IMPLICATIONS OF MODERATE ALTITUDE TRAINING FOR SEA-LEVEL ENDURANCE INELITE DISTANCE RUNNERS

Elite distance runners participated in one of two studies designed to investigate the effects of moderate altitude training (inspiratory par tial pressure of oxygen approximate to 115-125 mmHg) on submaximal, ma ximal and supramaximal exercise performance following return to sea-le vel. Study 1 (New Mexico, USA) involved 14 subjects who were assigned to a 4-week altitude training camp (1500-2000m) whilst 9 performance-m atched subjects continued with an identical training programme at sea- level (CON). Ten EXP subjects who trained at 1640 m and 19 CON subject s also participated in study 2 (Krugersdorp, South Africa). Selected m etabolic and cardiorespiratory parameters were determined with the sub jects at rest and during exercise 21 days prior to (PRE) and 10 and 20 days following their return to sealevel (POST). Whole blood lactate d ecreased by 23% (P < 0.05 vs PRE) during submaximal exercise in the EX P group only after 20 days at sea-level (study 1). However, the lactat e threshold and other measures of running economy remained unchanged. Similarly, supramaximal performance during a standardised track sessio n did not change. Study 2 demonstrated that hypoxia per se did not alt er performance. In contrast, in the EXP group supramaximal running vel ocity decreased by 2% (P < 0.05) after 20 days at sea-level. Both stud ies were characterised by a 50% increase in the frequency of upper res piratory and gastrointestinal tract infections during the altitude soj ourns, and two male subjects were diagnosed with infectious mononucleo sis following their return to sea-level (study 1). Group mean plasma g lutamine concentrations at rest decreased by 19% or 143 (74) mu M (P < 0.001) after 3 weeks at altitude, which may have been implicated in t he increased incidence of infectious illness.