Twenty-three studies investigating consumption of a range of macronutrient composition during the training period on athletic performance were evaluated.  Nine studies have reported that the consumption of a high carbohydrate diet (>60% of energy) during the training period and the week prior to competition results in improved muscle glycogen concentrations and/or significant improvements in athletic performance.  Two studies reported no additional performance benefits when consuming levels above 6 g carbohydrate/kg body weight.  Two studies report gender differences; women may have less ability to increase muscle glycogen concentrations through increased carbohydrate consumption, especially when energy intake is insufficient.   One study based on the consumption of a high fat diet (>65% of energy) for 10 days followed by a high carbohydrate diet (>65% of energy) for 3 days reported a significant improvement in athletic performance.   Nine studies report no significant effects of macronutrient composition on athletic performance during the training period and week prior to competition.