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Table 1 Changes in physical fitness variables levels between pre- mid- and post-season

From: Effects of chronic betaine supplementation on performance in professional young soccer players during a competitive season: a double blind, randomized, placebo-controlled trial

Variables Groups Pre-Season Mid-Season Post-Season Pre-Post Season 95 % CI Hedge’s g
M±SD M±SD M±SD % Change Hedge’s g Lower Upper
VO2max BG 48.7±2.2 49.4±2.0 51.1±2.5* 4.9 1.0 L 0.17 1.73
(ml.kg−1.min−1) PG 47.5±2.6 48.2±2.6 48.2±2.1 1.4 0.3 S -0.44 0.99
CMJ (cm) BG 40.1±5.1 42.6±4.9 46.9±5.1* 17.1 1.3 L 0.47 2.09
PG 42.5±4.7 43.6±5.1 44.9±4.5* 5.5 0.5 M -0.25 1.21
AcT (m/s) BG 1.96±0.14 1.99±0.14 1.99±0.18 1.4 0.2 S -0.58 0.90
PG 2.04±0.20 2.12±0.26 2.11±0.23 3.2 0.3 S -0.44 1.00
SpT (m/s) BG 4.16±0.34 4.12±0.36 3.92±0.25* -5.8 -0.8 L -1.54 0.00
PG 4.01±0.56 4.03±0.54 4.04±0.49 0.8 0.1 T -0.66 0.77
CoD (m/s) BG 2.37±0.15 2.40±0.21 2.41±0.22 2.0 0.2 S -0.51 0.98
PG 2.29±0.25 2.27±0.24 2.26±0.21 -1.4 -0.1 T -0.85 0.59
RaP (w) BG 708.4±168.6 717.1±164.2 845.1±157.0*# 19.3 0.8 L 0.03 1.57
PG 784.2±145.1 785.9±141.2 837.8±137.6*# 6.8 0.4 S -0.36 1.08
RaM (w) BG 406.1±92.5 413.5±92.0 435.1±59.1 7.1 0.4 S -0.39 1.10
PG 453.7±133.6 457.1±132.5 487.1±178.8 7.3 0.2 S -0.52 0.92
RaA (w) BG 542.4±107.7 551.0±107.8 616.9±100.0 13.7 0.7 M -0.08 1.44
PG 605.9±142.9 608.8±142.8 665.6±164.6 9.8 0.4 S -0.35 1.09
RaFi (w/s) BG 9.9±4.1 10.2±4.2 14.0±4.9 41.6 0.9 L 0.09 1.64
PG 10.5±3.2 10.8±2.5 13.1±2.3 25.1 0.9 L 0.15 1.66
Leg press (kg) BG 183.6±8.8 186.6±8.2 191.8±5.7* 4.5 1.1 L 0.26 1.84
PG 184.4±8.1 186.4±8.0 187.5±7.8* 1.7 0.4 S -0.35 1.09
Bench press (kg) BG 75.3±6.1 76.7±6.1 81.1±5.9*# 7.7 0.9 L 0.14 1.70
PG 75.6±6.7 77.1±6.3 78.2±6.5*# 3.4 0.4 S -0.35 1.09
VL on leg press (kg) BG 1027.7±194.1 1064.4±145.3 1113.2±116.0 11.5 0.5 M -0.25 1.26
PG 961.8±193.5 913.6±190.5 940.3±163.5 -0.8 -0.1 T -0.60 0.83
VL on bench press (kg) BG 321.0±69.3 326.9±68.5 387.7±63.2 23.1 1 L 0.17 1.74
PG 395.8±64.8 407.1±70.3 421.5±66.7 7.3 0.4 S -0.35 1.09
  1. M: Mean; SD: Standard deviation; BG: Betaine Group; PG: Placebo Group; VO2max: Maximal oxygen consumption; CMJ: Counter movement jump; AcT: Acceleration time; SpT: Sprint time; CoD: Change of direction; RaP: RAST of peak power; RaM: RAST of minimum power; RaA: RAST of average power; RaFi: RAST of fatigue index; VL: Volume load; P: Pre-Season; P2: Mid- Season; P3: Post- Season; T: Trivial; S: Small; M: Moderate; L: Large
  2. Represents a statistically significant difference compared to P1-P2 (p<0.05); #Represents a statistically significant difference compared to P2-P3 (p<0.05); *Represents a statistically significant difference compared to P1-P3 (p<0.05)