Horizontal force production and multi-segment foot kinematics during the acceleration phase of bend sprinting

This paper investigated horizontal force production, foot kinematics and metatarsophalangeal (MTP) joint push-off axis use during acceleration in bend (anti-clockwise) and straight-line sprinting. It was hypothesised that bend sprinting would cause the left step push-off to occur about the oblique axis, resulting in a decrease in propulsive force. Three-dimensional kinematic and ground reaction force data were collected from nine participants during sprinting on the bend (36.5 m radius) and straight. Anteroposterior force was reduced at 38-44% of stance during bend sprinting compared with the straight. This coincided with an increase in mediolateral force for the majority of the stance phase (3-96%) on the bend compared with the straight. In addition, a lower propulsive impulse was reported on the bend compared with the straight. Analysis of multi-segment foot kinematics provides insight into the possible mechanisms behind these changes in force production. Mean mediolateral centre of pressure position was more lateral in relation to the second metatarsal head in the left step on the bend compared with the straight, indicating the oblique axis was used for push-off at the MTP joint. Greater peak joint angles of the left foot were also reported, in particular, an increase in left step midfoot eversion and internal ankle rotation. It is possible these changes in joint kinematics are associated with the observed decrease in propulsive force. Therefore, practitioners should seek to strengthen muscles such as tibialis posterior in frontal and sagittal planes and ensure specificity of training which may aid in addressing these force reductions

Clinical measurement of the thoracic kyphosis : a study of the intra-rater reliability in subjects with and without shoulder pain

BACKGROUND: Clinical sagittal plane assessment of the thoracic kyphosis angle is considered an essential component of the postural examination of patients presenting with upper body pain syndromes. Cervical headaches and conditions involving the shoulder, such as subacromial pain syndrome, have all been associated with an increase in the thoracic kyphosis. Concomitantly a decrease in the thoracic kyphosis as a result of a stretching and strengthening rehabilitation programme is believed to be associated with a reduction in symptoms and pain and improvement in function. Clinicians generally measure the sagittal plane kyphosis angle visually. There is no certainty that this method is reliable or is capable of measuring angular changes over time or in response to intervention. As such a simple and reliable clinical method of measuring the thoracic kyphosis would enable clinicians to record this information. The aim of this investigation was to determine the intra-tester reliability of measuring the thoracic kyphosis angle using a clinical method METHODS: Measurements were made in 45 subjects with and 45 subjects without upper body symptoms. Measurements were made with the subjects in relaxed standing. Two gravity dependent inclinometers were used to measure the kyphosis. The first was placed over the region of the 1st and 2nd thoracic spinous processes. The other, over the region of the 12th thoracic and 1st lumbar spinous processes. The angle produced by each inclinometer was measured 3 times in succession. Each set of 3 measurements was made on two occasions (separated by a minimum of 30 minutes and additional data collection involving 46 further measurements of posture and movement on the same and an additional subject before the thoracic kyphosis measurements were re-measured) by one rater. The reliability of the measurements was analyzed using 2-way ANOVA intraclass correlation coefficients (ICC), 95% confidence intervals (CI) and standard error of measurement (SEM) for precision, for a single measurement [ICC(single)] and the average of 3 measures [ICC(average)]. The assessor remained 'blinded' to data input and the measurements were staggered to reduce examiner bias. RESULTS: The measurement of the thoracic kyphosis as used in this investigation was found to have excellent intra-rater reliability for both subjects with and without symptoms. The ICC(single) results for the subjects without symptoms were, .95; (95% CI .91-.97). The corresponding ICC(average) results were; .97; (95% CI .95-.99). The results for the subjects with symptoms were; 93; (95% CI .88-.96), for ICC(single) and for ICC(average); .97; (95% CI .94-.98). The SEM results for subjects without and with symptoms were 1.0 degrees and 1.7 degrees , respectively. CONCLUSIONS: The findings of this immediate test-retest reliability study suggest that the clinical measurement of the thoracic kyphosis using gravity dependent inclinometers demonstrates excellent intra-rater reliability. Additional research is required to determine the inter-rater reliability of this method