title: Whole-Body Cryostimulation Limits Overreaching in Elite Synchronized Swimmers.
abstract: BACKGROUND
  Elite athletes frequently undergo periods of intensified training (IT) within their normal training program. These periods can lead athletes into functional overreaching, characterized by high perceived fatigue, impaired sleep, and performance. Because whole-body cryostimulation (WBC) has been proven to be an effective recovery method in the short term (<76 h), we investigated whether daily WBC sessions during IT could prevent exercise and sleep-related signs of overreaching.
  
  
  METHODS
  After a normal training week (BASE), 10 elite synchronized swimmers performed two 2-wk IT periods in a randomized crossover fashion using WBC daily (ITWBC) or not (ITCON), separated by 9 d of light training. Swim time trials (400 m) were performed at BASE and after each IT to quantify blood lactate ([La]B), HR (HR400), salivary alpha amylase ([α-amylase]s400), and cortisol ([cortisol]s400) responses. Swimmers wore a wrist actigraph nightly to monitor sleep patterns.
  
  
  RESULTS
  Swim speed (400 m), [La]B400, and [α-amylase]s400 decreased from BASE to ITCON, although no significant changes were found after ITWBC. Decreased swim speed was correlated to decreased HR400 and [cortisol]s400. During ITCON, significant decreases in actual sleep duration (-21 ± 7 min) and sleep efficiency (-1.9% ± 0.8%) were observed, with increased sleep latency (+11 ± 5 min) and fatigue compared with BASE, although these variables did not change during ITWBC. Using a qualitative statistical analysis, we observed that daily WBC use resulted in a 98%, 59%, 66%, and 78% chance of preserving these respective variables compared with ITCON.
  
  
  CONCLUSIONS
  WBC use during IT helped mitigate the signs of functional overreaching observed during ITCON, such as reduced sleep quantity, increased fatigue, and impaired exercise capacity. These results support the daily use of WBC by athletes seeking to avoid functional overreaching during key periods of competition preparation.
authors.affiliation: 1Laboratory of Sport, Expertise and Performance, French National Institute of Sport, Expertise and Performance, Paris, FRANCE; 2Sports Performance Laboratory, Sports Medicine Program, University of California, Davis, Sacramento, CA; 3Medical Department, French National Institute of Sport, Expertise and Performance, Paris, FRANCE; and 4French Swimming Federation (FFN), Pantin, FRANCE.
authors.forename: Karine
authors.initials: K
authors.lastname: Schaal
authors.forename: Yann
authors.initials: Y
authors.lastname: LE Meur
authors.forename: Julien
authors.initials: J
authors.lastname: Louis
authors.forename: Jean-Robert
authors.initials: JR
authors.lastname: Filliard
authors.forename: Philippe
authors.initials: P
authors.lastname: Hellard
authors.forename: Gretchen
authors.initials: G
authors.lastname: Casazza
authors.forename: Christophe
authors.initials: C
authors.lastname: Hausswirth
mesh_terms: D056044:Actigraphy; D018592:Cross-Over Studies; D017679:Cryotherapy; D005221:Fatigue / Q000517:prevention & control*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis; D019344:Lactic Acid / Q000097:blood; D012463:Saliva / Q000737:chemistry; D012893:Sleep Wake Disorders / Q000517:prevention & control*; D013550:Swimming / Q000502:physiology*; D055815:Young Adult; D000516:alpha-Amylases / Q000032:analysis
chemical_list: D019344:Lactic Acid; D000516:alpha-Amylases; D006854:Hydrocortisone