Abstract
Pre-alkalization caused by dietary supplements such as sodium bicarbonate improves anaerobic exercise performance. However, the influence of a base-forming nutrition on anaerobic performance in hypoxia remains unknown. Herein, we investigated the effects of an alkalizing or acidizing diet on high-intensity performance and associated metabolic parameters in normoxia and hypoxia. In a randomized crossover design, 15 participants (24.5 ± 3.9 years old) performed two trials following four days of either an alkalizing (BASE) or an acidizing (ACID) diet in normoxia. Subsequently, participants performed two trials (BASE; ACID) after 12 h of normobaric hypoxic exposure. Anaerobic exercise performance was assessed using the portable tethered sprint running (PTSR) test. PTSR assessed overall peak force, mean force, and fatigue index. Blood lactate levels, blood gas parameters, heart rate, and rate of perceived exertion were assessed post-PTSR. Urinary pH was analyzed daily. There were no differences between BASE and ACID conditions for any of the PTSR-related parameters. However, urinary pH, blood pH, blood bicarbonate concentration, and base excess were significantly higher in BASE compared with ACID (p < 0.001). These findings show a diet-induced increase in blood buffer capacity, represented by blood bicarbonate concentration and base excess. However, diet-induced metabolic changes did not improve PTSR-related anaerobic performance.
Highlights
Many sport competitions staged at terrestrial altitudes ranging up to 3500 m often require single or multiple bouts of high-intensity, anaerobic exercise performance [1,2,3,4,5]
ACID (142.6 ± 71.9 mEq/day) compared with NOR BASE (−222.3 ± 118.6 mEq/day; p* < 0.001, d = 3.53), HYP ACID (175.6 ± 38.3 mEq/day) compared with HYP BASE (−255.0 ± 103.0 mEq/day; p* < 0.001, d = 4.77), HYP ACID compared with NOR BASE (p* < 0.001, d = 3.80), and NOR ACID compared with
Multiple linear regression analyses revealed no relevant predictors for peak force (PF), mean force (MF), and fatigue index (FI) incorporating the variables potential renal acid load (PRAL), fluid, CAL, pHu, pHb PRE portable tethered sprint running (PTSR), [HCO3 − ] PRE PTSR, and base excess (BE) PRE PTSR
Summary
Many sport competitions staged at terrestrial altitudes ranging up to 3500 m (e.g., track-and-field, cycling and team sport events, cross-country or alpine ski races, and mountain biking challenges) often require single or multiple bouts of high-intensity, anaerobic exercise performance [1,2,3,4,5]. Hyperventilation occurs as a hypoxic ventilatory response during acclimatization to high altitude, while carbon dioxide partial pressure (PCO2 ) falls and arterial pH increases according to the Henderson−Hasselbalch equation [10,13,14]. This respiratory alkalosis is subsequently compensated for by the increased renal elimination of bicarbonate ions ([HCO3 − ]), which results in a decrease in blood [HCO3 − ] and an arterial pH returning to normal [10,11,13]. The resulting decline in [HCO3 − ] and blood buffer capacity in the course of altitude adaption may significantly affect anaerobic exercise performance at altitude, above the lactate threshold [10,16,17,18,19]
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