Alpine Skiing With total knee ArthroPlasty (ASWAP): symmetric loading during skiing

The Influence of Trunk Impairment Level on the Kinematic Characteristics of Alpine Sit-Skiing: A Case Study of Paralympic Medalists

This study aimed to examine the relationship between the trunk impairment level and the trunk kinematic characteristics during alpine sit-skiing from a classification perspective. Three Paralympic medalists in sitting classes (LW10-2, LW11, and LW12-2) participated in the present study. To simulate the racing conditions, giant slalom gates were set. To measure the kinematics of the skier and sit-ski during skiing, a motion capture method with inertial measurement units was used. The muscle activities of the trunk muscles were evaluated using electromyography. Chest lateral flexion, chest flexion, and hip flexion/extension angle during sit-skiing were reduced due to impairment. Additionally, the insufficient lateral flexion (angulation) caused a decrease in edging angle, and that the insufficient chest and hip flexion/extension caused a lower loading in the latter half of the turn through smaller vertical movement. Since edging angle and loading are key factors in ski control, the three joint motions could be measures of sport-specific activity limitation in sit-skiing classification. Between the LW10-2 and LW11 skiers, no distinct differences in trunk kinematics were found. Assuming the scaling factor of race time as a measure of skiing performance, one possible reason is that the difference in skiing performance the LW10-2 and LW11 skiers is considerably smaller relative to differences between the LW11 and LW12-2 skiers. There were no distinct differences among classes in the results of muscle activity, and therefore, this information appears to play a minimal role for classification.

Quantitative Analysis of Patellar Tendon After Total Knee Arthroplasty Using Echo Intensity: A Nonrandomized Controlled Trial of Alpine Skiing

BACKGROUND

Despite the knee extensor weakness, less attention has been paid to the evaluation of patellar tendon after total knee arthroplasty (TKA). We previously observed patellar tendon hypertrophy after TKA. The purpose of this study is to reanalyze these ultrasound data to detect whether brightness mode ultrasound imaging reflects pathological changes of the patellar tendon after TKA.

METHODS

Twenty-eight participants with post unilateral TKA were assigned to an intervention group or control group. The intervention group underwent a 12-week skiing program. Patellar tendon mechanical properties were obtained by combining isometric dynamometry, ultrasound imaging, and electromyography in operated knee and nonoperated knee. Luminosity ratio (LR) was measured using echo intensity in a relaxed and maximally loaded phase.

RESULTS

Baseline comparisons revealed significant effects of the surgical side (P < .001) and loading phase (P = .017), but no interaction between leg and phase (P < .149). LR of the operated knee was significantly lower than LR of the nonoperated knee in relaxed (P < .001) and maximally loaded phases (P = .003). In addition, there was a significant correlation between LR of maximum phase and isometric knee extension torque (r² = 0.156, P = .038). However, LR was not related to patellar tendon stiffness, Young's modulus, or strain. There was a significant time effect in knee extension torque, but no time effects on LR and tendon force.

CONCLUSION

Patellar tendon LR is decreased along with degenerative change after TKA. Ultrasound imaging provides a promising metric to acquire in vivo patellar tendon pathological assessment after TKA.

Potential Health Benefits From Downhill Skiing

Objectives: Downhill skiing represents one of the most popular winter sports worldwide. Whereas a plethora of studies dealt with the risk of injury and death associated with downhill skiing, data on its favorable health effects are scarce. A more comprehensive overview on such effects might emerge from a multidisciplinary perspective.

Methods: A literature search has been performed to identify original articles on downhill/alpine skiing interventions or questionnaire-based evaluation of skiing effects and the assessment of health effects (cardiorespiratory, neurophysiological, musculoskeletal, psycho-social).

Results and Discussion: A total of 21 original articles dealing with potentially favorable health effects resulting from downhill skiing were included in this review. Results indicate that downhill skiing, especially when performed on a regular basis, may contribute to healthy aging by its association with a healthier life style including higher levels of physical activity. Several other mechanisms suggest further favorable health effects of downhill skiing in response to specific challenges and adaptations in the musculo-skeletal and postural control systems, to exposures to cold temperatures and intermittent hypoxia, and/or emotional and social benefits from outdoor recreation. However, reliable data corroborating these mechanisms is scarce.