Table 2
Pre- and post-intervention changes in the study variables within each group (control, non-competitive HIIT and competitive HIIT)
| Control group (n = 70) | Non-competitive HIIT (n = 70) | Competitive HIIT (n = 49) | ||||||||||
| Pre | Post | Effect size (d) | Sig. | Pre | Post | Effect size (d) | Sig. | Pre | Post | Effect size (d) | Sig. | |
| x̄ (SD) | x̄ (SD) | x̄ (SD) | x̄ (SD) | x̄ (SD) | x̄ (SD) | |||||||
| Perceived stress | 24.01 (7.88) | 24.13 (8.05) | 0.02 | t = 0.16 p = .877 | 24.74 (7.26) | 23.70 (7.82) | 0.09 | t = 0.75 p = .456 | 29.04 (7.24) | 26.82 (8.63) | 0.22 | t = 1.52 p = .135 |
| Sleep quality | 6.43 (4.37) | 7.13 (1.38) | –0.12 | t = –0.92 p = .361 | 6.04 (4.45) | 6.63 (1.36) | –0.12 | t = –1.04 p = .302 | 6.88 (3.31) | 6.67 (3.91) | 0.04 | t = 0.31 p = .761 |
| Sleep duration | 6.90 (1.49) | 5.86 (3.58) | 0.20 | t = 1.45 p = .197 | 7.24 (1.42) | 6.85 (2.67) | 0.14 | t = 1.09 p = .279 | 6.94 (1.99) | 6.06 (1.73) | 0.30 | t = 2.13 p = .038 |
| Intrinsic regulation | 3.97 (1.03) | 3.76 (0.74) | 0.23 | t = 1.78 p = .080 | 3.92 (0.98) | 3.45 (1.02) | –0.16 | t = –1.36 p = .177 | 3.67 (1.00) | 3.45 (1.02) | 0.17 | t = 1.20 p = .235 |
| Identified regulation | 3.86 (0.84) | 3.72 (0.82) | 0.10 | t = 0.77 p = .446 | 3.65 (0.85) | 3.90 (0.65) | –0.27 | t = –2.25 p = .028 | 3.84 (0.80) | 3.51 (0.89) | 0.30 | t = 2.09 p = .042 |
| Introjected regulation | 2.84 (1.13) | 2.88 (1.14) | –0.02 | t = –0.16 p = .875 | 2.65 (1.03) | 2.66 (1.12) | –0.01 | t = –0.08 p = .938 | 2.99 (1.02) | 2.99 (0.97) | 0.00 | t = 0.01 p = .993 |
| External regulation | 1.91 (0.81) | 1.99 (0.89) | –0.02 | t = –0.14 p = .891 | 1.91 (0.98) | 2.25 (0.79) | –0.31 | t = –2.56 p = .013 | 2.22 (0.97) | 2.19 (0.96) | 0.03 | t = 0.22 p = .829 |
| Amotivation | 1.69 (0.84) | 1.75 (0.92) | –0.13 | t = –0.99 p = .327 | 1.82 (0.98) | 1.91 (0.95) | –0.07 | t = –0.58 p = .566 | 2.31 (0.70) | 2.21 (0.75) | 0.11 | t = 0.74 p = .463 |
| PA enjoyment | 62.91 (11.07) | 62.27 (12.59) | 0.03 | t = 0.20 p = .839 | 64.03 (10.20) | 62.53 (8.92) | 0.13 | t = 1.05 p = .296 | 60.16 (9.39) | 60.06 (10.12) | 0.01 | t = 0.06 p = .954 |
| Self-esteem | 23.60 (3.69) | 26.05 (3.82) | –0.57 | t = –4.28 p < .001 | 24.64 (4.02) | 26.56 (6.38) | –0.25 | t = –2.13 p = .037 | 26.71 (2.61) | 23.18 (2.89) | 0.78 | t = 5.47 p < .001 |
| Note. SD = standard deviation, x̄ = mean, d = Cohen’s effect size, Sig. = p value from the paired-samples t-test, n = sample size. p values < .05 are shown in bold. | ||||||||||||
