Joint Kinetics of the Ankle and Knee When Running Over Obstacles

When running over obstacles of increasing height, heelstrike runners switch to a forefoot landing pattern once a critical obstacle height is reached. The primary purpose of this study was to determine whether ankle or knee joint kinetic variables trigger the gait change from a heelstrike to a forefoot striking pattern as obstacle height increases. Ten subjects were filmed from the sagittal plane as they ran at their preferred running speed over a force platform during six obstacle height conditions ranging from 10% to 22.5% of standing height, as well as an additional baseline condition with no obstacle (0%). An inverse dynamics approach was utilized to calculate ankle and knee joint kinetics at each condition. Although no variables were found which met all of the criteria necessary to be considered a determinant of the gait transition, there were variables which distinguished between a heelstrike and forefoot strike landing pattern as obstacle height increased. Differences in joint kinetics did not occur until a height was reached at which the landing strategy changed from a heelstrike to a forefoot landing pattern. Most differences occurred at the ankle joint, at which there was a greater maximum plantar flexor moment and a greater amount of energy absorbed when obstacles of sufficient height to require a forefoot landing pattern were negotiated

Ischemic Preconditioning on Swimming Performance: An Exploration into Practical Application

Topics in Exercise Science and Kinesiology Volume 4: Issue 1, Article 14, 2023. Ischemic preconditioning (IPC), in exercise science, is the practice of repeatedly creating an ischemic event within a limb before exercise in an effort to improve athletic ability. The athletic aid, currently under review for its applicability to aerobic sports, has garnered conflicting results in the last decade of study. This research investigated the effects of IPC over distances of 250 and 500 yards while imposing commonly suggested methodologies. Sixteen college-aged swimmers, either recreational or competitive, were given IPC treatment with individualized limb occlusion pressure (ILOP) accompanied by a sham protocol. Participants were requested to give maximal effort during the trials, and pain and exertion scores were collected at multiple points. Results showed that the distance of 250 yards (p-value = 0.02) was improved by the IPC treatment, but the distance of 500 yards was not (p-value = 0.53). There was no significant variation in the visual analog scale (VAS) or rating of perceived exertion (RPE) for either distance. Measurement of ILOP found 25% of participants needed higher pressure than standardized pressure some studies utilize and 19% required pressure 40 mmHg below the standard. It was concluded that IPC may have a short period of benefit corresponding to the improvement seen in the 250 yard swim and that ILOP should be used over a standard pressure

Intralimb coordination following obstacle clearance during running: the effect of obstacle height

The purpose of this study was to investigate the different coordination strategies used following obstacle clearance during running. Ten subjects ran over a level surface and over obstacles of six different heights (10, 12.5, 15, 17.5, 20 and 22.5% of their standing height). Analysis based upon the dynamical systems theory (DST) was used and the phasing relationships between lower extremity segments were examined. The results demonstrated that the increasing obstacle height elicited behavioral changes. The foot and the leg became more independent in their actions, while the leg and the thigh strengthened their already stable relationship. The 15% obstacle height seems to be a critical height for the observed changes

A dynamical systems investigation of lower extremity coordination during running over obstacles

Objective. To investigate intralimb coordination during running over a level surface and over obstacles of three different heights. Design. The phasing relationships between the foot and leg motions in the frontal plane, and the shank and thigh motions in the sagittal plane were used to compare patterns of coordination. Background. The coordinated actions of lower extremity segments are necessary to absorb the impact forces generated during running. The behavioral patterns of these segments can be studied under changing task demands using analysis techniques from the Dynamical Systems Theory. Methods. Ten subjects ran at their self-selected pace under four conditions: over a level surface and over obstacles of different heights (5%, 10%, 15% of their standing height). A force platform was used to record impact forces during landing after obstacle clearance, while kinematics were collected using a two-camera system. Results. The increases in obstacle height resulted in significant changes in impact forces (34% increase between the two extreme conditions) and more in-phase relationships between the segments during early stance. No changes were observed in the variability of the phasing relationships. Conclusions. The coordination changes observed might be compensatory strategies aimed to reduce forces and potential injury. However, since the impact forces still increased significantly, it is also possible that the observed changes might be at-risk movement patterns predisposing runners to injury. Relevance Tools from the Dynamical Systems Theory, such as intralimb coordination, can be used as a way to evaluate running mechanics so that comparisons can be made to various patient populations in subsequent studies. This approach might be a viable alternative to examine questions in therapeutics

The Acute Effects of Ischemic Preconditioning on Short-Duration Cycling: A Randomized Crossover Study

International Journal of Exercise Science 16(6): 148-158, 2023. There is recent interest from coaches and athletes regarding IPC as an effective way to generate better competitive outcomes. Regarding cycling specifically, the impact of IPC remains unclear. This study aimed to assess the effectiveness of IPC treatment for improving athletic performance during short-duration cycling. After the exclusion and inclusion criteria, there were 11 volunteers for the 3-minute cycling TT and 13 volunteers for the 6-minute cycling TT. All volunteers were competitive athletes of aerobic sports. The IPC treatment consisted of three alternating cycles of 5 minutes of 100% occlusion followed by 5 minutes of reperfusion to each leg. The sham treatment consisted of three alternating cycles of 1 minute of 100% occlusion followed by 1 minute of reperfusion to each leg. The main finding was that IPC significantly improved (p\u3c0.05) power output during 3-minute (4.22%) and 6-minute (2.29%) cycling TT relative to a sham. Additionally, about one-third of our participants required a tourniquet pressure higher than 220 mmHg to achieve 100% occlusion. These findings indicate ischemic preconditioning, administered bilaterally as three rounds of 5 minutes of total occlusion and ensuing reperfusion 20 minutes before a cycling TT, significantly enhanced average power output

Foot strike patterns after obstacle clearance during running

Purpose Running over obstacles of sufficient height requires heel strike (HS) runners to make a transition in landing strategy to a forefoot (FF) strike, resulting in similar ground reaction force patterns to those observed while landing from a jump. Identification of the biomechanical variables that distinguish between the landing strategies may offer some insight into the reasons that the transition occurs. The purpose of this study was to investigate the difference in foot strike patterns and kinetic parameters of heel strike runners between level running and running over obstacles of various heights. Methods Ten heel strike subjects ran at their self-selected pace under seven different conditions: unperturbed running (no obstacle) and over obstacles of six different heights (10%, 12.5%, 15%, 17.5%, 20%, and 22.5% of their standing height). The obstacle was placed directly before a Kistler force platform. Repeated measures ANOVAs were performed on the subject means of selected kinetic parameters. Results The statistical analysis revealed significant differences (P \u3c 0.004) for all of the parameters analyzed. The evaluation of the center of pressure and the ground reaction forces indicated that the foot strike patterns were affected by the increased obstacle height. Between the 12.5% and 15% obstacle conditions, the group response changed from a heel strike to a forefoot strike pattern. Conclusions At height \u3e 15%, the pattern was more closely related to the foot strike patterns found in jumping activities. This strategy change may represent a gait transition effected as a mechanism to protect against increased impact forces. Greater involvement of the ankle and the calf muscles could have assisted in attenuating the increased impact forces while maintaining speed after clearing the obstacle

Alliances and the innovation performance of corporate and public research spin-off firms

We explore the innovation performance benefits of alliances for spin-off firms, in particular spin-offs either from other firms or from public research organizations. During the early years of the emerging combinatorial chemistry industry, the industry on which our empirical analysis focuses, spin-offs engaged in alliances with large and established partners, partners of similar type and size, and with public research organizations, often for different reasons. We seek to understand to what extent alliances of spin-offs with other firms (either large- or small- and medium-sized firms) affected their innovation performance and also how this performance may have been affected by their corporate or public research background. We find evidence that in general alliances of spin-offs with other firms, in particular alliances with large firms, increased their innovation performance. Corporate spin-offs that formed alliances with other firms outperformed public research spin-offs with such alliances. This suggests that, in terms of their innovation performance, corporate spin-offs that engaged in alliances with other firms seemed to have benefitted from their prior corporate background. Interestingly, it turns out that the negative impact of alliances on the innovation performance of public research spin-offs was largely affected by their alliances with small- and medium-sized firms

Foot strike patterns after obstacle clearance during running

Etude biomécanique des mouvements du pied et de la cheville lors d'une course sur du plat ou sur sol accidenté