Sports activities and endurance capacity of bone tumor patients after rotationplasty.

OBJECTIVES: To investigate the preferred types of sports activities of patients with rotationplasty and to measure their physiologic performance characteristics through treadmill ergometry. DESIGN: Cross-sectional, descriptive analysis and repeated measures of different velocities. SETTING: Biomechanics research laboratory. PARTICIPANTS: Patients (n=61) with rotationplasty after bone tumor surgery, 30 of whom participated in a functional trial (treadmill), and a control group (n=20). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Patients' participation in sports compared with that of the healthy population, treadmill performance at 2 or 3 different speeds, heart rate, lactate accumulation, oxygen consumption, ventilatory equivalent, efficiency, respiratory minute volume, and respiratory quotient. RESULTS: High activity in sports participation (85%) in most common sports (8 competitive, 17 sports club members, the remaining subjects were recreational athletes). At the same treadmill speed, lactate accumulation and all cardiorespiratory functions were higher in rotationplasty patients than in the control group. CONCLUSIONS: Patients can re-engage in a high level of physical activity after rotationplasty for bone tumor treatment. This physical activity is necessary if patients want to maintain or improve a desired level of sports activity.

The influence of muscle fatigue on electromyogram and plantar pressure patterns as an explanation for the incidence of metatarsal stress fractures.

BACKGROUND: Stress fractures are common overuse injuries in runners and appear most frequently in the metatarsals. PURPOSE: To investigate fatigue-related changes in surface electromyographic activity patterns and plantar pressure patterns during treadmill running as potential causative factors for metatarsal stress fractures. STUDY DESIGN: Prospective cohort study with repeated measurements. METHODS: Thirty experienced runners volunteered to participate in a maximally exhaustive run above the anaerobic threshold. Surface electromyographic activity was monitored for 14 muscles, and plantar pressures were measured using an in-shoe monitoring system. Fatigue was documented with blood lactate measurements. RESULTS: The results demonstrated an increased maximal force (5%, P < .01), peak pressure (12%, P < .001), and impulse (9%, P < .01) under the second and third metatarsal head and under the medial midfoot (force = 7%, P < .05; pressure = 6%, P < .05; impulse = 17%, P < .01) toward the end of the fatiguing run. Contact area and contact time were only slightly affected. The mean electromyographic activity was significantly reduced in the medial gastrocnemius (-9%, P < .01), lateral gastrocnemius (-12%, P < .01), and soleus (-9%, P < .001) muscles. CONCLUSION: The demonstrated alteration of the rollover process with an increased forefoot loading may help to explain the incidence of stress fractures of the metatarsals under fatiguing loading conditions.