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The effect of water immersion, active recovery and passive recovery on repeated bouts of explosive exercise and blood plasma fraction
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Optimising recovery post-game or post-training could provide a competitive advantage to an athlete, especially if more than one bout of exercise is performed in a day. Active recovery is one common method that is thought to enhance the recovery process. Another recovery method that is gaining popularity is water immersion. The objective of this thesis was to analyse whether these two recovery methods provided greater recovery from explosive exercise than passive recovery. A physiological rationale that may explain the possibility of enhanced recovery with water immersion was initially investigated. The literature surrounding active recovery, water immersion and passive recovery on strength, cycling, running and jumping was then examined. Following these reviews an experimental study was conducted investigating the effects of water immersion, active recovery and passive recovery conducted after repeated bouts of explosive exercise. The rationale for active recovery post-exercise is that during intense exercise, fluid from the blood is forced into the working muscles due to the increase in mean arterial pressure, which increases muscle volume and decreases blood plasma fraction. Active recovery reduces this exercise induced edema and, with an associated increase in blood flow throughout the body, may increase the metabolism of waste substrates produced during exercise. Researchers have observed this increased substrate metabolism with reductions in post-exercise blood lactate accumulation following active recovery. Water immersion would appear to cause a similar physiological response to active recovery without the need to expend extra energy. When a large portion of the body is immersed, hydrostatic pressure acts on the body's fluids within the immersed region. Fluids from the extravascular space move into the vascular system reducing exercise-induced increases in muscular volume and reducing soft tissue inflammation. Additionally, blood volume increases and is redistributed towards the central cavity, which in turn increases cardiac preload, stroke volume, cardiac output, and blood flow throughout the body. Cardiac output increases in relation to the depth of immersion and have been observed to increase by as much as 102% during head-out immersions. These cardiovascular responses occur without any increase in energy expenditure. If extra-intravascular fluid movement is enhanced, then the movement and metabolism of waste substrates could increase. Observations of increased post-exercise blood lactate clearance with water immersion would support this theory. Most methodologies studying the performance benefits of active recovery and water immersion suffer many limitations. These limitations often consist of the experimental time schedule not replicating what is likely to occur in a practical situation, no isolation of water temperature and hydrostatic pressure effects, and lack of a sport-like exercise consisting of repeated expressions of explosive power. Light-intensity active recovery and water immersion do not appear to be detrimental to performance, but neither does there appear to be enough evidence to claim they are beneficial. Effects of active recovery and water immersion would seem to be trivial to small, with any benefits more likely following multiple bouts of high-intensity exercise and recovery or following muscle damaging exercise. There may be a link between blood plasma fraction and performance, however, evidence is inconclusive. Given these issues and limitations the aim of this research was to investigate whether combinations of active recovery, water immersion and passive recovery could maintain peak power and work during subsequent bouts of explosive exercise. We also investigated whether there was any difference in subjects' blood plasma faction and perceived fatigue between the recovery modes. A cross-over experiment was conducted on seven subjects over four weeks. On the same day of each week subjects performed three sessions of maximal jumping, each two hours apart, followed by a different recovery method. Each jump session consisted of three sets of 20 maximal jumps repeated every three seconds, with a minute's rest in-between. Immediately following the jumping subjects performed 10 minutes of either (A) active recovery on a cycle ergometer followed by seated rest, (I) immersion to the gluteal fold in 19°C water followed by seated rest, (AI) active recovery followed by immersion, or (P) seated passive rest. Jumping was conducted on an instrumented supine squat machine that allowed the measurement of total peak power and total work. Pre-jump, post jump and post-recovery blood was taken and the percentage of blood plasma fraction calculated. Perceived leg fatigue was also measured at these times. Observed differences in total peak power and total work between the recovery modes were non-significant. No differences were observed in the change of blood plasma fraction between the recovery modes or perceived fatigue. One reason for any lack of difference between the recovery modes may have been the brevity of the recovery time. Research that has observed significant benefits of active recovery and water immersion compared to passive recovery have used recovery times greater of 15 minutes or more. Additionally, changes in blood plasma fraction between active recovery, water immersion and passive recovery have not been apparent until at least 10 minutes post-recovery in previous research. Alternatively, rather than brevity, it may be that active recovery or water immersion simply does not provide any benefit to performance recovery. Overall there is a meagre amount of research into active recovery, water immersion and passive recovery. Further research that incorporates a variety of exercise and recovery protocols is required.