Konstantinidou and Chairopoulou. Arch Sports Med 2017, 1(1):20-30 *Corresponding author: Sylvia Konstantinidou, Division of Aquatic Sports, School of Physical Education and Sports Sciences, National & Kapodistrian University of Athens, Ethnikis Antistasis 41, Dafni 17237, Athens, Greece, E-mail: sylvia_konst@phed.uoa.gr Received: February 16, 2017: Accepted: May 05, 2017: Published online: May 08, 2017 Citation: Konstantinidou S, Chairopoulou C (2017) Physio- logical Adaptations of Apnea-Conditioned Athletes and their Implications for Synchronized Swimmers’ Performance. Arch Sports Med 1(1):20-30 Copyright: © 2017 Konstantinidou S, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Review Article Open Access • Page 20 • Archives of Sports Medicine DOI: 10.36959/987/225 | Volume 1 | Issue 1 Physiological Adaptations of Apnea-Conditioned Athletes and their Implications for Synchronized Swimmers’ Performance Sylvia Konstantinidou* and Chrysoula Chairopoulou School of Physical Education & Sports Science, National & Kapodistrian University of Athens, Greece Abstract Introduction: Apneas form an essential tool for training in aquatics including swimming, fn swimming and synchronized swimming (SS). We examine the direct responses and the long-term physiological adaptations to acute apnea and apnea training respectively in order to determine their potential impact on SS athletes’ performance. Evidence acquisition: A literature review was conducted using as keywords apnea, hypoxia, diving response and synchro- nized swimming. Evidence synthesis: Apnea-trained individuals demonstrate more efective responses to acute hypoxia compared to con- trols including stronger diving response and other hematological variables. Te latter involves an elevated hematocrit and hemoglobin and reduced blood acidosis. Long-term physiological adaptations to apnea training largely in divers include bigger lungs, stronger respiratory muscles and increased blood circulation in the brain possibly accountable for their supe- rior reaction to hypoxic conditions. Conclusions: Physiological responses to acute apnea and apnea training may favourably infuence SS athletes’ perfor- mance. Apnea adaptations are manifested not only in improved tolerance to hypoxia and oxygen conservation but also, in delayed blood acidosis. Attempts to illuminate apnea-conditioned athletes’ physiological adaptations to hypoxia may refer to the trigeminovagal refexes e.g., the diving response and to the cold shock response. Arguably, these interrelated yet not elucidated refexes are activated with apnea and cold water immersion. As apnea-training adaptations resemble alti- tude acclimatisation, future research may compare the impact of the exposure between these two conditions on athletes’ performance. Finally, attention should be drawn to the reduced chemo-sensitivity to hypoxia found in apnea-conditioned individuals as it might be life threatening. Keywords Apnea, Physiological adaptations, Synchronized swimming, Diving response Introduction Synchronized swimming (SS) is an Olympic sport that encompasses swimming, dancing and gymnastics combined with repeated water submersions. SS pro- grams are performed in solos, duets, trios, combos or in teams of men and women athletes. SS demands excellent swimming and sport-specifc skills e.g. sculling, aerobic endurance and anaerobic power and strength, extraordi- nary fexibility and agility [1-3]. Performance is scored equally for technical and artistic skills by a panel of judg- es [4]. SS athletes’ ability to control their breath while in mo- tion to perform routines and fgures is vital for achieving high scores. Figures are specifc lifs, throw and move while routines are divided into (a) technical and (b) free. Technical routines are compulsory rudiments executed in a specifc order though; “free routines” are open to athletes’ creativity. Routine duration increases with the number of competitors but it is also determined by their age and skill level. It ranges from 2.5 min to 5 min i.e.,