The Paradoxical Effect of Creatine Monohydrate on Muscle Damage Markers: A Systematic Review and Meta-Analysis

High-dose short-term creatine supplementation without beneficial effects in professional cyclists: a randomized controlled trial

BACKGROUND

Growing evidence supports the ergogenic effects of creatine supplementation on muscle power/strength, but its effects on endurance performance remain unclear. We assessed the effects of high-dose short-term creatine supplementation in professional cyclists during a training camp.

METHODS

The study followed a double-blind, randomized parallel design. Twenty-three professional U23 cyclists (19 ± 1 years, maximum oxygen uptake: 73.0 ± 4.6 mL/kg/min) participated in a 6-day training camp. Participants were randomized to consume daily either a recovery drink (containing carbohydrates and protein) with a 20-g creatine supplement (creatine group, n = 11) or just the recovery drink (placebo group, n = 12). Training loads and dietary intake were monitored, and indicators of fatigue/recovery (Hooper index, countermovement jump height), body composition, and performance (10-second sprint, 3-, 6-, and 12-minute time trials, respectively, as well as critical power and W') were assessed as study outcomes.

RESULTS

The training camp resulted in a significant (p < 0.001) increase of training loads (+50% for total training time and + 61% for training stress score, compared with the preceding month) that in turn induced an increase in fatigue indicators (significant time effect [p < 0.001] for delayed-onset muscle soreness, fatigue, and total Hooper index) and a decrease in performance (significant time effect [p = 0.020] for critical power, which decreased by -3.8%). However, no significant group-by-time interaction effect was found for any of the study outcomes (all p > 0.05).

CONCLUSIONS

High-dose short-term creatine supplementation seems to exert no consistent beneficial effects on recovery, body composition or performance indicators during a strenuous training period in professional cyclists.

Acute effects of exercise-induced muscle damage on sprint and change of direction performance: A systematic review and meta-analysis

The aim of this study is to determine the acute effects of resistance and plyometric training on sprint and change of direction (COD) performance in healthy adults and adolescents. A systematic literature search was conducted via Medline, Cinahl, Scopus and SportDiscus databases for studies that investigated: 1) healthy male, female adults, or adolescents; and 2) measured sprint or change of direction performance following resistance and plyometric exercises. Studies were excluded if: 1) resistance or plyometric exercises was not used to induce muscle damage; 2) conducted in animals, infants, elderly; 3) sprint performance and/or agility performance was not measured 24 h post muscle damaging protocol. Study appraisal was completed using the Kmet Quality Scoring for Quantitative Study tool. Forest plots were generated to quantitatively analyse data and report study statistics for statistical significance and heterogeneity. The included studies (n = 20) revealed sprint and COD performance was significantly impaired up to 72 hr following resistance and plyometric exercises; both protocols significantly increased creatine kinase (CK), delayed-onset muscle soreness (DOMS) and decreased countermovement jump (CMJ) up to 72 hr. The systematic review of 20 studies indicated that resistance and plyometric training significantly impaired sprint and COD performance up to 72 hours post-exercise. Both training protocols elevated exercise-induced muscle damage (EIMD) markers (CK, DOMS) and decreased CMJ performance within the same timeframe.

Nutritional interventions for exercise-induced muscle damage: an umbrella review of systematic reviews and meta-analyses of randomized trials

CONTEXT

Several meta-analyses have been conducted on the effect of nutritional interventions on various factors related to muscle damage. However, the strength of the evidence and its clinical significance are unclear.

OBJECTIVES

This umbrella review aimed to provide an evidence-based overview of nutritional interventions for exercise-induced muscle damage (EIMD).

DATA SOURCES

PubMed, Scopus, and ISI Web of Science were systematically searched up to May 2022.

DATA EXTRACTION

Systematic reviews and meta-analyses of randomized controlled trials investigating nutritional interventions' effects on recovery following EIMD were included. The certainty of the evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).

RESULTS

Fifty-three randomized controlled trial meta-analyses were included, evaluating 24 nutritional interventions on 10 different outcomes. The results revealed a significant effect of hydroxymethylbutyrate (HMB) supplementation and l-carnitine supplementation for reducing postexercise creatine kinase; HMB supplementation for reducing lactate dehydrogenase; branched-chain amino acids and leaf extract supplementation for reducing the delayed onset of muscle soreness; and l-carnitine, curcumin, ginseng, polyphenols, and anthocyanins for reducing muscle soreness, all with moderate certainty of evidence.

CONCLUSIONS

Supplementation with HMB, l-carnitine, branched-chain amino acids, curcumin, ginseng, leaf extract, polyphenols, and anthocyanins showed favorable effects on some EIMD-related outcomes.

PROTOCOL REGISTRATION

PROSPERO registration no. CRD42022352565.

Research trends and hotspots of exercise for people with sarcopenic: A bibliometric analysis

This study aimed to analyze the trends and themes in exercise and sarcopenia research using a bibliometric approach. The Web of Science citation database was used to identify papers published on exercise and sarcopenia. The retrieved data on institutions, journals, countries, authors, journal distribution, and keywords were analyzed scientometric ally using CiteSpace and VOSviewer. 2895 papers were included according to our specified inclusion criteria eventually. The data showed an upward trend in the number of published articles on exercise and sarcopenia. The countries with the highest number of publications were the United States, Japan, and England; research institutions were mainly composed of universities in Europe and the United States, and high-producing authors formed major collaborative teams, but cross-geographical and cross-institutional collaboration was not apparent; research was closely focused on 3 aspects: resistance exercise, resistance combined with other forms of exercise, and exercise combined with nutritional supplementation, of which resistance exercise was a particular focus; and recently, the research hotspots were mainly the effects of exercise on grip strength. The most cited articles were consensus guidelines published by the working group on sarcopenia in the elderly from different continents. The prevention and rehabilitation of sarcopenia in the elderly are gaining attention. Current primary exercise therapies for sarcopenia and exercise combined with nutritional supplementation have significant advantages and the potential to delay muscle decay. This suggests a promising area for future research that could benefit from further advances.