Betaine supplementation improves CrossFit performance and increases testosterone levels, but has no influence on Wingate power: randomized crossover trial

Figures & data

Table 1. Baseline characteristics of participants.

	2.5 g/d group	5.0 g/d group	p-value (T-test)
Age (years)	34.1 ± 6.0	34.2 ± 6.4	.964
Trainings (units per week)	4.3 ± 1.0	4.3 ± 1.1	.835
CrossFit experience (years)	4.1 ± 2.0	3.6 ± 2.4	.997
Height (cm)	179 ± 7	178 ± 5	.587
Body mass (kg)	81.9 ± 1.0	82.7 ± 9.0	.765
Fat mass (%)	18.4 ± 7.6	16.6 ± 5.5	.391
Total body water (%)	55.2 ± 3.7	56.1 ± 4.5	.465

Table 2. Participant dietary macronutrient for all study meetings.

	BETpre (mean±SD)	BETpost (mean±SD)	PLpre (mean±SD)	PLpost (mean±SD)	ANOVA
Carbohydrates (g/kg)	4.42 ± .89	4.36 ± .90	4.45 ± .78	4.43 ± .94	Time × treatment: p = 0.832 η^2 = 0.024
Protein (g/kg)	1.70 ± .33	1.76 ± .38	1.74 ± .38	1.80 ± .35	Time × treatment: p = 0.255 η^2 = 0.108
Fat (g/kg)	1.17 ± .34	1.18 ± .31	1.15 ± .35	1.16 ± .33	Time × treatment: p = 0.967 η^2 = 0.007

BET_post, after betaine; BET_pre, before betaine; PL_post, after placebo; PL_pre, before placebo.

Table 3. Effects of betaine supplementation on body mass and composition.

		BETpre (mean±SD)	BETpost (mean±SD)	PLpre (mean±SD)	PLpost (mean±SD)	ANOVA
BM (kg)	All	82.2 ± 8.9	82.1 ± 9.0	82.2 ± 9.4	82.1 ± 9.1	Time × treatment: p = 0.881 η^2 = 0.001
	2.5 g/d BET	81.6 ± 9.3	81.4 ± 9.4	81.9 ± 9.9	81.6 ± 9.1	Time × treatment × dose:
	5.0 g/d BET	82.9 ± 8.5	83.0 ± 8.7	82.5 ± 9.1	82.8 ± 9.3	p = 0.498 η ^2 = 0.012
FM (kg)	All	14.3 ± 6.6	13.9 ± 6.3	14.4 ± 6.4	14.1 ± 6.3	Time × treatment: p = 0.912 η^2 = 0.000
	2.5 g/d BET	15.0 ± 7.4	14.2 ± 6.9	15.1 ± 6.7	14.5 ± 6.5	Time × treatment × dose:
	5.0 g/d BET	13.5 ± 5.5	13.5 ± 5.7	13.6 ± 6.0	13.5 ± 6.2	p = 0.565 η^2 = 0.009
FFM (kg)	All	67.9 ± 7.1	68.2 ± 6.9	67.7 ± 6.8	68.0 ± 6.8	Time × treatment: p = 0.997 η^2 = 0.000
	2.5 g/d BET	66.6 ± 7.4	67.2 ± 7.0	66.8 ± 6.9	67.0 ± 6.8	Time × treatment × dose:
	5.0 g/d BET	69.4 ± 6.7	69.5 ± 6.8	68.9 ± 6.7	69.3 ± 6.9	p = 0.314 η^2 = 0.026
TBW (L)	All	45.5 ± 4.6	45.5 ± 4.5	45.5 ± 4.7	45.3 ± 4.5	Time × treatment: p = 0.683 η^2 = 0.004
	2.5 g/d BET	45.0 ± 5.2	45.0 ± 4.9	45.1 ± 5.3	44.8 ± 4.9	Time × treatment × dose:
	5.0 g/d BET	46.2 ± 4.6	46.1 ± 4.0	46.0 ± 3.9	45.9 ± 4.1	p = 0.823 η^2 = 0.001

All n = 43, 2.5 g/d n = 24, 5.0 g/d n = 19; BETpost, after betaine; BETpre, before betaine; BM, body mass; FFM, fat-free mass; FM, fat mass; PLpre, before placebo; PLpost, after placebo; SD, standard deviation; TBW, total body water.

Figure 1. Effects of betaine supplementation on WAnT. a. Effects of betaine on WAnT power, second by second. b. Effects of placebo on WAnT power second by second. c. Effects of betaine on WAnT power in 5-s intervals. d. Effects of betaine on WAnT power in 10-s intervals. BET post, after betaine; BET pre:,before betaine, PL post, after placebo; PL pre, before placebo.

Table 4. Effects of betaine supplementation on WAnT power.

		BETpre (mean±SD)	BETpost (mean±SD)	PLpre (mean±SD)	PLpost (mean±SD)	ANOVA
PP (W)	All	963 ± 215	1016 ± 163	981 ± 157	1011 ± 164	Time × treatment: p = 0.423 η^2 = 0.017
	2.5 g/d BET	936 ± 184	976 ± 132	967 ± 148	981 ± 149	Time × treatment × dose:
	5.0 g/d BET	997 ± 225	1066 ± 187	998 ± 170	1049 ± 176	p = 0.841 η^2 = 0.001
AP (W)	All	645 ± 94	660 ± 87	654 ± 91	657 ± 86	Time × treatment: p = 0.189 η^2 = 0.044
	2.5 g/d BET	633 ± 87	638 ± 87	639 ± 95	635 ± 88	Time × treatment × dose:
	5.0 g/d BET	660 ± 102	687 ± 81	673 ± 84	684 ± 79	p = 0.699 η^2 = 0.004
MP (W)	All	410 ± 67	405 ± 64	414 ± 56	419 ± 68	Time × treatment: p = 0.499 η^2 = 0.012
	2.5 g/d BET	397 ± 53	397 ± 61	397 ± 55	412 ± 85	Time × treatment × dose:
	5.0 g/d BET	427 ± 80	416 ± 71	435 ± 51	427 ± 40	p = 0.702 η^2 = 0.004

All n = 43, 2.5 g/d n = 24, 5.0 g/d n = 19; AP, average power; BET_post, after betaine; BET_pre, before betaine; MP, minimum power; PL_pre, before placebo; PL_post, after placebo; PP, peak power; SD, standard deviation.

Table 5. Effects of betaine supplementation on each Fight Gone Bad exercise.

		BETpre (mean±SD)	BETpost (mean±SD)	PLpre (mean±SD)	PLpost (mean±SD)	ANOVA Time × treatment
Wall ball	Round 1	30.0 ± 3.7	30.2 ± 4.2	30.5 ± 4.4	30.7 ± 5.1	p = 0.819 η^2 = 0.001
	Round 2	23.0 ± 4.8	24.5 ± 4.4	23.4 ± 4.9	24.7 ± 5.2	p = 0.728 η^2 = 0.003
	Round 3	21.9 ± 4.6	22.4 ± 4.8	22.1 ± 5.2	22.4 ± 5.5	p = 0.388 η^2 = 0.020
Sumo deadlift high pull	Round 1	20.0 ± 4.3	21.0 ± 5.7	20.3 ± 4.8	20.0 ± 4.8	p = 0.101 η^2 = 0.068
	Round 2	15.1 ± 4.4^a	16.3 ± 4.5^b	15.7 ± 4.6^ab	15.9 ± 4.3^ab	p = 0.043 η^2 = 0.104
	Round 3	14.2 ± 4.2^a	15.2 ± 4.0^b	14.6 ± 4.5^ab	14.5 ± 4.0^ab	p = 0.049 η^2 = 0.101
Box jump	Round 1	15.9 ± 4.3	16.4 ± 3.7	16.2 ± 4.6	16.3 ± 4.1	p = 0.236 η^2 = 0.036
	Round 2	13.2 ± 4.7^a	14.5 ± 4.3^b	13.7 ± 4.1^ab	13.7 ± 4.5^a	p = 0.010 η^2 = 0.161
	Round 3	12.5 ± 4.4	13.1 ± 4.3	13.1 ± 4.0	13.4 ± 4.5	p = 0.395 η^2 = 0.019
Push press	Round 1	17.2 ± 5.7^a	19.6 ± 5.7^b	19.4 ± 7.0^b	19.2 ± 6.1^b	p < 0.001 η^2 = 0.261
	Round 2	14.9 ± 5.7^a	16.9 ± 5.8^b	15.9 ± 6.0^ab	16.2 ± 5.8^ab	p = 0.013 η^2 = 0.153
	Round 3	15.4 ± 6.2^a	17.5 ± 6.5^b	16.0 ± 6.6^b	15.9 ± 5.3^ab	p = 0.003 η^2 = 0.199
Rowing	Round 1	14.2 ± 3.5	15.3 ± 3.2	14.8 ± 3.0	15.1 ± 2.7	p = 0.128 η^2 = 0.045
	Round 2	12.4 ± 3.4	13.1 ± 2.9	13.1 ± 3.5	13.6 ± 2.7	p = 0.535 η^2 = 0.010
	Round 3	14.3 ± 2.8	14.7 ± 2.7	14.4 ± 3.0	14.9 ± 3.1	p = 0.689 η^2 = 0.004
FGB Total score		252.4 ± 52.4^a	270.6 ± 46.7^b	263.1 ± 53.4^ab	262.4 ± 56.6^ab	p < 0.001 η^2 = 0.313

BETpost, after betaine; BETpre, before betaine; MTHFR, methyltetrahydrofolate reductase; PLpre, before placebo; PLpost, after placebo; SD, standard deviation.

Figure 2. Effects of betaine supplementation on FGB performance. A. Effects of betaine on each round of FGB. B. Effects of betaine on FGB total. BET post, after betaine; BET pre, before betaine; FGB, Fight Gone Bad; PL post, after placebo; PL pre, before placebo.

Table 6. Effects of betaine supplementation on testosterone, insulin-like growth factor 1, and cortisol concentrations.

		BETpre (mean±SD)	BETpost (mean±SD)	PLpre (mean±SD)	PLpost (mean±SD)	ANOVA
Testosterone(ng/mL)	All	4.77 ± 1.87^a	5.06 ± 2.02^b	4.84 ± 1.82^ab	4.82 ± 1.84^ab	Treatment × time: p = 0.046 η^2 = 0.098
	2.5 g/d BET	4.70 ± 2.10	4.98 ± 2.18	4.80 ± 1.90	4.75 ± 2.00	Time × treatment × dose:
	5.0 g/d BET	4.88 ± 1.58	5.17 ± 1.86	4.90 ± 1.77	4.90 ± 1.66	p = 0.928 η^2 = 0.000
Cortisol (ng/mL)	All	263 ± 130	265 ± 144	270 ± 148	270 ± 155	Treatment × time: p = 0.941 η^2 = 0.000
	2.5 g/d BET	254 ± 125	249 ± 125	278 ± 154	272 ± 166	Time × treatment × dose:
	5.0 g/d BET	274 ± 140	284 ± 167	260 ± 143	267 ± 144	p = 0.881 η^2 = 0.001
IGF-1 (ng/mL)	All	170 ± 85	179 ± 97	193 ± 101	180 ± 100	Treatment × time: p = 0.198 η^2 = 0.044
	2.5 g/d BET	173 ± 85	167 ± 98	191 ± 97	182 ± 100	Time × treatment × dose:
	5.0 g/d BET	166 ± 88	174 ± 99	195 ± 109	178 ± 103	p = 0.420 η^2 = 0.017

All n = 43, 2.5 g/d n = 24, 5.0 g/d n = 19; BET_post, after betaine; BET_pre, before betaine; IGF-1, insulin-like growth factor 1; PL_pre, before placebo; PL_post, after placebo; SD, standard deviation.