Pre-Workout meals help athletes in improving glycogen levels before training begins. A few pointers are described below that can help athletes optimize their workouts. The section is broken down to (a) What should you eat (b) When should eat (c) How much should you eat 

What type of pre-workout meal should you eat?

A pre-workout meal should be high in complex carbohydrate, moderate in protein and low in Fats. Most people and make the mistake of taking protein supplements or protein-rich food before starting a workout. The human body’s primary source of fuel is carbohydrates. Complex carbohydrates do not spike your blood sugar levels and provide you a slow and steady energy release. Protein provides only 10% of the energy needs. Complex carbohydrates should have a low Glycemic Index number.
Examples: Sweet Potato, Baked Potato, Quinoa

When should you have a pre-workout meal?

Most people make the mistake of starting exercise after having a meal. Time-space should be provided between the meal had and the exercise. This could be anywhere ranging from 1-3 hours; however, it is recommended to provide a minimum time gap of one hour or 60 minutes. Athletes must take account their body’s metabolic rate, and health conditions too. If the body has a slower metabolism than the time taken to for digestion would be greater. Hence, it is recommended that athletes do not eat very close to training or exercise sessions. Few reasons are 1] Partial digestion of food could lead to the athlete vomiting in the middle of the training session 2] After a meal, the blood flow is directed to the Gastrointestinal (GI) system for digestion. If you were to start exercising, the GI system and your Musculoskeletal system will be competing for blood flow. As the food needs to be digested, more blood is directed to the GI system. Circulation of blood to the muscles is reduced hence resulting in poor athletic performance.

How much should you eat before exercise?

If you are a recreational athlete who loves competing, then you should have one gm of carbohydrate per 1 kg of body weight, and protein 0.3 g per kg of body weight, with the carbohydrate to protein ratio 3:1. Example: if your body weight is 70 kg, the pre-workout meal should contain 70 g of carbohydrates and 21 g of protein. If you are a professional athlete then you should have 2-3 g of carbohydrates per one kg of body weight, with the carbohydrate to protein ratio of 7:1.
The type of sport plays a huge role too. If you are an endurance sport athlete then you should have more carbohydrates and a moderate amount of protein and fats in your pre-workout meal. If you are a power athlete example sprinter you should have more carbohydrates, moderate protein, and low fat.

How much water should you drink?

Dehydration causes a decline in athletic performance, hence it important that athletes being hydrated before and during the exercise. It is recommended to drink more than two liters of water during the day.