Creatine Monohydrate Supplementation, but not Creatyl-L-Leucine, Increased Muscle Creatine Content in Healthy Young Adults: A Double-Blind Randomized Controlled Trial

Abstract

Creatine (Cr) supplementation is a well-established strategy to enhance gains in strength, lean body mass, and power from a period of resistance training. However, the effectiveness of creatyl-L-leucine (CLL), a purported Cr amide, is unknown. Therefore, the purpose of this study was to assess the effects of CLL on muscle Cr content. Twenty-nine healthy men (n = 17) and women (n = 12) consumed 5 g/day of either Cr monohydrate (n = 8; 28.5 ± 7.3 years, 172.1 ± 11.0 cm, 76.6 ± 10.7 kg), CLL (n = 11; 29.2 ± 9.3 years, 170.3 ± 10.5 cm, 71.9 ± 14.5 kg), or placebo (n = 10; 30.3 ± 6.9 years, 167.8 ± 9.9 cm, 69.9 ± 11.1 kg) for 14 days in a randomized, double-blind design. Participants completed three bouts of supervised resistance exercise per week. Muscle biopsies were collected before and after the intervention for quantification of muscle Cr. Cr monohydrate supplementation which significantly increased muscle Cr content with 14 days of supplementation. No changes in muscle Cr were observed for the placebo or CLL groups. Cr monohydrate supplementation is an effective strategy to augment muscle Cr content while CLL is not.

Effectiveness of Creatine in Metabolic Performance: A Systematic Review and Meta-Analysis

“…Participants were split into two groups: one received 5 g of Cr monohydrate daily and the other a PLA. The trial lasted 14 days [12]. After 14 days, the result showed that Cr monohydrate administration increased muscle Cr content [12].…”

“…The trial lasted 14 days [12]. After 14 days, the result showed that Cr monohydrate administration increased muscle Cr content [12].…”

“…References: [11][12][13][14][15][16][17][18][19][20] Publication bias was seen in the three studies as shown in Figure 5.…”

Reply to G. Escalante and D. St. Mart

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We have addressed the scientifically relevant points put forth by Escalante & St. Mart (2023), and we appreciate the opportunity to put their comments on our study (Askow et al, 2022) in proper context to the readers of your journal. In the following, we have provided our responses to Escalante & St.

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Comment on: “Creatine Monohydrate Supplementation, but not Creatyl-L-Leucine Increased Muscle Creatine Content in Healthy Young Adults: A Double-Blind Placebo-Controlled Trial”

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Recently, an article by Askow et al (2022) was published ahead of print in the journal on August 25, 2022. Researchers in this study recruited 29 participants and had them consume 5 g/day of either creatine monohydrate (CM), creatyl-l-leucine (CLL), or a placebo for 14 days in a randomized, double-blind design.

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