When selecting a product, be sure it mentions that it is for use during workouts as this should indicate it has what's needed to extend and intensify your workouts while not having anything that will slow you down. (fitnessandpower.com)
Maybe this isnt what you wanted to hear, but the celebs trained by Jorgen de Mey start intensifying their workouts a few weeks before the holidays. (health.com)
Because of this, you could further intensify your workout because of this options. (healthandfitnessvitality.com)