Discipline and Sex Differences in Angle-specific Isokinetic Analysis in Elite Skiers

Abstract

Standard outcomes of traditional isokinetic testing do not detect differences between various muscle mechanical properties. This study i) explored a novel analysis throughout the range of motion based on statistical parametric mapping and ii) examined the impact of sex and discipline on hamstrings/quadriceps torque in elite alpine skiers. Twenty-eight national team skiers (14 females, 14 males; 14 technical, 14 speed) undertook an isokinetic evaluation of the knee flexors/extensors (range 30–90°, 0° representing full extension). There was no effect of sex (p=0.864, d=0.03) and discipline (p=0.360, d=0.17) on maximal hamstrings-to-quadriceps ratio and no effect of discipline on maximal torque (p>0.156, d≤0.25). Hamstrings torque and hamstrings-to-quadriceps ratio were lower in females than males toward knee extension only (p<0.05). Quadriceps torque was greater after 72° of knee flexion in technicians than downhill skiers (p<0.05). The current data showed that statistical parametric mapping analysis identified angle-specific differences that could not be evidenced when analyzing only maximal torques and reconstructed ratios. This may enhance screening methods to identify pathologic knee function or monitor rehabilitation programs, and inform sex- and discipline-specific training in alpine skiing.

On-Field Ski Kinematic According to Leg and Discipline in Elite Alpine Skiers

“…Since eccentric muscle contractions require different activation strategies and programming processes by the central nervous system (Fang et al, 2004), regular application of eccentric exercise training is also warranted for alpine skiers. Of note, in alpine skiers, eccentric cycling training increased isometric torque only at greater quadriceps length probably due to sarcomerogenesis (Gross et al, 2010), As disciplinespecific muscle adaptations depending on joint angle and contraction modes have been suggested in alpine skiers (Lešnik et al, 2012;Alhammoud et al, 2019), the present results may be used to adapt the training contents accordingly. Practically, the current results suggest that dryland strength and conditioning sessions should focus on slow movements at the specific angles of the OL and IL.…”

Modeling the Angle-Specific Isokinetic Hamstring to Quadriceps Ratio Using Multilevel Generalized Additive Models

“…To our knowledge, the only available data for the shape of functional H:Q ratio for the knee flexion across the range of motion is limited to observations in a sample of alpine skiers [17]. In the present sample of adolescent basketball players, the point of equality was not attained during the knee flexion.…”

“…The interpretation of knee joint-angle-specific functional H:Q ratios is very important to understand the dynamic knee joint stability [16,17]. Recently, the interest in joint-angle-specific functional H:Q ratios has increased substantially [12,14,15,16,17,37,38,39].…”

“…The interpretation of knee joint-angle-specific functional H:Q ratios is very important to understand the dynamic knee joint stability [16,17]. Recently, the interest in joint-angle-specific functional H:Q ratios has increased substantially [12,14,15,16,17,37,38,39]. Joint-angle-specific functional H:Q ratios have mostly been determined based on single angle-specific moments of force (e.g., 15°, 30°, and 45°) [11,15,16,37,39], or interpolating polynomial models using moment of force values for knee-joint angles within an interval (e.g., 5° intervals) [14].…”

“…Generally, joint-angle-specific functional H:Q ratios have been determined using a single angle-specific moment of force values of reciprocal concentric and eccentric muscle actions [10,14,15,16]. Moreover, visual or repeated-measures analysis of variance-based extrapolation are often considered within the observed range of motion [17], which may lead to unrealistic prediction values.…”