Vegetarian vs Omnivore Diet: Cycling Stamina

Just came across this, it's from 1968:

Dr. Per-Olaf Astrand conducted an informal study of diet and endurance using nine highly trained athletes, changing their diet every three days. At the end of every diet change, each athlete would pedal a bicycle until exhaustion. Those with a high protein and high fat meat (carnivore) diet averaged 57 minutes. Those that consumed a mixed (omnivore) diet, lower in meat, fat and protein averaged 1 hour and 54 minutes: twice the endurance of the meat and fat eaters. The vegetarian, high carbohydrate diet athletes lasted 2 hours and 47 minutes, triple the endurance of the high-protein group. (Source: Astrand, Per-Olaf, Nutrition Today 3:no2, 9-11, 1968)

(Story Link, thanks VeganRepresent Forums!)

Of course, this is far from conclusive or even well controlled, and it's already well established that carbs are essential in providing lasting fuel to muscles. I'm guessing the resistance/wattage was kept the same, etc.. Anyone have any more recent/thorough studies like this?