How to Establish a Hydration Plan for Half & Full Marathons [Follow-Along Week 9]

by marathonman

With 4 weeks until race day, I can tell that the accumulated fatigue of 45+ miles/week and numerous hard workouts is starting to get to me. Although I’m still definitely motivated to run and complete my workouts, I’m starting to feel fatigue in my legs both during & after my runs that I didn’t feel a few weeks or months ago. With the onset of warmer & more humid weather, it’s now more important that I’m adequately hydrated prior to and during my run.

In this post, I discuss the importance of hydration and how to establish a hydration plan for your race and how to practice it during your training.

Here’s the link to my Strava Dashboard so you can see the details of each of the workouts that completed this week & throughout my journey.

It should come as no surprise that proper hydration is important for both safety and performance. Warm and humid weather typically increase sweat rates and can accelerate the onset of dehydration. This can lead to an increased risk of early fatigue and heat related illnesses. Keeping your body properly hydrated will ensure that you maintain blood volume and cardiovascular function. Dehydration not only decreases blood volume, but also increase heart rate, slows heat loss in the body, which ultimately can cause runners to slow or eventually drop out of the race.

It’s important to determine your individual fluid needs because there is no single recommendation that applies to everyone. Ideally you want to balance fluid intake with sweat losses to avoid both dehydration and hyponatremia (too much fluid).

Signs of dehydration can be feeling faint or light headed, rapid heart rate, dry mouth or feeling very thirsty. The best 1st step is to drink some fluids to see if your condition improves.

Signs of hyponatremia (too much fluid) can be water sloshing in your stomach, severe headache or feeling bloated in the hands and feet with nausea or upset stomach. The best first step is to stop drinking until you begin to urinate.

How much to drink?

To determine your unique fluid needs, you need to estimate your sweat rate by weighting yourself nude and then run for 1 hour in the conditions at the pace you expect to race. Do not drink during this run. At the end of the run, strip down, and reweigh yourself nude. The difference in weight is your approximate hourly sweat rate. You’ll need to convert lbs to ounces (1 lb = 16 ozs) and then plan on consuming that much per hour during your race.

For example, if you lost 1lb of sweat, you should consume about 4ozs of fluid every 15 minutes during your race. During your training, you can test this program by weighing yourself prior to and after your runs. If you weigh 1-2lbs during longer runs, you’ve kept your weight nearly neutral except for water loss. If you gained weight during your run, it’s a sign that you drank too much, which can lead to hyponatremia (over hydration), which in can be fatal.

On those occasions when you know you’ll be losing a lot of sweat, I recommend drinking 10-20 oz’s of fluid about an hour before the race to ensure you start with adequate fluid in your system.

In summary, try to match your fluid intake to just below your weight loss (which should be 2-3lbs in a race like a marathon). Do not overdrink. If you’re feeling effects of hot weather, slow your pace. Recognize the warning signs of dehydration and hyponatremia. If you are not feeling well during or after the race and incorporating a few simple changes doesn’t make you feel better, then it’s best to seek immediate medical attention.

Source: International Institute for Race Medicine (amaasportsmed.org)

Monday June 4th – long run @ easy pace

The purpose of this run was to get miles on my legs and build aerobic capacity.

Run Distance, Time & Average Pace: 11.0 miles, 1:23:50 minutes, ave pace 7:37

Tuesday June 5th – short run @ easy pace

I completed this run early in the morning while on business in Boise. Ran along the beautiful campus of Boise State near downtown Boise. The purpose was to help recover from the previous day’s long run.

Run Distance, Time & Average Pace: 6.0 miles, 48:38 minutes, ave pace 8:06

Wednesday June 6th – short run @ easy pace + conditioning in hotel gym

6 mile easy run on forest preserve trails in Rosemont, IL (O’Hare airport area). After the run, I was able to get into the hotel gym, where I completed 20 minutes of body weight & dumbbell exercises.

Run Distance, Time & Average Pace: 6.2 miles, 48:16 minutes, ave pace 7:44

Thursday June 7th – Off Day

Business meetings & travel from Chicago to home. Rest & Recovery Day

If you’re interested in joining me, I can put together either a custom training plan or I can personally coach you. Either program will be specific to your goals and athletic abilities. Just click on the links for details.

Friday June 8th – Long Tempo Run

The purpose of today’s workout was to build strength. I increased the distance by a mile from my last tempo. Paces are the same, as shown in the image below. After a 1 mile warm-up, I complete 9 miles at marathon pace. As you can see, I was right on pace for the duration of the tempo.

Run Distance, Time, & Average Pace: 11.7 miles, 1:22:48 minutes, ave pace 7:03

Saturday June 9th – short run @ easy pace

Run Distance, Time, & Average Pace: 5.1 miles, 38:32 minutes, ave pace 7:26

Sunday June 10th– Long Run @ easy + brisk

My last long run. The purpose of this run is to get time on my legs and push the pace over the last 6-8 miles. I need to get used to running on tired legs. Most plans include one last long run about 3 – 3.5 weeks from the race. This run also capped my highest mileage week of the training plan. Weekly mileage will start to decrease over the next 2 weeks before my taper the last week prior to the race.

I completed the first half of the run with friends at a very easy (8:00+/mile) pace. I picked up the pace slightly during the second half of the run. There were some hills and the weather turned cool (upper 40s) with wind and rain the last 3+ miles. I didn’t complete any of the last miles under 7:00/mile as desired, but I’m happy with the effort considering the frequent hills and the fact that I was coming off a 9 mile tempo just 2 days earlier. My legs definitely felt tired the last few miles.

Run Distance, Time, Pace: 17.1 miles, 2:18:55 minutes, ave pace 8:06

Weekly total = 57.3 Miles