Trunk Strength Characteristics of Elite Alpine Skiers - A Comparison with Physically Active Controls

Abstract

Core muscle imbalances and weak trunk strength are relevant for injury prevention and performance. Information regarding core strength requirements and ideal flexion/extension ratios in alpine skiing is limited. We aimed to compare trunk strength capacities in elite alpine skiers with those of a matched control group. The concentric maximal trunk flexion and extension of 109 elite skiers and 47 active controls were measured at 150°/s in a ballistic mode using the CON-TREX® TP 1000 test system. The relative flexion peak torque was higher in male ski racers (p = 0.003; 2.44 ± 0.30 Nm/kg) than in the controls (2.32 ± 0.42 Nm/kg). The relative peak torque for extension was 4.53 ± 0.65 Nm/kg in ski racers and 4.11 ± 0.52 Nm/kg in the controls (p = 0.001). Female athletes were significantly stronger in both, relative flexion force (p = 0.006; skiers 2.05 ± 0.22 Nm/kg; controls 1.74 ± 0.28 Nm/kg) and relative extension force (p = 0.001; skiers 3.55 ± 0.53 Nm/kg; controls 3.14 ± 0.48 Nm/kg). No significant differences were found in the ratios of flexion to extension forces in females and males. Ski racers are engaged in extensive strength training for both leg and trunk muscles, which explains the higher peak values. Both groups indicated a low ratio from 0.54-0.59, which represents high trunk extensor muscles strength relative to flexor muscles.

Trunk Flexion to Extension Strength Ratio of 11- to 18- Year Old Youth Ski Racers: Data from 15 Years of Talent Development in Austria

“…Similar to previous findings in athletic populations [2,8,11,16,17] and non-athletic populations [1,11], relative trunk strength of male athletes was higher than that of females. The mean female relative trunk flexion strength was approximately 86% of the mean strength of males.…”

“…Previous research showed that male athletes had significantly better trunk strength characteristics than their female counterparts [2,8,11,16,17]. Sex-specific differences in trunk strength were found also in non-athletic populations [1,11]. The younger the athletes were, the smaller the sexspecific differences were distinctive, as Malina [15] revealed smaller sex-specific differences in absolute peak torque values for pre-pubertal athletes (younger than 12 years) than for pubertal athletes (> 12 years).…”

“…Previous research showed that male athletes had significantly better trunk strength characteristics than their female counterparts [2,8,11,16,17]. Sex-specific differences in trunk strength were found also in non-athletic populations [1,11].…”

“…However, there is a lack of research identifying sportspecific trunk strength characteristics and optimal flexion/ extension ratios, especially in youth and adolescent ski racers. Hildebrandt et al [11] investigated the isokinetic core strength of elite ski racers and compared them with physically active controls and revealed that the ski racers had significantly higher strength values in both males and females. However, no differences were found in the flexion/ extension ratio between the ski racers and the controls, both groups showed relatively low ratios (0.54-0.59), which indicates high trunk extensor muscles relative to flexor muscles [11].…”

“…Hildebrandt et al [11] investigated the isokinetic core strength of elite ski racers and compared them with physically active controls and revealed that the ski racers had significantly higher strength values in both males and females. However, no differences were found in the flexion/ extension ratio between the ski racers and the controls, both groups showed relatively low ratios (0.54-0.59), which indicates high trunk extensor muscles relative to flexor muscles [11]. These values were in line with studies investigating for example long-distance race car drivers [2] and elite rowers [16], in which ratios of 0.5-0.7 were identified,whereas in healthy untrained adults the ratios were higher (0.7-0.9) [2,16].…”