Ergogenic Aids 1. Ergogenic Aids. Caffeine

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1 Ergogenic Aids 1 Dr David Jenkins School of Human Movement Studies The University of Queensland Ergogenic Aids drug derived from a number of plants 2004 removed from WADA Prohibited List possible mechanisms of action responsible for improvements in exercise capacity. CNS stimulant improve alertness, concentration & reaction time. mobilise free fatty acids from adipose tissue increase intramuscular TG use (glycogen sparing effect). 1

2 can elicit an ergogenic effect independent of glycogen sparing and changes in RER. exercise can be improved in events lasting 30 minutes may increase free calcium in muscles and/or improve K + uptake by the Na/K + pumps. psychostimulation pathways reduces the perception of effort. generally been taken around 60 minutes prior to exercise doses equivalent to ~ 6 mg/kg (e.g mg in total). 2

3 provides small but worthwhile enhancement of performance over range of exercise. These include: short duration high intensity events (1-5 min) prolonged high intensity events (20-60 min) endurance events (90 min / continuous exercise) ultra-endurance events (4 hours +) prolonged intermittent high intensity protocols (team and racquet sports). Effect on strength/power & brief sprints (10-20 sec) unclear. may increase reaction time but high doses can impair fine-motor skills. Large individual differences Graham & Spriet (1995): metabolic / performance changes in response to various doses endurance athletes - placebo / caffeine capsules (3, 6 or 9mg/kg) before completing four identical exercise trials. Each trial required the athletes to run at 85%VO 2 max until exhaustion 3

4 Graham & Spriet (1995) Endurance capacity enhanced with both 3mg/kg and 6mg/kg doses No difference between the 9mg/kg trial and placebo. highest dose (9mg/kg) elicited greatest effect on adrenalin and FFA but had no effect on performance. lowest dose (3mg/kg) had least metabolic effects but improved performance. Graham & Spriet (1995) 4

5 Cox et al. (2002) - effect of different caffeine intake on metabolism and endurance performance. Cyclists completed a 2hr trial, cycling at 70%VO 2 max followed by a TT that lasted approximately minutes. caffeine 1 hr before exercise (6mg/kg; Precaf), 6 x 1g/kg caffeine every 20 minutes during exercise (Durcaf), 2 x 5ml/kg Coca-Cola (during the TT at min and again during the TT) or a placebo. TT improved by 3.4% (Precaf), 3.1% (Durcaf) and Cola. Cola contains around 1.5mg/kg of caffeine. protein synthesised from guanidine and arginine found in skeletal muscle dietary source - meat and fish (less than 1g per day). 5

6 energy production in the muscle creatine phosphate - immediate (anaerobic) energy source for rapid resynthesis of ATP. buffering of H+ delay the rate of fatigue during high intensity exercise (eg. multiple sprinting). some evidence that creatine supplementation can improve lean tissue when combined with resistance training. 20g of creatine per day for 5 days significantly increased resting creatine phosphate levels. 20g ~ 4.4 kg of fresh, red meat. maintenance dose: 3-5g per day prevent fall of creatine phosphate to pre-supplementation levels. 6

7 Harris, Balsom, Hultman and Greenhaff creatine supplementation increased resting CrP levels and improved sprint performance and strength. subsequent investigations failed to provide same consistency in outcome measures. Kelly and Jenkins (1998) - 9 competitive male bodybuilders one month supplementation significantly increased body mass, lean body mass, 3RM bench press strength. improved muscle mass and strength - increased intake of fluid by muscle stimulated protein synthesis. supplementation period - initial 5 day dose of 20g/day. 5g per day for remainder of experiment creatine consumed with CHO - improve uptake by the muscle. 7

8 McKenna (99) - effect of supplementation on intramuscular creatine levels and multiple sprint performance. 30g of creatine for five days five 10s sprints before and after supplementation resting muscle sampled before, after and again at 2 and 4 weeks following supplementation. McKenna et al (1999) no influence of creatine on multiple sprint performance despite increase in total muscle creatine concentrations and [CrP]. 4 weeks for resting TC and CrP levels to return to pre-supplementation levels. 8

9 mixed research findings - training status /diet low intakes of creatine (vegetarians) potentially most to gain by creatine supplementation Individual differences are marked Side Effects Supplementation of 20g over 5 days associated with weight gain of 2kg. attributed to water uptake by muscles. anecdotal reports of compartment syndrome and muscle soreness (swelling). 9