Tibial impacts and muscle activation during walking,jogging and running when performed overground,and on motorised and non-motorised treadmills

PurposeTo examine tibial acceleration and muscle activation during overground (OG), motorised treadmill (MT) and non-motorised treadmill conditions (NMT) when walking, jogging and running at matched velocities.MethodsAn accelerometer recorded acceleration at the mid-tibia and surface EMG electrodes recorded rectus femoris (RF), semitendinosus (ST), tibialis anterior (TA) and soleus (SL) muscle activation during OG, MT and NMT locomotion whilst walking, jogging and running.ResultsThe NMT produced large reductions in tibial acceleration when compared with OG and MT conditions across walking, jogging and running conditions. RF EMG was small-moderately higher in the NMT condition when compared with the OG and MT conditions across walking, jogging and running conditions. ST EMG showed large and very large increases in the NMT when compared to OG and MT conditions during walking whilst SL EMG found large increases on the NMT when compared to OG and MT conditions during running. The NMT condition generated very large increases in step frequency when compared to OG and MT conditions during walking, with large and very large decreases during jogging and very large decreases during running.ConclusionsThe NMT generates large reductions in tibial acceleration, moderate to very large increases in muscular activation and large to very large decreases in cycle time when compared to OG and MT locomotion. Whilst this may decrease the osteogenic potential of NMT locomotion, there may be uses for NMTs during rehabilitation for lower limb injuries.     

Effects of different hydration supports on stride kinematics,comfort, and impact accelerations during running

BackgroundDifferent supports for hydration can influence total body mass and affect running biomechanics.Research questionDo different hydration supports affect the perceived exertion and comfort, stride kinematics, and impact accelerations during running?MethodsThis was a crossover study design. Thirteen trail runners completed a treadmill running test divided into four different durations and randomized hydration supports conditions, lasting 8 min each at moderate intensity: A) waist bag (0.84 kg); B) medium load backpack (0.84 kg); C) full load backpack (3.40 kg); and D) a control condition without water support. Impact accelerations were measured for 30 s in 4, 6, and 8 min. The rate of perceived exertion and heart rate were registered on minutes 4 and 8. At the last minute of each condition, comfort perception was registeredResults and significanceNo condition affected the stride kinematics. Full load backpack condition reduced head acceleration peak (−0.21 g; p = 0.04; ES=0.4) and head acceleration magnitude (−0.23 g; p = 0.03; ES=0.4), and increased shock attenuation (3.08 g; p = 0.04; ES=0.3). It also elicited higher perceived exertion (p < 0.05; ES>0.8) being considered heavier (p < 0.01; ES > 1.1). The waist bag condition was more comfortable in terms of noise (p = 0.006; ES=1.3) and humidity/heat (p = 0.001; ES=0.8). The waist bag was the most comfortable support. On the other hand, the full backpack elicited lower comfort and was the only generating compensatory adjustments. These results may help to improve design of full load backpack aiming at comfort for runners.     

Joint power and kinematics coordination in load carriage running: Implications for performance and injury

Investigating the impact of incremental load magnitude on running joint power and kinematics is important for understanding the energy cost burden and potential injury-causative mechanisms associated with load carriage. It was hypothesized that incremental load magnitude would result in phase-specific, joint power and kinematic changes within the stance phase of running, and that these relationships would vary at different running velocities. Thirty-one participants performed running while carrying three load magnitudes (0%, 10%, 20% body weight), at three velocities (3, 4, 5 m/s). Lower limb trajectories and ground reaction forces were captured, and global optimization was used to derive the variables. The relationships between load magnitude and joint power and angle vectors, at each running velocity, were analyzed using Statistical Parametric Mapping Canonical Correlation Analysis. Incremental load magnitude was positively correlated to joint power in the second half of stance. Increasing load magnitude was also positively correlated with alterations in three dimensional ankle angles during mid-stance (4.0 and 5.0 m/s), knee angles at mid-stance (at 5.0 m/s), and hip angles during toe-off (at all velocities). Post hoc analyses indicated that at faster running velocities (4.0 and 5.0 m/s), increasing load magnitude appeared to alter power contribution in a distal-to-proximal (ankle → hip) joint sequence from mid-stance to toe-off. In addition, kinematic changes due to increasing load influenced both sagittal and non-sagittal plane lower limb joint angles. This study provides a list of plausible factors that may influence running energy cost and injury risk during load carriage running.     

The shock attenuation characteristics of four different insoles when worn in a military boot during running and marching

A study was undertaken to determine if placing shock absorbing insoles in the boots of Royal Marine recruits would attenuate the peak pressure at the foot-boot interface, when marching at 4.8 kph carrying a 32 kg (70 lb) Bergen and running at 12.8 kph in loose order plus webbing weighing 10 kg (22 lb). Four types of insoles were assessed: viscoelastic polymetric insole (Cambion(R)) polymetric foam insole (PPT(R)) Saran insole (military issue) and Sorbothane(R). There was a fifth control condition in which no insoles were used. Pressure measurements during heel strike and forefoot loading were taken using Paratec equipment with pressure measuring insoles placed in the boots. Data were obtained from eleven subjects and indicated that all the insoles significantly (P<0.05) attenuated the peak pressures generated during heel strike and forefoot loading. The performance of the four insoles in terms of peak pressure attenuation ranked in order with the best first were: Sorbothane Cambion PPT Saran. The Sorbothane insole was substantially and significantly (P<0.05) better than the other insoles in terms of attenuating peak pressures during heel strike. During running, mean peak pressure at heel strike was 494 kPa in the control condition, this was reduced to 377 kPa when wearing Sorbothane insoles (a reduction of 27%). When marching the Sorbothane insoles reduced the mean peak pressure at heel strike from 395 kPa (control) to 303 kPa (23% reduction). During forefoot loading the peak pressure attenuation of all four insoles was similar, although on average the Sorbothane insole performed slightly better than the others and was significantly different (P<0. 05) to the Cambion insole. Mean peak forefoot loading pressure in the control condition when running was 413 kPa, with the Sorbothane insole it was 367 kPa, during marching the respective mean peak pressures were 397 and 323 kPa. It is concluded that of the four types of insoles assessed the Sorbothane insoles attenuated the greatest amounts of the peak pressure generated at heel strike and during forefoot loading when running and marching wearing military boots.     

Variability of within-step acceleration and daily wellness monitoring in Collegiate American Football

Objectives

It is commonplace to consider accelerometer load and any resultant neuromuscular fatigue in training programs. With these data becoming accepted in sport alongside wellness questionnaires this study aimed to investigate if a deeper analysis of the accelerometry data can provide actionable insight into training-induced disruptions.

Diagnostic of footwork characteristics and running speed demands in tennis on different ground surfaces

BackgroundAnalysis of court surface effects on foot work and running speed and analysis of correlation between general speed and jump performance and the complex running performance in tennis.Materials and Methods12 male tennis players performed a tennis specific baseline shuttle run test including one change of direction (SR), either on clay or on an indoor carpet court. Additionally, subjects completed a linear sprint test, a counter movement jump (CMJ), and a drop jump (DJ).ResultsSR running time (clay: 3.63 ± 0.08 s; carpet: 3.31 ± 0.15 s), change direction time (clay: 1.24 ± 0.09; carpet: 1.09 ± 0.04 s) and ground contact time during the last step while changing direction (clay: 0.92 ± 0.13; carpet: 0.47 ± 0.13 s) were significantly longer on clay (P < 0.05). Linear sprint and jump tests showed no or only weak correlations with SR on both surfaces.ConclusionFoot work and running speed demands in tennis are different depending on the court surface and require specific training interventions and testing procedures.     

The influence of sleep and training load on illness in nationally competitive male Australian Football athletes: A cohort study over one season

Objectives

To determine the incidence of illness, and identify the relationship between sleep, training load and illness in nationally competitive Australian football athletes. Second, to assess multivariate effect between training load and/or sleep variables.

Both a single sacral marker and the whole-body center of mass accurately estimate peak vertical ground reaction force in running

BackgroundWhile running, the human body absorbs repetitive shocks with every step. These shocks can be quantified by the peak vertical ground reaction force ($F_{v,\text{m}\text{a}\text{x}}$). To measure so, using a force plate is the gold standard method (GSM), but not always at hand. In this case, a motion capture system might be an alternative if it accurately estimates $F_{v,\text{m}\text{a}\text{x}}$.Research questionThe purpose of this study was to estimate $F_{v,\text{m}\text{a}\text{x}}$ based on motion capture data and validate the obtained estimates with force plate-based measures.MethodsOne hundred and fifteen runners participated at this study and ran at 9, 11, and 13 km/h. Force data (1000 Hz) and whole-body kinematics (200 Hz) were acquired with an instrumented treadmill and an optoelectronic system, respectively. The vertical ground reaction force was reconstructed from either the whole-body center of mass (COM-M) or sacral marker (SACR-M) accelerations, calculated as the second derivative of their respective positions, and further low-pass filtered using several cutoff frequencies (2−20 Hz) and a fourth-order Butterworth filter.ResultsThe most accurate estimations of $F_{v,\text{m}\text{a}\text{x}}$ were obtained using 5 and 4 Hz cutoff frequencies for the filtering of COM and sacral marker accelerations, respectively. GSM, COM-M, and SACR-M were not significantly different at 11 km/h but were at 9 and 13 km/h. The comparison between GSM and COM-M or SACR-M for each speed depicted root mean square error (RMSE) smaller or equal to 0.17BW (≤6.5 %) and no systematic bias at 11 km/h but small systematic biases at 9 and 13 km/h (≤0.09 BW). COM-M gave systematic biases three times smaller than SACR-M and two times smaller RMSE.SignificanceThe findings of this study support the use of either COM-M or SACR-M using data filtered at 5 and 4 Hz, respectively, to estimate $F_{v,\text{m}\text{a}\text{x}}$ during level treadmill runs at endurance speeds.     

Use of a tibial accelerometer to measure ground reaction force in running: A reliability and validity comparison with force plates

Objectives

The use of microsensor technologies to conduct research and implement interventions in sports and exercise medicine has increased recently. The objective of this paper was to determine the validity and reliability of the ViPerform as a measure of load compared to vertical ground reaction force (GRF) as measured by force plates.

Effect of vitamin supplementation on lung injury and running performance in a hot, humid, and ozone-polluted environment

In this study, the effect of vitamin C and E supplementation on lung injury and performance of runners were analyzed. Using a randomized, double‐blinded, crossover design, nine runners participated in two experimental trials: a 2‐week Vitamin trial (vitamin C = 500 mg/day + vitamin E = 100 IU/day) and a 2‐week Placebo trial. At the end of each supplementation period the runners performed an 8‐km time‐trial run in a hot (31°C), humid (70% rh), and ozone‐polluted (0.10 ppm O₃) environmental chamber. Nasal lavage and blood samples were collected pre‐, post‐, and 6‐h post‐exercise to assess antioxidant status and CC16 as lung injury marker. Higher plasma (pre‐ and post‐exercise) and nasal lavage (post‐exercise) antioxidant concentration were found for the Vitamin trial. Nevertheless, this did not result in performance differences (Vitamin trial: 31:05 min; Placebo trial: 31:54 min; P = 0.075) even though significant positive correlations were found between antioxidant concentration and improvement in time to complete the run. CC16 was higher post‐exercise in the Placebo trial (P < 0.01) in both plasma and nasal lavage. These findings suggest that antioxidant supplementation might help to decrease the lung injury response of runners when exercising in adverse conditions, but has little effect on performance.