Effects of β-alanine supplementation during a 5-week strength training program: a randomized, controlled study

Incremental BS test

Significantly greater pre-post training (

time

factor) improvements (

p

F

 = 72.425;

ES

 = 0.751;

SP

 = 1.000): 15.95% in the PLA group (95% CI, 90.90, 106.52) and 20.17% in the BA group (95% CI, 92.16, 106.62). However, no significant effects (

p

 = 0.356) on this variable were observed of the interaction

time

x

group

(

F

 = 0.888;

ES

 = 0.036;

SP

 = 0.148) (Table 

3

) (Additional file 

1

). Once analysis of covariance had ruled out an effect of the pre-training variables acting as covariate of the kilograms lifted at Pmax, no significant differences (2.36%,

p

 = 0.371) were observed between the two groups (PLA: 95% CI, 99.99, 111.11; BA: 95% CI, 103.74, 114.04) (

F

 = 0.832;

ES

 = 0.035;

SP

 = 0.141) (Additional file 

2

).

Table 3

Effects of the 5-week resistance training program in the PLA and BA groups

Kg at 1RM (kg)

PLA

123.92 ± 18.02 (112.38–135.45)

139.33 ± 15.13 (129.45–149.22)

15.41

12.44%

121.16–142.09

0.484

< 0.001*

0.014*

BA

124.57 ± 20.42 (113.89–135.25)

148.50 ± 17.73 (139.35–157.65)

23.93

19.21%

126.85–146.22

AV at 1RM (m·s−1)

PLA

0.325 ± 0.073 (0.29–0.36)

0.370 ± 0.125 (0.29–0.45)

0.045

12.16%

0.31–0.39

0.328

0.023*

0.354

BA

0.324 ± 0.049 (0.29–0.36)

0.426 ± 0.137 (0.35–0.50)

0.102

31.57%

0.34–0.41

PV at 1RM (m·s−1)

PLA

0.844 ± 0.222 (0.71–0.8)

0.951 ± 0.203 (0.86–1.05)

0.107

12.7%

0.80–1.00

0.802

0.044*

0.626

BA

0.881 ± 0.224 (0.76–1.00)

0.947 ± 0.113 (0.86–1.04)

0.066

7.49%

0.82–1.01

AP at 1RM (W)

PLA

392.16 ± 87.69 (342.70–441.63)

474.8 ± 104.58 (409.99–539.61)

82.64

21.07%

384.77–482.19

0.185

< 0.001*

0.056

BA

395.14 ± 78.86 (349.35–440.94)

559.70 ± 112.20 (499.71–619.70)

164.56

41.65%

432.33–522.52

PP at 1RM (W)

PLA

1159.5 ± 338.91 (939.31–1379.69)

1467.42 ± 334.48 (1297.52–1637.31)

307.92

26.56%

1136.50–1490.42

0.332

< 0.001*

0.774

BA

1258.79 ± 393.66 (1054.92–1462.64)

1599.64 ± 235.49 (1442.35–1756.94)

300.85

23.89%

1265.38–1593.05

Kg at Pmax (kg)

PLA

91.42 ± 15.73 (83.02–99.81)

106.00 ± 12.43 (97.71–114.28)

14.58

15.95%

90.90–106.52

0.896

< 0.001*

0.356

BA

90.29 ± 12.53 (82.51–98.06)

108.50 ± 15.03 (100.83–116.17)

18.21

20.17%

92.16–106.62

AV at Pmax (m·s−1)

PLA

0.735 ± 0.096 (0.69–0.78)

0.698 ± 0.072 (0.66–0.74)

− 0.037

−5.03%

0.68–0.75

0.861

0.373

0.226

BA

0.710 ± 0.054 (0.67–0.75)

0.716 ± 0.055 (0.68–0.75)

0.006

0.85%

0.68–0.74

PV at Pmax (m·s−1)

PLA

1.289 ± 0.122 (1.22–1.36)

1.246 ± 0.088 (1.19–1.30)

− 0.043

− 3.34%

1.22–1.32

0.497

0.323

0.354

BA

1.291 ± 0.102 (1.23–1.35)

1.289 ± 0.086 (1.24–1.34)

− 0.002

−0.15%

1.25–1.34

AP at Pmax (W)

PLA

654.75 ± 113.98 (586.27–723.23)

725.08 ± 106.84 (664.74–785.43)

70.33

10.74%

628.31–751.53

0.904

< 0.001*

0.034*

BA

631.21 ± 115.73 (567.82–694.61)

758.50 ± 96.33 (702.63–814.37)

127.29

20.17%

637.82–751.90

PP at Pmax (W)

PLA

1397.25 ± 245.66 (1242.88–1551.62)

1565.75 ± 146.17 (1445.86–1685.63)

168.5

12.06%

1351.76–1611.24

0.494

< 0.001*

0.137

BA

1408.43 ± 269.93 (1265.51–1551.34)

1673.57 ± 238.06 (1562.58–1784.57)

265.14

18.83%

1420.88–1661.12

Mean AV (m·s−1)

PLA

0.673 ± 0.046 (0.65–0.70)

0.705 ± 0.058 (0.68–0.73)

0.032

4.75%

0.67–0.71

0.988

< 0.005*

0.905

BA

0.674 ± 0.049 (0.65–0.70)

0.704 ± 0.033 (0.68–0.73)

0.050

5.05%

0.68–0.71

Mean AP (W)

PLA

506.73 ± 68.56 (458.34–555.21)

589.07 ± 73.10 (543.27–634.87)

82.34

16.25%

502.80–593.04

0.611

< 0.001*

0.383

BA

514.13 ± 90.68 (469.29–558.97)

612.44 ± 79.92 (570.04–654.84)

98.31

19.12%

521.51–605.06

For the variable AP at Pmax, significant effects (p < 0.001) were noted of time (PLA: 10.74%, 95% CI, 628.31, 751.53; BA: 20.17%, 95% CI, 637.82, 751.90) (F = 60.61; ES = 0.716; SP = 1.000) and of time x group (F = 5.034; p = 0.034; ES = 0.173; SP = 0.577) (Table 3) (Additional file1). When we assessed the covariables, significant differences between groups (4.61%, p = 0.037) were confirmed for this variable (PLA: 95% CI, 681.18, 750.46; BA: 95% CI, 734.38, 798.50) (F = 4.893; ES = 0.175; SP = 0.563) (Additional file 2).

In addition, for PP at Pmax, significant differences (p < 0.001) were also detected in the factor time (F = 47.54; ES = 0.665; SP = 1.000). Improvements were 12.06% (95% CI, 1351.76, 1611.24) and 18.83% (95% CI, 1420.88, 1661.12) for the PLA and BA groups respectively, with no effects of time x group (F = 2.361; p = 0.137; ES = 0.090; SP = 0.314) (Table 3) (Additional file 1).

When we examined factors related to the participants’ 1RM, some significant effects were observed. For the variable kilograms lifted at 1RM differences were significant (p < 0.001) for both time (PLA: 12.44%, 95% CI, 121.16, 142.09; BA: 19.21%, 95% CI, 126.85, 146.22) (F = 151.764; ES = 0.863; SP = 1.000) and time x group (F = 7.103; p = 0.014; ES = 0.228; SP = 0.725) (Table 3) (Additional file 1). Analysis of covariance confirmed these significant differences between groups (54.42%, p = 0.005) eliminating the effect of the covariate pre-training (PLA: 95% CI, 135.40, 143.82; BA: 95% CI, 144.37, 152.16) (F = 9.737; ES = 0.297; SP = 0.848) (Additional file 2).

For AP at 1RM, the time factor had a significant effect (p < 0.001) (PLA: 21.07%, 95% CI, 384.77, 482.19; BA: 42.65%, 95% CI, 432.33, 522.52) (F = 36.862; ES = 0.606; SP = 1.000) while the impact of time x group approached significance (p = 0.056; F = 4.049; ES = 0.144; SP = 0.489) (Table 3) (Additional file 1). However, by adjusting pre-training levels through analysis of covariance, significant differences (102.42%, p = 0.045) were indeed confirmed for AP at 1RM between groups (PLA: 95% CI, 416.26, 535.20; BA: 95% CI, 503.85, 613.97) (F = 4.507; ES = 0.164; SP = 0.529). (Additional file 2).

Significant pre-posttraining differences (p < 0.001) were also observed in two last variables related to power, PP at 1RM (PLA: 26.56%, 95% CI, 1136.50, 1490.42; BA: 23.89%, 95% CI, 1265.38, 1593.05) (F = 32.797; ES = 0.577; SP = 1.000) and mean AP (PLA: 16.25%, 95% CI, 502.80, 593.04; BA: 19.12%, 95% CI, 521.51, 605.06) (F = 100.680; ES = 0.808; SP = 1.000). However, no significant effects on these variables of time x group were noted (F = 0.085; p = 0.774; ES = 0.004; SP = 0.059; F = 0.791; p = 0.383; ES = 0.032; SP = 0.137, respectively) (Table 3) (Additional file 1). Using as covariates in the univariate ananlysis of variance the pre-training variables, we confirmed the lack of significant differences between BA and PLA for PP at 1RM (− 10.50%, p = 0.359, PLA: 95% CI, 1359.53, 1628.13; BA: 95% CI, 1452.75, 1701.25) and mean AP (17.66%, p = 0.314, PLA: 95% CI, 566.31, 618.08; BA: 95% CI, 585.80, 633.72) (Additional file 2).

No significant effects were recorded on the variables related to velocity of movement (AV at Pmax, PV at Pmax and peak velocity at 1RM) of either time or group (Table 3) (Additional file 1).

For mean AV, significant differences (p = 0.005) were observed according to time (PLA: 95% CI, 0.67, 0.71; BA: 95% CI, 0.67, 0.71) (F = 9.529; ES = 0.284; SP = 0.842), with similar improvements observed in PLA and BA (4.75%, 4.45%, respectively) (Table 3) (Additional file 1).

The following tables (Tables 

4

and

5

) provide mean pre-post training improvements for BA versus PLA in the number of sets accomplished (

p

 = 0.025; 95% CI, 0.82, 2.35, BA: 95% CI, 2.08, 3.49) and number of kilograms lifted (

p

 = 0.014; 95% CI, 10.58, 20.25, BA: 95% CI, 19.45, 28.41) in the 1RM test (Additional file 

3

).

Table 4

Mean improvements in the number of sets executed in the pre- versus post-training BS incremental test at 1RM

Placebo

9.83 ± 1.80

11.41 ± 1.50

1.58 ± 1.44a

0.82–2.35

5.709/ 0.630

β-Alanine

10.07 ± 2.26

12.85 ± 1.74

2.79 ± 1.12

2.08–3.49

Table 5

Mean improvements in the number of kilograms lifted in the pre- versus post-training BS incremental test at 1RM

Placebo

123.92 ± 18.02

139.33 ± 15.13

15.41 ± 5.82a

10.58–20.25

7.103/ 0.725

β-Alanine

124.57 ± 20.42

148.50 ± 17.73

23.92 ± 9.64

19.45–28.41

Regression lines for AV recorded in PLA and BA pre- and post-training in the BS incremental load test were similar. This indicates that both 5 weeks of training and supplementation with BA did not modify the relationship between AV and relative work intensity. In contrast, the mean tendency for AP was higher in the BA group than PLA group after training, while means before training failed to vary between the groups, suggesting a beneficial effect of BA supplementation plus training on the BS incremental load test (Fig. 

2

).

Fig. 2

a Average velocity β-alanine VS. placebo-Pretest; b Average velocity β-alanine VS. placebo-Posttest; c Average power β-alanine VS. placebo-Pretest; d Average power β-alanine VS. placebo-Posttest

Regression lines for the variables recorded in the CMJ test, jump height and AP indicated no significant impacts of supplementation during training on these variables (Fig. 

3

).

Fig. 3

a Jump height β-alanine VS. placebo-Pretest; b Jump height β-alanine VS. placebo-Posttest; c Average power β-alanine VS. placebo-Pretest; d Average power β-alanine VS. placebo-Posttest