PURPOSE: The purpose of this study was to examine the relationships between hamstring muscle thickness and knee flexion peak torque, and rate of torque development (RTD) calculated during 0–50 ms (RTD50) and 0–200 ms (RTD200).METHODS: Thirty-six active individuals' dominant side hamstring thickness were measured using portable ultrasound device. Participants performed maximal isometric voluntary contraction (MVIC) of knee flexion. Peak torque was identified as the maximum torque during MVIC testing. RTD was calculated initial 50 ms and 200 ms after the onset of joint torque. Pearson's correlation (r) coefficients were utilized to assess relationships between muscle thickness and knee flexion peak torque, RTD50 and RTD200. The significant level of hypothesis verification is set-up as α=0.05.RESULTS: Greater peak torque and RTD200 was associated with greater muscle thickness of semitendinosus and semimembranosus (p<0.05). Greater RTD50 was associated with greater muscle thickness of semitendinosus only. Biceps femoris thickness was not associated with knee flexion peak torque, RTD50, and RTD200.CONCLUSION: These results suggest that the training specific hamstring muscle (medial hamstrings) for improving muscle thickness would be effective for increasing knee flexion peak torque and RTD.
Joints ; Knee ; Torque ; Ultrasonography

OBJECTIVE: This study was aimed to determine effectiveness and tolerability of Osmotic-controlled Release Oral delivery (OROS) methylphenidate (MPH) and its optimal dose administered openly over a period of up to 12 weeks in drug naive Korean children with ADHD. METHODS: Subjects (n=143), ages 6 to 18-years, with a clinical diagnosis of any subtype of ADHD were recruited from 7 medical centers in Korea. An individualized dose of OROS-MPH was determined for each subject depending on the response criteria. The subjects were assessed with several symptom rating scales in week 1, 3, 6, 9 and 12. RESULTS: 77 of 116 subjects (66.4%) achieved the criteria for response and the average of optimal daily dose for response was to 30.05+/-12.52 mg per day (0.90+/-0.31 mg/kg/d) at the end of the study. Optimal dose was not significantly different between ADHD subtypes, whereas, significant higher dose was needed in older aged groups than younger groups. The average of optimal daily dose for response for the subjects aged above 12 years old was 46.38+/-15.52 per day (0.81+/-0.28 mg/kg/d) compared to younger groups (p<0.01). No serious adverse effects were reported and the dose did not have a significant effect on adverse effects. CONCLUSION: Optimal mean dose of OROS-MPH was significantly different by age groups. Higher dose was needed in older aged groups than younger groups. Effectiveness and tolerability of OROS-MPH in symptoms of ADHD is sustained for up to 12 weeks.
Aged ; Child ; Humans ; Korea ; Methylphenidate ; Weights and Measures