but an imprecise estimate (SMD 0.26 [95% CI -0.33,0.84] p = 0.83). Quality Index scores ranged from 4 to 15 out of 17. Foot orthoses and shock absorbing insoles may adversely affect running economy in distance runners. Future research should consider their potential effects on running performance.
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2.
Contemporary Nutrition Strategies to Optimize Performance in Distance Runners and Race Walkers.
Burke, LM, Jeukendrup, AE, Jones, AM, Mooses, M
International journal of sport nutrition and exercise metabolism. 2019;(2):117-129
Abstract
Distance events in Athletics include cross country, 10,000-m track race, half-marathon and marathon road races, and 20- and 50-km race walking events over different terrain and environmental conditions. Race times for elite performers span ∼26 min to >4 hr, with key factors for success being a high aerobic power, the ability to exercise at a large fraction of this power, and high running/walking economy. Nutrition-related contributors include body mass and anthropometry, capacity to use fuels, particularly carbohydrate (CHO) to produce adenosine triphosphate economically over the duration of the event, and maintenance of reasonable hydration status in the face of sweat losses induced by exercise intensity and the environment. Race nutrition strategies include CHO-rich eating in the hours per days prior to the event to store glycogen in amounts sufficient for event fuel needs, and in some cases, in-race consumption of CHO and fluid to offset event losses. Beneficial CHO intakes range from small amounts, including mouth rinsing, in the case of shorter events to high rates of intake (75-90 g/hr) in the longest races. A personalized and practiced race nutrition plan should balance the benefits of fluid and CHO consumed within practical opportunities, against the time, cost, and risk of gut discomfort. In hot environments, prerace hyperhydration or cooling strategies may provide a small but useful offset to the accrued thermal challenge and fluid deficit. Sports foods (drinks, gels, etc.) may assist in meeting training/race nutrition plans, with caffeine, and, perhaps nitrate being used as evidence-based performance supplements.
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3.
Effect of an 11-Week In-Water Training Program With Increased Resistance on the Swimming Performance and the Basic Kinematic Characteristics of the Front Crawl Stroke.
Gourgoulis, V, Valkoumas, I, Boli, A, Aggeloussis, N, Antoniou, P
Journal of strength and conditioning research. 2019;(1):95-103
Abstract
Gourgoulis, V, Valkoumas, I, Boli, A, Aggeloussis, N, and Antoniou, P. Effect of an 11-week in-water training program with increased resistance on the swimming performance and the basic kinematic characteristics of the front crawl stroke. J Strength Cond Res 33(1): 95-103, 2019-The purpose of the study was to assess the effect of an 11-week in-water training program with increased resistance on the swimming performance and the basic kinematic characteristics of the front crawl stroke in young female swimmers. Twelve swimmers were matched in pairs according to their best performance in 50-m front crawl swimming and then were randomly assigned to an experimental or to a control group. Both groups followed exactly the same swimming training program. The only exception was that the experimental group performed a sprint training section with increased resistance pulling a water parachute, whereas the control group performed the same section without parachute. Before and after the intervention program, the best performance of both groups in 50-, 100-, and 200-m front crawl swimming were assessed. Moreover, the basic kinematic characteristics of the stroke were calculated during 50-m front crawl swimming with maximal intensity. Two-way repeated measures analyses of variance revealed significant improvement in the best performance in all swimming distances only in the experimental group (3.22-7.26%). As far as the basic kinematic characteristics of the stroke are concerned, significant modifications were found only in the mean swimming velocity in the experimental group (2.18%), whereas no significant changes were observed in the stroke length, the stroke rate, and the duration of the propulsive, and nonpropulsive phases in both groups. Thus, the findings of the current study revealed a positive effect of the in-water resistance training program in the swimming performance of young female swimmers of moderate performance level, without any negative influence in the basic kinematic characteristics of the stroke.
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4.
Mixed-methods pre-match cooling improves simulated soccer performance in the heat.
Aldous, JWF, Chrismas, BCR, Akubat, I, Stringer, CA, Abt, G, Taylor, L
European journal of sport science. 2019;(2):156-165
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Abstract
This investigation examined the effects of three pre-match and half-time cooling manoeuvres on physical performance and associated physiological and perceptual responses in eight University soccer players during a non-motorised treadmill based individualised soccer-specific simulation [intermittent soccer performance test (iSPT)] at 30°C. Four randomised experimental trials were completed; following 30-min (pre-match) and 15-min (half-time) cooling manoeuvres via (1) ice slurry ingestion (SLURRY); (2) ice-packs placed on the quadriceps and hamstrings (PACKS); (3) mixed-methods (MM; PACKS and SLURRY concurrently); or no-cooling (CON). In iSPT first half, a moderate increase in total (Mean ± Standard Deviation: 108 ± 57 m, qualitative inference: most likely, Cohen's d: 0.87, 90%CL: ±0.31), high-speed (56 ± 46 m, very likely, 0.68 ± 0.38) and variable run (15 ± 5 m, very likely, 0.81 ± 0.47) distance covered was reported in MM compared with CON. Additionally, pre-match reductions in thermal sensation (-1.0 ± 0.5, most likely, -0.91 ± 0.36), rectal (-0.6 ± 0.1°C, very likely, -0.86 ± 0.35) and skin temperature (-1.1 ± 0.3°C, very likely, -0.88 ± 0.42) continued throughout iSPT first half. Physical performance during iSPT first half was unaltered in SLURRY and PACKS compared to CON. Rectal temperature was moderately increased in SLURRY at 45-min (0.2 ± 0.1°C, very likely, 0.67 ± 0.36). Condition did not influence any measure in iSPT second half compared to CON. Only MM pre-match cooling augmented physical performance during iSPT first half, likely due to peripheral and central thermoregulatory factors favourably influencing first half iSPT performance. Further practical half-time cooling manoeuvres which enhance second half performance are still required.
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5.
Faster and Slower Posttraining Recovery in Futsal: Multifactorial Classification of Recovery Profiles.
Wilke, CF, Fernandes, FAP, Martins, FVC, Lacerda, AM, Nakamura, FY, Wanner, SP, Duffield, R
International journal of sports physiology and performance. 2019;(8):1089-1095
Abstract
PURPOSE To investigate the existence of faster vs slower recovery profiles in futsal and factors distinguishing them. METHODS 22 male futsal players were evaluated in countermovement jump, 10-m sprint, creatine kinase, total quality of recovery (TQR), and Brunel Mood Scale (fatigue and vigor) before and immediately and 3, 24, and 48 h posttraining. Hierarchical cluster analysis allocated players to different recovery profiles using the area under the curve (AUC) of the percentage differences from baseline. One-way ANOVA compared the time course of each variable and players' characteristics between clusters. RESULTS Three clusters were identified and labeled faster recovery (FR), slower physiological recovery (SLphy), and slower perceptual recovery (SLperc). FR presented better AUC in 10-m sprint than SLphy (P = .001) and SLperc (P = .008), as well as better TQR SLphy (P = .018) and SLperc (P = .026). SLperc showed better AUC in countermovement jump than SLphy (P = .014) but presented worse fatigue AUC than SLphy (P = .014) and FR (P = .008). AUC of creatine kinase was worse in SLphy than in FR (P = .001) and SLperc (P < .001). The SLphy players were younger than SLperc players (P = .027), whereas FR were slower 10-m sprinters than SLphy players (P = .003) and SLperc (P = .013) and tended to have higher maximal oxygen consumption than SLphy (effect size =1.13). CONCLUSION Different posttraining recovery profiles exist in futsal players, possibly influenced by their physical abilities and age/experience.
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6.
Impact of Ad Libitum Versus Programmed Drinking on Endurance Performance: A Systematic Review with Meta-Analysis.
Goulet, EDB, Hoffman, MD
Sports medicine (Auckland, N.Z.). 2019;(2):221-232
Abstract
BACKGROUND Debate continues on how athletes should hydrate during exercise. Several studies have recently been published comparing the effect of ad libitum (ALD) and programmed drinking (PD) on endurance performance (EP). OBJECTIVE This work examined whether one drinking strategy offers an EP advantage over the other. DESIGN Systematic review and meta-analysis of crossover controlled trials. DATA SOURCES PubMed and SPORTDiscus database searches. ELIGIBILITY CRITERIA FOR SELECTING STUDIES Key criteria were (1) experiments performed under controlled settings; (2) exercise lasting ≥ 1 h; (3) exercise initiated in an euhydrated state; (4) fluid intake during PD > ALD; (5) fluid composition matched for electrolytes; and (6) carbohydrate intake varied by > 25% between conditions when the exercise was 1 h and matched for exercise > 1 h. RESULTS Seven publications, producing eight effect estimates, including cycling and running exercises and representing 82 subjects, were included. Mean (± standard deviation) ambient temperature, exercise intensity and duration of the experiments were 28 ± 6 °C, 81 ± 12% of maximal heart rate and 96 ± 25 min, respectively. Mean rate of fluid consumption for the PD and ALD conditions was 1073 ± 247 mL/h and 505 ± 156 mL/h, respectively. Mean change in body mass for the PD and ALD conditions was - 1.0 ± 0.5% and - 2.1 ± 0.7%, respectively. Compared with PD, ALD improved EP by 0.98 ± 0.44% (95% confidence interval 0.11-1.84%). The greater EP conferred by ALD is likely trivial. CONCLUSIONS Despite ALD being associated with an hourly rate of fluid consumption half as much as PD, and resulting in a dehydration level considered sufficient to impair EP, both strategies were found to similarly impact 1-2 h cycling or running performances conducted at moderate to high intensity and under temperate to warm ambient conditions.
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7.
Nutrition and Altitude: Strategies to Enhance Adaptation, Improve Performance and Maintain Health: A Narrative Review.
Stellingwerff, T, Peeling, P, Garvican-Lewis, LA, Hall, R, Koivisto, AE, Heikura, IA, Burke, LM
Sports medicine (Auckland, N.Z.). 2019;(Suppl 2):169-184
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Abstract
Training at low to moderate altitudes (~ 1600-2400 m) is a common approach used by endurance athletes to provide a distinctive environmental stressor to augment training stimulus in the anticipation of increasing subsequent altitude- and sea-level-based performance. Despite some scientific progress being made on the impact of various nutrition-related changes in physiology and associated interventions at mountaineering altitudes (> 3000 m), the impact of nutrition and/or supplements on further optimization of these hypoxic adaptations at low-moderate altitudes is only an emerging topic. Within this narrative review we have highlighted six major themes involving nutrition: altered energy availability, iron, carbohydrate, hydration, antioxidant requirements and various performance supplements. Of these issues, emerging data suggest that particular attention be given to the potential risk for poor energy availability and increased iron requirements at the altitudes typical of elite athlete training (~ 1600-2400 m) to interfere with optimal adaptations. Furthermore, the safest way to address the possible increase in oxidative stress associated with altitude exposure is via the consumption of antioxidant-rich foods rather than high-dose antioxidant supplements. Meanwhile, many other important questions regarding nutrition and altitude training remain to be answered. At the elite level of sport where the differences between winning and losing are incredibly small, the strategic use of nutritional interventions to enhance the adaptations to altitude training provides an important consideration in the search for optimal performance.
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Cycling time trial performance is improved by carbohydrate ingestion during exercise regardless of a fed or fasted state.
Learsi, SK, Ghiarone, T, Silva-Cavalcante, MD, Andrade-Souza, VA, Ataide-Silva, T, Bertuzzi, R, de Araujo, GG, McConell, G, Lima-Silva, AE
Scandinavian journal of medicine & science in sports. 2019;(5):651-662
Abstract
PURPOSE We tested the hypothesis that carbohydrate ingestion during exercise improves time trial (TT) performance and that this carbohydrate-induced improvement is greater when carbohydrates are ingested during exercise in a fasted rather than a fed state. METHODS Nine males performed 105 minutes of constant-load exercise (50% of the difference between the first and second lactate thresholds), followed by a 10-km cycling TT. Exercise started at 9 am, 3 hours after either breakfast (FED, 824 kcal, 67% carbohydrate) or a 15-hour overnight fast (FAST). Before exercise, after every 15 minutes of exercise and at 5 km of the TT, participants ingested 2 mL kg-1 body mass of a non-caloric sweetened solution containing either carbohydrate (8% of maltodextrin, CHO) or placebo (0% carbohydrate, PLA). RESULTS Irrespective of the fasting state, when carbohydrate was ingested during exercise, the rating of perceived exertion (RPE) was lower throughout the constant-load exercise, while the plasma glucose concentration and carbohydrate oxidation were higher during the last stages of the constant-load exercise (P < 0.05). Consequently, TT performance was faster when carbohydrate was ingested during exercise (18.5 ± 0.3 and 18.7 ± 0.4 minutes for the FEDCHO and FASTCHO conditions, respectively) than when the placebo was ingested during exercise (20.2 ± 0.8 and 21.7 ± 1.4 minutes for the FEDPLA and FASTPLA conditions, respectively), regardless of fasting. CONCLUSION These findings indicate that even when breakfast is provided before exercise, carbohydrate ingestion during exercise is still beneficial for exercise performance. However, ingesting carbohydrate during exercise can overcome a lack of breakfast.
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No effect of beetroot juice supplementation on exercise economy and performance in recreationally active females despite increased torque production.
Wickham, KA, McCarthy, DG, Pereira, JM, Cervone, DT, Verdijk, LB, van Loon, LJC, Power, GA, Spriet, LL
Physiological reports. 2019;(2):e13982
Abstract
This study investigated the effects of acute and chronic beetroot juice (BRJ) supplementation on submaximal exercise oxygen uptake (VO2 ), time trial (TT) performance, and contractile properties of the plantar flexors in females. Study 1: Using a double blind, randomized, crossover design, 12 recreationally active females using hormonal contraceptives supplemented acutely (2.5 h) and chronically (8 days) with 280 mL BRJ/d (~26 mmoles nitrate [ NO3- ]) or a NO3- -free placebo (PLA). On days 1 and 8, participants cycled for 10 min at 50% and 70% VO2peak and completed a 4 kJ/kg body mass TT. Plasma [ NO3- ] and nitrite ([NO2- ]) increased significantly following BRJ supplementation versus PLA. There was no effect of BRJ supplementation on VO2 at 50% or 70% VO2peak , or TT performance. Study 2: 12 recreationally active females (n = 7 from Study 1) using hormonal contraceptives participated in a baseline visit and were supplemented acutely (2.5 h) and chronically (8 days) with 280 mL BRJ/d. Maximum voluntary strength (MVC) of the plantar flexors was assessed and a torque-frequency curve performed. BRJ had no effect on MVC, voluntary activation, peak twitch torque, time to peak torque, or half relaxation time. Following both acute (46.6 ± 4.9% of 100 Hz torque) and chronic (47.2 ± 4.4%) supplementation, 10 Hz torque was significantly greater compared to baseline (32.9 ± 2.6%). In summary, BRJ may not be an effective ergogenic aid in recreationally active females as it did not reduce submaximal exercise VO2 or improve aerobic TT performance despite increasing low frequency torque production.
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10.
KCNA4 Gene Variant is Auxiliary in Endurance Running Performance Level.
Flecha-Velazquez, K, Fahey, TD, Martínez, JL, Lopez-Taylor, JR, Rivera, MA
International journal of sports medicine. 2019;(5):354-358
Abstract
The present is an observational study following a genetic epidemiology model using a case-control design. We tested the hypothesis of an association between the prevalence of the genotypic and allelic frequencies distribution of the potassium voltage-gated channel of the shaker related subfamily member 4 gene (KCNA4) rs1323860 (C/T transition) and endurance performance level in Hispanic male marathon runners (MR). The subjects (n=1876) were adult Hispanic male MR. Fast-MR (cases; n=938) were finishers in the top 3rd percentile. Slow MR (controls; n=938) were finishers in the lowest 3rd percentile of their respective age. Genomic DNA was purified from a whole blood sample. Polymerase chain reaction was used to amplify a KCNA4 SNP which consists of a C/T (rs1323860) transition. The observed genotype frequencies, in both Cases and Controls, met Hardy-Weinberg equilibrium (X2, P≥0.05). Genotype and allele frequencies were statistically different (P<0.01) between cases and controls. Odds ratio revealed that the C allele was 1.33 times more likely prevalent in the cases than in the controls (95% CI; 1.17, 1.51; P<0.001). The magnitude of the statistical power for the present study was 0.86. In conclusion, the findings strongly suggest that KCNA4 gene rs1323860 (C/T transition) is auxiliary in the complex phenotype of endurance running performance level in Hispanic male marathon runners.