Nausea after Repeated Sprints: Is Lactic Acidosis Really the Culprit?

Introduction Nausea caused by exhaustive sprinting is associated with high lactate ([La-]) and hydrogen ion concentrations ([H+]) and fall in blood pCO(2), thus raising the issue of whether there is a causal link between nausea and these variables. For this reason, this study aimed to determine whether interspersing repeated sprints (RS) with periods of active, compared with passive, recovery results in lower levels of both nausea and changes in [La-], [H+], and pCO(2). Methods Twelve male participants completed two separate sessions comprising four 30-s sprints separated by 20 min of either active (AR; cycling at 40% VO2peak) or passive recovery (PR). At 6 and 18 min of each recovery period, nausea was assessed via a visual analog scale (VAS), and blood samples were collected to measure [La-], [H+], and pCO(2). Results RS significantly increased VAS score in both AR (P < 0.001) and PR (P < 0.01). After the first sprint, VAS was higher than preexercise in only AR (P < 0.01). AR was associated with lower VAS, [La-], [H+], and higher pCO(2) (all P = 0.001) compared with PR after sprints 2-4. Linear mixed modeling indicated that each of the variables significantly predicts VAS scores (P < 0.0001). Repeated-measures correlation (r (rm) (2) ) indicated that [La-] had the closest association with VAS (r (rm) (2) = 0.22, P < 0.0001). Conclusion The lower levels of both nausea and changes in [La-], [H+], and pCO(2) in response to AR suggest that nausea associated with RS may be causally related with these variables. However, the absence of a close relationship between these variables after the first sprint and the findings that [La-], [H+], and pCO(2) only account for 13%-22% of the variation in VAS indicate that other mechanisms may also mediate nausea.

Automated summary

This study found that active recovery (AR) following repeated sprints (RS) led to lower levels of nausea and changes in lactate ([La-]), hydrogen ion concentrations ([H+]), and pCO(2) compared to passive recovery (PR). These findings suggest a causal relationship between nausea and these variables in response to RS, but other mechanisms may also play a role in mediating nausea as [La-], [H+], and pCO(2) only accounted for 13%-22% of the variation in VAS scores.