In an interview with two physical therapists I heard, they recommended eating some high-quality protein immediately after finishing a hard workout to aid in recovery.
Another thing I read recently was by a physician commenting on overtraining; if your legs feel heavy you might be overtrained and in need of more rest and nutrition.
https://www.hss.edu/article_overtraining.asp
"Overreaching is muscle soreness above and beyond what you typically experience that occurs when you don’t sufficiently recover between workouts. Overreaching usually happens after several consecutive days of hard training and results in feeling run down. Luckily, the effects of overreaching can be easily reversed with rest. Overtraining occurs when an athlete ignores the signs of overreaching and continues to train. Many athletes believe that weakness or poor performance signals the need for even harder training, so they continue to push themselves. This only breaks down the body further.Full recovery from overtraining is difficult and can require weeks or months of time off from working out..."