Science Summary: Nutrition and Hydration (Cardio or Weights Part 11)

This post is a continuation on my series through Alex Hutchinson’s Which Comes First, Cardio or Weights? All of the following questions are taken from this book and the answers are paraphrased from the authors words with my interpretations and thoughts added in.

— Scott

Should I carbo-load by eating pasta the night before a competition?

Short Answer: It really depends on the competition.  For short bouts of intensity, it isn’t necessary.  For long periods of exertion without the ability to eat, it may help postpone running out of glycogen.

Long Answer:  An Australian study in 2002 showed that in order to maximize carbohydrate stores, you would need to eat 10g of carbs per 1kg body weight.   This comes out to about 700g of carbs for a 150lb person which is 2800cal of pure carbs, far more than you will get from pasta for dinner.  Having a higher store of carbs will not increase performance but will allow you to perform longer before your body “hits a wall” and begins to burn fat stores. Another factor to consider is that, with excess carbs, your body will also retain significantly more water weight which will increase your weight at the time of the competition.

What should I eat to avoid stomach problems during exercise?

Short Answer: It really depends on your body and your digestive system.  Generally you want to eat 3-4 hours before exercise and avoid foods high in fats or fiber.

Long Answer:  Typically it takes 3-4 hours for a sedentary individual to digest food.  Foods that are high in fat and fiber slow down the digestive process even more.  Athletic individuals process food even faster as shown by a Indiana University study where athletes had digestion times as low as 30 minutes.  Eating carb heavy foods may also cause issues as the insulin spike caused combined with exercise may create an unsafe drop in blood sugar.

What should I eat and drink to refuel after working out?

Short Answer: After a workout you want to restore energy levels and provide you body the materials to repair.  To achieve this your body needs carbohydrates and protein.

Long Answer:  It really depends on the goal of the workout.  If you are looking to lose weight, a study at the University of Massachusetts found that obese individuals  who ate post workout did not experience the same positive changes in insulin sensitivity as their counterparts who did not eat.  If your goal is to gain muscle mass, your body is going to need the materials to repair.  When it comes down to what to eat, researchers are divided on the bet ratios of carbs-protein claiming anywhere between 2.5:1 and 6:1 ratios.

How much should I drink to avoid dehydration during exercise?

Short Answer: Drink if you are thirsty.

Long Answer:  This one goes back to the central governor theory talked about in this post.  Your brain limits your output based off of the data it receives from your body.  When water levels get low, it reduces output and signals with thirst.

Is it possible to hydrate too much?

Short Answer:  Yes, it’s called hyponatremia and it will kill you.

Long Answer:  The most famous example of hyponatremia is the case of a women who drank as much water as she could in order to win a Wii game console and ended up dying from it.  There are dozens of other examples which tend to be more common in endurance races where people are over concerned about dehydration.

What ingredients do I really need in a sports drink?

Short Answer: Fluids, carbs, and salt.

Long Answer: When you sweat, you’re losing fluid and need to rehydrate.  That part is pretty straightforward.  For carbs, you are expending energy when you workout and need to replace that energy.  Simple carbs are absorbed easily and can be put to use right away.  The amount of carbs is dependent on the exercise though, high carb sports drinks are intended for high intensity workouts lasting more than an hour.  For less exhaustive exercise, lower calorie drinks are a better option.  In addition to the fluids lost in sweat, your body loses salt which essential to muscle function.  In most cases, salt levels aren’t an issue unless you’re a top level athlete competing at full intensity.

Will taking antioxidant vitamins block the health benefits of exercise?

Short Answer: Most likely, yes.

Long Answer:  Your body naturally produces antioxidants when you exercise.  By artificially introducing these with supplements, your body never adapts to the strenuous conditions caused by exercise which prevents many of the benefits.  A 2009 study done at the University of Jena found that over a four week program, participants who combined antioxidant vitamins and exercise saw no change in insulin sensitivity while the control group, who exercised without antioxidants, showed significantly increased sensitivity.

Should I be taking probiotics?

Short Answer:  There have been studies which suggest certain probiotics do boost immune system function.

Long Answer:  A 2008 study done by the Australian Institute of Sport found that runners who consumed the probiotic Lactobacillus fermentum experienced significantly less respiratory trouble than the control group.  A similar study testin the effectiveness of Lactobacillus rhamnosus found that participants who consumed the probiotic recovered from gastrointestinal distress more quickly.

Will vitamin D make me a better athlete?

Short Answer:  There has yet to be a definitive link between vitamin D and performance.

Long Answer:  Current research on the topic suggests a majority of people are vitamin D deficient.  By treating this deficiency, performance is improved up until the person is no longer deficient at which point athletic performance stops improving.

Is there any benefit to deliberately training with low energy stores?

Short Answer:  Fasted exercise does cause your body to work differently, but not necessarily better.

Long Answer:  Fasted exercise prompts your body to burn fat supplies rather than carbohydrate supplies.  While this sounds like a good thing, the excess carbs end up being converted to body fat anyways.  The conclusion is you should train for how you plan to compete.  If you will be in a carbohydrate depleted state for competition, it may be beneficial to train in that state as well.

Can I get the nutrients I need for a heavy exercise regime from a vegetarian or vegan diet?

Short Answer:  Yes, it’s going to take more planning though.

Long Answer:  Over the past few decades, several studies have compared vegan/vegetarian athletes against athletes on standard diets and found no difference in performance.  When it comes to getting the necessary nutrients though, vegan/vegetarian athletes need to be much more aware of what they are eating and what heir body needs.