Nutrition - Effects of hydration status and electrolyte balance/imbalance on health and performance

Question 1

Potential effects of dehydration on performance

Answer 1

Mild dehydration (2%-3% water weight loss) can increase core body temp. and effect athletic performance by increasing fatigue and decreasing motivation, neuromuscular control, accuracy, power, strength, muscular endurance, and overall performance.

Question 2

Lost avg. sweat per hour of practice for NFL WRs and RBs

Answer 2

Avg. body mass: 93kg +/- 6 (204.6 +/- 13.2 lbs)

Lost avg. sweat per hour of practice: 1.4 +/- 0.45 L (47.3 +/- 15.2 fl. oz.).

Question 3

Lost avg. sweat per hour of practice for NFL linemen

Answer 3

Avg. body mass: 135.6 +/- 17kg (298 +/- 37.4 lbs)
Lost avg. sweat per hour or practice: 2.25 +/- 0.68 L (75.1 +/- 1.5 fl oz.)
Have a higher risk of dehydration due to more equipment and sometimes their body size.

Question 4

Lost avg. sweat during a 40-minute game for NBA players

Answer 4

Lost avg. sweat during 40-min game…avg. playing time 21 +/- 8 minutes: 1.0 to 4.6 L (33.8-155.5 fl oz).

Question 5

Lost avg. sweat in sedentary people

Answer 5

Respiration and sweat combined contribute to water losses equal to approx. 0.3L (20.2 fl oz) per hour.

Question 6

Preventing dehydration

Answer 6

Athletes should try to prevent water weight losses exceeding 2% of bodyweight while also restoring electrolytes lost through sweat.
Assess hydration status via urine specific gravity (USG), measure changes in body weight from pre- to post-workout.

Question 7

Measuring hydration by measuring changes in BW pre- to post-workout

Answer 7

Athletes should weight themselves in minimal, lightweight clothing, after drying off and urinating, immediately before and after workout.
Sweaty clothes should be removed before weighing.
Each pound (0.45kg) lost during practice represents 16 oz. (0.5 L) of fluid.
A loss of 2% or more of BW indicates the athlete is not adequately replacing fluid lost through sweat.

Question 8

Calculating sweat rate

Answer 8

gives better idea of fluid needs during exercise.

Sweat Rate = preexercise BW - post exercise BW + fluid intake during exercise - urine produced

Question 9

What are electrolytes?

Answer 9

Minerals dissolved in the body’s fluids, creating electrically charged ions.
Major electrolytes lost in sweat include: sodium, chloride, and to a lesser extent and in order, potassium, magnesium, and calcium.

Question 10

How does loss of electrolytes affect the body during activity?

Answer 10

Sodium influences fluid regulation by helping retain more of the fluid consumed.
All electrolytes lost in sweat are essential to muscle contraction and nerve conduction.
Any disturbances in the balance of electrolytes in body fluids could potentially interfere w/ performance.