It is evident that there is a physiological adaption and marked response in ‘diving animals’ (Andersson, Liner, Runow & Schagatay, 2002, 2004). This diving response is a collection of reflexes which conserve oxygen for the brain and heart during submergence; these responses consist of apnea (breath-holding), reduction in heart rate, peripheral vasoconstriction and an augmented dependence on anaerobic metabolism. However, this evidence is less clear in humans (Andersson et al. 2002, 2004). The question that arises: is there potential oxygen conservation in diving man?
Anderson et al. (2002) identifies that the human diving response is initiated to some degree by apnea and increased by several factors which include hypoxia and cold-water face immersions. Anderson et al. (2002, 2004) also recognizes that the human diving response has an oxygen-conserving effect during exercise.
This study explores the trainability of apnea capacity in cold water by testing the effects of immersing the face of exercising subjects in cold water. B. Methodology Ten healthy male test subjects, aged (18-30yr), height (170-190cm), weight (71-103 kg) and all nonsmokers with informed consent and clearance from research ethics committee, will participate in the study. All subjects must be involved in breath-hold diving (e. g. underwater sports like rugby/ hockey) for at least two hours per week. A series of experiments, each consisting of two test conditions will be done. Apnea with immersion in cold water (10 °C) and apnea in air (as a control) (24. 3°C). Subjects will exercise on stationery cycles to increase overall oxygen use, while face-immersion in cold water which will be positioned in a container, safely secured to the cycle. For immersion tests, subjects should immerse the face up to the temples.
Posture for each subject will be controlled during all apneas. At the beginning of the test, subjects should take a deep but not maximal breath and then hold it. Subjects should not hyperventilate before holding their breath. Each apnea will last 35s with exercise at a constant workload of 80W-starting five minutes before the first apnea and continuing five minutes after the last apnea.
Each test will be repeated five times to determine whether subjects can achieve greater reduced heart rates by habituation. C. Measurements According to Anderson et al. (2002) instrumentation should be checked for anomalies before the test begins. Vital capacity of each subject will be measured at rest with a spirometer. The heart rate will continuously be measured with a heart rate monitor. The mean arterial blood pressure during apnea and exercise measured with Finapres and arterial haemoglobin oxygen saturation with an earlobe pulse oximeter (Anderson et al. 2002).
Sex differences: Males and females may have differences in heart rates and therefore respond differently to facial immersions. 2. Paired analysis: Subject undergoes both test conditions which is more powerful than unpaired or two-sample analysis. E. Limitations and variables of methodology 1. Training effect: Trained swimmers/divers may show greater reduced heart rate due to extended breath hold times.
2. Psychological control: Stress or a sense of control or lack thereof can affect the outcome. 3. Water: Critical components of water such as wetness, temperature or even pressure may affect the desired outcome. 4. Increased sample size: More individuals measured in sample; increases the statistical difference in the population. F. Conclusion, results of the study should demonstrate a higher diving response in cold-water immersion than in air, suggesting that there will be more oxygen available for vital organs (Anderson et al. 2002, 2004) and therefore; encouraging the idea of apnea training in cold water.
References
Andersson, J. P. A. , Liner, M. H. , Runow, E. , Schagatay, E. K. A (2002). [Electronic version]. Diving response and arterial oxygen saturation during apnea and exercise in breath-hold divers. Jounal of Applied Physiology 93(3), 882-886. Retrieved February 13, 2007, from http://jap. physiology. org/cgi/reprint/93/3/882. pdf Andersson, J. P. A. , Liner, M. H. , Runow, E. , Schagatay, E. K. A (2004). [Electronic version]. Cardiovascular and respiratory responses to apneas with and without face immersion in exercising humans. Journal of Applied Physiology 96(3), 1005-1010. Retrieved February 13, 2007, from http://jap. physiology. org/cgi/content/full/96/3/1005