The effects of Sodium Bicarbonate supplementation on performance in high-intensity intermittent training, a review of current literature.
By Mark O`Connell BSc.(Hons), Functional Movement Testing.ie/IT Tallaght.
The role of Sodium bicarbonate (SB or NaHCO3 or) as an ergogenic aid within sport has enjoyed a long established history of scientific research dating from the early 1930`s, the driving factor for early research was to increase sports performance in endurance sports, primary being long distance events of either cycling or running, from early studies researchers identified that that exercise released harmful by-products from the muscle and this altered the body`s natural pH balance, once altered this contributed to fatigue and reduced performance, so the task was to limit the effect of these by-products by inducing alkalosis by the ingestion of a pH buffer, Sodium bicarbonate ( Carr et al, 2011, Dennig et al, 1931 Dill et al, 1932).
As the human body stores a limited reserve of SB to use as a natural buffering agent to help limit both intracellular and extracellular changes in both blood and muscle pH levels due to exercise, it was noted that to limit fatigue the athlete would be require to use supplementation to make up for this physiological limitation (Van Montfoort et al, 2004).
Normal functioning arterial blood pH is approximately 7.4 with muscle pH levels typically 7.0, but with the onset of vigorous exercise as with high-intensity intermittent training (HIIT), arterial pH may lower to 7.1 and muscle pH decrease to 6.8, this is characterised with the release of hydrogen ions (H+) from the muscle as a response to vigorous exercise, this balance is known as the blood acid-base balance and it`s main function is to regulate H+ ion concentrations (McNaughton et al, 2008).
High-intensity intermittent training (HIIT) may be described as short-duration efforts of sub-maxiamal efforts (90%> V̇o2 max) coupled with peroids of light active recovery and rest periods, work rates may consist of <10 second`s of maximal sprint intervals with a recovery period of between 60–300 seconds to allow for recovery and preparation for the next high intense burst of activity (Spencer et al, 2005).
Due to HIIT activity predomintly using the anerobic energy system and using limited amounts of oxygen, this requires high rates of anaerobic glycolysis to fuel activity from the conversion of glucose to pyruvate during short, intense periods of high intensity exercise with periods lasting from 10 seconds to 2 minutes (Tomlin & Wenger,2001).
HIIT require high amounts of ATP produced from anaerobic glycolysis, and results in a buildup of H+ ions within the intracellular buffer resulting in an increase in extracellular pH in both blood and muscular pH acidity and an increase in blood lactate acid resulting in fatigue and a decrease in sports performance.
Previous research has also this view by reporting that due to the body having a limited amount of SB available to counteract the physiological effects of HITT, the accumulation of H+ ions and blood Lactate (Lac-) as these waste by-products are associated with the drop in blood and muscular pH levels and are essential factors to the individual’s sports performance (Hobson et al, 2014).
Due to these factors, there is an opportunity for sports and exercise professionals to use SB supplementation within HIIT especially within field sports based on practical application methods from current research, an appropriate SB supplementation dosage and ingestion protocol may aid in reducing players fatigue and increase intermittent performance in their chosen sport.
Mechanisms of action:
Role of the anaerobic glycolysis pathway during HIIT:
Of the three energy pathways used to produce energy for activity, the anaerobic glycolytic pathway is responsible for providing the energy for high intensity exercise, through the breakdown of carbohydrates via muscle glycogen. The process may be described as during intense exercise the body requires high amount of energy in the form of Adenosine Triphosphate (ATP), this is produced by the breakdown of glucose to 2 ATP molecules via glycolysis and this then creates 4 ATP molecules, the muscle requires 2 ATP to complete muscular contraction, and two ATP molecules are used as the process is anaerobic and uses no oxygen, this limits the body`s ability to reproduce ATP at the rate needed to maintain HIIT (Jansson et al, 1988).
As these energy stores become depleted this results in a release in H+ ion concentrations and lactate (Lac-) waste by-products from energy production in both the blood and muscle ( McNaughton et al, 2008).
This combination of both H+ / Lac- inhibits the release of calcium from the sacroplasmic reticulum and stops the interaction of both actin and myosin in the sliding-filament theory, resulting in a loss of muscular contraction as well as a drop in pH levels that inhibit the ability of the pathway to reproduce ATP (Shelton & Kumar, 2010).
Mechanism of action of SB during HITT:
As previous studies on SB have agreed that as an alkalizing agent, its primary function is a buffering action against the effect of acidosis and agreed that it`s effects of action is the ability to draw out acid created in the muscle cells into the blood and reduce intracellular acidity levels , this results in an increase in extracellular pH as both H+ and Lac- are transported out of the cell using active transport and with the increase in activity from the H+/Lac- co-transporter, which is more effective during an increase in the intracellular/extracellular H+gradient (McNaughton et al, 1997, VanMontfoort et al, 2004).
Review of key literature:
While previous research into SB and its effect on sports performance has studied and reported for over 30 years (Jones et al, 1977) and previous studies have also reported on SB supplementation within high intensity training, there is little research into the effects of SB on HIIT as in field sports (Matson and Vu Tan, 1993).
A previous meta-analysis research article consisting of 29 studies concluded that SB supplementation showed an improvement in sprint performance in high intensity training lasting from 45 seconds to six minutes (Matson and Vu Tan, 1993).
This review was supported by two previous studies that concluded that SB supplementation in high intensity activity to last between 1-7 and 1-10 minutes at 85% individual V̇o2 max and agreed that there was an increase in the participant’s performance (Linderman and Fahey, 1991., Maughan and Greenhaff, 1994).
Previous research into HIIT by Raymer et al (2004), found that SB supplementation before HIIT was beneficial in maintaining acid-base homeostasis during exercise and found an increase of the studies participants in time to exhaustion (TTE) an improvement in peak power output (POpeak) of 12%. This was supported by a study in 200m free-style swimming and found that SB supplementation participants to have increased performance times compared to both a control and placebo groups with 1.5 second improvement against both groups (Lindh et al, 2007).
Yet, this research was not supported by Linderman and Gosselink (1994), who having researched 16 published studies only found one study to report that SB supplementation to have a positive effect on sprint performance in events lasting less than 60 seconds.
The most recent meta-analysis by Carr et al (2011) stated that SB supplementation can improve performance in HIIT by 1.7% in events lasting less than 10 seconds in male athletes, they also commented on small improvements within endurance events or activities lasting over 10 minutes.
It was suggested as high-intensity events of up to one hour are conducted at work rates below to the individuals lactate threshold and do not require additional bicarbonate buffering due to the natural process of removing lactate via the Cori cycle.
This is not the case with intermittent sports (e.g. field sports) where HIIT produce high levels of H+ and Lac- and that SB supplementation has a positive effect of reducing the onset of fatigue(Edge et al, 2006).
Previous research has commented on one of the most important factors within SB supplementation, being recommended dosage, research by Requena et al (2005) as suggested that the optimal timing of SB supplementation to be between 60-90 minutes before training.
The majority of literature supports two suggested loading phases for SB supplementation before training or competition and recommended supplementation with water to avoid the risk of hyperosmotic diarrhea and gastro-intestinal distress (Carr et al, 2011 Matsuura et al. 2007, ).
The two phases are:
1) The Acute loading phase – 300mg/kg (SB/Body weight) between 60-90 minutes before training or competition.
2) Chronic loading – 500mg/Kg (SB/Body weight) ingested over 5-6 days in four periods of the day.
Within studies on HIIT, the most common dosage chosen by researchers is 300mg per kg of individual’s body weight, due to its ability to give a physiological dose response and improve performance while reducing the risk of negative side effects (Lindh et al, 2007, Rayner et al,2004, Van Montfoort et al, 2004)
Potential risk of sodium bicarbonate ingestion:
Recent research has studied ingestion methods for SB supplementation and has commented on antidotal evidence from athletes that regular baking soda mixed with water to result in stomach cramp or was undrinkable. This led researchers to offer two method`s of ingestion being capsules or flavored effervescent powder within urinary alkalanisers (Carr et al, 2011).
Research on the risks and side effects of SB ingestion has reported that negative effects for the athletes include diarrhea, bloating, stomach cramps and gastrointestinal (GI) discomfort. This has commonly being due to inappropriate ingestion protocols either with rapid ingestion or a too high ingestion dose or the dosage ingested was not consumed with enough water and resulted in reduced cell absorption (Kolkhorst et al. 2004).
From having reviewed the current research on the topic of interest, the authors has suggested two area`s for recommended further research, while even having the benefit of extensive research being conducted on SB ingestion within high intensity sports and reported improvements in athletic performance, very little research has being conducted on SB effects within field sports and improvement in performance, even though field sports are both high intensity and intermittent in nature, it is recommended to conduct future research into SB supplementation on field sports, also the author has recognized that current research has offered two dosage amounts from injection, with the vast majority of studies reporting that a dosage of 300mg/kg to be most effective, it is recommended to conduct studies using alternative dosage amounts or dosage timings (e.g. 100mg/kg-vs.-200mg/kg-vs.-300mg/kg..etc) in pre and post competition to compare against the standard 300 mg/kg dosage recommendation.
Practical application of Sodium bicarbonate within High-intensity intermittent training:
Based on current research, practical recommendations for SB ingestion in HIIT is to consume 300mg/kg of SB via capsule or powder form between 60-90 minutes prior to training/competition with a recommended 2 liters of water over the same time period to reduce GI discomforts.