Purpose: It has been suggested that exercise-induced changes in plasma volume (PV) confound the interpretation of biochemical data obtained during the recovery period from exercise. No studies have sought to assess the effect of short-duration, high-intensity exercise on PV change and plasma lipid and lipoprotein concentrations. The purpose of this study was to compare power profiles, changes in PV, and plasma lipid and lipoprotein concentrations immediately after and 24 h after exercise.
Methods: Subjects undertook two 30-s, high-intensity cycle ergometer protocols after optimization of resistive loads calculated from total body mass (TBM) and fat-free mass (FFM). Power output indices were recorded and blood samples were analyzed before, immediately after, and 24 h after exercise.
Results: Peak power outputs were significantly greater in FFM (1020+/-134 vs 953+/-114 W for FFM and TBM, respectively, P<0.05). No differences were found between TBM and FFM for mean power output, fatigue index, or work done. Significant decreases (P<0.05) in PV of 12.0+/-5.7 and 12.3+/-6.7% were recorded immediately after exercise for both TBM and FFM, respectively. At 24 h after exercise, a significant (P<0.05) increase in PV of 4.2+/-10.3% was recorded for TBM only. Significant increases (P<0.01) were recorded for serum triglyceride, cholesterol, HDL cholesterol, and LDL cholesterol immediately after exercise for both TBM and FFM. These increases disappeared when corrected for PV changes, with the exception of LDL cholesterol in TBM, which still displayed a significant increase compared with the preexercise values (2.50+/-0.74 mM (before) vs 2.72+/-0.84 mM (immediately after)).
Conclusions: Our data show that short-duration, high-intensity cycle ergometer exercise tests can induce significant plasma volume decreases in untrained subjects, which may affect the interpretation of bloodborne biochemical parameters.