THREE-DIMENSIONAL ACCELERATION DURING RUNNING IN TRAINED ATHLETES AND UNTRAINED SUBJECTS

The present study aimed to evaluate the three-dimensional (30) accelerations during running in trained athletes compared to untrained subjects. Ten endurance-trained male athletes and 10 untrained male subjects wore a 3D accelerometer at the L3 level and ran on a 400-m track at three different speeds. The acceleration amplitude was calculated for each direction from the acceleration time series for 10 strides. Additionally, the positive and negative peak values of vertical and anterior-posterior accelerations were calculated. Analysis of covariance tests showed a significant difference between athletes and untrained subjects in the vertical acceleration amplitude. Significant interaction effects were found for upward acceleration and forward-backward acceleration ratio. These results suggest that athletes have characteristic patterns in the vertical acceleration and forward-backward acceleration ratio

Effects of Aquatic Pole Walking on the Reduction of Spastic Hypertonia in a Patient with Hemiplegia: A Case Study

Here we report an acute effect of aquatic pole walking (PW) training intervention on a 64-year-old male patient with chronic hemiparesis and symptoms of spasticity in the right lower limb. A comparison of over ground walking before and after 20 minutes of aquatic PW training revealed a significant improvement in gait performance. As a main result, the average speed of walking after the intervention was 0.16 m/s after the intervention as compared to 0.04 m/s in the initial condition. The time taken for each stride cycle was drastically decreased, mainly due to shortening of the stance time. Underlying the improved gait performance was the emergence of functional muscle activity in the paralyzed and spastic leg muscles. The result observed in this patient should be further tested among a large population of patients presenting similar symptoms. Moreover, the basic mechanisms underlying aquatic PW intervention should be further elucidated

Effects of hyperoxia on dynamic muscular endurance are associated with individual whole-body endurance capacity.

Low-intensity training involving high repetitions is recommended to enhance muscular endurance. Hyperoxic conditions could increase the number of repetitions until exhaustion and thereby improve the results of muscular endurance training. This study aimed to investigate the acute effects of hyperoxia on dynamic muscular endurance, and determine individual factors that may be related to these effects. A single-blinded, counterbalanced crossover design was used. Twenty-five young men performed repetitions of the one-arm preacher curl at 30% of their 1-repetition maximum until exhaustion under hyperoxic and normoxic conditions. The maximum number of repetitions was recorded as an index of muscular endurance. Electromyogram (EMG) and near-infrared spectroscopy parameters were measured in the biceps brachii. The maximum number of repetitions was greater (P < 0.001) under hyperoxic conditions (132 ± 59 repetitions) than under normoxic conditions (114 ± 40 repetitions). The root mean square amplitude of EMG and oxygenated hemoglobin concentration for the last five repetitions under normoxic conditions were greater than those under hyperoxic conditions (P = 0.015 and P = 0.003, respectively). The percent change in the maximum number of repetitions between hyperoxic and normoxic conditions had significant positive correlations with individual maximal oxygen uptake measured using an incremental cycle ergometer test (r = 0.562, 95% confidence intervals [CI] = 0.213-0.783, P = 0.003), but not with muscle strength (τ = -0.124, 95% CI = -0.424-0.170, P = 0.387). The 95% CI for the correlation coefficient between the percent change in the maximum number of repetitions and muscular endurance included 0 (τ = 0.284, 95% CI = -0.003-0.565, P = 0.047); this indicated no significant correlation between the two parameters. The results suggest that hyperoxia can acutely enhance dynamic muscular endurance, with delayed elevation of EMG amplitude due to fatigue, and the effects are associated with individual whole-body endurance capacity

Stride-to-stride variability and fluctuations at intensities around lactate threshold in distance runners

Stride-to-stride variability and fluctuations in running have been widely investigated in relation to fatigue, injury, and other factors. However, no studies have examined the relationship of stride-to-stride variability and fluctuations with lactate threshold (LT), a well-known performance indicator for distance runners that represents the threshold at which fast-twitch muscle fibers are activated and the glycolytic system is hyperactivated. In this study, we examined a relationship between LT and stride-to-stride variability and fluctuations in trained middle- and long-distance runners (n = 33). All runners were asked to perform multistage graded exercise tests while wearing accelerometers on the upper surface of their shoes. The LT was determined by measuring blood lactate concentrations after each stage. Three gait parameters for each step were calculated based on the acceleration data: stride time (ST), ground contact time (CT), and peak acceleration (PA). The coefficient of variation (CV) and the long-range correlations (α) for each parameter were also calculated. The effects of the runner's group and the relative intensity for CV and α on gait parameters were evaluated using a two-way repeated measures analysis of variance. Although no significant effect was observed in the CV and α of ST, significant intensity main effects were observed for the CV and α of CT and PA. The lack of significant changes in ST might be the result of runners' adequate control of ST to minimize energy cost. All the parameters showing significant changes with increasing intensity decreased dramatically when they were close to LT. This might have been caused by an increase in physiological load near LT and be interpreted as a variation in motor control because of alternations in the mobilized muscle fibers and physiological changes around the LT. The α should be useful for non-invasive LT detection

Effects of Aquatic Pole Walking on the Reduction of Spastic Hypertonia in a Patient with Hemiplegia: A Case Study

Here we report an acute effect of aquatic pole walking (PW) training intervention on a 64-year-old male patient with chronic hemiparesis and symptoms of spasticity in the right lower limb. A comparison of over ground walking before and after 20 minutes of aquatic PW training revealed a significant improvement in gait performance. As a main result, the average speed of walking after the intervention was 0.16 m/s after the intervention as compared to 0.04 m/s in the initial condition. The time taken for each stride cycle was drastically decreased, mainly due to shortening of the stance time. Underlying the improved gait performance was the emergence of functional muscle activity in the paralyzed and spastic leg muscles. The result observed in this patient should be further tested among a large population of patients presenting similar symptoms. Moreover, the basic mechanisms underlying aquatic PW intervention should be further elucidated