The Effects of L-Citrulline on Blood-Lactate Removal Kinetics Following Maximal-Effort Exercise

Abstract

The accumulation of lactate in muscle and blood during high-intensity exercise is negatively correlated with the duration exercise can be sustained. Removal of lactate is a key component of acute recovery between consecutive bouts of such exercise. Low-intensity exercise enhances recovery by accelerating lactate turnover in metabolically active tissues, largely mediated by blood flow to these tissues. Therefore, the purpose of this research was to clarify if L-citrulline, a nutritional supplement purported to promote vasodilation via enhanced nitric oxide availability, would augment the removal of blood lactate during active recovery (AR). L-citrulline ingestion will augment the rate of blood lactate concentration decrease during AR, reduce the oxygen-cost of submaximal exercise, and increase timeto-exhaustion and peak oxygen uptake (V_O2peak) during a test of maximal aerobic power. Healthy university students (five males & five females) participated in this double-blind, randomized, placebocontrolled study. Participants exercised on a cycle ergometer at submaximal steady-state intensities followed by progressively increasing intensity to exhaustion, 10 min of AR, and then supramaximal intensity exercise to exhaustion. Oxygen uptake was measured throughout the trial and blood lactate was sampled repeatedly during AR. The protocol elicited very high peak blood lactate concentrations after exercise (11.3 þ 1.3 mmol/L). L-citrulline supplementation did not significantly alter blood lactate kinetics during AR, the oxygen cost of exercise, V_O2peak, or time-to-exhaustion. Despite a strong theoretical basis by which L-citrulline could augment lactate removal from the blood, L-citrulline supplementation showed no effect as an exercise-recovery supplement.

Impact of a short-term nitrate and citrulline co-supplementation on sport performance in elite rowers: a randomized, double-blind, placebo-controlled crossover trial

“…As lactate clearance relies on oxidative capacity, it is plausible that the reported effects of supplementation on aerobic metabolism could positively impact on athletes’ oxidative capacity and therefore be an indirect sign of improved aerobic performance. Some studies have also reported lower blood lactate concentrations after CIT supplementation (Rhim et al 2020 ; Divito et al 2022 ), but the literature regarding BR supplements remains unclear. In fact, potential mechanisms related to lower blood lactate values after CIT supplementation might be related to enhanced aerobic pathway, as reported for instance by higher levels of plasma lactate dehydrogenase enzyme (Rhim et al 2020 ), which could be in accordance to previously identified effects of NO-related supplements such as BR.…”

Effects of acute β-alanine supplementation on countermovement jump performance after a 4x400 m running fatigue protocol

“…The ATP yield from glycolysis is highest in exhaustive short-term exercise (i.e., 400 meters sprint), which increases muscle acidosis (measured by blood lactate) (Hirvonen, Nummela, Rusko, Rehunen, & Härkönen, 1992). In addition, this level of acidosis attains an individual maximum (Hirvonen, et al, 1992) and stays elevated for 3-to-5-min post-exercise (Divito, McLaughlin, & Jacobs, 2021).…”