And I'm not sure how I missed this when it came out, but last year, the European Journal of Clinical Nutrition, published a systematic review and meta-analysis of randomized controlled trials involving chocolate milk and exercise recovery.
After excluding studies that didn't meet their inclusion criteria, the (non-conflicted) authors were left with 12 studies, 2 deemed of high quality, 9 of fair quality, and 1 of low quality with 11 having extractable data on at least one performance/recovery marker including ratings of perceived exertion, time to exhaustion, heart rate, serum lactate, and serum creatine kinase.
Their overall conclusion?
The systematic review and meta-analysis revealed that chocolate milk consumption had no effect on any of those variables when compared to placebo or other sport drinks.
Their most generous conclusion?
If they excluded one study from their analysis of the effect of chocolate milk on time to exhaustion then chocolate milk was found to increase time to exhaustion by 47 seconds over a placebo beverage. They also found, in another subgroup analysis, that lactate was slightly attenuated in chocolate milk drinkers compared to placebo (a finding that was not present in the high quality RCT looking at same).
(for a brief discussion on the stats involved and the subgroup analysis, here's a post on same from epidemiologist @GidMK who concluded that chocolate milk is "not a fitness drink").
Happy to have this post published so that I can share the next time someone inevitably tries to suggest that chocolate milk is magic.