Effect of High-Intensity Submaximal Work, with or without Rest, on Subsequent V square O sub(2max)

Purpose: In practice, tests of maximal oxygen uptake (V square O sub(2max)) are often preceded by a lactate profile, a highly intense but submaximal exercise bout. The V square O sub(2max) response to preceding high-intensity submaximal exercise, with or without a rest period, has not been determined. If V square O sub(2max) is limited after a lactate profile, exercise-induced hypoxemia (EIH) may explain the deficit. The purposes of this study were to: 1) examine the effects of high-intensity submaximal exercise, with or without rest, on subsequent V square O sub(2max); and 2) evaluate the role of EIH in causing any observed changes. Methods: Ten healthy, well-trained, male cross-country skiers (age = 20.5 plus or minus 4.7 yr, height = 181.6 plus or minus 6.0 cm, mass = 72.1 plus or minus 5.7 kg) completed three exercise trials: an incremental run to fatigue (MAX), MAX preceded by a high-intensity submaximal run (lactate profile) and a 20-min rest period (discontinuous protocol [DC]), and MAX preceded by a high-intensity submaximal exercise run with no rest (continuous protocol [C]). V square O sub(2), minute ventilation, and arterial oxygen saturation were measured throughout, and diffusion capacity was evaluated 2 min postexercise. Results: No significant between trial differences were observed, although the difference between V square O sub(2max) determined during the MAX trial (62.7 plus or minus 6.7 mL times kg super(-1) times min super(-1)) and during the DC trial (58.3 plus or minus 4.4 mL times kg super(-1) times min super(-1)) approached significance (P = 0.059). DC V square O sub(2max) responses could be separated into two groups: five responders whose V square O sub(2max) suffered during the DC trial (decreased >7.5% from MAX) and five nonresponders, whose V square O sub(2max) was unaffected by preceding submaximal exercise and a rest period. Responders showed greater aerobic capacity during the MAX trial. Conclusion: V square O sub(2max) is significantly reduced in approximately 50% of cross-country skiers when a maximal exercise test is preceded by high-intensity submaximal exercise and a 20 min rest period; the role of EIH in causing these reductions is unclear.