Practical precooling: Effect on cycling time trial performance in warm conditions

Abstract

The purpose of this study was to compare the effects of two practical precooling techniques (skin cooling vs. skin + core cooling) on cycling time trial performance in warm conditions. Six trained cyclists completed one maximal graded exercise test (VO2(peak) 71.4 +/- 3.2 ml x kg(-1) x min(-1)) and four approximately 40 min laboratory cycling time trials in a heat chamber (34.3 degrees C +/- 1.1 degrees C; 41.2% +/- 3.0% rh) using a fixed-power/variable-power format. Cyclists prepared for the time trial using three techniques administered in a randomised order prior to the warm-up: (1) no cooling (control), (2) cooling jacket for 40 min (jacket) or (3) 30-min water immersion followed by a cooling jacket application for 40 min (combined). Rectal temperature prior to the time trial was 37.8 degrees C +/- 0.1 degrees C in control, similar in jacket (37.8 degrees C +/- 0.3 degrees C) and lower in combined (37.1 degrees C +/- 0.2 degrees C, P < 0.01). Compared with the control trial, time trial performance was not different for jacket precooling (-16 +/- 36 s, -0.7%; P = 0.35) but was faster for combined precooling (-42 +/- 25 s, - .8%; P = 0.009). In conclusion, a practical combined precooling strategy that involves immersion in cool water followed by the use of a cooling jacket can produce decrease in rectal temperature that persist throughout a warm-up and improve laboratory cycling time trial performance in warm conditions.

Self-Paced Exercise Performance in the Heat After Pre-Exercise Cold-Fluid Ingestion

“…[11][12][13][14][15][16][17][18][19][20][21] Direct comparisons with the magnitude of ergogenic effect observed in previous studies are limited because authors of only 2 studies 3,4 used the same protocol as we did, and only Kay et al 4 used the same mode of exercise. Kay et al 4 observed a 6.0% (900 m) improvement in performance when using an identical exercise protocol after 60 minutes of coolwater immersion, and Booth et al 3 observed a 4.2% improvement in distance run in 30 minutes after 60 minutes of coolwater immersion.…”

“…Although these improvements are slightly higher than our findings, our effect does fall within the range of improvement commonly observed for self-paced exercise performance after precooling. 11,15,16,19 For example, Arngrimsson et al 16 observed a 1.1% (13-second) improvement in running time (approximately 19 minutes) for 5 km when participants wore cooling vests during a 38-minute warmup. Quod et al 19 observed a 3.8% (42-second) improvement in time to complete a fixed amount of work during self-paced cycling (approximately 18 minutes) when exercise was preceded by 30 minutes of coolwater immersion and 40 minutes of wearing a cooling vest before a 20-minute warmup.…”

“…No differences were observed for change in T rec during exercise between the cold-fluid condition (1.3 ± 0.3°C) and control-fluid condition (1.5 ± 0.3°C; t 6 = 1.50, P = . 19). Figure 1 illustrates the T rec response to rest and exercise.…”

Precooling and Warm-up Effects on Time Trial Cycling Performance During Heat Stress

“…This demonstrates that maintaining a favorable core to skin thermal gradient, independent of lowering T c before exercise, can positively impact performance. In contrast, another study showed that when applying different cooling procedures prior to a 40-min cycling time trial in the heat, only the procedure (water immersion followed by ice vest) which reduced T c sk and had no effect on performance (Quod et al, 2008) sk per se did not affect intensity during a 7.5-km cycling time trial (Levels et al, 2012). However, wearing a cooling vest and refrigerated band around the head -sk but not T c and improved 20-min cycling time trial performance in a hot and humid environment (29 °C, ~ 80% relative humidity) by an average increase in power output of 17 W compared to control (Gonzales et al, 2014).…”

“…Lowering the initial T c sk ) prior to exercise via precooling has been shown to enhance exercise time to exhaustion (Lee & Haymes, 1995;González-Alonso et al, 1999;Uckert & Joch, 2007) and distance covered in a given period of time (Booth et al, 1997;Kay et al, 1999;Quod et al, 2008) under hot conditions. Some investigators have speculated that a high critical T c (~ 40 °C) is a major limiting physiological factor related to impaired performance in hyperthermia, regardless of the baseline T c at the start of exercise (González-Alonso et al, 1999) and the rate of T c rise (MacDougall et al, 1974).…”