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Table 2 Special Judo Fitness Test (SJFT) data analysis

From: Dose-dependent effect of caffeine supplementation on judo-specific performance and training activity: a randomized placebo-controlled crossover trial

  All Caffeine consumers Caffeine non-consumers Uor t P rg or d
n = 22 n = 10 n = 12
SJFTR1
 Baseline 5.3 (0.7)a 5.1 (0.9)a 5.5 (0.5)a 45.0 0.34 0.25
 3 mg/kg 5.6 (0.6)ab 5.7 (0.5)b 5.6 (0.7)ab 51.5 0.60 −0.14
 6 mg/kg 5.9 (0.6)bc 5.7 (0.5)ab 6.0 (0.6)b 45.0 0.34 0.25
 9 mg/kg 6.0 (0.6)c 6.0 (0.5)b 6.0 (0.7)b 60.0 0.97 0.00
 Placebo 5.6 (0.6)ab 5.6 (0.5)ab 5.6 (0.7)ab 57.0 0.87 −0.05
 Χ2 21.46 12.85 11.67    
 P < 0.001 0.01 0.02    
 Kendall’s W 0.24 0.32 0.24    
SJFTR2
 Baseline 10.0 (1.2)B 9.9 (1.3)A 10.1 (1.1)B 0.36 0.72 0.16
 3 mg/kg 10.1 (1.0)B 9.9 (1.1)B 10.3 (1.0)A 0.98 0.34 0.42
 6 mg/kg 10.4 (0.8)B 10.2 (0.6)A 10.5 (1.0)A 49.0 0.49 0.18
 9 mg/kg 10.5 (0.8)A 10.7 (0.7)A 10.3 (0.9)A 41.0 0.22 −0.32
 Placebo 10.3 (0.9)B 10.3 (0.8)B 10.3 (1.0)B 57.0 0.87 −0.05
 Χ2 or F 6.93 6.84 0.97    
 P 0.14 0.14 0.43    
 Kendall’s W or \( {\eta}_p^2 \) 0.08 0.17 0.08    
SJFTR3
 Baseline 9.2 (1.3)aA 9.1 (1.4)A 9.3 (1.2)A 0.42 0.68 0.18
 3 mg/kg 9.5 (1.0)aA 8.9 (0.9)A 9.9 (0.9)A 26.0 0.03 0.57
 6 mg/kg 9.9 (1.1)bA 9.6 (1.0)A 10.2 (1.1)A 43.5 0.22 0.28
 9 mg/kg 10.2 (1.1)bA 9.9 (1.1)A 10.4 (1.0)A 42.0 0.25 0.30
 Placebo 9.4 (1.1)aA 9.5 (1.1)A 9.3 (1.2)A 55.0 0.77 −0.08
 Χ2 19.58 6.79 19.93
 P 0.006 0.15 < 0.001
 Kendall’s W 0.22 0.17 0.42
SJFT Index
 Baseline 13.2 (2.2) 13.9 (2.3) 12.6 (2.0)
 3 mg/kg 12.7 (1.8) 13.5 (1.9) 12.0 (1.4)
 6 mg/kg 12.6 (1.4) 13.1 (1.2) 12.3 (1.4)
 9 mg/kg 12.5 (1.3) 12.7 (1.3) 12.3 (1.3)
 Placebo 12.6 (1.7) 13.0 (1.4) 12.2 (1.9)
Dosage effect
 F 2.38    
 P 0.06    
\( {\eta}_p^2 \) 0.10    
Dosage x caffeine consumption effect
 F 1.51    
 P 0.21    
\( {\eta}_p^2 \) 0.07    
Statistical significance between SJFTR2 and SJFTR3 within the same caffeine dosage
 Z or t (Baseline) 2.56 1.56 3.00
 P 0.01 0.15 0.01
 rc or d 0.66 0.60 0.65
 Z or t (3 mg/kg) 2.83 2.37 1.57
 P 0.005 0.02 0.12
 rc or d 0.79 0.89 0.64
 Z or t(6 mg/kg) 2.13 1.52 1.83
 P 0.03 0.14 0.07
 rc or d 0.64 0.57 0.66
 Z or t (9 mg/kg) 1.13 1.84 −0.69
 P 0.26 0.07 0.50
 rc or d 0.30 0.61 −0.18
 Z or t (Placebo) 3.29 2.03 2.67
 P 0.001 0.04 0.008
 rc or d 0.80 0.72 0.89
  1. Values are means (SD). abc – different letter inscriptions refer to statistical differences between caffeine dosages; ABC – different letter inscriptions refer to statistical differences between SJFT rounds (R2 and R3) within the same caffeine dosages. SJFT, Special Judo Fitness Test