Background Recent studies suggest that acute-combined carnosine and anserine supplementation has the potential to improve the performance of certain cycling protocols. Yet, data on optimal dose, timing of ingestion, effective exercise range, and mode of action are lacking. Three studies were conducted to establish dosing and timing guidelines concerning carnosine and anserine intake and to unravel the mechanism underlying the ergogenic effects. Methods First, a dose response study A was conducted in which 11 men randomly received placebo, 10, 20, or 30 mg.kg −1 of both carnosine and anserine. They performed 3x maximal voluntary isometric contractions (MVC), followed by a 5 x 6 s repeated cycling sprint ability test (RSA), once before the supplement and 30 and 60 minutes after. In a second study, 15 men performed 3x MVCs with femoral nerve electrical stimulation, followed by an RSA test, once before 30 mg.kg −1 carnosine and anserine and 60 minutes after. Finally, in study C, eight men performed a high intensity cycling training after randomly ingesting 30 mg.kg −1 of carnosine and anserine, a placebo or antihistamines (reduce post-exercise blood flow) to investigate effects on muscle perfusion. Results Study A showed a 3% peak power (p = 0.0005; 95% CI = 0.07 to 0.27; ES = 0.91) and 4.5% peak torque (p = 0.0006; 95% CI = 0.12 to 0.50; ES = 0.87) improvement on RSA and MVC, with 30 mg.kg −1 carnosine + anserine ingestion 60 minutes before the performance yielding the best results. Study B found no performance improvement on group level; however, a negative correlation (r = −0.54; p = 0.0053; 95% CI = −0.77 to −0.19) was found between carnosinase enzyme activity (responsible for carnosine and anserine breakdown) and performance improvement. No effect of the supplement on neuromuscular function nor on muscle perfusion was found. Conclusions These studies reveal that acute ingestion of 30 mg.kg −1 of both carnosine and anserine, 60 minutes before a high intensity exercise, can potentially improve performance, such as short cycling sprints or maximal muscle contractions. Subjects with lower carnosinase activity, and thus a slower breakdown of circulating dipeptides, appear to benefit more from this ergogenic effect. Finally, neither the involvement of a direct effect on neuromuscular function, nor an indirect effect on recovery through increased muscle perfusion could be confirmed as potential mechanism of action. The ergogenic mechanism therefore remains elusive.

Classic in vitro experiments (Severin's phenomenon) demonstrated that acute carnosine supplementation may potentiate muscle contractility. However, upon oral ingestion, carnosine is readily degraded in human plasma by the highly active serum carnosinase-1 (CN1). We developed a novel strategy to circumvent CN1 by pre-exercise ingestion of combined carnosine (CARN) and anserine (ANS), the methylated analog with similar biochemical properties but more resistant to CN1. First, in vitro hydrolysis was tested by adding carnosine and anserine to human plasma, alone or in combination. Secondly, 5 subjects were supplemented with 25mg/kg anserine or 25mg/kg of each anserine and carnosine to test in vivo bioavailability. Thirdly, two double-blind, placebo-controlled, crossover studies investigated the effect of pre-exercise ANS+CARN (20mg/kg BW of each) supplementation on performance during a single all-out Wingate test following 6-minute high-intensity cycling (study A) or 3 repeated Wingate tests (study B). In vitro experiments demonstrated slower degradation of anserine vs carnosine, which was further slowed by simultaneously adding carnosine. In vivo bioavailability of plasma anserine was more prominent (2.5-fold increased AUC) when ANS+CARN vs ANS was ingested. Study A showed significantly higher (+6±11%; p=0.04) power in the first 5s of the Wingate test following ANS+CARN (12.8±2.4W/kg) vs placebo (12.1±2.2W/kg). Study B demonstrated increased peak power (+3%) throughout 3 consecutive Wingate tests (ANS+CARN 10.5±0.6W/kg vs placebo 10.2±9.9W/kg). These experiments reveal a novel acute nutritional method to effectively raise plasma anserine and carnosine by high-dose combined supplementation. This approach led to improved initial cycling power, revealing a new nutritional strategy to increase exercise performance.

Histidine-containing dipeptides (HCDs) are pleiotropic homeostatic molecules linked to inflammatory, metabolic and neurological diseases, as well as exercise performance. Using a sensitive UHPLC-MS/MS approach and an optimized quantification method, we performed a systematic and extensive profiling of HCDs in the mouse, rat, and human body (in n=26, n=25, n=19 tissues, respectively). Our data show that tissue HCD levels are uniquely regulated by carnosine synthase, an enzyme preferentially expressed by fast-twitch skeletal muscle fibers and brain oligodendrocytes. Cardiac HCD levels are remarkably low. The low abundant HCD N-acetylcarnosine is enriched in human skeletal muscles. Here, N-acetylcarnosine is continuously secreted into the circulation as the most stable plasma HCD, which is further induced by acute exercise in a myokine-like fashion. Carnosine is preferentially transported within red blood cells in humans but not rodents. We provide a novel basis to unravel tissue-specific, paracrine, and endocrine roles of HCDs in human health and disease.

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Background chicken meat extract is a popular functional food in Asia. It is rich in the bioactive compounds carnosine and anserine, two histidine-containing dipeptides (HCD). Studies suggest that acute pre-exercise ingestion of chicken extracts has important applications towards exercise performance and fatigue control, but the evidence is equivocal. This study aimed to evaluate the ergogenic potential of the pre-exercise ingestion of a homemade chicken broth (CB) vs a placebo soup on a short-lasting, high-intensity cycling exercise. Methods fourteen men participated in this double-blind, placebo-controlled, crossover intervention study. Subjects ingested either CB, thereby receiving 46.4 mg/kg body weight of HCD, or a placebo soup (similar in taste without HCD) 40 min before an 8 min cycling time trial (TT) was performed. Venous blood samples were collected at arrival (fasted), before exercise and at 5 min recovery. Plasma HCD were measured with UPLC-MS/MS and glutathione (in red blood cells) was measured through HPLC. Capillary blood samples were collected at different timepoints before and after exercise. Results a significant improvement (p = 0.033; 5.2%) of the 8 min TT mean power was observed after CB supplementation compared to placebo. Post-exercise plasma carnosine (p <  0.05) and anserine (p <  0.001) was significantly increased after CB supplementation and not following placebo. No significant effect of CB supplementation was observed either on blood glutathione levels, nor on capillary blood analysis. Conclusions oral CB supplementation improved the 8 min TT performance albeit it did not affect the acid-base balance or oxidative status parameters. Further research should unravel the potential role and mechanisms of HCD, present in CB, in this ergogenic approach.