Bicarbonate loading

Introduction
Sodium bicarbonate is a naturally occurring substance in the body. Its' main function is to help preserve the pH balance in intracellular fluid at a pH point around 7.35. The human body can only tolerate small fluctuations in the pH value and values +/- 1.00 (acidosis when the value falls below 7.35 and alkalosis when the value rises above 7.35). Sodium bicarbonate (NaHCO3) acts like a buffer when acidosis occurs bringing it back to near normal values.

To create energy for exercise activity the human body has a number of interlocking systems that allow it to generate varying amounts of adenosine tri-phosphate (ATP). ATP combines with phosphocreatine (PCr) to create the conditions where various chemical reactions can occur that allow muscle fibers to move against each other and so cause movement. The stored amounts of ATP and PCr in the body are small and need to be constantly regenerated. This is achieved through the interplay of three main energy producing systems. The ATP-PCr system is the easiest for the body to utilise. It is a purely chemical reaction and instant energy can be created for around 5-6 seconds of maximal activity. This system is backed up by anaerobic glycolysis and uses stored amounts of carbohydrate (glycogen) in muscle and the liver to help create ATP. It can last for 7-10 minutes at a maximal rate. However, the main bi-product called lactate is an acid and is one of the factors involved in slowing down the ATP-PCr chemical energy production and contributes to feelings of fatigue. Aerobic activity requires oxygen (O2) to produce ATP and as this is relatively slow at getting to the working muscle is the last system to generate energy. It can however, last for many hours and is the major source of human ATP.

Although anaerobic glycolysis is responsible for producing lactic acid (lactate) it is also a naturally occurring substance in the body, which can be tolerated, in small amounts. The normal fate of lactic acid (LA) is to be exhaled as H2O in breath or turned into pyruvate, which is used, in the chemical pathway that aids ATP production. However, when values start to reduce pH in working muscle, and subsequently the blood stream, causing acidosis to occur these two pathways are unable to cope with the increased amounts of LA. It is at this time NaCHO3 is used to buffer the free hydrogen ions (H+) causing the fall in pH to dangerous values. Maximal anaerobic exercise may cause pH to fall as low as 6.2-6.3, which, if not countered, can cause death.

The theory behind bicarbonate loading (the ingestion of extra amounts of bicarbonate) is that if it buffers LA in maximal anaerobic activity it could halt the pH decline and allow the activity to continue. This in turn might give one person an advantage over another allowing the 'loaded' athlete to compete harder for longer in continuous activity lasting for periods up to 10 minutes.

Research studies on the topic
Bicarbonate loading has been studied for around 60 years. The results from many of the studies pre 1970 were inconsistent due to variances in the study design and application. Often the administered dose of bicarbonate was too small to have an effect. However, from the 1970's onwards the doses used have been in the range of 0.20-0.30g/kg-body weight and generally administered 1-2 hours prior to exercise. This administration might have been by capsule, diluted solution or intravenously.

Depending on the actual dosage, gastrointestinal discomfort has been reported by subjects. This might involve vomiting, stomach cramps or diahorrea. Tissue sampling has been variously by blood sample or muscle biopsy or both. Varying exercise intensities have been used (normally related to % VO2 max) over varying work times and recovery periods. Swimming, cycling, running all feature in the exercise modes, which have included some, field-tests. Time to exhaustion, average power output over 30-120s, timed performances and perceived rate of exhaustion (RPE) have been the variables tested. Early studies were encouraged by observations that serum pH values at rest were increased after bicarbonate was administered and it is thought that the elevated serum pH facilitated the efflux of lactate from muscle. Williams (1992) suggests this to be "universally accepted".

Williams (1992) goes on to cite several studies that indicate inconsistent effects on VO2/VE from those that observed no changes to Cho et al (1990) who reported rises in VO2 max in trained cyclists. However, the main focus of attention has been in anaerobic type activities.

Several studies appear to report positive effects on the psychological perception of effort (RPE). Robertson et al (1987) used arm and leg exercise at 80% VO2 max and found reductions in RPE but at 20-60% VO2 max little/no change occurred. Later Swank and Robertson (1989) reported lower RPE values in repeated 5-min exercise bouts at 90% VO2 max with 10-min rest periods. This was attributed to blood alkalinity increasing and bicarbonate supplementation.

Laboratory studies involving maximal single exercise bouts of 30s - 10-min+ with short recovery periods have found that supplementation has not been effective in work periods around 30s. Speculation has been that PCr also acts as a buffer in these periods or that the time scale was too short for bicarbonate to have a positive impact on H+ efflux (Costill et al 1984). Lavender and Bird (1989) reported greater power outputs in repeated maximal cycle tests in 8 of 10 x 10s sprints. The greater differences being observed in the latter sprints (presumably when lactate accumulation was at it's greatest).

It would appear that repeated exercise bouts with some recovery periods offer the greatest opportunity for benefits from bicarbonate supplementation. McKenzie et al (1986) found that does of 0.15g/kg body weight (BW) and 0.30g/kg BW had a beneficial effect on time taken to exhaustion and total work possible in a test involving 6 x 1 min cycle sprints at 125% VO2 max with 1 min rest periods where the final work period was to exhaustion. Costill et al (1984) used a 0.2g/kg BW dose and reported a 42% increase in time to exhaustion in a similar test involving 5 x 1 min work periods with the final one being to exhaustion. Fox, Bowers and Foss (1994) report on several studies showing treadmill running to exhaustion times increasing from 4.5 min to 7.3 min and an 800m run study cutting almost 3s off the final time.

Field studies appear to support experimental research when using trained athletes. Simmonds and Hardt (1973), Gao et al (1988), Cho et al (1990), Wilkes et al (1983) and Goldfinch et al (1988) all reported improved performances in timed swims, 400-800m runs and cycle performances.

Practical applications
Bicarbonate loading/supplementation is not at present an illegal doping activity as described by the IOC or Sport England (the reader is recommended to inquire about its' status with Governing Body's before consideration). However, it may cause some gastrointestinal discomfort as described and prolonged use may cause severe alkalosis and other side effects such as apathy, irritability, cardiac arrhythmia's and more severe gastrointestinal problems. The dosage required (0.2g-0.3g/kg BW) may cause the user some difficulties and large amounts of fluid may be needed to aid ingestion (a 90kg man would need a dose of 18-27g according to most studies).

This being the case it would appear that bicarbonate loading is most effective in maximal exercise 80%+ VO2 max where repeated bouts of work lasting more than 30s are needed with some kind of rest period between the bouts. This kind of activity can be seen in many karate applications. This might involve rigorous kata activity, sambon, kumite, many of the practice/training drills such as ten no kata/kihon or even some elements of competition work. There may be those reading this who will instantly see the application as being purely 'sport' orientated. Whilst it may have 'sport' applications the opportunity for the martial art karateka to 'stay in the zone' of high quality physical performance may allow improved opportunities for increased learning to take place both in a physical sense (training overload) and an emotional/psychological sense. Being able to experience a higher level of practice may allow the karateka to attain it easier without future supplementation ("Now I know what it's like I can attempt to repeat it"). There may be a case for future research studies into karate specific activities using bicarbonate supplementation in a controlled environment as it appears to have been little studied.

References
"Cho,S., Chung, D., Park, S., Choi, I., "The effect of induced metabolic alkalosis with sodium bicarbonate on racing time, maximal oxygen uptake and anaerobic lactate threshold in competitive cyclists" Korean J Sports Sci 2:71-84, 1990
"Costill, D., Verstappen, H., Kuipers, H., Janssen, E., Fink, W., "Acid base balance during repeated bouts of exercise influence of HCO3" Int. J. Sports Med. 5:228-231, 1984
"Fox, E., Bowers, R., Foss, M (1994) "The physiological basis for exercise and sport" Brown and Benchmark, Duboque, Iowa
"Gao, J., Costill, D., Hosswill, C., Park, S., "Sodium bicarbonate ingestion improves performance in interval swimming" Euro. J. Appl. Physiol 58:171-174 1988
"Goldfinch, J., McNaughton, L., Davies, P., "Induced metabolic alkalosis and its effects on 400m racing times" Euro. J. Appl. Physiol. 57:45-48 1988
"Lavender, G., Bird, S., "Effect of sodium bicarbonate ingestion upon repeated sprints" Br. J. Sports Med. 23:41-44 1989
"Mckenzie, D., Coutts, K., Stirling, D., Hochen, H., Kutcha, G., "Maximal work production following two levels of artificially induced metabolic alkalosis" J. Sports Sci. 4:35-38 1986
"Robertson, R., Falkel, J., Drash, A., Swank, A., Metz, K., Spungeon, S., LeBoeur, J., "Effects of induced alkalosis on physical work capacity during arm and leg exercise" Ergonomics 30:19-31 1987
"Simmonds, R., Hardt, A., "The effects of alkali ingestion on the performance of trained swimmers" J. Sports Med. 13:159-163 1973
"Swank, A., Robertson, R., "Effects of induced alkalosis on perception of exertion during intermittent exercise" J. Appl. Physiol 67:1852-1857 1989
"Wilkes, D., Gledhill, N., Smyth, R., "Effects of acute induced metabolic alkalosis on 800m racing time" Med. Sci. Sports Exercise 15:277-280 1983
"Williams, M. H., "Bicarbonate loading" Gatorade Sports Science Exchange 4:36 1992

Thanks are given for the support of the Gatorade Sports Science Institute in the completion of this review and in particular to Carol LaCrosse. Access to the above may be made by viewing the Gatorade web site.