Supplementation of caffeine and sodium bicarbonate together could not improve performance and performance-related factors in CrossFit participants: a randomized, double-blind, placebo-controlled study

Figures & data

Figure 1. Schematics of experimental steps.

Figure 2. A comparison of variables between supplementations, PLA, and CON conditions before and after the Cindy protocol.

Figure 3. A comparison of variables between supplementations, PLA, and CON conditions during the Cindy protocol and the study.

Table 1. Descriptive statistics of handgrip strength, lower torso muscle power, performance, maximal heart rate, rate of perceived exertion, and gastrointestinal side effects variables in five supplementation conditions (mean ± SD).

Condition	Stage	Handgrip*	Sargent jump*	Repetitions of Cindy protocol	Maximum heart rate	RPE	GSE
CAF+PLA	1	4.20 ± 55.30	4.97 ± 55.30	71.59 ± 439.60	6.15 ± 197.25	0.58 ± 6.06	0.48 ± 1.35
	2	4.02 ± 54.10	5.24 ± 54.25	—	—	—	—
NaHCO3+PLA	1	4.14 ± 55.25	4.94 ± 54.20	65.56 ± 432.95	6.09 ± 195.25	0.48 ± 6.41	1.37 ± 2.75
	2	4.77 ± 53.25	5.59 ± 53.70	—	—	—	—
CAF+NaHCO3	1	4.36 ± 55.80	5.64 ± 55.00	75.96 ± 445.35	5.14 ± 196.10	0.42 ± 5.89	1.09 ± 2.45
	2	4.44 ± 54.20	4.45 ± 54.45	—	—	—	—
PLA+PLA	1	4.24 ± 55.40	5.03 ± 54.40	70.42 ± 428.20	5.32 ± 193.20	0.63 ± 6.37	0.44 ± 1.25
	2	4.47 ± 52.80	4.69 ± 53.95	—	—	—	—
CON*	1	3.92 ± 54.70	4.87 ± 53.80	68.34 ± 419.50	6.23 ± 191.40	0.48 ± 6.75	0.57 ± 1.30
	2	3.69 ± 51.57	4.79 ± 52.50	—	—	—	—

Note: *Control condition: The subjects did not receive any supplements in this condition. *Handgrip strength and surgent jump height were measured in two stages before and after the Cindy protocol: the first time (stage 1) to evaluate the effect of supplementation in each condition on strength and power in rest condition and the second time (step 2) to evaluate the effect of supplementation on strength and power in fatigue condition. CAF, caffeine; NaHCO₃, sodium bicarbonate; PLA, placebo; CON, control; RPE, rate of perceived exertion; GSE, gastrointestinal side effects.

Table 2. RPE in each level of the Cindy protocol (every 4 min).

Conditions	Sig	4 min (Level 1)	8 min (Level 2)	12 min (Level 3)	16 min (Level 4)	20 min (Level 5)
CAF	0.13	2.05 ± 0.66	3.90 ± 0.83	6.30 ± 0.71	8.45 ± 0.80	9.60 ± 0.48
NaHCO3	0.09	2.45 ± 0.66	4.35 ± 0.79	6.50 ± 0.59	9.05 ± 0.66	9.70 ± 0.45
CAF+NaHCO3	0.02*	2.15 ± 0.57	4.05 ± 0.73	6.05 ± 0.73	7.95 ± 0.80	9.25 ± 0.43
PLA	0.12	2.25 ± 0.62	4.30 ± 1.05	6.75 ± 0.88	9.00 ± 0.63	9.55 ± 0.49
CON	0.18	2.50 ± 0.59	4.80 ± 0.92	7.25 ± 0.76	9.35 ± 0.57	9.85 ± 0.35

Note: CAF, caffeine; NaHCO₃, sodium bicarbonate; PLA, placebo; CON, control.