Nobuo Takeshima

Impact of moderate intensity physical activity on the functional fitness of older women

BACKGROUND: Poor lower limb stability during dynamic movement is thought to increase the risk of musculoskeletal injury. Biomechanically, stability is determined by a number of factors including the external load and contributions from passive and active tissues. One approach for studying lower limb stability is the single leg squat (SLS) test, which requires coordinated lower limb movement across a range of joint motions under external load. Although clinicians typically assess SLS quality from a single point of view (i.e. frontal plane), a 3D investigation of SLS kinematics would help to determine factors that differentiate clinician-defined “good” from “poor” quality performance. PURPOSE: To determine the kinematic parameters that characterise a good or a poor SLS performance in young adults. METHODS: 22 healthy young adults (13 male, 9 female; age: 23.8 ±3.1 years; height: 1.73 ±0.07 m; mass: 69.4 ±12.7 kg) free from musculoskeletal impairment were recruited. Video footage was collected in the frontal plane as participants performed three SLSs on each leg. SLS quality was assessed by a panel of physiotherapists using a ten-point ordinal scale. Performances were subsequently divided into tertiles corresponding to poor, intermediate and good SLS technique. 3D trajectories of 28 reflective markers attached to the pelvis, and lower limbs were simultaneously recorded at 200 Hz using a 10-camera, motion capture system (Vicon Motion Systems, Oxford, UK). Pelvis, hip and knee angles were calculated using a validated lower limb biomechanical model that incorporated functional identification of hip and knee joint centres. RESULTS: Mean rating of SLS quality as assessed by the panel of physiotherapists was 6.3±1.9 (range: 2.4 - 9.1). 3D analysis of SLS performance revealed that poor squatters had increased hip adduction (22.4 ±6.1 vs 14.7 ±4.7 deg, p<0.01), reduced knee flexion (73.1 ±8.7 vs 90.1 ±12.1 deg, p<0.01) and increased medal-lateral displacement of the knee joint centre (53.7 ±16.8 vs 38.4 ±14.3 mm, p=0.02) compared to good squatters. CONCLUSION: In healthy young adults a poor SLS is characterised by inadequate knee flexion and excessive frontal plane motion at the knee and hip. It is recommended that clinicians standardise knee flexion angle when using the SLS test as it might confound the perception of SLS quality.Purpose: To evaluate changes in performance and cardiac autonomic control (i.e. heart rate [HR] variability [HRV]) in elite soccer players during their pre-season training regime. n nMethods: Eight Spanish Premier League soccer players were examined at the first (week 1) and the last week (week 8) of the pre-season period (July-September). Nocturnal HR recordings on 4 days per week were averaged to evaluate the weekly HRV. Players also completed the Yo-Yo intermittent recovery test level 1 (Yo-Yo IR1) for the assessment of specific fitness. n nResults: During the pre-season period, there was no significant change (4.5 ± 23.9%) in Yo-Yo IR1 performance (2,475 ± 421 vs. 2,600 ± 786 m, p=0.55), while there was a significant decrement (6.3 ± 4.3%) in maximal HR (HRmax) recorded during the test (191 ± 7 vs. 179 ± 8 bpm, p = 0.004). Over the 8-week pre-season, significant increases in the standard deviation of the long-term continuous HRV (SD2) (174 ± 56 vs. 212 ± 53 ms, p = 0.017), and in the standard deviation of all HR intervals (SDNN) (135 ± 50 vs. 163 ± 41 ms, p = 0.023) were noted. No significant correlations were identified between Yo-Yo IR1 and HRV measures at week 1. In contrast, Yo-Yo IR1 performance was significantly correlated with SDNN (r =0.89, p=0.007) and SD2 (0.92, p=0.003) at week 8. Greater values in HRV at week 1 were substantially associated with lower HRV changes at the end of pre-season (r values ranged from -0.79 to -0.98, p< 0.05). Furthermore, HRV changes were significantly correlated with decreases in HRmax during the pre-season (r values from 0.83 to 0.94, p<0.05). n nConclusions: The current results confirm that despite minimal changes in specific fitness (i.e. Yo-Yo IR1), pre-season training significantly improved various HRV indices in elite soccer players with greater changes evident for those with lower initial HRV levels. Nocturnal HRV may provide an important monitoring tool for identification of cardiovascular function changes in top-class soccer players during pre-season regimes.

Evaluating activities of daily living using an infrared depth sensor: KINECTTM

Abstract Purpose: With a growing proportion of elderly people in the population, the maintenance of activities of daily living (ADLs) in elderly people is crucial to keep medical costs down. We investigated the ADL measurement accuracy of KINECTTM and Kinect Studio. To eliminate the subjectivity of conventional methods, we numerically assessed motions with computer analysis. Methods: Eighteen actions that repeated “move” and “stationary” phases, including movement of arms, legs, head and torso were measured using KINECTTM. Errors and standard deviations of joint coordinates at the stationary points outputted from KINECT Studio were evaluated. Simultaneous measurements were performed with KINECTTM using conventional high-performance motion capture, and the output was treated as a true value for comparison. Results: In most motions, errors of the joint coordinates were within 100u2009mm; however, there were two cases where errors due to the skeleton-model estimation by KINECT Studio increased. Firstly, when a part of the body unexpectedly moved out of the infrared measurable area, and secondly, when parts of the body overlapped each other on the KINECTTM image. Conclusions: KINECTTM and Kinect Studio are effective for ADL assessment when positions that cause large errors are excluded. Since KINECTTM has sufficient precision, it should also be possible to develop a more appropriate ADL evaluation system with a new algorithm of skeleton-model estimation that does not depend on KINECT Studio. Implications for Rehabilitation The KINECTTM and Kinect Studio are effective for ADL assessment when positions that cause large errors are excluded With an increasing proportion of elderly people in the population, the maintenance of activities of daily living (ADLs) in elderly people is crucial to keep medical costs down Systems such as the KINECTTM can support these goals