Intramuscular buffers (pH)

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This post is a spin off from the more general pH discussion... Below

are some notes I did when researching nutrition for a 400m sprinter

(if they are of any use to anyone):

Histidine is a very good intracellular buffer due to a favourable pKa

value (Robergs, 2002). In animals and humans it has been consistently

shown that histidine related compounds, buffering capacity, and

percentage fast twitch fibres correlate well (Abe, 2000b; Mannion et

al., 1995). It has been suggested histidine related compounds

contribute to speed endurance as during sprint training (30s sprint

cycling twice per week) intramuscular concentrations may elevate to

213% of baseline values in 8 weeks without supplementation (Suzuki et

al., 2004).

Acute supplementation (30 min pre exercise) of histidine done recently

via carnosine (0.4g) and anserine (1.1g) ingestion showed no increase

in power output values during repeated sprinting (10x 5s sprints with

25s rest; Suzuki et al., 2006). The protocol used (5s work – 25s rest)

may have been relatively easy compared to a much shorter rests (10s;

Glaister et al., 2005), so the subjects may not have been fatigued

enough to notice a difference between placebo and histidine

conditions. An interesting finding of this study was however that

histidine did contribute to buffering, shown by bicarbonate sparing

and higher blood pH values (Suzuki et al., 2006), thus it contributed

to blood buffering. Suzuki et al. (2006) started exercising 30-minutes

after ingestion as: " carnosine, anserine, and their related compounds

were detected, and their concentrations reached their peak in 30 min " .

They detected the compounds in the blood. If the goal is for the

histidine to take advantage of its favourable pKa value and act as an

intramuscular buffer, longer time should have been given for the next

step (muscular storage) to occur. Thus to see benefits from histidine

related compounds chronic ingestion (loading) studies are required.

The same group have also experimented with chronic ingestion but with

endurance type activity (Maemura et al., 2006). The results suggest

loading is possible with 4g of CBEX (a chicken extract; 1.2g carnosine

and 2.8g anserine) per day (in two equal doses, morning and afternoon)

for 30 days (Maemura et al., 2006). This loading lead to enhanced

high-intensity endurance performance (time spent at 100% VO2max) and

increased intramuscular histidine containing compounds (Maemura et

al., 2006).

Products containing hisidine compounds could potentially be the best

thing since sliced bread, but it should be noted however some authors

of the papers published in the group promoting the use of carnosine

and anserine in a product called CBEX actually produce the supplement

(Nippon meat packers, Inc., Japan). If chronic loading proves

successful with respect to muscular histinine concentrations and

performance enhancements in truly unbiased research then the future

may be bright for this type of supplementation for any activity where

intramuscular buffers may be a limiting factor for performance such as

the 400m sprint (Black, 1988).

With respect to its safety: Histidine related compounds and their

associated dipeptides can be stored in vast quantities safely with no

side-effects to the cell (Abe et al., 2000b).

References

Abe, H. (2000b). Role of histidine-related compounds as intracellular

proton buffering constituents in vertebrate muscle. Biochemistry

(Moscow). 65, 757-765, Translated from: Biokhimiya. 65, 891-900.

Black, W. (1988). Training for the 400m. Track Coach. 102, 3243-3245.

Glaister, M., Stone, M.H., , A.M., , M., Moir, G.L.

(2005). The Influence of Recovery Duration on Multiple Sprint Cycling

Performance. Journal of Strength and Conditioning Research. 19(4),

831–837

Maemura, H., Goto, K., Yoshioka, T., Sato, M., Takahata, Y.,

Morimatsu, F., Takamatsu, K. (2006). Effects of carnosine and anserine

supplementation on relatively high intensity endurance performance.

International Journal of Sport and Health Science. 4, 86-94.

Mannion, A.F., Jakeman, P.M., Willan, P.L. (1995). Skeletal muscle

buffer value, fibre type distribution and high intensity exercise

performance in man. Experimental Physiology. 80, 89-101.

Robergs, R.A. (2002). Blood acid-base buffering: explainaion of the

effectiveness of bicarbonate and citrate ingestion. Journal of

Exercise Physiology Online. 5, 1-5.

Suzuki, Y., Ito, O., Takahashi, H., Takamatsu, K. (2004). The effect

of sprint training on skeletal muscle carnosine in humans.

International Journal of Sport and Health Science. 2, 105-110.

Suzuki, Y., Nakao, T., Maemura, H., Sato, M., Kamahara, K., Morimatsu,

F., Takamatsu, K. (2006). Carnosine and anserine ingestion enhances

contribution of nonbicarbonate buffering. Medicine and Science in

Sports and Exercise. 38, 334-338.

Gallyer,

Bolton, UK