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1.
Brief in-play cooling breaks reduce thermal strain during football in hot conditions.
Chalmers, S, Siegler, J, Lovell, R, Lynch, G, Gregson, W, Marshall, P, Jay, O
Journal of science and medicine in sport. 2019;(8):912-917
Abstract
OBJECTIVES The study examined if three feasible strategies involving additional in-play cooling periods attenuate the core (rectal) temperature rise during simulated football matches. DESIGN Four counterbalanced experimental trials in an environmental chamber set to 35 °C ambient temperature, 55% relative humidity, and 30 °C WBGT. METHODS Twelve healthy well-trained football players completed a regular simulated match (REG), regular simulated match with additional 3-min cooling periods at the 30-min mark of each half inclusive of chilled water consumption (COOLwater), regular simulated match with additional 3-min cooling periods at the 30-min mark of each half inclusive of chilled water consumption and the application of an ice towel around the neck (COOLtowel), regular simulated match with an extended (+5 min; total of 20-min) half-time break (HTextended). RESULTS The difference in rectal temperature change was significantly lower in the COOLwater (-0.25 °C), COOLtowel (-0.28 °C), and HTextended (-0.21 °C) trials in comparison to the REG (all p < 0.05). Exercising heart rate and session rating of perceived exertion was lower in the COOLwater (-13 bpm; -1.4 au), COOLtowel (-10 bpm; -1.3 au), and HTextended (-8 bpm; -0.9 au) trials in comparison to the REG trial (all p < 0.05). The cooling interventions did not significantly change skin temperature or thermal sensation in comparison to the REG (all p > 0.05). CONCLUSIONS All three cooling interventions attenuated core body thermal strain during simulated matches. The laboratory-based study supports the use of brief in-play cooling periods as a means to attenuate the rise in core temperature during matches in hot and humid conditions.
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Physical Function and Strength in Relation to Inflammation in Older Adults with Obesity and Increased Cardiometabolic Risk.
Tay, J, Goss, AM, Locher, JL, Ard, JD, Gower, BA
The journal of nutrition, health & aging. 2019;(10):949-957
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Abstract
BACKGROUND Inflammation is implicated in functional decline and the development of disability in aging. This study aimed to investigate the association of inflammation with physical function and muscle strength in older adults with obesity and increased cardiometabolic risk. DESIGN In baseline assessments from the CROSSROADS randomized controlled trial, serum interleukin-6 (IL-6), tumor necrosis factor-α (TNFα) and C-reactive protein (hs-CRP) were assayed in 163 older adults (37% males, 24% African American, BMI 34±3, age 70±5yrs) with hypertension, dyslipidemia and/or diabetes. Physical function was assessed by six-minute walk test (6MWT), chair sit-and-reach (CSR), hand-grip and knee-extension strength; specific-strength as muscle strength/mass ratio. Analyses included ANCOVA and multiple linear regression adjusted for thigh skeletal muscle (MRI), arm lean mass (DXA) and moderate-to-vigorous intensity physical activity (MVPA; accelerometry). RESULTS Higher hs-CRP (p<0.01) and IL-6 (p=0.07) were associated with lower 6MWT and CSR, respectively. A composite inflammation score combining all 3 inflammatory markers showed the strongest inverse association with 6MWT (p<0.01). MVPA moderated associations such that amongst participants who engaged in low MVPA, 6MWT distances and CSR scores were significantly lower in those with high IL-6 and TNFα (p<0.05), respectively. In participants with high MVPA, higher hs-CRP (p<0.05) and TNFα (p=0.07) were associated with poorer upper-extremity specific-strength. CONCLUSIONS Chronic inflammation was associated with poorer physical function and specific strength in older adults with obesity and increased cardiometabolic risk. This association was strongest in participants with multiple elevated inflammatory markers. Physical activity levels below current recommendations mitigated the deleterious effects of inflammation on lower body mobility, underscoring the benefits of exercise for preserving physical function with age.
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Neuromuscular, physiological and perceptual responses to an elite netball tournament.
Birdsey, LP, Weston, M, Russell, M, Johnston, M, Cook, CJ, Kilduff, LP
Journal of sports sciences. 2019;(19):2169-2174
Abstract
To examine responses to an International netball tournament, female athletes (n= 11) played three matches over consecutive days. External (accelerometry) and internal (heart rate; HR, session; sRPE, and differential; dRPE, rating of perceived exertion) load measures quantified match intensity. On match-day mornings, and three days after match 3, well-being (brief assessment of mood; BAM+), biochemical (creatine kinase concentration; CK), neuromuscular (jump height; JH, peak power output; PPO) and endocrine function (salivary cortisol; C, testosterone; T, concentrations) were assessed. External load was similar between matches whereas dRPE and sRPE were greatest for match 3. Following match 1, CK increased, whereas BAM+, JH, C and T decreased. Following two matches, BAM+, PPO, and T decreased with CK increasing versus baseline. Following consecutive matches, CK (likely moderate; 27.9% ± 19.5%) and C (possibly moderate; 43.3% ± 46.8%) increased, whilst BAM+ (possibly moderate; -20.6% ± 24.4%) decreased. Three days post-tournament BAM+, T, PPO, and JH decreased. Mid-court elicited higher mean HR (possibly moderate; 3.7% ± 3.8%), internal and external intensities (possibly very large; 85.7% ± 49.6%) compared with goal-based positions. Consecutive matches revealed a dose-response relationship for well-being and physiological function; a response evident three days post-tournament.
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Challenging the Myth of Non-Response to the Ergogenic Effects of Caffeine Ingestion on Exercise Performance.
Del Coso, J, Lara, B, Ruiz-Moreno, C, Salinero, JJ
Nutrients. 2019;(4)
Abstract
The ergogenicity of caffeine on several exercise and sport situations is well-established. However, the extent of the ergogenic response to acute caffeine ingestion might greatly vary among individuals despite using the same dosage and timing. The existence of one or several individuals that obtained minimal ergogenic effects or even slightly ergolytic effects after caffeine intake (i.e., non-responders) has been reported in several previous investigations. Nevertheless, the concept non-responding to caffeine, in terms of physical performance, relies on investigations based on the measurement of one performance variable obtained once. Recently it has been suggested that correct identification of the individual ergogenic effect induced by caffeine intake requires the repeated measurement of physical performance in identical caffeine⁻placebo comparisons. In this communication, we present data from an investigation where the ergogenic effect of acute caffeine intake (3 mg/kg) was measured eight times over a placebo in the same individuals and under the same conditions by an incremental cycling test to volitional fatigue and an adapted version of the Wingate cycling test. The ergogenic response to caffeine varied from 9% to 1% among individuals, but all participants increased both cycling power in the incremental test and Wingate mean power at least three to eight times out of eight the caffeine⁻placebo comparisons. These data expand the suggestion of a minimal occurrence of caffeine non-responders because it shows that all individuals responded to caffeine when caffeine is compared to a placebo on multiple and repeated testing sessions.
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Physiological and Tactical On-court Demands of Water Polo.
Botonis, PG, Toubekis, AG, Platanou, TI
Journal of strength and conditioning research. 2019;(11):3188-3199
Abstract
Botonis, PG, Toubekis, AG, and Platanou, TI. Physiological and tactical on-court demands of water polo. J Strength Cond Res 33(11): 3188-3199, 2019-The purpose of the present review is to provide a quantification of the specific game's activities performed by elite water polo players and a comprehensive overview of the physiological requirements reflecting physical and tactical on-court demands in water polo. Game analysis demonstrates that various swimming movements occur throughout a match play, although approximately 50% of these are recorded in horizontal body position. The various offensive and defensive tactical actions transiently modify the playing intensity, which overall corresponds to the players' lactate threshold. Even play corresponds to 60% of total game actions, whereas the respective percentage of power-play and counterattacks may exceed 30%. The ability to perform high-intensity activities with short recovery periods is critical for water polo players. Elite water polo players present a high level of aerobic power and endurance as indicated by their maximal oxygen uptake and speed at the lactate threshold. Depending on the positional roles, outfield players are characterized as centers or peripherals. The overall physiological load seems to be similar between players at various positions, despite that centers execute more dynamic body contacts, whereas peripherals more swimming bouts. Despite limitations concerning the experimental setting, the current findings indicate that the incidence of fatigue deteriorates playing intensity and performance. Nonetheless, data from the reviewed studies should be cautiously interpreted because in some of the studies, players' substitutions were not allowed. A high conditioning level is essential for water polo, as it is associated with superior technical and tactical efficacy and lower decline of physical or technical performance within the game.
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High-intensity interval exercise lowers postprandial glucose concentrations more in obese adults than lean adults.
Kong, Z, Shi, Q, Sun, S, Tong, TK, Zhang, H, Nie, J
Primary care diabetes. 2019;(6):568-573
Abstract
AIMS: To compare postprandial glucose responses to high-intensity interval exercise (HIE) between obese and lean individuals. METHODS Thirty healthy young adult males (15 obese, 15 lean) ate a standardised meal, then performed HIE (4 × 30-s Wingate cycling/4-min rest) or a no-exercise control trial (CON). Blood glucose was measured preprandially and up to 150 min postprandially. RESULTS Compared to CON, HIE reduced postprandial glucose concentrations at 120-150 min in obese (p < 0.001) and lean men (p < 0.05), with greater reductions in obese than lean subjects at 120 (-27.0% vs. -8.3%), 135 (-31.9% vs. -15.7%), and 150 min (-21.8% vs. -10.6%). The total glucose area under the curve (AUC) for the testing period was lower with HIE than CON among obese men (p < 0.05), but not lean men (p > 0.05). We found moderate correlations between body mass and postprandial glucose changes (r = 0.39-0.44, p < 0.05), and between glucose AUC and body mass and fat free mass (r = 0.39-0.48, p < 0.05). CONCLUSIONS Our findings suggest that HIE may act as a time-efficient lifestyle intervention strategy for improving obesity-related diabetes risk factors, and might play a role in primary diabetes prevention for the healthy but sedentary population.
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An Exploratory Double-Blind Study of Caffeine Effects on Performance and Perceived Exertion in Judo.
Saldanha da Silva Athayde, M, Kons, RL, Detanico, D
Perceptual and motor skills. 2019;(3):515-529
Abstract
This study analyzed the effects of caffeine ingestion during judo matches on judo athletes' match-derived performance and perceived exertion responses. We applied a double-blind randomized crossover (caffeine vs. placebo conditions) research design. Twelve male athletes performed three 5-minute matches separated by 15 minutes of passive rest. Immediately after each match, the athletes completed ratings of perceived exertion (RPEs), and one minute before beginning the second and third matches, they provided ratings of perceived recovery (RPRs). We filmed all matches for subsequent analysis of the athletes' technical skills. We found no interaction between condition and time of RPE, RPR, and match-derived technical variables, but number of attacks and RPR decreased over the matches, and RPE increased in both conditions. Three participants showed individual positive responses to caffeine ingestion for number of attacks. Attacks, efficiency, and effectiveness presented low sensitivity in both conditions, as only large changes could be identified. We conclude that caffeine ingestion did not provoke changes in either perceived exertion or match-derived performance. Match-derived technical variables were not sensitive for detecting small or medium effects of caffeine, but perceived exertion may detect at least medium effect after caffeine ingestion.
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Hydrogen Rich Water Improved Ventilatory, Perceptual and Lactate Responses to Exercise.
Botek, M, Krejčí, J, McKune, AJ, Sládečková, B, Naumovski, N
International journal of sports medicine. 2019;(14):879-885
Abstract
The potential anti-fatigue and performance benefits of hydrogen rich water (HRW) have resulted in increased research interest over the past 5 years. The aim of this study was to assess physiological and perceptual responses to an incremental exercise protocol after administration of 600 ml HRW within 30 min before exercise. This randomized, double blinded placebo-controlled cross over study included twelve healthy males aged 27.1±4.9 years. The exercise protocol consisted of a 10 min warm-up at 1.0 W.kg-1, followed by 8 min at 2.0, 3.0, and 4.0 W.kg-1, respectively. Cardio-respiratory variables, lactate and ratings of perceived exertion (RPE) were assessed in the last minute of each step. A significantly lower blood lactate was found with HRW (4.0±1.6 and 8.9±2.2 mmol.l-1) compared to Placebo (5.1±1.9 and 10.6±3.0 mmol.l-1) at 3.0, and 4.0 W.kg-1, respectively. Ventilatory equivalent for oxygen and RPE exhibited significantly lower values with HRW (32.3±7.2, and 17.8±1.2 points, respectively) compared to Placebo (35.0±8.4, and 18.5±0.8 points, respectively) at 4 W.kg-1. To conclude, acute pre-exercise supplementation with HRW reduced blood lactate at higher exercise intensities, improved exercise-induced perception of effort, and ventilatory efficiency.
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Creatine supplementation can improve impact control in high-intensity interval training.
da Silva Azevedo, AP, Michelone Acquesta, F, Lancha, AH, Bertuzzi, R, Poortmans, JR, Amadio, AC, Cerca Serrão, J
Nutrition (Burbank, Los Angeles County, Calif.). 2019;:99-104
Abstract
OBJECTIVES This study aimed to investigate the effects of creatine (Cr) supplementation on biomechanical parameters related to shock attenuation during a session of high-intensity interval training (HIIT). METHODS A single-blinded, placebo-controlled, crossover design was adopted to test eight male elite soccer players during HIIT sessions under two conditions: after placebo supplementation and after Cr supplementation. HIIT test sessions consisted of an intermittent test (five bouts of running) with a constant load applied until exhaustion was reached. The vertical component of ground reaction force and electromyography data were recorded by Gaitway and Lynx-EMG Systems, respectively. Heart rate, rated perceived exertion (Borg's Scale) and lactate concentration information were also obtained. RESULTS Cr supplementation did not affect heart rate, rated perceived exertion, and lactate concentration. Decreased values of magnitude of the first peak of the vertical component of ground reaction force (17.2-24.2%) and impulse of the first 50 ms (Imp50; 34.3%) were observed for Cr, but higher values of time to reach the first peak were detected for Cr compared with placebo. Significant modifications in muscle activation were also observed, mainly in the pre-activation phase, and changes were observed in intermediary bouts. CONCLUSIONS Cr supplementation has the potential to influence biomechanical parameters related to impact control during a single session of HIIT based on running. In particular, the findings of the current study indicate possible improvements in shock attenuation and a safer practice of HIIT under Cr supplementation.
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Monitoring Blood Biomarkers and Training Load Throughout a Collegiate Soccer Season.
Huggins, RA, Fortunati, AR, Curtis, RM, Looney, DP, West, CA, Lee, EC, Fragala, MS, Hall, ML, Casa, DJ
Journal of strength and conditioning research. 2019;(11):3065-3077
Abstract
Huggins, RA, Fortunati, AR, Curtis, RM, Looney, DP, West, CA, Lee, EC, Fragala, MS, Hall, ML, and Casa, DJ. Monitoring blood biomarkers and training load throughout a collegiate soccer season. J Strength Cond Res 33(11): 3065-3077, 2019-This observational study aimed to characterize the responses of a comprehensive panel of biomarkers, observed ranges, training load (TL) metrics, and performance throughout the collegiate soccer season (August-November). Biomarkers (n = 92) were collected before the start of pre-season (PS), in-season weeks (W)1, W4, W8, and W12 in NCAA Division I male soccer players (n = 20, mean ± SD; age = 21 ± 1 years, height = 180 ± 6 cm, body mass = 78.19 ± 6.3 kg, body fat = 12.0 ± 2.6%, VO2max 51.5 ± 5.1 ml·kg·min). Fitness tests were measured at PS, and W12 and TL was monitored daily. Changes in biomarkers and performance were calculated via separate repeated-measures analysis of variance. Despite similar fitness (p > 0.05), endocrine, muscle, inflammatory, and immune markers changed over time (p < 0.05). Total and free testosterone was lower in W1 vs. PS, whereas free cortisol remained unchanged at PS, W1, and W4 (>0.94 mg·dL). Oxygen transport and iron metabolism markers remained unchanged except for HCT (W1 vs. PS) and total iron binding capacity (W8-W12 vs. W1). Hepatic markers albumin, globulin, albumin:globulin, and total protein levels were elevated (p < 0.05) at W12 vs. W1, whereas aspartate aminotransferase and alanine aminotransferase levels were elevated at W1-W12 and W8-W12 vs. PS, respectively. Vitamin E, zinc, selenium, and calcium levels were elevated (p < 0.05) at W12 vs. W1, whereas Vitamin D was decreased (p < 0.05). Fatty acids and cardiovascular markers (omega-3 index, cholesterol:high-density lipoprotein [HDL], docosahexenoic acid, low-density lipoprotein [LDL], direct LDL, non-HDL, ApoB) were reduced at W1 vs. PS (p ≤ 0.05). Immune, lipid, and muscle damage biomarkers were frequently outside clinical reference ranges. Routine biomarker monitoring revealed subclinical and clinical changes, suggesting soccer-specific reference ranges. Biomarker monitoring may augment positive adaptation and reduce injuries from stressors incurred during soccer.