Author(s): FREITAG, N., WEHNING, S., PEITZ, M., SCHUMANN, M., LEGERLOTZ, K., BÖHLKE N., Institution: OLYMPIC TRAINING CENTRE BERLIN, Country: GERMANY, Abstract-ID: 534

INTRODUCTION:
The Isometric Mid-Thigh Pull (IMTP) is a valid, reliable, and safe test to assess maximal isometric strength in adults as well as in children and adolescents. It also shows strong associations with sport-specific performance outcomes. However, standardized IMTP testing is not yet consistently implemented in youth high-performance sport settings, which may limit comparability across athletes and, in the case of athlete monitoring, over time. Grip strength may act as a limiting factor and reduce the accuracy of peak-force outcomes. While lifting straps are recommended in adult IMTP protocols to minimize grip constraints, their use is often impractical in youth testing environments due to limited familiarity and time demands in large groups. This study investigated the acute effects of double overhand grip (OH), mixed grip (MG) and OH with lifting straps (STR) on peak force during the IMTP in youth athletes. Subgroup analyses examined whether grip-related differences depend on sex or type of sport (grip-sport vs. non-grip-sport athletes).
METHODS:
Eighty youth athletes (12.93 ± 1.08 yrs; 42 males, 38 females) from swimming (n = 28), diving (n = 21), judo (n = 12), and gymnastics (n = 19) completed IMTP tests in all grip conditions using a randomized crossover design using a chain-based IMTP setup with a force sensor (gStrength, Exsurgo Technologies, Sterling, Virginia, United States) fixed between a base plate and chain. Peak force measurements were taken from the force sensor manufacturers’ app and analysed across the different test conditions using a one-way repeated-measures ANOVA. Effect sizes were reported as partial eta squared (ηp²) and Cohen’s f. For subgroup analyses, relative peak-force differences between grip conditions were calculated and evaluated using factorial ANOVAs with sex and sport type as between-subject factors.
RESULTS:
Peak force differed significantly between grip conditions (OH = 1011.2 ± 254.7 N, MG = 1343.7 ± 290.1 N, STR = 1428.1 ± 364.4 N), F(1.75, 138.03) = 142.90, p < .001, ηp² = 0.64 (f = 1.33). Pairwise comparisons showed significantly higher peak force in MG and STR compared to OH (both p < 0.001, adjusted). Peak force did not significantly differ between STR and MG (p = 0.058). Subgroup analyses revealed no main effects of sex or sport type and no interaction effects on relative peak-force differences between grip conditions (all p > 0.05).
CONCLUSION:
Grip selection substantially influences maximal force outcomes in youth IMTP assessments. The OH appears to limit peak force, whereas MG and STR enable significantly higher force expression. Although no significant differences were observed, results showed a trend toward higher values with STR. Therefore, MG appears sufficient for large-scale field testing, whereas straps may be preferable in more controlled or performance-focused assessments to maximize force expression and standardization.