Frampton, Cobbold, Nozdrin et al
April 2021 - Sports Medicine
Authors wanted to see if a single bout of aerobic exercise would impact glucose, insulin, or glucagon in healthy adults
17,141 potential papers were found, 51 accepted after reviewing inclusion and exclusion factors. 45 studies examined glucose, 38 examined insulin, and 5 examined glucagon. GRADE scoring revealed moderate quality evidence.
Results:
Glucose: a single bout of continuous aerobic exercise did not yield significant changes in glucose concentration across all studies (45 studies) when compared to resting
Subgroup analysis showed a significant reduction in glucose in those postprandial (-0.27mmol/L) vs fasting (0.15mmol/L)
A difference was also seen when examining the exercise modality with a significant decrease in glucose concentrations (-0.22mmol/L) in the cycle ergometer vs the treadmill exercise (0.26mmol/L)
Covariates were identified as VO2Max and Exercise Duration: those more fit saw lower drops in glucose, and the longer the exercise the less drop in glucose concentrations
Insulin: a single bout of continuous aerobic exercise did yield a significant decrease in insulin across studies (38 studies) when compared to resting: -18.07pmol/L
Subgroup analysis revealed a bigger decrease in insulin in those postprandial (-42.63pmol/L) vs those fasting (-3.4pmol/L).
No differences in insulin values across exercise modalities
Glucagon: a single bout of continuous aerobic exercise did yield a significant increase in glucagon across all studies (5 studies) when compared to resting: 24.6ng/L
Limitations: population is healthy adults (cannot extrapolate to other populations), use of modalities limited to aerobic cycling or treadmill training (no resistance training), glucagon studies had limited sample size (n=47).
Conclusion: a single bout of aerobic exercise can help to reduce insulin and increase glucagon regardless of feeding status in healthy adults. When in postprandial state, a single bout of aerobic exercise can significantly decrease serum glucose and insulin concentrations compared to a fasting state. More research is needed on glucagon and exercise response as it relates to fasting vs postprandial.