Benno M. Nigg
Alexander Bahlsen and Benno M. Nigg
Impact forces analysis in heel-toe running is often used to examine the reduction of impact forces for different running shoes and/or running techniques. Body mass is reported to be a dominant predictor of vertical impact force peaks. However, it is not evident whether this finding is only true for the real body mass or whether it is also true for additional masses attached to the body (e.g., running with additional weight or heavy shoes). The purpose of this study was to determine the effect of additional mass on vertical impact force peaks and running style. Nineteen subjects (9 males, 10 females) with a mean mass of 74.2 kg/56.2 kg (SD = 10.0 kg and 6.0 kg) volunteered to participate in this study. Additional masses were attached to the shoe (.05 and .1 kg), the tibia (.2, .4, .6 kg), and the hip (5.9 and 10.7 kg). Force plate measurements and high-speed film data were analyzed. In this study the vertical impact force peaks, Fzi, were not affected by additional masses, the vertical active force peaks, Fza, were only affected by additional masses greater than 6 kg, and the movement was only different in the knee angle at touchdown, ϵ0, for additional masses greater than .6 kg. The results of this study did not support findings reported earlier in the literature that body mass is a dominant predictor of external vertical impact force peaks.
Aurel Coza, Benno M. Nigg and Ladina Fliri
Soft-tissue vibrations can be used to quantify selected properties of human tissue and their response to impact. Vibrations are typically quantified using high-speed motion capture or accelerometry. The aim of this study was to compare the amplitude and frequency of soft-tissue vibrations during running when quantified by highspeed motion capture and accelerometry simultaneously. This study showed: (a) The estimated measurement errors for amplitude and frequency were of the same order of magnitude for both techniques. (b) There were no significant differences in the mean peak frequencies and peak amplitudes measured by the two methods. (c) The video method showed an inability to capture high frequency information. This study has shown that a tradeoff has to be made between the accuracy in amplitude and frequency when these methods are employed to quantify soft tissue vibrations in running.
Benno M. Nigg and H. Alexander Bahlsen
The purpose of this study was to determine the influence of lateral heel flare on pronation, external impact forces, and takeoff supination for different midsole constructions. Data were collected using force platforms and high-speed film cameras. Fourteen male subjects participated in the study, running heel-toe at a speed of 4 m/s. The analysis of kinetic and kinematic variables showed that changes in lateral heel flare of 16°, 0°, and a rounded heel can be used to influence initial pronation during heel-toe running. It could be shown that changes in lateral heel flare do not have a relevant influence on changes in total and/or maximal pronation. Changes in lateral heel flare do have an effect on vertical impact force peaks if the midsole is relatively hard but not if the midsole is relatively soft. Based on the present study, a running shoe with a relatively hard midsole material and a neutral flare would have low initial pronation values and low vertical impact force peaks.
Darren J. Stefanyshyn and Benno M. Nigg
The purpose of this study was to compare the moment-angle relationship of the ankle joint during running and sprinting to determine how the dynamic angular stiffness is influenced by different activities. For both running and sprinting, the results indicated that the ankle joint produced an exclusively extensor moment, absorbing energy during the first half of the stance phase and producing energy during the second half. The biphasic nature of the joint absorbing energy followed by the joint producing energy, while continually creating an extensor moment, was similar to a spring being compressed and allowed to extend. The dynamic stiffness of the ankle joint was 5.68 N · m/° for running and 7.38 N · m/° for sprinting. It appeared that the stiffness of the ankle joint was not a specialized characteristic of each individual but rather a specialized characteristic of the activity or demand placed upon it.
Benno M. Nigg, Gerald K. Cole and Gert-Peter Brüggemann
Impact forces have been speculated to be associated with the development of musculoskeletal injuries. However, several findings indicate that the concepts of “impact forces” and the paradigms of their “cushioning” may not be well understood in relation to the etiology of running injuries and that complex mechanisms may be responsible for injury development during running. The purposes of this paper are (a) to review impact mechanics during locomotion, (b) to review injuries and changes of biological tissue due to impact loading, and (c) to synthesize the mechanical and biological findings. In addition, directions for future research are discussed. Future research should address the development of noninvasive techniques to assess changes in the morphology and biochemistry of bone, cartilage, tendon, and ligaments; researchers should also try to simulate impact loading during activities such as running, focusing on the interaction of the various loading parameters that determine the acceptable windows of loading for biological tissues.
Bernd J. Stetter, Erica Buckeridge, Vinzenz von Tscharner, Sandro R. Nigg and Benno M. Nigg
This study presents a new approach for automated identification of ice hockey skating strides and a method to detect ice contact and swing phases of individual strides by quantifying vibrations in 3D acceleration data during the blade–ice interaction. The strides of a 30-m forward sprinting task, performed by 6 ice hockey players, were evaluated using a 3D accelerometer fixed to a hockey skate. Synchronized plantar pressure data were recorded as reference data. To determine the accuracy of the new method on a range of forward stride patterns for temporal skating events, estimated contact times and stride times for a sequence of 5 consecutive strides was validated. Bland-Altman limits of agreement (95%) between accelerometer and plantar pressure derived data were less than 0.019 s. Mean differences between the 2 capture methods were shown to be less than 1 ms for contact and stride time. These results demonstrate the validity of the novel approach to determine strides, ice contact, and swing phases during ice hockey skating. This technology is accurate, simple, effective, and allows for in-field ice hockey testing.
Maurice Mohr, Matthieu B. Trudeau, Sandro R. Nigg and Benno M. Nigg
To determine the effect of shoe mass on performance in basketball-specific movements and how this affects changes if an athlete is aware or not of the shoe’s mass relative to other shoes.
In an experimental design, 22 male participants were assigned to 2 groups. In the “aware” group, differences in the mass of the shoes were disclosed, while participants in the other group were blinded to the mass of shoes. For both groups lateral shuffle-cut and vertical-jump performances were quantified in 3 different basketball-shoe conditions (light, 352 ± 18.4 g; medium, 510 ± 17 g; heavy, 637 ± 17.7 g). A mixed ANOVA compared mean shuffle-cut and vertical-jump performances across shoes and groups. For blinded participants, perceived shoeweight ratings were collected and compared across shoe conditions using a Friedman 2-way ANOVA.
In the aware group, performance in the light shoes was significantly increased by 2% (vertical jump 2%, P < .001; shuffle cut 2.1%, P < .001) compared with the heavy shoes. In the blind group, participants were unable to perceive the shoe-weight variation between conditions, and there were no significant differences in vertical-jump and shuffle-cut performance across shoes.
Differences in performance of the aware participants were most likely due to psychological effects such as positive and negative expectancies toward the light and heavy shoes, respectively. These results underline the importance for coaches and shoe manufacturers to communicate the performance-enhancing benefits of products or other interventions to athletes to optimize their performance outcome.
Simon M. Luethi, Edward C. Frederick, Michael R. Hawes and Benno M. Nigg
The purpose of this study was to analyze the influence of footwear on the kinematics and the mechanical load on the lower extremities during fast lateral movements in tennis. The method used was a prospective study. Two types of tennis shoes were randomly distributed among 229 tennis players. The subjects were measured before starting a 3-month test period. The study showed that the kinematics of the lower extremities and internal load conditions during fast lateral movements in tennis are highly influenced by the type of shoe worn. The results further suggest that a prospective biomechanical analysis can be used to establish assumptions concerning the etiology of pain and injuries in sports related activities.
Benno M. Nigg, Edward C. Frederick, Michael R. Hawes and Simon M. Luethi
Pain, discomfort, and/or injuries in tennis can be influenced by the individual movement pattern and the external and/or internal boundary conditions. The influence of external boundary conditions on the occurrence of short-term pain was studied in a prospective study with 229 subjects. The boundary conditions investigated were shoe, temperature, type and length of game and subjective assessment of comfort, sole grip, and lateral stability Pain was reported by 40% of the 171 subjects included in the final analysis. It was frequently reported in the first two playing sessions but less frequently afterward. Discomfort was the dominant type of pain, accounting for 71.6% of all reported cases. The foot was the major site of pain (85%). The boundary conditions influencing pain were found to be the shoe (the more flexible shoe 1 had less pain than the suffer shoe 2), the type of game (competitive more than recreational), and the length of the game (longer playing sessions with more pain). Subjective assessment of comfort, sole grip, and lateral support also showed differences for the pain/no pain groups. Subjects who complained about these aspects were more frequently in the pain groups. The results show that the occurrence of pain in tennis can be influenced by various external boundary conditions.