The effects of beta‐alanine supplementation on physical working capacity at heart rate threshold

Abstract

Beta-alanine (BA) supplementation has been shown to delay neuromuscular fatigue as a result of increased muscle carnosine concentrations. Carnosine has also been found in brain and cardiac tissue. The physical working capacity test at heart rate threshold (PWC(HRT)) is a global estimate of the onset of fatigue during exercise, influenced by central and peripheral factors. The purpose of this study was to determine the effects of 28 days of BA supplementation on the PWC(HRT). Thirty subjects (mean ± SD; age: 21·0 ± 2·1 years; body mass: 72·7 ± 14·5 kg; height: 170·1 ± 7·9 cm) were randomly assigned to BA (n = 15) or placebo (PL, n = 15) groups. Testing included eight to nine total visits: an enrolment day, physical screening, peak oxygen consumption (V(·)O(2peak)) and two PWC(HRT) assessments over 4 days. Significant differences existed between BA and PL for PWC(HRT) (P = 0·001; mean∆: BA∆ = +24·2 watts, PL∆ = +11·2 watts), but not for V(·)O(2peak) (P = 0·222), time to exhaustion (TTE; P = 0·562) or ventilatory threshold (VT; P = 0·134). Results suggest that BA may increase heart rate training threshold. These results, in combination with one previous study reporting a potential effect of BA on HR, suggest that future studies should evaluate both central and peripheral aspects of fatigue with BA intake.

International society of sports nutrition position stand: Beta-Alanine

“…The effects of beta-alanine supplementation on time to exhaustion (TTE) are presented in Fig. 1 [ 3 , 22 , 54 – 60 ], with effects on fixed end-point exercise, such as races and time trials, presented in Fig. 2 [ 20 , 61 – 67 ].…”

“…3 ). Using slightly different methodology to quantify neuromuscular fatigue, Smith-Ryan et al [ 60 ] found a modest (5.6 %) improvement of physical working capacity at heart rate threshold in young men and women consuming beta-alanine (RE = 111.9). The effects of beta-alanine on neuromuscular fatigue appear to be more pronounced in longer studies utilizing older subjects.…”

“…Interestingly, humans also have carnosine within the brain, eye, and heart tissue [ 37 , 109 ]. Therefore some initial data has explored the neuronal effects of carnosine [ 80 , 110 ], as well as potential effects on cardiac tissue and heart rate [ 60 ]. Future research exploring the effects of beta-alanine to induce changes in carnosine concentrations in these tissues would be beneficial, as well as explorations of potential physiological effects in humans.…”

Wet, volatile, and dry biomarkers of exercise-induced muscle fatigue

“…To sustain endurance performance of the muscle the ability to deliver oxygen to the muscle and the ability of the muscle to utilise a given oxygen load for a sustained period of time (respiratory exchange rate) are important [ 87 ]. Maximal oxygen uptake (VO 2 max) as measured by breath-by-breath open-circuit spirometry is thus a well-established parameter to assess muscle performance [ 88 ]. VO2 max decreases with EIMUF but decreases also during age [ 89 ].…”

“…A plateau of VO 2 , or 3. A respiratory exchange rate >1 [ 88 ]. Ventilatory threshold is defined as intersection of 2 regression lines (V E and VO 2 ) [ 88 ].…”