KINE 442 - Exercise Physiology - Week 12 Lecture 2 - Dehydration during Exercise PDF

KINE 442 – Exercise Physiology Week 12 Unit 2 - Lecture 1 – Dehydration during Exercise  Physiology of Dehydration During Exercise How Dehydration Occurs Rehydration takes time Water loss through sweating try to drink during >...

KINE 442 – Exercise Physiology Week 12 Unit 2 - Lecture 1 – Dehydration during Exercise  Physiology of Dehydration During Exercise How Dehydration Occurs Rehydration takes time Water loss through sweating try to drink during > - exercise Sweating: body’s mechanism for dissipating heat generated by increased burning of energy by body during exercise Effectiveness in cooling body depends on humidity Water lost through sweating comes from: Intracellular & extracellular compartments (including plasma) Measure by Muscle tissue & skin weighing yourself Internal organs before & After Bone ↑matabalism = heat need to cool body down Copyright © 2016 Wolters Kluwer All Rights Reserved 2  Physiology of Dehydration During Exercise (continued) Factors contributing to decreased aerobic performance with dehydration by a viscosity ↓ volume = a pressure Loading… Exercise feels harder more intense Copyright © 2016 Wolters Kluwer All Rights Reserved 3  Physiology of Dehydration During Exercise (continued) Effect of Dehydration on Anaerobic Capabilities Increased dehydration = increased decline in performance same with overhydration Dehydration resulting in: >5% loss of total body mass = strength decrements 3% to 4% of loss of body mass = loss of muscular endurance Strength & anaerobic capabilities less affected than aerobic because: Decrease in plasma volume & cardiac output don’t affect anaerobic activity Anaerobic capability decrements more likely w. heat exposure Strength decrements more likely in upper body Copyright © 2016 Wolters Kluwer All Rights Reserved 4  Physiology of Dehydration During Exercise (continued) Marathon Endurance capabilities are decreased by dehydration of as little as 2% of total body mass Fluid is ingested to prevent hydration & replace de electrolytes Factors affecting amount of fluid intake needed: Loading… The greater the body mass, the greater the fluid intake needed The greater the heat & humidity, the greater the fluid intake needed 36 F optimal temperature ° don't > - have to work too hard to thermoregulate Alternate Viewpoint - http://bjsm.bmj.com/content/45/14/1101.short lost most water-faster would say otherwise so why ? Lab Copyright © 2016 Wolters Kluwer All Rights Reserved 5  KINE 442 – Exercise Physiology Week 12 Lecture 2.2 – Dehydration during Exercise (continued)  Physiology of Dehydration During Exercise (continued) Freestyle Wrestling Weight-class sport requiring strength & power Combination of caloric & fluid restriction is used Dehydration of 5% to 6% results in decrements in strength & anaerobic performance One study showed significant decreases in some but not all physiological measures Decreases were result of combined effect of weight loss, dehydration, & competing in tournament Copyright © 2016 Wolters Kluwer All Rights Reserved 7  Physiology of Dehydration During Exercise (continued) After weight loss, strength measures decrease in wrestlers Copyright © 2016 Wolters Kluwer All Rights Reserved 8  Physiology of Dehydration During Exercise (continued) Team Ball Sports: Basketball and Soccer Decreased aerobic performance in later stages of contest Decreased anaerobic capabilities = decreased sprinting ability Decreased strength or power = decreased jumping ability Basketball Decreased shooting percentage (by 8%) Repeated sprint ability (by 2%) Lateral movement ability (by 5%) Soccer decreased performance of Yo-Yo intermittent recovery test (by 15%) (Might) try adding midfielders to defense if more team crushed is getting Copyright © 2016 Wolters Kluwer All Rights Reserved 9  Physiology of Dehydration During Exercise (continued) Susceptibility to Dehydration Environmental factors High temperature High humidity Weight-class sports Protective equipment (prevents evaporation Dark-colored clothing or equipment Illness involving fever or diarrhea Age Harder you're older when active throughout your life ↳ better to be consistantly Copyright © 2016 Wolters Kluwer All Rights Reserved 10  KINE 442 – Exercise Physiology Week 12 Lecture Loading… 2.3 – Hydration Assessment  Hydration Assessment Methods Field Hydration Methods Assessment of body mass Euhydration: maintenance within ±1% of pre- exercise value Dehydration: losses >1% of pre-exercise body mass Assessment of urine color Euhydration: light color Dehydration: dark color May be skewed by: Consumption of supplements (darkening urine) ↑ osmolarity Drinking fluids after an exercise session ↑ ↑ water loss anxiety = Copyright © 2016 Wolters Kluwer All Rights Reserved 12 Hydration Status: Body Mass and Urine Color Indices Have to measure consistantly to measure hydration normal Day Day very is to fluctuation in weight Copyright © 2016 Wolters Kluwer All Rights Reserved 13 Copyright © 2016 Wolters Kluwer All Rights Reserved  Hydration Assessment Methods (continued) Laboratory Hydration Assessment Methods Dilution methods via plasma osmolality measurement Urine volume Urine specific gravity Urine osmolality pepole can weigh monitor Urine color Copyright © 2016 Wolters Kluwer All Rights Reserved 15  KINE 442 – Exercise Physiology Week 12 Lecture 2.4 – Hyponaturemia and Hydration Guidelines  Hyponatremia Drinking too much water (“water intoxication”) Low blood sodium concentration (117−128 mmol⋅L-1) Causes osmotic imbalance leading to: Fluid movement to brain Swelling of brain leading to disorientation, confusion, general weakness, grand mal seizures, coma, & even death Also caused by excessive sodium loss in sweat More likely in women than in men Copyright © 2016 Wolters Kluwer All Rights Reserved 17  Maintaining Hydration Hydration Guidelines Begin activity in a euhydrated state Maintain hydration during activity Rehydrate after activity Fluid should be palatable & cool & contain electrolytes should taste good Developing a Hydration Plan Individualized hydration plans should be developed Plan will need to be modified due to changing seasons & conditions Copyright © 2016 Wolters Kluwer All Rights Reserved 18 Copyright © 2016 Wolters Kluwer All Rights Reserved