Eating for exercise

Regular exercise along with a sound diet is key to staying healthy.  You will live longer, and they will be healthier years. Regular exercisers miss fewer days of work, have a lower overall cancer rate, experience fewer heart attacks, and are less likely to have to deal with chronic diseases such as diabetes and dementia.


You can tap into the benefits of exercise with just fifteen or twenty minutes of your time a day. Aerobic exercise (get that heart rate up) four days a week combined with resistance work the other three.  As you experience the benefits, you may find yourself adding extra weight time in the gym or walking/cycling longer distances. And you may even go on to train for a 10k run or a multi-day walking/bicycling vacation.


A common concern is how to go about planning your diet to guarantee the proper nutrition and hydration for training as well as when participating in longer events.


Muscles use both sugar and fat as an energy source. The harder you exercise, the more important sugar becomes as the preferred energy source. And in a sprint, only sugar will do.


On a balanced diet you will have enough stored sugar (as glycogen) to support 70 - 90 minutes of high level aerobic activity.


Training doesn’t require special sports drinks or power bars - even competitive  athletes get the nutrients they need from ordinary foods. You won’t need to eat for a gym workout or walk/run/ride of less than an hour at a casual pace.  Only when you are doing longer rides or runs will you need to add snacks with additional carbohydrate calories to avoid “running out of gas” as your body is forced to use less efficient fat metabolism. If that happens, you will have “bonked” (cycling) or “hit the wall” (running).


You should eat a good breakfast at least an hour before exercising - whatever you normally eat for breakfast. Avoid high sugar-added foods such as pancakes with syrup as they can may cause a steep rise in blood sugar, stimulate a surge in insulin, and result in a sudden drop in blood sugar with its associated weakness.


Many athletes undertaking a long event (where sugar supplements will be needed) will drink their supplement (liquid to facilitate stomach emptying and minimize nausea) five minutes before the starting gun, and then continue them every 15 minutes for the remainder of their ride/run.


And if they are training daily, or are on a multi-day cycling vacation, adding an extra carbohydrate snack or drink immediately after finishing will start the replacement of the body’s internal glycogen stores to be ready for the next day.


While exercising is the one time sugary drinks or snacks are OK. The exercising muscle doesn’t need insulin to use the sugar in a sports drink, soda, or energy bar. This ongoing blood glucose uptake prevents blood sugar spikes and explains why a walk after dinner, using the meal’s carbohydrates for energy (keeping them from being shunted into fat cells), is such a healthy habit.


Hydration is actually less important than you might think. Most trainers encourage using thirst as a guide to fluid replacement rather than focusing on a set fluid replacement schedule, as over correcting by drinking too much plain water can dilute the blood sodium with its own set of problems.


Hot and humid conditions, with water loss from sweating, are one time fluid replacement is needed during exercise. But how much depends on the length of the planned exercise.


Studies on the effects of dehydration on physical performance don’t show a negative  performance impact until body weight drops by 1 - 2 % (about 3 pounds for the average rider). Since you can lose up to 2 quarts of sweat an hour (3.5 pounds)  you have some cushion to protect you from over replacement.


How about energy drinks like Red Bull or Monster with their additives to pep you up when you are lagging? Several studies have highlighted frequent problems with elevated blood pressure, and several cases of sudden death have been reported. It might be safer to stick with a cold coke for fluids containing a caffeine boost, or gatorade if just for the fluid alone.


Where does this leave you? For a workout of an hour or less, drink when you are thirsty and eat if you are hungry. It is not clear why some exercisers feel the need for a snack 30 minutes into a
 workout or on a ride, but if your body is sending this message, best listen to it. But know there is no evidence that you are risking your health by not eating or drinking.


The physiology of digestion, nutrition, and athletic performance has been a personal interest for many years, so if you are considering training for a longer ride or run, my website “Cycling Performance Tips” (http://www.cptips.com/) will help you with additional suggestions on nutrition and hydration.


Additional references:

https://vitals.lifehacker.com/what-to-eat-before-and-after-a-strength-training-workou-1798556343

http://www.drmirkin.com/fitness/eat-to-compete.html