Transcript The Importance of HYDRATION

The Importance of
HYDRATION
By
Robert Robergs, Ph.D., FASEP, EPC
Exercise Physiology Laboratories
Exercise Science Program
Dep’t Physical Performance and Development
The University of New Mexico
How Much Water is in
the Body?
100 %
60 %
Total body mass
How Much Water is Needed by
the Body?
INTAKE
Metabolism
250 mL
10%
OUTPUT
200 mL
Moist Foods 750 mL
700 mL
2500 mL
30%
Beverages = 60% 1500 mL
1500 mL
Sweat 8%
Feces 4%
Skin and
Lungs 28%
Urine 60%
Exercise or a Hot or Humid Environment?
Normal
OUTPUT
Heat
8L
Sweat
Feces
Skin &
Lungs
200 mL
700 mL
11.5 L
2.5 L
3L
Urine
1500 mL
500 mL
Where is the Water Located?
From Where is it Lost?
~ 2.75 L
Blood
Loss (%)
~ 12 L
Between
Cells
For ~ 4% dehydration
50
40
~ 35 L
Cells
10
Cells
Costill & Fink, 1976.
Between
Cells
Blood
Dehydration is quantified by the amount of body weight
lost.
For example
Pre-exercise weight = 70.0 kg
Post-exercise weight = 68.5 kg
Weight Loss = 1.5 kg
(1.5 / 70 ) x 100 = 2.1 %
Heat Stroke
Heat
Exhaustion
PROBLEM #1
It is very difficult to prevent a significant dehydration
~1200 mL/hr
PROBLEM #2
It is very difficult to regulate the kidneys to maintain
hydration
GFR = 120 L/day
~ 99% of this water is
reabsorbed
For most beverages, increasing
fluid ingestion causes a
decreased effectiveness of water
reabsorption
Can Pre-exercise Hydration Be
Increased?
YES
Robergs & Griffin. Sports Med. 26(3):145-167, 1998
~ 400 – 700 mL
How Does Glycerol Work?
1. Glycerol hyper-hydration is accompanied by a
decrease in urine volume
Recent Research (in-review) from
Our Laboratory
Study 1
Compared,
a. Distilled water (DW)
b. 100 mEq/L NaCl (80 mEq), KCl (20 mEq) solution (EL)
c. Gatorade (CHO-EL)
d. Glycerol hyper-hydration (1.2 g/kg glycerol bolus + 26 mL/kg water)
(GBol)
e. Glycerol solution (5.75 g glycerol/100 mL = 5.75 % glycerol) (GSol)
f. d + e (GG)
Subjects and Methods
Male
9
Female
3
Weight (kg)
73.212.8
LBM (kg)
62.511.2
Body Fat (%)
14.27.8
DW, EL,
CHO-EL, GSol = 4.0, 6.4, 5.2, 5.2, and 5.2 mL/kg
GBol = 40% glycerol, 6.4, 5.2, 5.2, and 5.2 mL/kg DW
GG = 40% glycerol, 6.4, 5.2, 5.2, and 5.2 mL/kg GSol
Results
Will be presented as two studies:
1. Comparing methods of glycerol ingestion to
CHO-EL.
2. Comparing glycerol solution (Gsol) to EL,
CHO-EL and DW
Symptoms
8
6
4
2
Nausea Severity
Headache Severity
Blurred Vision
10
10
10
8
6
4
2
0.5
1.0
1.5
2.0
0.5
2.5
10.0
1.5
2.0
5.0
2.5
0.0
2.0
Time (hrs)
CHO-EL
4
2
0.5
2.5
1.0
1.5
2.0
2.5
Time (Hrs)
10.0
8
6
4
2
GG
GSol
7.5
GBol
CHO-EL
5.0
2.5
0.0
0
1.5
DW
6
2.5
Nausea Severity
Headache Severity
7.5
Vision
1.0
10
1.0
EL
Time (Hrs)
Time (Hrs)
0.5
8
0
0
0
GSol
0.5
1.0
1.5
2.0
Time (hrs)
2.5
0.5
1.0
1.5
2.0
Time (hrs)
2.5
Osmolal Clearance
(mOsmol/min)
Osmolal Clearance
12
*
10
8
GG
GSol
GBol
CHO-EL
6
4
*
2
0
0
1
2
3
Time (hrs)
4
5
Osmolal Clearance
Osmolal Clearance
(mOsmol/min)
9
8
7
*
6
5
GSol
4
3
EL
2
DW
1
CHO-EL
0
0
1
2
3
Time (hrs)
4
5
Free Water Clearance
(mL/min)
Free Water Clearance
10
6
*
2
GG
GSol
GBol
CHO-EL
-2
-6
-10
0
1
2
3
Time (hrs)
4
5
Free Water Clearance
(mL/min)
Free Water Clearance
12
10
8
6
4
GSol
2
EL
0
DW
*
-2
CHO-EL
-4
0
1
2
3
Time (hrs)
4
5
 Body Weight (% LBM)
Change in Body Water
2
1
GG
0
*
GSol
GBol
-1
CHO-EL
-2
0
1
2
3
TIme (hrs)
4
5
 Body Weight (% LBM)
Change in Body Water
2.0
1.5
*
1.0
0.5
0.0
DW
-0.5
GSol
-1.0
EL
-1.5
CHO-EL
-2.0
0
1
2
3
Time (hrs)
4
5
What we recommend to athletes:
4-5% (grams/100 mL) glycerol, 4 %
CHO, 4 mEq/L Na+ and K+
eg: glycerol = 1.25 g/mL
1 L of 5% glycerol solution
50 g or 40 mL of glycerol, and add half strength Gatorade to
equal 1 L
Drink prior to exercise (1 to 2 L over 2 hrs)
Drink as needed during exercise
Thank you