After a good night's sleep, the athlete really felt his oats and performed well in the competition.
После хорошего ночного сна, спортсмен действительно был полон энергии и хорошо выступил в соревновании.
Definitions
To feel energetic, confident, or self-assured, often behaving in a lively or assertive way; sometimes used to describe someone acting with newfound boldness or enthusiasm.