The analysis of venous blood flow velocity increase during ankle exercise / 体力科学

Ankle exercises are useful for preventing deep vein thrombosis, as they increase venous blood flow velocity. The cause for the increased venous blood flow velocity during ankle exercises may be the skeletal-muscle pump, but the mechanism is not clearly understood. The purpose of this study was to investigate the effects of the dorsiflexion angle and gastrocnemius muscle contraction on venous blood flow velocity during ankle exercises and to investigate the mechanism of the increase in venous blood flow velocity. The blood flow velocity in the popliteal vein, ankle joint angle, and surface electromyographic activity of the gastrocnemius muscle were measured at rest and during ankle exercises in the prone position in young healthy volunteers. The significant increase in venous blood flow velocity was observed during dorsiflexion phase, max dorsiflexion and during planter flexion phase. The peak venous blood flow velocity was different in each subject and classified into four types. The correlations of venous blood velocity to ankle joint angle and with the surface electromyographic activity of the gastrocnemius muscle were not statistically significant. These findings suggest that venous blood flow velocity increases not only during plantar flexion and dorsiflexion.

Late Subaxial Lesion after Overcorrected Occipitocervical Reconstruction in Patients with Rheumatoid Arthritis

STUDY DESIGN: Retrospective case-control study, level 4. PURPOSE: To clarify the risk factors for late subaxial lesion after occipitocervical (O-C) reconstruction. We examined cases requiring fusion-segment-extended (FE) reconstruction in addition to/after O-C reconstruction. OVERVIEW OF LITERATURE: Patients with rheumatoid arthritis (RA) frequently require O-C reconstruction surgery for cranio-cervical lesions. Acceptable outcomes are achieved via indirect decompression using cervical pedicle screws and occipital plate–rod systems. However, late subaxial lesions may develop occasionally following O-C reconstruction. METHODS: O-C reconstruction using cervical pedicle screws and occipital plate–rod systems was performed between 1994 and 2007 in 113 patients with RA. Occipito-atlanto-axial (O-C2) reconstruction was performed for 89 patients, and occipito-subaxial cervical (O-under C2) reconstruction was performed for 24 patients. We reviewed the cases of patients requiring FE reconstruction (fusion extended group, FEG) and 26 consecutive patients who did not require FE reconstruction after a follow-up of >5 years (non-fusion extended group, NEG) as controls. RESULTS: FE reconstructions were performed for nine patients at an average of 45 months (range, 24–180 months) after O-C reconstruction. Of the 89 patients, three (3%) underwent FE reconstruction in cases of O-C2 reconstruction. Of the 24 patients, five (21%) underwent FE reconstruction in cases of O-under C2 reconstruction (p=0.003, Fisher exact test). Age, sex, RA type, and neurological impairment stage were not significantly different between FEG and NEG. O-under C2 reconstruction, larger correction angle (4° per number of unfixed segment), and O-C7 angle change after O-C reconstruction were the risk factors for late subaxial lesions on radiographic assessment. CONCLUSIONS: Overcorrection of angle at fusion segments requiring O-C7 angle change was a risk factor for late subaxial lesion in patients with RA with fragile bones and joints. Correction should be limited, considering the residual mobility of the cervical unfixed segments.

Effects of the movement velocity training on sprint performance / 体力科学

To investigate the effects of training focused on the movement velocity of the lower limbs (movement velocity training) on short sprint performance in young female non-athletes. Twenty-nine healthy young females (mean age: 20.1 ± 0.9 years) participated in this study. The subjects were randomized into a movement velocity training group (MV group, n=15) and a resistance training group (R group, n=14). MV group performed six lower limb exercises at high velocity (as fast as possible) with no load. R group performed five lower limb strength exercises using a resistance band. Both training programs were applied for 20 minutes per session, 5 days a week for 6 weeks. The following outcomes were measured at baseline and after 6 weeks of training: 30 m sprint time, 20- 26m running velocity, step length, step frequency, and muscle strength and movement velocity of knee extension. Significant group × time interactions were observed for the 30-m sprint time with the MV group exhibiting a significant improvement on simple main effect analysis. For the other parameters (step length, step frequency, and muscle strength and movement velocity of knee extension), group × time interactions were not observed and a significant main effect was observed. These findings suggest that training focused on the movement velocity of the lower limbs can be effective for improving sprint performance.