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FOOT LOADING CHANGES AFTER A FATIGUING RUN
Musculoskeletal Impairments
Presentation O-106
S109
FOOT LOADING CHANGES AFTER A FATIGUING RUN Dieter Rosenbaum, Tobias Engl, Arne Nagel
Motion Analysis Lab, Orthopaedic Dept., University Hospital Muenster, Germany
Introduction
Results
Stress or fatigue fractures account for a high percentage of running related injuries [4, 5]. With the fitness and wellness movement the incidence of stress fractures increasingly affect recreational athletes [3]. In runners, these fractures prevail in the tibia, navicular and the metatarsals [1]. Stress fractures in the metatarsals predominantly affect the second and third ray [2]. Intrinsic biomechanical factors for stress fractures that have been identified are a high arch foot, leg length discrepancies and an excessive forefoot varus position [3]. Furthermore, extrinsic factors like a rapid increase in the running mileage appear to be related to stress fractures [4]. Plantar pressures were shown to be affected by an exhaustive run above the anaerobic threshold [6]. Thus, mechanical overloading of skeletal structures appears to be potentially detrimental. Pedobarography is routinely used for identifying regions of excessive foot loading. Additional information about the pathomechanics might be helpful for preventing metatarsal stress fractures. Therefore, the aim of the present study was to investigate the potential changes of foot loading characteristics after a fatiguing long-distance run.
In spite of the constant running speed and cadence (112±10 steps per minute), the heart rate increased significantly towards the end of the run (on average, from 146±12 to 160±12 beats per minute) and indicated that the runners were fatigued. After the run, loading parameters during barefoot walking were significantly reduced under the toes (up to 30%) and significantly increased under the central and lateral metatarsal heads (up to 14%). Surprisingly, midfoot loading was significantly reduced and did not indicate a more pronounced flattening of the arch. In-shoe loading parameters revealed slight changes early in the run (after 10 km) but were more clearly affected at the end of the run (after 28 km).
Methods
Figure 1: Changes in regional impulses (* p<0.05)
25 experienced runners (23 male, 2 female) consented to participate in the study. Subjects were free of injuries and participated in regular running activities. An average weekly running distance of 49.3 24.5 km revealed that the subjects were fairly active recreational runners (mean age 43.5 8.7 years, body mass 73.9 9.1 kg, height 177.7 7.8 cm and body mass index (BMI) 23.4±1.9 kg/cm2). Subjects were asked to run a distance of 28 km at their individual speed for basic endurance training. They ran 5 laps on a 5 km outdoor loop and additional laps on an indoor track for the in-shoe measurements. Heart rate (Polar S810) and step activity (StepWatch, Cyma USA) were constantly monitored. Pressure measurements during barefoot walking were taken before and after the run with a capacitive platform (emed ST, Novel Munich). Inshoe pressure measurements during running were recorded on an indoor track at the beginning of the run, during the run (after 10 km) and at the end of the run (pedar mobile insoles, Novel Munich). Barefoot and in-shoe foot loading parameters were determined for ten selected foot regions: medial and lateral hindfoot and midfoot, medial, central, and lateral forefoot and toes.
Discussion
16th ESB Congress, Oral Presentations, Monday 7 July 2008
Running under fatigued conditions led to increased loading of the foot, especially in the metatarsal head regions whereas the loads under the toes were reduced. The load appears to be transferred from the toes to the metatarsal heads. In the midfoot, however, the expected increased loading could not be seen since the pressures were even reduced under fatigued conditions. In conclusion, the observed changes may be due to local muscle fatigue as indicated by the decreased toe loading during push-off. This mechanism might cause an increased metatarsal bending stress that is potentially harmful and could lead to the development of stress fractures.
References 1. Brukner P et al. CJSM. 6: 85-9, 1996. 2. Fredericson M et al. Orthopäde 26: 961-71, 1997. 3. Korpelainen R et al. AJSM. 29: 304-10, 2001. 4. Lehman RC et al. Foot Ankle. 7: 245-52, 1987. 5. Matheson GO et al. AJSM. 15: 46-58, 1987. 6. Weist, R et al. AJSM. 32: 1893-8, 2004.
Journal of Biomechanics 41(S1)
Presentation O-106
S109
FOOT LOADING CHANGES AFTER A FATIGUING RUN Dieter Rosenbaum, Tobias Engl, Arne Nagel
Motion Analysis Lab, Orthopaedic Dept., University Hospital Muenster, Germany
Introduction
Results
Stress or fatigue fractures account for a high percentage of running related injuries [4, 5]. With the fitness and wellness movement the incidence of stress fractures increasingly affect recreational athletes [3]. In runners, these fractures prevail in the tibia, navicular and the metatarsals [1]. Stress fractures in the metatarsals predominantly affect the second and third ray [2]. Intrinsic biomechanical factors for stress fractures that have been identified are a high arch foot, leg length discrepancies and an excessive forefoot varus position [3]. Furthermore, extrinsic factors like a rapid increase in the running mileage appear to be related to stress fractures [4]. Plantar pressures were shown to be affected by an exhaustive run above the anaerobic threshold [6]. Thus, mechanical overloading of skeletal structures appears to be potentially detrimental. Pedobarography is routinely used for identifying regions of excessive foot loading. Additional information about the pathomechanics might be helpful for preventing metatarsal stress fractures. Therefore, the aim of the present study was to investigate the potential changes of foot loading characteristics after a fatiguing long-distance run.
In spite of the constant running speed and cadence (112±10 steps per minute), the heart rate increased significantly towards the end of the run (on average, from 146±12 to 160±12 beats per minute) and indicated that the runners were fatigued. After the run, loading parameters during barefoot walking were significantly reduced under the toes (up to 30%) and significantly increased under the central and lateral metatarsal heads (up to 14%). Surprisingly, midfoot loading was significantly reduced and did not indicate a more pronounced flattening of the arch. In-shoe loading parameters revealed slight changes early in the run (after 10 km) but were more clearly affected at the end of the run (after 28 km).
Methods
Figure 1: Changes in regional impulses (* p<0.05)
25 experienced runners (23 male, 2 female) consented to participate in the study. Subjects were free of injuries and participated in regular running activities. An average weekly running distance of 49.3 24.5 km revealed that the subjects were fairly active recreational runners (mean age 43.5 8.7 years, body mass 73.9 9.1 kg, height 177.7 7.8 cm and body mass index (BMI) 23.4±1.9 kg/cm2). Subjects were asked to run a distance of 28 km at their individual speed for basic endurance training. They ran 5 laps on a 5 km outdoor loop and additional laps on an indoor track for the in-shoe measurements. Heart rate (Polar S810) and step activity (StepWatch, Cyma USA) were constantly monitored. Pressure measurements during barefoot walking were taken before and after the run with a capacitive platform (emed ST, Novel Munich). Inshoe pressure measurements during running were recorded on an indoor track at the beginning of the run, during the run (after 10 km) and at the end of the run (pedar mobile insoles, Novel Munich). Barefoot and in-shoe foot loading parameters were determined for ten selected foot regions: medial and lateral hindfoot and midfoot, medial, central, and lateral forefoot and toes.
Discussion
16th ESB Congress, Oral Presentations, Monday 7 July 2008
Running under fatigued conditions led to increased loading of the foot, especially in the metatarsal head regions whereas the loads under the toes were reduced. The load appears to be transferred from the toes to the metatarsal heads. In the midfoot, however, the expected increased loading could not be seen since the pressures were even reduced under fatigued conditions. In conclusion, the observed changes may be due to local muscle fatigue as indicated by the decreased toe loading during push-off. This mechanism might cause an increased metatarsal bending stress that is potentially harmful and could lead to the development of stress fractures.
References 1. Brukner P et al. CJSM. 6: 85-9, 1996. 2. Fredericson M et al. Orthopäde 26: 961-71, 1997. 3. Korpelainen R et al. AJSM. 29: 304-10, 2001. 4. Lehman RC et al. Foot Ankle. 7: 245-52, 1987. 5. Matheson GO et al. AJSM. 15: 46-58, 1987. 6. Weist, R et al. AJSM. 32: 1893-8, 2004.
Journal of Biomechanics 41(S1)