The authors examined the effects of combined creatine (Cr) and glycerol (Gly) supplementation on responses to exercise in the heat. Subjects (N = 24) were matched for body mass and assigned to either a Cr or placebo (Pl) group. Twice daily during two 7-d supplementation regimens, the Cr group received 11.4 g of Cr·H2O and the Pl group received 11.4 g of glucose. Subjects in both groups also ingested 1 g of Gly/kg body mass (twice daily) in either the first or the second supplementation regimen. This design allowed 4 possible combinations of supplements to be examined (Pl/Pl, Pl/Gly, Cr/Pl, and Cr/Gly). Exercise trials were conducted pre- and post supplementation at 30 °C and 70% relative humidity. In the Pl group, total body water (TBW) increased by 0.50 ± 0.28 L after Gly and in the Cr group by 0.63 ± 0.33 L after Pl and by 0.87 ± 0.21 L after Gly. Both Cr/Pl and Cr/Gly resulted in significantly attenuated heart rate, rectal temperature, and perceived effort during exercise, although no regimen had any effect on performance. The addition of Gly to Cr significantly increased TBW more than Cr alone (P = 0.02) but did not further enhance the attenuation in HR, Tre, and RPE during exercise. These data suggest that combined Cr and Gly is an effective method of hyper hydration capable of reducing thermal and cardiovascular responses.
Chris Easton, Stephen Turner and Yannis P. Pitsiladis
Vasilis Nikolopoulos, Melissa J. Arkinstall and John A. Hawley
The purpose of this study was to determine the effect of carbohydrate ingestion before and during intense constant load cycling to volitional fatigue on surface electromyographic (sEMG) activity from the vastus lateralis (VL) and vastus medialis (VM) muscles. After 24-h diet and training control, 8 well-trained subjects [maximal O2 uptake (VO2max) 66 ± 2 ml · kg–1· min–1; mean ± SD] ingested 8 ml · kg–1 of either a 6.4% carbohydrate-electrolyte (CHO) or a placebo (PLA) solution immediately before, followed by 2 ml · kg–1 of the same solution every 15 min while cycling to exhaustion at 84 ± 1% of VO2max. Exercise time to fatigue was 13% longer with CHO ingestion compared to PLA (58:54 ± 8:48 vs. 51:18 ± 5:54 min:s, NS). VO2 (4.22 ± 0.11 vs. 4.20 ± 0.14 L · min–1), heart rate (172 ± 4 vs. 176 ± 4 beats · min–1), ratings of perceived effort (18 ± 0.1 vs. 19 ± 0.1), and rates of carbohydrate oxidation (314 ± 28 vs. 324 ± 26 μmol · kg–1 · min–1) were similar for both PLA and CHO at exhaustion. There was no main treatment effect of CHO ingestion on blood glucose or lactate concentrations, nor plasma prolactin levels either during exercise or at fatigue. However, CHO ingestion attenuated the rise in EMG root mean square (RMS) activity during the latter stages (>45 min) of exercise and at the point of exhaustion for both VM (0.325 ± 0.010 vs. 0.403 ± 0.020 mV; p = .006) and VL (0.298 ± 0.011 vs. 0.370 ± 0.007 mV; p = .0004). We conclude that in well-trained subjects, the ingestion of carbohydrate attenuated the increase in surface electromyographic activity during intense, constant load cycling leading to exhaustion in ~1 h. The precise mechanism(s) underlying this effect cannot be attributed to alterations in CHO availability but, instead, may be linked to changes in afferent sensory input.
Thomas J. Birk and Marianne Mossing
The purpose of this study was to determine whether heart rate and ventilation can be predicted from RPE. Also, this study determined whether breathing or heart rate sensations caused perceived effort or strain (degree of perceived central strain). Eight ambulatory active teenagers (ages 13-16 years, M= 14.75) with spastic cerebral palsy performed a discontinuous maximum bicycle ergometer protocol. Rate of perceived exertion (RPE), heart rate (HR) (V5 lead), and V̇E (Wright respirometer) were recorded each minute. Results indicated that Minutes 1 and 2 of Stage 1 were significantly correlated for RPE and ventilation, and RPE and heart rate were significantly correlated for Minutes 3 and 4 of Stages 1 and 2. Low standard error of estimates values were also evident for each of these minutes wherein significant correlations resulted. Initially, pulmonary strain was perceived as greater than HR for a given RPE value. However, by the conclusion of the second stage, breathing was slightly less than cardiac strain. Results suggest that RPE can be used to predict heart rate after the 2nd minute of discontinuous exercise training or testing. The accurate estimation of ventilation for the initial minutes of exercise may be limited since some anxiety, secondary to hyperventilation, could result. Also, breathing is perceived as a greater strain than heart rate initially but appears to equal and be slightly lower at the conclusion of aerobic exercise.
Michal Botek, Jakub Krejčí, Andrew J. McKune and Barbora Sládečková
trivial effect on postrace RPE, suggesting that increased race intensity was not accompanied by increased perceived effort. These findings are in line with a recently published study in which perceptual strain at an exercise intensity of 4 W·kg −1 for 8 minutes was lower after acute preexercise HRW
Stacey Alvarez-Alvarado, Graig M. Chow, Nicole T. Gabana, Robert C. Hickner and Gershon Tenenbaum
than a passive view of perceptions. The effort-related attention model, which builds on Rejeski’s ( 1985 ) parallel-processing model, views attention allocation as an imperative mediator between physical workload and perceived effort/exertion ( Tenenbaum, 2001 ). Specifically, during low physical
Gavriil G. Arsoniadis, Gregory C. Bogdanis, Gerasimos Terzis and Argyris G. Toubekis
increased anaerobic contribution and induced higher perceived effort, as indicated by the higher BL concentration and RPE. The last observation highlights the importance to consider the interplay of both biomechanical and physiological alterations during training as these are interconnected in order to
Pedro L. Valenzuela, Carlos Amo, Guillermo Sánchez-Martínez, Elaia Torrontegi, Javier Vázquez-Carrión, Zigor Montalvo, Alejandro Lucia and Pedro de la Villa
, elbow flexion), 7 and only in recent years, its effects on whole-body dynamic exercise (ie, cycling) have been tested. 7 Some benefits of tDCS have been reported, such as improvements in performance itself (eg, power output or time to exhaustion) or decreases in the perceived effort for a given
Filipe M. Clemente, Ana F. Silva, Cain C.T. Clark, Daniele Conte, João Ribeiro, Bruno Mendes and Ricardo Lima
league in the season. All the players were monitored for perceived effort and well-being status throughout the season, incorporated into their daily routines. The players were monitored over 36 consecutive weeks, including 237 training sessions and 37 official matches. For each week, the inclusion
Darren J. Paul, Gustavo Tomazoli and George P. Nassis
a method to identify the player’s readiness prior to an upcoming session, rather than making inferences based on the previous days’ rate of exertion. Indeed, using overall perceived effort (as deduced from RPE) might represent an oversimplification of the psychophysiological construct, which in turn
Deborah Hebling Spinoso, Nise Ribeiro Marques, Dain Patrick LaRoche, Camilla Zamfollini Hallal, Aline Harumi Karuka, Fernanda Cristina Milanezi and Mauro Gonçalves
). Greater perceived effort and fatigue, in turn, may reduce habitual gait speed, reduce activity participation, contribute to mobility and ADL disabilities, and increase the probability of falling ( Crombie et al., 2004 ; Parijat & Lockhart, 2008 ; Simonsick, Schrack, Glynn, & Ferrucci, 2014