Idrottsforskning 2018 för en hållbar barn- och elitidrott. Muscle metabolism in fatigue and recovery: with special focus on glycogen

Transcription

1 Idrottsforskning 2018 för en hållbar barn- och elitidrott Muscle metabolism in fatigue and recovery: with special focus on glycogen Niels Ørtenblad Professor, PhD Institute of Sports Science and Clinical Biomechanics University of Southern Denmark, Odense, Denmark. University of British Columbia Australian Catholic University Mid Sweden University Nationellt Vintersportcentrum Maximal metabolic power as a function of sustainable performance Beneke and Böning, Biochemical Society (2008) 1

2 Muscle fatigue A reduction of force or power output of the working muscle over time A reversible weakness of muscle function associate with intense activity Tight balance between energy utilisation and energy production ATP ATP production ATP utilization ADP + P i The energy (ATP) is used for the muscle contractions Energy utilisation must be meet by an equal energy (ATP) production The ATP is produced through different pathways and sources (fat, carbohydrate, protein) 2

3 Where does the energy come from? Glycogen (glukose) In the liver blood Fat and glucose from stomach/intestine blood Fedt Fat depots Glycogen (glucose) In the muscle Energy systems - capacity and power Amount of energy (capacity) PCr Energi production rate (Power) i.e. production of ATP Glycogen to lactate Energy Energy Oxidation of Muscle glycogen Energy Fat Rate is approximately 50% of glycogen Energy 3

4 Role of muscle glycogen in fatigue to hit the wall With low muscle glycogen depots, one have to use fat to regain ATP. Glycogen (glukose) In the liver blood Fat and glucose from stomac/intestine blood ATP Fedt Fat depots Glycogen (glucose) In the muscle Fat can only regain ATP at low rates 50% as fast ATP production as from glycogen ATP production ATP utilization Energy utilisation has to be decreased slow down running speed (exercise intensity) ADP + P i hitting the wall sukkerkold etc. Low carbohydrate and high fat intake fatigue considerable and sometimes excessive Performance Krogh A & Lindhard J (1920) Biochem J 14:

5 Clear relationship between glycogen concentration in human skeletal muscle and endurance during exercise at 75% VO 2max 189 min 126 min 59 min Bergström, Hermansen, Hultman, Saltin (1967) Acta Physiol Scand Muscle glycogen is associated with performance Glycogen (glukose) In the liver blood Fat and glucose from stomac/intestine blood Fedt Fat depots Glycogen (glucose) In the muscle Important energy store for the performance during prolonged exercise 5

6 What does it look like? C IMF Glycogen SS glycogen Intra Glycogen Z Intra glycogen (µm 3 µm -3 ) X magnification IMF Glycogen X magnification Nielsen, Holmberg, Schrøder, Saltin & Ørtenblad, # J Physiol (2011) Ørtenblad, Nielsen, Saltin & Holmberg, J Physiol (2011) Muscle glycogen, before and after 1 hour intense exercise in elite cross-country skiers Before 59% After +1 hour ski-competition 31% Z M Mi M Mi Z Z Nielsen, Holmberg, Schrøder, Saltin & Ørtenblad, J Physiol (2011) 6

7 Glycogen utilisation during a soccer game 1 st and 2 nd division Danish soccer players 50% of fibres empty or almost empty 43% On average a decrease in glycogen of 50-90% Krustrup et al., Eur J Appl Physiol (2011) Krustrup et al. MSSE (2006) Utilisation glycogen during a soccer game 1 st and 2 nd division Danish soccer players It took 48 hours before glycogen depots were filled up!! 73% 43% Krustrup et al., Eur J Appl Physiol (2011) Krustrup et al. MSSE (2006) 7

8 NVC sprint study - outline Skisprint - 4 x 3½ min all-out with 45 min pause 21% of muscle glycogen is used within 3½ min!! 73% used without glucose during restitution 50%used provided optimal glucose intake in recovery periods Sprint 1 45 min Sprint 2 45 min Sprint 3 45 min Sprint 4 Gejl, Ørtenblad, Andersson, Plomgaard, Holmberg and Nielsen, Jounal ofphysiology (2017) Why Muscle is low glycogen muscle glycogen utilization causing and impaired exercises muscle of varied function intensity fatigue?? Glycogen depletion increases dramatically with increasing exercise intensity. Data represent a sampling from studies compiled from cycling exercise protocols only and represent glycogen use in the vastus lateralis muscle Impey et al Sports Med

9 Why is low muscle glycogen causing impaired muscle function fatigue?? Muscle fibre Ca 2+ contraction Increase in muscle calcium (Ca 2+ ) is the signal initiating the muscle contraction low levels of Calcium (Ca 2+ ) in the muscle is associated with muscle fatigue. An impaired muscle Ca 2+ regulation is observed in nearly all studies, with different exercise intensities and modes!! Muscle fibre Ca 2+ contraction soccer 9

10 Why is low muscle glycogen causing impaired muscle function fatigue?? Muscle fibre Ca 2+ contraction Increase in muscle calcium (Ca 2+ ) is the signal initiating the muscle contraction low levels of Calcium (Ca 2+ ) in the muscle is associated with muscle fatigue. Activation and contraction of skeletal muscle Ca 2+ Muscle fibre Increase in muscle calcium (Ca 2+ ) is the signal initiating the muscle contraction Calcium (Ca 2+ ) levels in the muscle is associated with muscle fatigue. There is a clear association between low muscle glycogen levels and impaired muscle Ca 2+ regulation 10

11 Association between low glycogen levels and impaired muscle Ca 2+ regulation fatigue 120 Glycogen contents vs Ca 2+ release rate Relative SR vesicle Ca 2+ release rate (% control) r 2 = 0.41, P < Skeletal muscle glycogen content (mmol/kg dw) There is a clear association between low muscle glycogen levels and impaired muscle Ca 2+ regulation Ørtenblad, Nielsen, Saltin & Holmberg, J Physiol (2011) How can improve exercise performance?? Postpone the fatigue with carbohydrate 11

12 Carbohydrate intake improves performance Trained cyclists 2 hours cycling at 60% VO 2 max then subjects had to complete a set amount of work as quickly as possible (approximately 1 h) Glukose + fruktose Indtag 90 gr/time 56: watt Kulhydrat indtag under arbejde forbedrer præstationen (>2.5 timer) Glu:Fruc mix forbedrer performance mere! Glucose Indtag 90 gr/time Placebo 67:00 Sweet water 231 watt 60: watt 8% højere power Currell and Jeukendrup, Med Sci Sport Ex (2008) ROLE OF CARBOHYDRATE INTAKE ON PERFORMANCE Carbohydrate intake during prolonged exercise improves the performance Time til exhaustion ± carbohydrate Low intensity exercise followed by test ± carb Effect size 15% Effect size 7% Meta-analysis = summary of a larger number of studies Meta-analyse Temesi et al., The Journal of Nutrition

13 Carbohydrate intake improves performance Glycogen (glukose) In the liver blood Fat and glucose from stomac/intestine blood Fedt Fat depots Glycogen (glucose) In the muscle Important energy store for performance during prolonged exercise Carbohydrate intake and performance The longer performance time the more improvement with carbohydrate supplementation Stellingwerff and Cox, Appl Physiol Nutr Metab (2014) 13

14 CARBOHYDRATE INTAKE BEFORE, DURING AND AFTER EXERCISE What are the general recommendations for carbohydrate intake before, during and after exercise? WHEN TO THINK OF CARBOHYDRATE INTAKE? Carbohydrate intake improves performance It is only relevant to think of carbohydrate intake if exercise is performed with high intensity (intermittent exercise) for 1 hour or if exercise time is +1 ½ time. 14

15 CARBOHYDRATE INTAKE BEFORE EXERCISE All about filling up depots liver and muscle with glucose (glycogen) Aim to have a high carbohydrate intake the last days before competition (app gr/ kg/ day = gr / day). This, can be combined with low training amount glycogen loading. Intake of 1-2 gr carbohydrate / kg, 3-6 hours before competition. CARBOHYDRATE INTAKE DURING EXERCISE Why 60 gr per hour? The general recommendation is to intake ~60 g carbohydrate per hour during exercise. 15

16 It is not possible to uptake more than 60 gr glucose /hour Carbohydrate uptake and utilisation (gr/hour) Glucose Glucose Glucose Glucose 10 Low to moderate intake High intake More glucose will built up in the intestine gut problems 120 carbohydrate intake during exercise (gr/hour) Glucose What is the limiting factor for the carbohydrate uptake? By by-passing the gut and infuse carbohydrate directly in the vein, then the carbohydrate uptake in muscle is 2-3 gr /min!! Glucose Glucose Glucose Glucose Glucose The maximum carbohydrate uptake and utilisation through the gut (stomach and intestine) is approx. 1 gr carbohydrate/min (= 60 gr/time) Uptake from intestine to the blood is the main limiting factor for the carbohydrate uptake 16

17 CARBOHYDRATE INTAKE DURING EXERCISE General recommendations Intake as liquid solution (energy drink), typically 6-8% solution (6-8 gr/100 ml). (avoid drinks with very high carb., 10-15% gut/intestine problems!). This can be done by intake of app. 800 ml drink per hour (6-8% carbohydrate). Drink often, i.e ml every min (if possible) Start out early and drink routinely. Make the drink drinkable Drink colder than surroundings taste NaCl The general recommendation is to intake ~60 g carbohydrate per hour during exercise. Drinks or energy bars? There is no difference between intake of energy bar, gels, or energy drinks. However, remember to drink water if you use energy bars, gels etc. which is concentrated carbohydrate (stomach concentration should end up with no more than 6-8%!!) 17

18 CARBOHYDRATE INTAKE DURING EXERCISE General recommendations Intake as liquid solution (energy drink), typically 6-8% solution (6-8 gr/100 ml). (avoid drinks with very high carb., 10-15% gut/intestine problems!). This can be done by intake of app. 800 ml drink per hour (6-8% carbohydrate). Drink often, i.e ml every min (if possible) Start out early and drink routinely. Make the drink drinkable Drink colder than surroundings taste NaCl But what is carbohydrate? The general recommendation is to intake ~60 g carbohydrate per hour during exercise. Not all carbohydrate is equal what is carbohydrate? Some cabohydrates are digested fast others slow (stivelse) Intestine (diet) (stivelse) Glucose Galactose Fructose Liver glycogen (glucose) Glukose 18

19 Multiple carbohydrate sources (glucose + fructose) enables a larger carbohydrate uptake Carbohydrate uptake and utilisation (gr/hour) Low to moderate intake Multiple carb source (fructose + glucose) High intake Less gut problems Mono carb source (glucose) Gut problems 120 carbohydrate intake during exercise (gr/hour) Glucose Galactose Fructose Glucose Trained cyclists 2 hours cycling at 60% VO 2 max then subjects had to complete a set amount of work as quickly as possible (approximately 1 h) Glucose + fructose Indtag 90 gr/time 56: watt Glucose Indtag 90 gr/time 60: watt Placebo 67:00 sweet water 231 watt 8% higher power Currell and Jeukendrup, Med Sci Sport Ex (2008) 19

20 DIFFERENT FORMS OF CARBOHYDRATE Many commercial energy drinks contains 2:1 ratio or the like of glucose + fructose. Carbohydrate transported to the blood 2:1 ratio of glucose:fructose can increase the carbohydrate uptake and utilisation during exercise Take care!! High amounts of fructose causes gut problems. Large individual differences in tolerance! Carbohydrate intake during exercise Carbohydrate intake and exercise duration < min No 1-2 hours app. 30 gr carbohydrate/hour 2-3 hours app. 60 gr carbohydrate/hour, evt 2 glucose: 1 fructose +2½ hours app gr carbohydrate/hour inclusive more complex carbohydrates (maltodextrin). Trained up to 90 gr carbohydrate/hour. By using different forms of carbohydrate the uptake and utilisation (oxidation) can be increased from 60 gr carbohydrate / hour to gr carbohydrate / hour. Maltodextrin and the like complex carbohydrates are not sweet and does not bind as much water as equal amounts of glucose. 20

21 How to intake the carbohydrate? Intake during running vs skiing, rowing, ball games etc. Large individual differences in how one : can tolerate (gut/intestine problems). prefer (taste, temp, form). how long one can eat/drink. how much one can intake per serving. Follow general recommendation find your own way of intake. Importantly, try and test before the important competition! Does the weight /size of the person noget for indtaget af kulhydrat We indicate carbohydrate recommendations in gr/hour why not in gr/hour/kg? There is no association between weight and carbohydrate uptake recommendations are in gr/hour 21

22 Guidelines to carbohydrate intake during exercise Recommendations are dependent on exercise duration. In general its recommended to increase the carbohydrate intake with increasing exercise time. Type of carbohydrate varies as well as the habituation to intake varies. CARBOHYDRATE INTAKE DURING TRAINING During most training situations and regiments, there is no reason to speculate in carbohydrate intake, energy drink, sports bar etc. provided that you have a relatively normal daily diet. Only during long training sessions or training more times per day with high intensity, one should focus on carbohydrate intake. It has been debated and discussed that the training outcome can be increased by avoiding carbohydrate during exercise train low compete high 22

23 CARBOHYDRATE INTAKE AFTER EXERCISE 73% I the late 80 s it was demonstrated tat if you intake carbohydrate immediately after exercise, then you will have 43% a faster and larger refilling of the carbohydrate stores, than if you wait 2 hours. This led to the idea of an open window where one preferably can fill up with carbohydrate. However, for most people with a normal habitual diet it is not critically to have carbohydrate storages filled up within normal recovery time (one day or days). Of note!! This may not be true after exercise involving eccentric exercise (running, soccer etc.!) Effects of mouth rinse with carbohydrate on performance A number of new studies have followed up on previous data demonstrating that there can be performance enhancing effects by rinsing the mouth with carbohydrate (glucose). Artificial sweeteners have no effect. Try to have a jelly etc. in the mouth during prolonged exercise 23

24 Collaborators on presented projects University of Southern Denmark Ass prof. Joachim Nielsen Kasper Gejl Rasmus Jensen Prof. Henrik Daa Schrøder University of Copenhagen Prof. Bengt Saltin Mid Sweden University, Östersund Prof. Hans-Christer Holmberg Erik Andersson Karolinska Institutet, Stockholm Prof. Håkan Westerblad Ass. Prof. Arthur Cheng 24