The effect of minimal differences in the skin-to-air vapor pressure gradient at various dry-bulb temperatures on self-paced exercise performance

Author(s):  
Felicity M. Bright ◽  
Brad Clark ◽  
Ollie Jay ◽  
Julien D. Periard

The effects of dry-bulb temperature on self-paced exercise performance, along with thermal, cardiovascular and perceptual responses, were investigated by minimizing differences in the skin-to-air vapor pressure gradient (Psk,sat-Pa) between temperatures. Fourteen trained male cyclists performed 30-km time trials in 13˚C and 44% relative humidity (RH), 20˚C and 70% RH, 28˚C and 78% RH, and 36˚C and 72% RH. Power output was similar in 13˚C (275±31 W; mean and SD) and 20˚C (272±28 W; P=1.00), lower in 36˚C (228±36 W) than 13˚C, 20˚C and 28˚C (262±27 W; P<0.001) and lower in 28˚C than 13˚C and 20˚C (P<0.001). Peak rectal temperature was higher in 36˚C (39.6±0.4˚C) than all conditions (P<0.001) and higher in 28˚C (39.1±0.4˚C) than 13˚C (38.7±0.3˚C; P<0.001) and 20˚C (38.8˚C±0.3˚C; P<0.01). Heart rate was higher in 36˚C (163±14 beats·min-1) than all conditions (P<0.001) and higher in 20˚C (156±11 beats·min-1; P=0.009) and 28˚C (159±11 beats·min-1; P<0.001) than 13˚C (153±11 beats·min-1). Cardiac output was lower in 36˚C (16.8±2.5 l·min-1) than all conditions (P<0.001) and lower in 28˚C (18.6±1.6 l·min-1) than 20˚C (19.4±2.0 l·min-1; P=0.004). Ratings of perceived exertion were higher in 36˚C than all conditions (P<0.001) and higher in 28˚C than 20˚C (P<0.04). Self-paced exercise performance was maintained in 13˚C and 20˚C at a matched evaporative potential, impaired in 28˚C and further compromised in 36˚C in association with a moderately lower evaporative potential and marked elevations in thermal, cardiovascular and perceptual strain.

Author(s):  
Ben M. Krings ◽  
Brandon D. Shepherd ◽  
Hunter S. Waldman ◽  
Matthew J. McAllister ◽  
JohnEric W. Smith

Carbohydrate mouth rinsing has been shown to enhance aerobic exercise performance, but there is limited research with resistance exercise (RE). Therefore, the purpose of this investigation was to examine the effects of carbohydrate mouth rinsing during a high-volume upper body RE protocol on performance, heart rate responses, ratings of perceived exertion, and felt arousal. Recreationally experienced resistance-trained males (N = 17, age: 21 ± 1 years, height: 177.3 ± 5.2 cm, mass: 83.5 ± 9.3 kg) completed three experimental sessions, with the first serving as familiarization to the RE protocol. During the final two trials, the participants rinsed a 25-ml solution containing either a 6% carbohydrate solution or an artificially flavored placebo in a randomized, counterbalanced, and double-blinded fashion. The participants rinsed a total of nine times immediately before beginning the protocol and 20 s before repetitions to failure with the exercises bench press, bent-over row, incline bench press, close-grip row, hammer curls, skull crushers (all completed at 70% one-repetition maximum), push-ups, and pull-ups. Heart rate, ratings of perceived exertion, and felt arousal were measured at the baseline and immediately after each set of repetitions to failure. There were no differences for the total repetitions completed (carbohydrate = 203 ± 25 repetitions vs. placebo = 201 ± 23 repetitions, p = .46, Cohen’s d = 0.10). No treatment differences were observed for heart rate, ratings of perceived exertion, or felt arousal (p > .05). Although carbohydrate mouth rinsing has been shown to be effective in increasing aerobic performance, the results from this investigation show no benefit in RE performance in resistance-trained males.


2011 ◽  
Vol 46 (6) ◽  
pp. 592-599 ◽  
Author(s):  
Christopher Byrne ◽  
Craig Owen ◽  
Aurélien Cosnefroy ◽  
Jason Kai Wei Lee

Context: Precooling is the pre-exercise reduction of body temperature and is an effective method of improving physiologic function and exercise performance in environmental heat. A practical and effective method of precooling suitable for application at athletic venues has not been demonstrated. Objective: To confirm the effectiveness of pre-exercise ingestion of cold fluid without fluid ingestion during exercise on pre-exercise core temperature and to determine whether pre-exercise ingestion of cold fluid alone without continued provision of cold fluid during exercise can improve exercise performance in the heat. Design: Randomized controlled clinical trial. Setting: Environmental chamber at an exercise physiology laboratory that was maintained at 32°C, 60% relative humidity, and 3.2 m/s facing air velocity. Patients or Other Participants: Seven male recreational cyclists (age = 21 ± 1.5 years, height = 1.81 ± 0.07 m, mass = 78.4 ± 9.2 kg) participated. Intervention(s): Participants ingested 900 mL of cold (2°C) or control (37°C) flavored water in 3 300-mL aliquots over 35 minutes of pre-exercise rest. Main Outcome Measure(s): Rectal temperature and thermal comfort before exercise and distance cycled, power output, pacing, rectal temperature, mean skin temperature, heart rate, blood lactate, thermal comfort, perceived exertion, and sweat loss during exercise. Results: During rest, a greater decrease in rectal temperature was observed with ingestion of the cold fluid (0.41 ± 0.16°C) than the control fluid (0.17 ± 0.17°C) over 35 to 5 minutes before exercise (t6 = −3.47, P = .01). During exercise, rectal temperature was lower after ingestion of the cold fluid at 5 to 25 minutes (t6 range, 2.53–3.38, P ≤ .05). Distance cycled was greater after ingestion of the cold fluid (19.26 ± 2.91 km) than after ingestion of the control fluid (18.72 ± 2.59 km; t6 = −2.80, P = .03). Mean power output also was greater after ingestion of the cold fluid (275 ± 27 W) than the control fluid (261 ± 22 W; t6 = −2.13, P = .05). No differences were observed for pacing, mean skin temperature, heart rate, blood lactate, thermal comfort, perceived exertion, and sweat loss (P &gt; .05). Conclusions: We demonstrated that pre-exercise ingestion of cold fluid is a simple, effective precooling method suitable for field-based application.


Author(s):  
Gabriela Tomedi Leites ◽  
Paulo Lague Sehl ◽  
Giovani Dos Santos Cunha ◽  
Adriano Detoni Filho ◽  
Flavia Meyer

DOI: http://dx.doi.org/10.5007/1980-0037.2016v18n2p143 It’s unclear whether the combination of intense, chronic training and heat exposure during prepubescence improves thermoregulatory responses to exercise in artistic gymnastics athletes. The objective of this study was to compare thermoregulatory and perceptual responses between artistic gymnastics athletes and non-athlete girls while exercising both in heat and thermoneutral conditions. Seven athletes (8.7 ± 1.3 yrs) and 7 nonathletes (9.4 ± 1.5 yrs) cycled for 30 min at load (W) of ~55% VO2peak, on two separate occasions in a randomized order: heat (35˚C, 40% relative humidity) and thermoneutral conditions (24˚C, 50% relative humidity). Rectal temperature, heart rate, rate of perceived exertion, thermal sensation, thermal comfort and irritability were measured throughout the exercise. Initial rectal temperature was similar between athletes and non-athletes in both heat (37.2 ± 0.4 vs. 37.4 ± 0.2˚C, respectively) and thermoneutral conditions (37.3 ± 0.2 vs. 37.3 ± 0.3˚C). Final rectal temperature was similar between groups (38.0 ± 0.2 vs. 38.2 ± 0.2˚C in heat and 37.8 ± 0.2 vs. 37.9 ± 0.2˚C in thermoneutral conditions). Initial heart rate was lower in athletes in the heat (76 ± 7 vs. 91 ± 11 bpm, P = 0.01); however, throughout cycling, it became similar between groups. Athletes reported similar perceptual responses compared to non-athletes, with the exception of higher thermal comfort in the 10th minute of exercise in thermoneutral conditions (P = 0.003). It was concluded that athletes were similar to non-athletes with respect to thermoregulatory and perceptual responses during 30 min of cycling at similar relative intensities.


2015 ◽  
Vol 118 (10) ◽  
pp. 1258-1265 ◽  
Author(s):  
Julien D. Périard ◽  
Sébastien Racinais

This study examined the time course and extent of decrease in peak oxygen uptake (V̇o2peak) during self-paced exercise in HOT (35°C and 60% relative humidity) and COOL (18°C and 40% relative humidity) laboratory conditions. Ten well-trained cyclists completed four consecutive 16.5-min time trials (15-min self-paced effort with 1.5-min maximal end-spurt to determine V̇o2peak) interspersed by 5 min of recovery on a cycle ergometer in each condition. Rectal temperature increased significantly more in HOT (39.4 ± 0.7°C) than COOL (38.6 ± 0.3°C; P < 0.001). Power output was lower throughout HOT compared with COOL ( P < 0.001). The decrease in power output from trial 1 to 4 was ∼16% greater in HOT ( P < 0.001). Oxygen uptake (V̇o2) was lower throughout HOT than COOL ( P < 0.05), except at 5 min and during the end-spurt in trial 1. In HOT, V̇o2peak reached 97, 89, 85, and 85% of predetermined maximal V̇o2, whereas in COOL 97, 94, 93, and 92% were attained. Relative exercise intensity (%V̇o2peak) during trials 1 and 2 was lower in HOT (∼84%) than COOL (∼86%; P < 0.05), decreasing slightly during trials 3 and 4 (∼80 and ∼85%, respectively; P < 0.05). However, heart rate was higher throughout HOT ( P = 0.002), and ratings of perceived exertion greater during trials 3 and 4 in HOT ( P < 0.05). Consequently, the regulation of self-paced exercise appears to occur in conjunction with the maintenance of %V̇o2peak within a narrow range (80-85% V̇o2peak). This range widens under heat stress, however, when exercise becomes protracted and a disassociation develops between relative exercise intensity, heart rate, and ratings of perceived exertion.


1999 ◽  
Vol 2 (1) ◽  
pp. 17-26
Author(s):  
Leon Straker ◽  
Carol Cain

A comparison between semi-squat and squat techniques was made for floor to knuckle height lifting using maximum acceptable weight (MAW), ratings of perceived exertion (RPE) and heart rate. Semi-squat lifting resulted in greater MAW with lower RPE and lower heart rate compared to squat lifting. Discomfort was most commonly reported in knees/quadriceps with squat lifting. Twelve of the 13 subjects preferred the semi-squat technique. The results provide evidence that the semi-squat technique may have benefits over the squat technique for lifting a medium sized box from floor to knuckle height.


2009 ◽  
Vol 23 (4) ◽  
pp. 1292-1299 ◽  
Author(s):  
Michelle Mielke ◽  
Terry J Housh ◽  
C Russell Hendrix ◽  
Clayton L Camic ◽  
Jorge M Zuniga ◽  
...  

2005 ◽  
Vol 100 (2) ◽  
pp. 357-361 ◽  
Author(s):  
Meir Magal ◽  
Robert F. Zoeller

Ratings of perceived exertion (RPE) are used for exercise programming of cardiac rehabilitation patients, whenever it is difficult to use heart rate to set intensity due to medication or other factors. This investigation examined the physiological responses to two stepping exercise modes (upright and recumbent) at the same RPE. Analysis indicated significant physiological differences between the modes of exercise which may be mediated by postural differences. Specifically, the physiological responses to the recumbent exercise, but not the upright exercise, had the expected relationship with RPE, with recumbent stepping requiring less physiological effort than the upright stepping at the same RPE. As such, we cannot recommend with confidence that the prescription for upright exercise be made based on data from recumbent exercise or vice-versa.


2021 ◽  
Vol 38 (5) ◽  
pp. 343-349
Author(s):  
Ananda S. Cardoso ◽  
Guilherme P. Berriel ◽  
Pedro Schons ◽  
Rochelle R. Costa ◽  
Luiz Fernando M. Kruel

The aim of this research was to evaluate the behavior of vertical jumps performance in professional volleyball athletes during matches and training and their relationships with fatigue and recovery through heart rate variability (HRV), ratings of perceived exertion (RPE) and perceived recovery status (PRS). Nine male professional volleyball athletes participated in the study, with mean age: 25.66 ± 5.7 years, mean body mass: 97.81 ± 8.65 Kg and mean height: 200.94 ± 5.19 cm, with experience in national and international competitions. HRV and PRS were evaluated in the morning of matches and in the presentation for the first day of training after matches. RPE was collected immediately after matches and at the end of training days. Jumps performance was monitored during the matches and during the first days of training. The data was grouped by matches and training sessions. Significance level adopted was α ≤ 0.05. There were no alterations in HRV and PRS evaluated after matches and before training sessions, as well as in RPE after training. Jumps height was greater during the matches (p< 0.013) and there were no differences in the number of jumps. There was a positive correlation between the number of jumps during matches and PRS before matches (r= 0.336, p= 0.015) and a negative correlation between the number of jumps during training and pre-training PRS (r= -0.318, p= 0.002). We conclude that the recovery period proposed by the team proved to be sufficient for the athletes to maintain the same condition for returning to training. This information can assist physical trainers to prescribe training loads for the return to training.


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