TY  - JOUR
JF  - Journal of Applied Physiology
A1  - Hannah, R
A1  - Stannard, RL
A1  - Minshull, C
A1  - Artioli, GG
A1  - Harris, RC
A1  - Sale, C
UR  - http://dx.doi.org/10.1152/japplphysiol.00991.2014
SN  - 1522-1601
IS  - 5
N1  - Copyright © 2015 the American Physiological Society
SP  - 604
VL  - 118
KW  - electrical stimulation
KW  -  force-frequency relationship
KW  -  muscle contractile properties
KW  -  ?-alanine
KW  -  Adult
KW  -  Calcium
KW  -  Dietary Supplements
KW  -  Double-Blind Method
KW  -  Electric Stimulation
KW  -  Electromyography
KW  -  Exercise
KW  -  Humans
KW  -  Isometric Contraction
KW  -  Knee
KW  -  Knee Joint
KW  -  Male
KW  -  Muscle Contraction
KW  -  Muscle Fatigue
KW  -  Muscle Relaxation
KW  -  Muscle
KW  -  Skeletal
KW  -  Rest
KW  -  beta-Alanine
N2  - ?-Alanine (BA) supplementation improves human exercise performance. One possible explanation for this is an enhancement of muscle contractile properties, occurring via elevated intramuscular carnosine resulting in improved calcium sensitivity and handling. This study investigated the effect of BA supplementation on in vivo contractile properties and voluntary neuromuscular performance. Twenty-three men completed two experimental sessions, pre- and post-28 days supplementation with 6.4 g/day of BA (n = 12) or placebo (PLA; n = 11). During each session, force was recorded during a series of knee extensor contractions: resting and potentiated twitches and octet (8 pulses, 300 Hz) contractions elicited via femoral nerve stimulation; tetanic contractions (1 s, 1-100 Hz) via superficial muscle stimulation; and maximum and explosive voluntary contractions. BA supplementation had no effect on the force-frequency relationship, or the force responses (force at 25 and 50 ms from onset, peak force) of resting or potentiated twitches, and octet contractions (P > 0.05). Resting and potentiated twitch electromechanical delay and time-to-peak tension were unaffected by BA supplementation (P > 0.05), although half-relaxation time declined by 7-12% (P < 0.05). Maximum and explosive voluntary forces were unchanged after BA supplementation. BA supplementation had no effect on evoked force responses, implying that altered calcium sensitivity and/or release are not the mechanisms by which BA supplementation influences exercise performance. The reduced half-relaxation time with BA supplementation might, however, be explained by enhanced reuptake of calcium, which has implications for the efficiency of muscle contraction following BA supplementation.
ID  - discovery1461923
TI  - ?-Alanine supplementation enhances human skeletal muscle relaxation speed but not force production capacity.
AV  - public
Y1  - 2015/03/01/
EP  - 612
ER  -