β-alanine Supplementation on Knee Extensor Contractile and Force Properties
Condition: Muscle Function
Study type: Interventional
Phase: Phase 4

Summary: 
      Carnosine (made by bonding β-alanine and histidine) has been suggested to contribute to the
      extension of physical exercise, counteracting the decline in muscle performance due to
      fatigue. However this process is largely restricted by the levels of β-alanine available in
      the human body. Carnosine levels can be raised through long term ingestion of food products,
      such as meat, fish and poultry, however it can also be significantly increased by β-alanine
      supplementation. Improved β-alanine levels can potentially advance exercise capacity and
      exercise performance, which may have been previously limited. Recently research has
      demonstrated no beneficial effect of β-alanine supplementation on neuromuscular performance
      in active, healthy males when they were well rested, with no prior exercise or fatigue of the
      assessed muscle. It remains unknown if β-alanine supplementation would aid physical
      performance when the muscle has already been fatigued. This is currently being investigated
      in older adults (60-80 years), however there is no clear comparison between the potential
      effects in younger and older participants.

      Therefore this investigation hopes to examine the effects of 4 week β-alanine supplementation
      on lower limb contractile and force properties, pre and post muscle specific fatigue in 18-30
      year old males.
    

Detailed description: 
      Carnosine (β-alanyl-L-histidine) is a naturally occurring dipeptide formed by bonding
      histidine and β-alanine in a reaction catalysed by carnosine synthase. One role of carnosine
      within the human system, is as an intracellular pH buffer due to its pKa of 6.83. Carnosine
      is suitable over the whole exercise induced intramuscular pH transit-range. Carnosine in
      untrained populations can neutralise 2.4 to 10.1mmol H+.kg-1 of dry mass muscle as
      intramuscular pH declines, adding at least 7% to 10% to total intramuscular buffering
      capacity. It has also been argued that carnosine in combination with anserine can contribute
      as much as 40% to the buffering capacity between pH ranges of 6.5 to 7.5. β-alanine has been
      suggested as the rate limiting factor for muscle carnosine synthesis, through ingestion of
      β-alanine in diet (meat, fish and poultry) or via short-term supplementation, demonstrating
      significant increases in muscle carnosine concentrations. Increases in carnosine
      concentrations between 40% and 80% have been shown, depending upon dose (between 3.2 and 6.4
      g·d-1) and duration of administration (between 4 and 10 weeks). Increasing β-alanine
      concentrations therefore enhance carnosine synthesis with the muscle fibers and improves
      intramuscular buffering capacity. Exercise performance and capacity measurements that
      previously were limited by the accumulation of H+ have been demonstrated significant
      improvements through supplementation with β-alanine.

      Research already conducted at Nottingham Trent University and approved by this ethical
      advisory committee has demonstrated no significant effect of β-alanine supplementation on
      neuromuscular performance in healthy, active males. However, this research was conducted with
      well rested participants, with no prior exercise or fatigue of the assessed muscle; therefore
      there was no accumulation of H+ demonstrated within the muscle. These previous investigations
      are therefore contemplating how β-alanine supplementation alters performance when
      intramuscular buffering has not been altered (at the start of the exercise), whereas the
      proposed study will examine the effect of β-alanine supplementation on performance when
      intramuscular pH has already been challenged (due to fatiguing exercise). It is hypothesised
      that β-alanine supplementation over 4 weeks will beneficially alter the contractile and force
      properties of the muscle fibres within the lower limb muscles, improving physical performance
      when the muscle is already fatigued.

      Aims of the project:

      To examine the effects of 4 week β-alanine supplementation on knee extensor contractile and
      force properties, pre and post induced muscle specific fatigue in 18-30 year old males.
    

Intervention name(s): beta-alanine; Placebo
Intervention type(s): Dietary Supplement; Dietary Supplement
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: Triple (Participant, Investigator, Outcomes Assessor)
Primary purpose: Basic Science
Keywords: beta-alanine; carnosine; neuromuscular; stimulation; skeletal muscle