Both of these results were achieved after just five to six days of creatine supplementation. But what about that little problem of weight gain?
Research suggests that most of the short-term weight gain from creatine supplementation is due to water retention during the loading phase - it will therefore dissipate over time. In the longer term, any weight gain is likely to be an actual increase in muscular mass, as the higher-quality workouts lead to muscle growth.
In reality, a marathon runner covering 50 to 100 miles per week in training is unlikely to add much muscle, even using creatine, but the effects of faster interval training could be significant.
In addition, while most manufacturers and sellers of creatine advocate a loading phase (20 to 30 grams per day for 4 to 5 days), research indicates that this is not necessary - a daily dose of 4 to 5 grams will achieve the same results over a 30 day period, without the sudden weight gain.
Indeed, some people advocate spreading about a half-gram of of creatine on your food throughout the day as a way to consume the creatine and not gain water weight.
Finally, bear in mind that the research suggests that one of the ways in which creatine can help is by facilitating the transport of lactic acid from the muscles. It is therefore becoming more commonly used by endurance athetes (e.g. Ironman triathletes) to help speed up recovery.
Used judiciously you should see an improvemeent in your high-intensity training sessions, and ultimately, your race times.