# Criterion-Related Validity and Reliability of the Front Plank Test in Adults: The ADULT-FIT Project
## 2 Materials and Methods
### Procedures  
All test sessions were conducted in the Physical Activity and Sport laboratory of the University of Cadiz (Cadiz, Spain). Participants came to the laboratory on two different days (one week apart). On the first day, participants completed a questionnaire to determine their physical activity and injury history. Subsequently, body composition was measured, after which a warm-up was performed. The warm-up included general mobility exercises such as supine low back rotation, cat-camel, quadruped thoracic rotation, and cobra lift. Additionally, specific trunk muscle activation was performed, consisting of 3 sets of 20 s of work and 20 s of rest for front plank, and 1 set of 10 repetitions for the gluteal bridge. Once the warm-up was completed, all sensors were placed, and the maximum voluntary isometric contraction (MVIC) was performed for each muscle. Subsequently, FPT was performed. After a complete rest (5-7), the force of the trunk musculature was measured on the isokinetic device. In the second session, the participant performed the same warm-up and the FPT was assessed without sEMG. All assessments were performed by two assessors (AR-P and JC-P), who were experienced with the measuring device (Humac Norm, CSMi,  
\begin{table}
\begin{tabular}{l c c c c c} \hline \hline  & **Total** & **Male** & **Female** & **Young Adults** & **Adults** \\  & **(n = 84)** & **(n = 52)** & **(n = 32)** & **(n = 64)** & **(n = 20)** \\ \hline Age (years) & 28.16 \(\pm\) 12.32 & 24.37 \(\pm\) 8.75 & 34.31 \(\pm\) 14.75 *** & 21.84 \(\pm\) 3.02 & 48.35 \(\pm\) 8.37 *** \\ Weight (kg) & 68.83 \(\pm\) 11.13 & 74.77 \(\pm\) 8.14 & 59.18 \(\pm\) 8.20 *** & 69.53 \(\pm\) 11.12 & 66.60 \(\pm\) 11.11 \\ Height (cm) & 1.71 \(\pm\) 0.10 & 1.77 \(\pm\) 0.07 & 1.62 \(\pm\) 0.07 *** & 1.72 \(\pm\) 0.1 & 1.67 \(\pm\) 0.08 * \\ BMI (kg/m\({}^{2}\)) & 23.31 \(\pm\) 2.31 & 23.80 \(\pm\) 2.25 & 22.51 \(\pm\) 2.21 * & 23.14 \(\pm\) 2.11 & 23.84 \(\pm\) 2.84 \\ Waist circumference (cm) & 76.40 \(\pm\) 7.12 & 79.23 \(\pm\) 5.91 & 71.80 \(\pm\) 6.56 *** & 75.71 \(\pm\) 6.26 & 78.58 \(\pm\) 9.22 \\ Level of physical activity & 4.01 \(\pm\) 1.42 & 4.33 \(\pm\) 1.23 & 3.50 \(\pm\) 1.57 ** & 4.19 \(\pm\) 1.32 & 3.42 \(\pm\) 1.61 * \\ (d/w) & 19.59 \(\pm\) 6.64 & 16.13 \(\pm\) 3.81 & 25.10 \(\pm\) 6.49 *** & 17.93 \(\pm\) 5.16 & 25.15 \(\pm\) 8.08 *** \\ Body fat (\%) & 52.44 \(\pm\) 9.98 & 59.21 \(\pm\) 5.08 & 41.63 \(\pm\) 5.07 *** & 54.07 \(\pm\) 9.31 & 46.93 \(\pm\) 10.42 ** \\ Trank Fat-free mass (kg) & 29.82 \(\pm\) 4.78 & 32.72 \(\pm\) 2.86 & 25.20 \(\pm\) 3.39 *** & 30.45 \(\pm\) 4.42 & 27.71 \(\pm\) 5.44 * \\ Trunk Fat Mass (\%) & 19.26 \(\pm\) 6.52 & 18.69 \(\pm\) 4.73 & 20.17 \(\pm\) 8.67 & 17.99 \(\pm\) 5.87 & 23.54 \(\pm\) 6.98 *** \\ Lean Trunk Mass (kg) & 28.41 \(\pm\) 4.57 & 31.18 \(\pm\) 2.75 & 23.99 \(\pm\) 3.22 *** & 29.91 \(\pm\) 4.24 & 26.38 \(\pm\) 5.17 * \\ \hline \hline \end{tabular}  
* Data are presented as mean \(\pm\) standard deviation. BMI = body mass index; d/w = days per week; kg = kilograms. The variables were compared by sex and age. Significance level
* \(p<\) 0.05 *
* \(p<\) 0.01 **
* \(p<\) 0.001.  
\end{table}
Table 1: Descriptive characteristics of the sample and differences according to sex and age groups.  
Stoughton, MA, USA), at the same time of day (\(\pm\)1 h) for each participant and in similar environmental conditions (\(\sim\)21 \({}^{\circ}\)C and \(\sim\)60% humidity).