title: The effect of prolonged physical activity performed during extreme caloric deprivation on cardiac function.
abstract: BACKGROUND
  Endurance exercise may induce transient cardiac dysfunction. Data regarding the effect of caloric restriction on cardiac function is limited. We studied the effect of physical activity performed during extreme caloric deprivation on cardiac function.
  
  
  METHODS
  Thirty-nine healthy male soldiers (mean age 20 ± 0.3 years) were studied during a field training exercise lasted 85-103 hours, with negligible food intake and unlimited water supply. Anthropometric measurements, echocardiographic examinations and blood and urine tests were performed before and after the training exercise.
  
  
  RESULTS
  Baseline VO(2) max was 59 ± 5.5 ml/kg/min. Participants' mean weight reduction was 5.7 ± 0.9 kg. There was an increase in plasma urea (11.6 ± 2.6 to 15.8 ± 3.8 mmol/L, p<0.001) and urine osmolarity (692 ± 212 to 1094 ± 140 mmol/kg, p<0.001) and a decrease in sodium levels (140.5 ± 1.0 to 136.6 ± 2.1 mmol/L, p<0.001) at the end of the study. Significant alterations in diastolic parameters included a decrease in mitral E wave (93.6 to 83.5 cm/s; p = 0.003), without change in E/A and E/E' ratios, and an increase in iso-volumic relaxation time (73.9 to 82.9 ms, p = 0.006). There was no change in left or right ventricular systolic function, or pulmonary arterial pressure. Brain natriuretic peptide (BNP) levels were significantly reduced post-training (median 9 to 0 pg/ml, p<0.001). There was no elevation in Troponin T or CRP levels. On multivariate analysis, BNP reduction correlated with sodium levels and weight reduction (R = 0.8, p<0.001).
  
  
  CONCLUSIONS
  Exposure to prolonged physical activity performed under caloric deprivation resulted in minor alterations of left ventricular diastolic function. BNP levels were significantly reduced due to negative water and sodium balance.
authors.affiliation: Heart Institute, Hadassah - Hebrew University Medical Center, Jerusalem, Israel. davidplaner@gmail.com
authors.forename: David
authors.initials: D
authors.lastname: Planer
authors.forename: David
authors.initials: D
authors.lastname: Leibowitz
authors.forename: Amir
authors.initials: A
authors.lastname: Hadid
authors.forename: Tomer
authors.initials: T
authors.lastname: Erlich
authors.forename: Nir
authors.initials: N
authors.lastname: Sharon
authors.forename: Ora
authors.initials: O
authors.lastname: Paltiel
authors.forename: Elad
authors.initials: E
authors.lastname: Jacoby
authors.forename: Chaim
authors.initials: C
authors.lastname: Lotan
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Moran
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D001835:Body Weight; D031204:Caloric Restriction; D004452:Echocardiography / Q000379:methods; D015444:Exercise; D006321:Heart / Q000502:physiology / Q000503:physiopathology*; D006801:Humans; D007557:Israel; D008297:Male; D008889:Military Personnel; D020097:Natriuretic Peptide, Brain / Q000097:blood; D010101:Oxygen Consumption; D010806:Physical Education and Training; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology; D018497:Ventricular Dysfunction, Right / Q000503:physiopathology
chemical_list: D015415:Biomarkers; D020097:Natriuretic Peptide, Brain