other ergogenic aids the application of a nutritional, physical, mechanical, psychologic,...
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Other Ergogenic Aids
The application of a nutritional, physical, mechanical, psychologic, physiologic or
pharmacologic procedure or aid to improve physical work capacity
Discuss issues you should consider when evaluating evidence regarding a possible ergogenic aid
Creatine
Methylguanidine-acetic acid Naturally occurring most muscle tissue Synth by body – mainly liver and kidney –
transported via blood to muscle Normal intake ~2g/d (fish, red meat, trace
amnts plants) Broken down, same rate, to creatinine and
excreted in urine.
PCr
Provision of phosphate for ATP regeneration at start of high-intensity exercise.
PCr + ADP + H+ Cr + ATPcreatine kinase
Store limited – depleted within 5s supramaximal exercise
High PCr stores may reduce anaerobic glycolysis and lactic acid formation
Also potential for buffering H+
Cr supplementation
Harris et al., (1992) Cr monohydrate ↑ total muscle Cr 5g, 4-6x/d for several days Suggested could improve performance
Greenhaff et al., (1993) 20g.d for 5 days 6% improvement in repeated bouts of max knee
extension ~2/3 of studies different modes report +ve effects
– rest no effect (Williams et al., 1999)
Cr loading Generally 20g/d (4 x 5g) for 6 d
↑~25mmol/kg dw (~20% increase) Hultman et al., (1996) – after load – subsequent dose of 2g/d
maintenance for 35 d (otherwise levels declined) Similar results with 3g.d for 28 days Considerable individual variation – habitual diet? 160 mmol/kg dw appears to be max – only 20% of subjects
achieve this Co ingest with simple CHO ↑ uptake (Green et al., 1995,1996) Those who show largest increase also show largest performance
benefit (Casey et al., 1996)
Cr and weight gain
↑ 0.5 to 3.5kg BM (~1kg) Water retention (↑ intracellular osmolarity); anabolic effect? (Kreider et al., 1998)
↑BM not beneficial endurance Balsom et al. (1993) ↓ running performance PCr not limiting in endurance May benefit sprints in intermittent exercise eg.
Football (Cox et al., 2002, Mujika et al., 2000)
Cr and High-intensity exercise
~70% studies find improvements in strength, force production and torque
Balsom et al., (1993) significantly less fatigue in repeated sprints.
Cr and resistance training
Vandenberghe et al., (1997) - ↑max strength and FFM
Combination of Cr ingestion and strength training> strength training alone
Wagenmakers (1999) – suggest allows more repetitions in training and thus better training and anabolic effect
Anabolic effect may be due to cell swelling acting as an anabolic signal (Lang et al., 1998)
However, no studies show that Cr affects protein metabolism
Cr safety
No studies of detrimental health effects Anecdotal reports
GI disturbances, CV and muscular problems, nausea, vomiting, diarrhoea, kidney and liver function alterations, muscle cramps and elevated bp
Evidence incomplete Contamination supplements?
Cr safety
Recent case study 24-yr old ♂ acute renal failure, proteinuria Creatine + multiple other supplements Acute interstitial nephritis Thorsteinsdottir et al., (2006)
Buffers - bicarbonate Most imp extracellular buffer Na bicarbonate/Na citrate (less GI distress)/Na lactate –
ergogenic effect on middle distance events Buffers H+ and increases diffusion of H+ out of cells Goldfinch et al., (400m - 1988) Wilkes et al., (800m - 1983),
Matson and Tran (review - 1993) Increased peak power and total work in max cycling
(McNaughton et al., 1997, 2001) However controversial – other studies no effect Tiryaki and
Atterbom (600m – 1995);Horswill et al., (2 min sprints - 1998), Inbar et al., (Wingate, 1993)
Dosage? Duration of admin? Acute vs. chronic admin Tolerable dose – 300mg/kg bw
Recent studies
Douroudos et al., (2006) NaHCO3 0.5g.kg.d for 5d increased mean power in Wingate
Berger et al., (2006) NaHCO3 delays appearance of the slow component
Buffers - phosphate Dietary phosphate incorporated into
ATP, CP Thiamine pyrophosphate – coenzyme of carboxylase –
required for decarboxylation of pyruvic acid, keto acids, 2-oxoglutarate
Na phosphate (blood buffer) 2,3-disphosphoglycerate (DPG) – most research focussed
on this Number of studies ~4g.d-1 for 3-6 days increasing
VO2max, AT, exercise performance However other studies no effect. To date no conclusive evidence.
Glycerol
Capacity declines when dehydration >threshold
Threshold differs depending on temperature Body water loss < 1.8% in hot, < 3.2% in
temperate ambient conditions Prehydration may be beneficial when rate of
fluid consumption cannot limit BW loss to these levels
Glycerol Focus on role as hyperhydrating agent rather than fuel for exercise Improves water reabsorption (Wapnir et al., 1996), and retention
(Gleeson et al., 1986; Koenigsberg et al., 1995) Effect is independent of ADH and aldosterone Filtered by glomerulus, reabsorbed across tubular walls increasing
corticomedullary gradient for reabsorption of water Metabolised and excreted slowly so can work over extended period
of time Recent meta-analysis – improves endurance performance ~2.62%
(Goulet et al., 2007) Loading Protocols: 1-1.5 g glycerol.kg-1 BM consumed 2 hours pre-event in conjunction
with 25-35 ml fluid per kg (AIS, 2006) 1 – 1.2g glycerol.kg-1 BM with 26 ml fluid.kg-1 BM – taken during 60 -
90 min period, exercise to commence after bloated feelings subsided (Goulet et al., 2007)
Glycerol However…. A number of studies no effect on thermoregulation (Inder et al.,
1998, Latzka et al., 1997; 1998) Volume of water too low?
Significant side effects: Nausea, heartache, blurred vision, headaches, GI problems,
dizzy, light-header, bloated. Extra weight of fluid increase metabolic cost of exercise?
Ebert et al., (2007) dehydration (-2.5% BM) reduced TTE compared to euhydration (+0.3% BM)
↑risk hyponatraemia? Although [Na] decline, magnitude not sufficient to cause
hyponatraemia
http://www.ais.org.au/nutrition/SupProvision.asp