Date of Award
Master of Science (MS)
Department of Family and Consumer Sciences
Purpose: To conduct a meta-analysis to evaluate how protein hydrolysate and carbohydrate (CHO) mixtures compare with intact protein CHO mixtures in regards to post-exercise plasma insulin and glucagon responses in healthy endurance trained male participants. Methods: Studies were identified via the online databases PubMed, Google scholar, Cochrane, and MDPI. Investigations that measured insulin and/or glucagon via needle biopsy during recovery (with the first measurement taken ≤ 30 min post-exercise) following a standardized exercise bout (any type) with the ingestion of carbohydrate only vs. carbohydrate and protein (pro) were included in this meta-analysis. Random-effects meta-analyses (CHO+pro vs. CHO only) and subgroup analyses (CHO+hydrolyzed pro vs. CHO+intact pro) were conducted to evaluate intervention efficacy. Results: Overall, 33 trials derived from 20 articles were included in this meta-analysis. Of which 9 trials were included for insulin area under curve (AUC), 9 trials were included for muscle fractional synthesis rate (FSR), 30 trials were included for plasma glucose peaks over time, 6 trials were included for muscle glycogen synthesis rate, 8 trials were included for muscle glycogen storage, and 5 trials were included for plasma glucagon peaks over time. The ingestion of CHO+pro induced significant higher insulin peaks than the ingestion of CHO only from 30 minutes to 240 minutes postexercise (30-180 min:p < 0.001, 210-240 min: p < 0.01). The ingestion of CHO+pro also induced significantly higher insulin AUC than the ingestion of CHO only (the standard mean difference was 2.70, 95% CI 1.25–4.16, p < 0.001; I2 = 90.82%) and muscle FSR (the standard mean difference was 2.66, 95% CI 1.27–4.05, p < 0.001; I2 = 92.82%). No differences on insulin peaks over time between the ingestion of CHO+intact pro and CHO+hydrolyzed pro were found by the subgroup analyses (p > 0.05). On the other hand, although the ingestion of CHO+pro reported significantly lower plasma glucose peaks from 30 to 120 minutes postexercise (30-90 min: p < 0.001; 120 min: p < 0.01) than the ingestion of CHO only, no difference on muscle glycogen synthesis rate was found between the intervention and control group (The standard mean difference was 0.82, 95% CI (-0.41)–2.05, p > 0.05; I2 = 85.53%). Finally, no differences on glucagon peaks between the intervention and control group from 30 to 60 minutes were found (p > 0.05). Conclusion: The co-ingestion of CHO+pro should be a better strategy for recovery for endurance-type male athletes than the ingestion of CHO only. However, more research is warranted to understand whether there are differences between the ingestion of intact protein and its hydrolyzed counterpart with CHO, or whether the protein-induced thermic effect of food (TEF) should be led by the glucagon responses and could be beneficial for long term weight management.
Kuo, Tzu-Yu, "A Meta-analytic Comparison of Protein Hydrolysate and Intact Protein Effects on Postexercise Plasma Insulin and Glucagon Responses in Healthy, Trained Males" (2022). Theses and Dissertations. 1553.