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Table 2 Levels of the monitored indices before and after the 12-week supplementation with HMB preparation and placebo

From: The efficacy of a β-hydroxy-β-methylbutyrate supplementation on physical capacity, body composition and biochemical markers in elite rowers: a randomised, double-blind, placebo-controlled crossover study

Research period   PREHMB vs. PLA HMB Difference PLACEBO Difference
  p valuea p valueb p valueb
BM (kg) Pre 0.925 86.5 ± 9.3 0.016 86.2 ± 9.0 0.063
Post   84.6 ± 8.1 84.8 ± 8.5
FFM (kg) Pre 0.921 72.7 ± 6.3 0.117 72.9 ± 6.1 0.001
Post   71.7 ± 5.6 70.9 ± 5.7
FM (kg) Pre 0.755 13.8 ± 4.4 0.073 13.3 ± 4.7 0.197
Post   12.8 ± 4.0 14.1 ± 4.3
\( \dot{\mathrm{V}}{\mathrm{O}}_2 \max \) (mL · min−1) Pre 0.681 5794 ± 676 0.240 5897 ± 735 0.067
Post   5905 ± 709 5723 ± 745
\( \dot{\mathrm{V}}{\mathrm{O}}_2 \max \) (mL · min−1 · kg−1) Pre 0.572 67.3 ± 6.9 0.033 68.8 ± 8.0 0.438
Post   70.0 ± 6.9 67.8 ± 8.5
Tref (min) Pre 0.947 17.6 ± 3.1 0.043 17.7 ± 3.1 0.233
Post   19.0 ± 3.6 18.5 ± 3.7
Wmax (W) Pre 0.777 372 ± 52 0.052 378 ± 52 0.625
Post   397 ± 56 384 ± 60
Wmax (W · kg−1) Pre 0.621 4.31 ± 0.50 0.039 4.39 ± 0.41 0.234
Post   4.70 ± 0.55 4.55 ± 0.65
HRmax (bpm) Pre 0.962 185 ± 13 0.258 185 ± 9 0.136
Post   188 ± 9 188 ± 10
TVT (min) Pre 0.440 12.5 ± 2.1 0.003 12.8 ± 1.9 0.619
Post   13.7 ± 2.2 12.6 ± 2.6
WVT (W) Pre 0.187 278 ± 41 0.012 294 ± 36 0.310
Post   309 ± 42 284 ± 47
WVT (W · kg−1) Pre 0.248 3.24 ± 0.51 0.001 3.42 ± 0.32 0.554
Post   3.66 ± 0.36 3.36 ± 0.49
HRVT (bpm) Pre 0.399 157 ± 9 0.001 160 ± 10 0.598
Post   166 ± 11 161 ± 9
CK (U · L−1) Pre 0.865 328 ± 160 0.004 348 ± 169 0.008
Post   241 ± 103 265 ± 156
LDH (U · L−1) Pre 0.573 318 ± 36 0.033 326 ± 45 0.002
Post   302 ± 35 302 ± 39
Testosterone (mg · dL−1) Pre 0.895 510 ± 202 0.352 510 ± 154 0.569
Post   552 ± 160 487 ± 160
Cortisol (mg · dL−1) Pre 0.585 19.9 ± 5.3 0.331 20.0 ± 5.9 0.516
Post 20.6 ± 5.8 20.8 ± 4.1
T/C ratio (T · C−1*10−2) Pre 0.51 3.39 ± 1.77 0.53 3.36 ± 0.99 0.30
Post   3.41 ± 1.08 3.03 ± 1.11
Peak power (W) Pre 0.615 1003 ± 125 0.027 1028 ± 147 0.853
Post   1054 ± 116 1024 ± 122
Peak power (W · kg−1) Pre 0.488 11.65 ± 1.01 0.020 11.92 ± 1.16 0.960
Post   12.26 ± 0.83 11.91 ± 1.15
Average power (W) Pre 0.924 725 ± 87 0.648 722 ± 87 0.660
Post   720 ± 83 718 ± 82
Average power (W · kg−1) Pre 0.854 8.36 ± 0.60 0.688 8.32 ± 0.55 0.736
Post   8.30 ± 0.59 8.28 ± 0.65
Minimal power (W) Pre 0.478 503 ± 75 0.095 486 ± 52 0.763
Post   475 ± 54 491 ± 78
Minimal power (W · kg−1) Pre 0.465 5.80 ± 0.78 0.119 5.63 ± 0.55 0.821
Post   5.49 ± 0.53 5.67 ± 0.76
  1. Values are expressed as mean ± SD
  2. BM body mass, FFM fat-free mass, FM fat mass, \( \dot{V}{O}_2 max \) maximal oxygen uptake, Tref exercise time before athlete’s refusal to continue exercising, Wmax maximum load, HRmax maximum heart rate, VT ventilatory threshold, T VT time to VT, W VT load at VT, HR VT heart rate at VT, CK creatine kinase, LDH lactate dehydrogenase, T/C ratio testosterone/cortisol ratio
  3. aDepending on the data distribution: independent samples t-tests or Mann–Whitney U tests
  4. bDepending on the data distribution: dependent samples t-tests or Wilcoxon-signed rank tests