This randomized, double-blind, placebo-controlled crossover study aims to evaluate the effect of acute sodium bicarbonate supplementation, compared with placebo, on physical capacity and blood biochemical marker concentrations in highly trained female basketball players.
Sodium bicarbonate (SB) is commonly proposed as an ergogenic aid due to its potential to enhance extracellular buffering capacity, thereby supporting acid-base balance and delaying fatigue during repeated high-intensity exercise. This mechanism may be particularly relevant in basketball, where performance depends on repeated short-duration, high-intensity efforts, rapid recovery between actions, and the ability to maintain power output during demanding phases of play. Although the ergogenic effects of SB supplementation have been widely investigated, existing evidence has primarily focused on male participants, and data regarding highly trained female athletes remain limited. This creates an important knowledge gap, especially in team sports such as basketball, where sex-specific physiological responses, training status, and sport-specific demands may influence the effectiveness and tolerability of supplementation strategies. This study will evaluate the effect of a single dose of SB compared with placebo. Participants will receive SB or placebo in a randomized, double-blind, placebo-controlled crossover design. The SB dose will be 0.3 g/kg body mass, administered 90 minutes before the exercise protocol, with intervention visits separated by a washout period. By using a randomized, double-blind, placebo-controlled crossover design, this study will allow for the evaluation of individual responses to acute SB supplementation under controlled laboratory conditions. The findings may help clarify whether acute SB intake is an effective and tolerable strategy for supporting physical capacity and biochemical responses in highly trained female basketball players.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
100
Sodium bicarbonate supplementation; Participants will receive a single oral dose of sodium bicarbonate (SB) at 0.3 g/kg body mass, administered in opaque gelatin capsules 90 minutes before the exercise protocol during the first intervention visit.
Participants will receive a single oral dose of placebo (PL), administered in identical opaque gelatin capsules 90 minutes before the exercise protocol during the first intervention visit.
Department of Sports Dietetics, Poznan University of Physical Education Poznań
Poznan, Poland
RECRUITINGChanges in anaerobic power during the repeated modified Wingate Anaerobic Test
Assessment of peak power (PP), average power (AP), minimum power (MP), and power drop (PD) \[W (watts)\] during the repeated modified Wingate Anaerobic Test using the Monark 894E cycle ergometer (Monark, Sweden)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in interval mean power during the repeated modified Wingate Anaerobic Test
Assessment of mean power \[W (watts)\] in predefined 5 second intervals, including 1 to 5 s and 6 to 10 s, during each 10 second effort of the repeated modified Wingate Anaerobic Test using the Monark 894E cycle ergometer (Monark, Sweden)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in second-by-second power output during the repeated modified Wingate Anaerobic Test
Assessment of power output \[W (watts)\] for each 1 second segment, including 1 s, 2 s, 3 s, 4 s, 5 s, 6 s, 7 s, 8 s, 9 s, and 10 s, during each 10 second effort of the repeated modified Wingate Anaerobic Test using the Monark 894E cycle ergometer (Monark, Sweden)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in time to peak power during the repeated modified Wingate Anaerobic Test
Assessment of time to peak power (TTP) \[s (seconds)\] during each 10 second effort of the repeated modified Wingate Anaerobic Test using the Monark 894E cycle ergometer (Monark, Sweden)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in countermovement jump height
Assessment of countermovement jump (CMJ) height \[cm (centimeters)\] during three consecutive CMJ attempts using the OptoJump Next optical measurement system (Microgate, Italy)
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Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in countermovement jump power
Assessment of countermovement jump (CMJ) power \[W (watts)\] during three consecutive CMJ attempts using the OptoJump Next optical measurement system (Microgate, Italy).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in blood bicarbonate, base excess, anion gap, and lactate concentrations
Assessment of blood bicarbonate, base excess, anion gap, and lactate concentrations \[mmol/L\] in capillary blood using the ABL90 FLEX PLUS blood gas analyzer (Radiometer, Denmark)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in hydrogen ion concentration
Assessment of hydrogen ion concentration \[nmol/L\] in capillary blood using the ABL90 FLEX PLUS blood gas analyzer (Radiometer, Denmark)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in pH in blood
Assessment of blood pH \[pH units\] in capillary blood using the ABL90 FLEX PLUS blood gas analyzer (Radiometer, Denmark)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in oxygen uptake, carbon dioxide production, and minute ventilation during the repeated modified Wingate Anaerobic Test
Assessment of oxygen uptake (VO₂), carbon dioxide production (VCO₂), and minute ventilation (VE) \[L/min\] during the repeated modified Wingate Anaerobic Test using the K5 wearable metabolic system (Cosmed, Italy)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in relative oxygen uptake during the repeated modified Wingate Anaerobic Test
Assessment of relative oxygen uptake (VO₂), and carbon dioxide production (VCO₂) \[mL/kg/min\] during the repeated modified Wingate Anaerobic Test using the K5 wearable metabolic system (Cosmed, Italy)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in respiratory exchange ratio during the repeated modified Wingate Anaerobic Test
Assessment of respiratory exchange ratio (RER) \[ratio\] during the repeated modified Wingate Anaerobic Test using the K5 wearable metabolic system (Cosmed, Italy)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in breathing frequency during the repeated modified Wingate Anaerobic Test
Assessment of breathing frequency (BF) \[breaths/min\] during the repeated modified Wingate Anaerobic Test using the K5 wearable metabolic system (Cosmed, Italy)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in tidal volume during the repeated modified Wingate Anaerobic Test
Assessment of tidal volume (VT) \[L\] during the repeated modified Wingate Anaerobic Test using the K5 wearable metabolic system (Cosmed, Italy)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in heart rate during the exercise protocol
Assessment of maximum heart rate (HRmax) and mean heart rate (HRmean) \[bpm\] during the exercise protocol using the HRM-Dual heart rate monitor (Garmin Ltd., United States)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in rate of perceived exertion
Assessment of rate of perceived exertion (RPE) \[Borg scale points\] using the 15 point Borg scale, ranging from 6 to 20 points
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in gastrointestinal symptoms
Assessment of gastrointestinal symptoms (GI) \[NRS points\] using a 19 item gastrointestinal symptom questionnaire with an 11 point numerical rating scale, ranging from 0 to 10 points
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in body mass, fat-free mass, fat mass, total body water, intracellular water, and extracellular water
Assessment of body mass, fat-free mass, fat mass, total body water, intracellular water, and extracellular water \[kg (kilograms)\] using the WPT 60/150 OW scale with integrated stadiometer (Radwag, Poland) and the 101 BIVA PRO body composition analyzer (Akern S.r.l., Italy)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in fat-free mass percentage, fat mass percentage, total body water percentage, intracellular water percentage, and extracellular water percentage
Assessment of fat-free mass percentage, fat mass percentage, total body water percentage, intracellular water percentage, and extracellular water percentage \[% (percent)\] using the 101 BIVA PRO body composition analyzer (Akern S.r.l., Italy)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in white blood cell count, white blood cell subpopulations, red blood cell count, and platelet count
Assessment of white blood cell count, white blood cell subpopulations, red blood cell count, and platelet count \[count/L\] in capillary blood using the Mythic 18 hematology analyzer (Orphée, Switzerland)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in hemoglobin concentration
Assessment of hemoglobin concentration \[mmol/L\] in capillary blood using the Mythic 18 hematology analyzer (Orphée, Switzerland)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in hematocrit
Assessment of hematocrit \[L/L\] in capillary blood using the Mythic 18 hematology analyzer (Orphée, Switzerland)
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in alanine aminotransferase, aspartate aminotransferase, creatine kinase, and lactate dehydrogenase activities
Assessment of alanine aminotransferase (ALAT), aspartate aminotransferase (ASAT), creatine kinase (CK), and lactate dehydrogenase (LDH) activities \[U/L\] in capillary blood using the ACCENT-220S biochemical analyzer (PZ Cormay S.A., Poland).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in creatinine concentration
Assessment of creatinine concentration \[µmol/L\] in capillary blood using the ACCENT-220S biochemical analyzer (PZ Cormay S.A., Poland).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in urea concentration
Assessment of urea concentration \[mmol/L\] in capillary blood using the ACCENT-220S biochemical analyzer (PZ Cormay S.A., Poland).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in iron, unsaturated iron-binding capacity, and total iron-binding capacity concentrations
Assessment of iron, unsaturated iron-binding capacity (UIBC), and total iron-binding capacity (TIBC) concentrations \[µg/dL\] in capillary blood using the ACCENT-220S biochemical analyzer (PZ Cormay S.A., Poland).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in ferritin concentration
Assessment of ferritin concentration \[ng/mL\] in capillary blood using the ACCENT-220S biochemical analyzer (PZ Cormay S.A., Poland).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in transferrin concentration
Assessment of transferrin concentration \[g/L\] in capillary blood using the ACCENT-220S biochemical analyzer (PZ Cormay S.A., Poland).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in partial pressure of carbon dioxide and oxygen
Assessment of partial pressure of carbon dioxide (pCO₂) and partial pressure of oxygen (pO₂) \[mmHg\] in capillary blood using the ABL90 FLEX PLUS blood gas analyzer (Radiometer, Denmark).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in oxygen saturation and hemoglobin fractions
Assessment of oxygen saturation (sO₂), oxyhemoglobin fraction (FO₂Hb), carboxyhemoglobin fraction (FCOHb), deoxyhemoglobin fraction (FHHb), and methemoglobin fraction (FMetHb) \[% (percent)\] in capillary blood using the ABL90 FLEX PLUS blood gas analyzer (Radiometer, Denmark).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in potassium, sodium, ionized calcium, and chloride concentration
Assessment of potassium (K⁺), sodium (Na⁺), ionized calcium (Ca²⁺), and chloride (Cl-) concentrations \[mmol/L\] in capillary blood using the ABL90 FLEX PLUS blood gas analyzer (Radiometer, Denmark).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in plasma osmolality
Assessment of plasma osmolality \[mOsm/kg\] in capillary blood using the ABL90 FLEX PLUS blood gas analyzer (Radiometer, Denmark).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in dietary energy intake
Assessment of dietary energy intake \[kcal\] based on 48 hour dietary records analyzed using AvoDiet dietary software (JustForFood sp. z o.o., Poland).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)
Changes in dietary macronutrient intake
Assessment of protein, carbohydrate, fat, and dietary fiber intake \[g (grams)\] based on 48 hour dietary records analyzed using AvoDiet dietary software (JustForFood sp. z o.o., Poland).
Time frame: At the Day 0 (familiarization visit), Day 7 (baseline visit), Day 14 (experimental visit 1), and Day 21 (experimental visit 2)