Effects of brief leg cooling after moderate exercise on cardiorespiratory responses to subsequent exercise in the heat

Abstract

We investigated the effects of brief leg cooling after moderate exercise on the cardiorespiratory responses to subsequent exercise in the heat. Following 40 min of ergometer cycling [65% peak oxygen uptake (VO(2peak))] at 35 degrees C (Ex. 1), seven male subjects [21.9 (1.1) years of age; 170.9 (1.9) cm height; 66.0 (2.0) kg body mass; 46.7 (2.0) ml kg(-1) min(-1) VO(2peak)] immersed their legs in 35 degrees C (control condition, CONT) or 20 degrees C (cooling condition, COOL) water for 5 min and then repeated the cycling (as before, but for 10 min) (Ex. 2). Just before Ex. 2, esophageal temperature ( T(es)) was lower in COOL than in CONT [36.9 (0.2) vs 37.5 (0.1) degrees C] ( P<0.01), as also were both mean skin temperature [33.9 (0.2) vs 35.2 (0.2) degrees C] ( P<0.01), and heart rate (HR) [93.2 (6.0) vs 102.7 (4.9) beats min(-1)] ( P<0.05). During Ex. 2, no differences between CONT and COOL were observed in oxygen uptake, arterial blood pressure, blood lactate concentration, or ratings of perceived exertion; however, T(es), skin temperature, and HR were lower in COOL than in CONT. Further, during the first 5 min of Ex. 2, minute ventilation was significantly lower in COOL than in CONT [50.3 (2.0) vs 53.4 (2.6) l min(-1)] ( P<0.01). These results suggest that brief leg cooling during the recovery period may be effective at reducing thermal and cardiorespiratory strain during subsequent exercise in the heat.

Effect of cold water immersion on repeat cycling performance and thermoregulation in the heat

“…The results of the present study indicate that all cold water immersion Water immersion and repeat cycling performance 437 protocols effectively enhanced the maintenance of repeat performance compared with active recovery; suggesting that the reduction in core temperature observed before the second exercise task was beneficial, supporting the notion of an anticipatory regulatory response to exercise in the heat. A decreased heart rate following pre-cooling strategies has been observed (Hayashi et al, 2004;Marsh & Sleivert, 1999;Olschewski & Bruck, 1988;Wilson et al, 2002) and the results of the present study support such a decrease. In the present study, heart rate was significantly reduced during 40 min of passive rest in the heat following all cold water immersion protocols compared with active recovery of the same duration.…”

“…Previously, cold water immersion has been used as a method of pre-cooling before exercise in an attempt to improve performance in hot and humid environmental conditions. Various studies have shown cold water immersion (Eston & Peters, 1999;Merrick et al, 1999) and pre-cooling (Hayashi et al, 2004;Kay et al, 1999;Marsh & Sleivert, 1999) to be effective, providing positive results for recovery and/or subsequent performance.…”

“…While active recovery has been shown to enhance the removal of lactate (Bonen & Belcastro, 1976;Gupta, Goswami, Sadhukhan, & Mathur, 1996;Hayashi et al, 2004;Taoutaou et al, 1996), the effect of active recovery on subsequent performance remains inconclusive, with some studies suggesting active recovery can result in the maintenance of performance (Bogdanis, Nevill, Lakomy, Graham, & Louis, 1996;Monedero and Donne, 2000;Signorile, Ingalls, & Tremblay, 1993;Thiriet et al, 1993), whereas others have suggested that subsequent performance is not maintained or enhanced by active recovery (Watson & Hanley, 1986;Weltman & Regan, 1983). The conflicting findings may be attributed to differences in methodologies, exercise protocols/modalities, and markers of recovery.…”

Strategies to combat heat strain during and after firefighting

“…This technique was found to lower core temperature by 2 1C (tympanic) more rapidly (6 min) than other techniques such as cold air spraying and cool water bath immersion (approximately 18 min- Weiner and Khogali, 1980). More recently, whole leg water immersion for 5 min at 20 1C after work in the heat has been shown to be effective in reducing thermal and cardiovascular strain in subsequent work (Hayashi et al, 2004). These methods of cooling which may generate less intense cold stimulus intensities at the skin than with hand immersion, therefore avoiding the potential reflexive reduction of skin blood flow, may be worth considering by the emergency services as alternative cooling techniques.…”

The cross-sectional relationships among hyperthermia-induced hyperventilation, peak oxygen consumption, and the cutaneous vasodilatory response during exercise

“…During prolonged dynamic exercise at a constant workload in the heat, minute ventilation ( _ VE) increases progressively, suggesting that the increase could be associated with increasing body temperature (Dempsey et al 1975;Fujii et al 2008b, c;Hayashi et al 2004Hayashi et al , 2006Nybo and Nielsen 2001). We recently reported that _ VE increases in proportion to increasing core temperature during dynamic exercise at 50% of peak oxygen uptake ( _ VO 2peak ), although there was a great deal of individual variability in the ventilatory response to increasing body temperature (Hayashi et al 2006).…”