Lactate is an important energy intermediate and metabolic buffer, and may be ergogenic. We investigated if lactate supplementation is an effective approach to enhance the exercise performance and acid–base balance of trained cyclists during exercise devised to simulate the demands of endurance road race cycling. Sixteen endurance-trained male cyclists ($\stackrel{·}{\mathrm{V}}$O_2max 59 ± 7 mL·kg⁻¹·min⁻¹) consumed 120 mg·kg⁻¹ body mass of lactate or a placebo 70 min prior to performing an exercise performance test, comprising five repeated blocks consisting of 1 km and 4 km time trials interspersed with 10 min of moderate-intensity exercise. Blood acid–base balance (including [H⁺] and [HCO₃⁻]), heart rate, perceived exertion, and gastro-intestinal tolerance were assessed. There was no effect of lactate supplementation on exercise performance (p = 0.320), despite a reduction in RPE (p = 0.012) and increases in [SID] (p = 0.026) and [HCO₃⁻] (p = 0.041). In addition, gastro-intestinal side effects were observed, but there was no effect on heart rate. Lactate supplementation did not improve exercise performance, despite positive changes in acid–base balance and RPE. This suggests that the alkalising effects of the supplement can reduce perceived effort, but these benefits do not translate into performance improvements.

Biological sex may mediate 'dyspnoea' during submaximal exercise, but whether it mediates air hunger (AH), a highly unpleasant form of dyspnoea, remains unclear. Forty healthy adults (twenty females) completed 6-min of quiet breathing (rest) followed by a hyperoxic CO₂ rebreathing task to evoke AH. AH intensity (AH-I) and unpleasantness (AH-U) were measured every 30-s. The Multidimensional Dyspnoea Profile (MDP) was administered after CO₂ rebreathing. Compared to males, AH-I and AH-U thresholds occurred at lower PETCO₂ in females (AH-I: 44.15 ± 2.81 vs 48.90 ± 4.47 mmHg, P < 0.001; AH-U: 43.86 ± 2.57 vs 47.59 ± 2.75 mmHg, P < 0.001) and after a smaller increase in PETCO₂ above resting PETCO₂ (AH-I: 7.04 ± 2.63 vs 10.08 ± 5.28 mmHg, P = 0.027; AH-U: 6.75 ± 2.22 vs 8.77 ± 2.99 mmHg, P = 0.020). AH-I and AH-U were higher in females than males at standardised absolute V̇_E of 25, 30 and 35 L/min (P < 0.05). AH-U, but not AH-I, remained higher (main effect of sex, P = 0.026) in females than males at standardised relative V̇_E of 20, 25, and 30 % MVV. More females (n = 9) than males (n= 4) terminated CO₂ rebreathing due to maximal AH perception (P = 0.001). Compared to males, females reported greater intensities of 'mental effort/concentration' (7 ± 3 vs 4 ± 3), 'tight/constricted lungs' (6 ± 3 vs 2 ± 2), and 'breathing work/effort' (6 ± 2 vs 4 ± 3) (all P < 0.05) on the MDP. Our findings suggest that sex differences exist in the perception of AH, which are not entirely accounted for by sex differences in ventilatory capacity.

Self-control reflects the effortful inhibition of attentional, behavioural, and emotional impulses to achieve a desired long-term goal. Prior self-control exertion does not affect air hunger and tolerance to progressive hypercapnia, but whether it affects the mechanistically distinct sense of breathing effort remains unknown. Fourteen healthy young adults (13 males, 1 female) initially completed three familiarisation trials comprising an incremental inspiratory pressure-threshold loading (IPTL) test, which began at a load of 10 cmH₂O followed by a 10 cmH₂O increase every minute until task failure. Thereafter, participants completed three experimental trials comprising IPTL preceded by rest (Control; CTRL), a congruent Stroop task (CONG) requiring no self-control exertion, or an incongruent Stroop task (INCONG) requiring self-control exertion. Breathing effort was measured at the end of each threshold load. Time to task failure during IPTL was 13% shorter in INCONG (8.60 ± 1.69min) than CTRL (9.96 ± 1.79min) and CONG (9.87 ± 1.57min) (P < 0.001). The maximum sustainable threshold pressure sustained for a full 1min was lower in INCONG (84 ± 19 cmH₂O) than CTRL (96 ± 18 cmH₂O) and CONG (99 ± 17 cmH₂O) (P < 0.001). The rate of increase in breathing effort during IPTL was greater in INCONG (0.14 ± 0.03A.U./cmH₂O) than CTRL (0.12 ± 0.03A.U./cmH₂O) (P = 0.016) and CONG (0.12 ± 0.03A.U./cmH₂O) (P = 0.014). Prior self-control exertion increased the sense of breathing effort and reduced time to task failure during subsequent IPTL. These findings suggest that the sense of breathing effort is modulated by state self-control.