Dear Monique,
I am aware that I need to consume a sports drink during training forboth fluid and fuel replacement. How do I know that I am meeting my fluidneeds? I have heard that significant weight loss after training means thatI am not keeping up with my sweat rate.
Thanks,
CBDear CB,
Other than lab testing there is no exact way in which you can measuresweat losses, but you can make an educated estimation. In hot weather thesimplest calculation that you can make involves checking body weight changesbefore and after training, and correcting for fluid intake during training.Fluid loss from urine loss would also affect this equation, as would weightgain from any solid food consumed. For the example below, let’s look athow you can calculate sweat losses during a bike ride when consuming acarbohydrate-electrolyte beverage.1. Check your weight before and after training and calculateyour weight loss.
160 lb. to 158 lb. (73 kg to 72 kg)
2 lb. weight loss during training (0.9 kg)
(To obtain weight in kilograms, divide weight in pounds by 2.2.)2. Know the amount of fluid that you consumed during the trainingsession. Fifteen ounces of fluid weighs about 1 pound (an easier estimateis 1000-ml fluid equals 1.0 kg body weight). You can also weigh the bottlebefore and after your training session to see how much the fluid you consumedweighs.Let’s say you consume 60 ounces (1800 ml) of fluid during a three-hourbike ride. This fluid weighs 4 lb. (1.8 kg)3. Add the answers in 1 and 2.
2-lb. weight loss during training plus you consumed 4 lb. of fluidduring training
This equals 6 lb. of fluid lost.
(0.9 + 1.8 kg = 2.7 kg)4. 6 lb. equals 90 ounces fluid divided by 3 hours = 30ounces per hour for sweat losses.
(2.7 kg equals 2700 ml fluid divided by 3 hours = 900 ml/hr).In this example the athlete sweats about 30 ounces or 3.75 cups of fluidper hour (900 ml). Sweat rates can vary from 24 ounces or 3 cups of fluidper hour (720 ml) to 80 ounces or 10 cups (2500 ml or more) per hour.A two-pound fluid loss is fairly significant and indicates that youneed to drink more when training. Athletes who gain weight during training,may actually be drinking too much. Overdrinking is a concern in the developmentof hyponatremia or low blood sodium. However, most athletes do not meettheir fluid needs and chances are that you will not match 100 percent ofyour sweat losses. Check you weights before and after training, and determineif you need to step up your fluid intake efforts. Rehydration should alsobe a main priority after training. Aim for 20 ounces (600 ml) of fluidafterwards for every pound lost during training. You should also includesome sodium in your rehydration fluids and food choices as part of yourrecovery meals and snacks to improve your fluid balance. This is especiallyimportant following training sessions where optimal fluid intake may bemore challenging and your weight loss is greater.
Thanks,
Monique