Die effek van krioterapie op die akute herstel van universiteit-netbalspelers se onderbeenspiere
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In the last few years researchers have more and more focussed on the possible use of cryotherapy as an acute and long term recovery facilitating technique by sportsmen and women. Barnette (2006) did, however, state that research supporting cryotherapy as a recovery facilitating technique, is not convincing and that the majority of research show that it has a negative impact on the recovery of subjects after exercise. It is against this background that the aim of the study was firstly to critically analyse the available literature of the past fifteen years (1992-2007) with regard to the study subject; die nature of the cryotherapy technique that was used as well as the findings with regards to the effects of these types of techniques on a wide variety of physiological variables, physical and motor performance; secondly, to provide guidelines for the use of cryotherapy as a recovery facilitating technique and thirdly to determine the effect of cryotherapy on the acute recovery of University netball players' lower leg muscles in an isokinetic ankle exercise. Firstly, it was shown that ice water immersion and ice pack application are the most common techniques that are used in cryotherapy studies. The results in the majority of articles indicated that cryotherapy had a non-significant acute effect on isokinetic, eccentric and concentric peak torque as well as time to reach peak torque and the angle at which the peak torque was reached; isometric, maximal and sub-maximal strength and accuracy of strength execution; normalized, average vertical ground reaction force as well as time of reaching peak power and vertical jump height; baseball pitching accuracy, proprioception, ankle joint range of movement, positioning and speed during execution of a movement; blood lactate removal and blood flow speed as well as muscle soreness after completion of an exercise. With regard to the long term effects of cryotherapy research showed that isotonic hand grip strength and endurance, plasma adrenaline, non-adrenaline, dopamine, renine, aldosterone, heart rate and blood pressure after 6 weeks; respiratory gas exchange ratio, heart rate, muscle glycogen concentration, plasma lactate, glucose and free fatty acids after 8 weeks or brachial artery cross-section and vascular endothelial growth factor after 4 weeks of exercise and cryotherapy did not experience any significant changes between the cryotherapy and control group. Other physical, motor performance and physiological variables did not show a certain trend with regards to the way they were affected by cryotherapy. In some cases variables were affected significantly negatively while the opposite was true in other cases where variables were significantly positively influenced. With regard to the results of the study on the acute recovery of University netball players' lower leg muscles due to cryotherapy, it was found that the acute recovery of only four isokinetic variables were significantly influenced (p = 0.05) by cryotherapy, namely: left leg relative total dorsiflexion work, average peak dorsiflexion torque, right dorsiflexion and plantar flexion endurance. The acute recovery of the first mentioned strength endurance related variable was significantly negatively influenced by the cryotherapy. In contrast with this result the acute recovery of the three last mentioned isokinetic muscle relative peak torque and endurance related variables were significantly positively influenced by the cryotherapy. The overall conclusion that can therefore be drawn from the above-mentioned results show that the majority of isokinetic plantar- and dorsiflexion torque variables (12 out of 16, 75%) as well as other physical, motor performance and physiological variables experience no significant effect with regards to acute and long term recovery due to cryotherapy. The research did, however, show that the effectiveness of cryotherapy was influenced by the adiposity thickness, nature of the cryotherapy application, type of medium that was used for cryotherapy application and the length of time during which cryotherapy was applied. The recommendation for the use of cryotherapy as a recovery facilitating technique can be summarised as follows: the temperature of the cryotherapy medium that is used, must vary between 5°C and 10°C; the duration of cryotherapy between 15 and 20 minutes; the most general application area: for ice water immersion - immersed up until the level of the gluteal fold or crista ileac and the whole arm or forearm; for ice pack application - on the thigh, ankle and peripheral of the shoulder; the most common and effective ice pack application is direct on the skin surface by means of a bag filled with between 500 g and 1 500 g cubic formed ice. For long term use more that 2 consecutive days of cryotherapy application is recommended.
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