You are looking at 101 - 110 of 1,849 items for :

  • Journal of Applied Biomechanics x
  • Athletic Training, Therapy, and Rehabilitation x
  • Refine by Access: All Content x
Clear All
Restricted access

Volume 38 (2022): Issue 5 (Oct 2022)

Restricted access

The Influence of Cell Phone Usage on Dynamic Stability of the Body During Walking

Hamed Shahidian, Rezaul Begg, and David C. Ackland

Dual-task walking and cell phone usage, which is associated with high cognitive load and reduced situational awareness, can increase risk of a collision, a fall event, or death. The objective of this study was to quantify the effect of dual-task cell phone talking, texting, and reading while walking on spatiotemporal gait parameters; minimum foot clearance; and dynamic stability of the lower limb joints, trunk, and head. Nineteen healthy male participants walked on an instrumented treadmill at their self-selected speed as well as walking while simultaneously (1) reading on a cell phone, (2) texting, and (3) talking on a cell phone. Gait analyses were performed using an optical motion analysis system, and dynamic stability was calculated using the Maximum Lyapunov Exponent. Dual-task cell phone usage had a significant destabilizing influence on the lower limb joints during walking. Cell phone talking while walking significantly increased step width and length and decreased minimum foot clearance height (P < .05). The findings suggest that dual-task walking and cell phone conversation may present a greater risk of a fall event than texting or reading. This may be due to the requirements for more rapid information processing and cognitive demand at the expense of motor control of joint stability.

Restricted access

Nonlinear Analyses Distinguish Load Carriage Dynamics in Walking and Standing: A Systematic Review

Kolby J. Brink, Kari L. McKenzie, and Aaron D. Likens

Load carriage experiments are typically performed from a linear perspective that assumes that movement variability is equivalent to error or noise in the neuromuscular system. A complimentary, nonlinear perspective that treats variability as the object of study has generated important results in movement science outside load carriage settings. To date, no systematic review has yet been conducted to understand how load carriage dynamics change from a nonlinear perspective. The goal of this systematic review is to fill that need. Relevant literature was extracted and reviewed for general trends involving nonlinear perspectives on load carriage. Nonlinear analyses that were used in the reviewed studies included sample, multiscale, and approximate entropy; the Lyapunov exponent; fractal analysis; and relative phase. In general, nonlinear tools successfully distinguish between unloaded and loaded conditions in standing and walking, although not in a consistent manner. The Lyapunov exponent and entropy were the most used nonlinear methods. Two noteworthy findings are that entropy in quiet standing studies tends to decrease, whereas the Lyapunov exponent in walking studies tends to increase, both due to added load. Thus, nonlinear analyses reveal altered load carriage dynamics, demonstrating promise in applying a nonlinear perspective to load carriage while also underscoring the need for more research.

Restricted access

The Effects of Cadence Manipulation on Joint Kinetic Patterns and Stride-to-Stride Kinetic Variability in Female Runners

Cheyanne Massie, Kelsey Redman, Samantha Casper, Danielle Wissink, Renee Dade, Anna Lowery, Kim Ross, Kanikkai Steni Balan Sackiriyas, and Thomas Gus Almonroeder

Altering running cadence is commonly done to reduce the risk of running-related injury/reinjury. This study examined how altering running cadence affects joint kinetic patterns and stride-to-stride kinetic variability in uninjured female runners. Twenty-four uninjured female recreational runners ran on an instrumented treadmill with their typical running cadence and with a running cadence that was 7.5% higher and 7.5% lower than typical. Ground reaction force and kinematic data were recorded during each condition, and principal component analysis was used to capture the primary sources of variability from the sagittal plane hip, knee, and ankle moment time series. Runners exhibited a reduction in the magnitude of their knee extension moments when they increased their cadence and an increase in their knee extension moments when they lowered their cadence compared with when they ran with their typical cadence. They also exhibited greater stride-to-stride variability in the magnitude of their hip flexion moments and knee extension moments when they deviated from their typical running cadence (ie, running with either a higher or lower cadence). These differences suggest that runners could alter their cadence throughout a run in an attempt to limit overly repetitive localized tissue stresses.

Restricted access

Comparison of Kinematic Movement Patterns Between 2 Subgroups of Females With Low Back Pain and Healthy Women During Sit-to-Stand and Stand-to-Sit

Neda Orakifar, Mohammad Jafar Shaterzadeh-Yazdi, Reza Salehi, Mohammad Mehravar, Neda Namnik, and Seyyed Arash Haghpanah

The purpose of study was to compare the kinematic patterns of the thoracic, lumbar, and pelvis segments and hip joints between 2 low back pain subgroups and healthy women during sit-to-stand and stand-to-sit. Kinematic data of 44 healthy women and 2 subgroups of females with low back pain in 2 subgroups of movement system impairment model (rotation-extension [Rot.Ext] and rotation-flexion [Rot.Flex]) were recorded. Participants performed sit-to-stand and stand-to-sit at a preferred speed. Each task was divided into a pre buttock lifted off/on (pre-BOff/n) phase and a post-BOff/n phase. The Rot.Ext subgroup showed greater range of motion in the thoracic during pre-BOff phase of sit-to-stand (P < .001) and pre-BOn phase of stand-to-sit (P = .01) compared to the other 2 groups. The Rot.Flex subgroup displayed limited left hip joint excursion during sit-to-stand pre-BOff (P = .04) and stand-to-sit post-BOn phases (P = .02). The Rot.Flex subgroup showed greater pelvis tilt excursion during sit-to-stand post-BOff (P = .04) and stand-to-sit pre-BOn (P = .01) and post-BOn phases (P = .01). In subgroups of women with chronic low back pain, there were kinematic changes in adjacent body segments/joints of lumbar spine during sit-to-stand and stand-to-sit tasks.

Restricted access

Effect of Load on Muscle Activity, Kinematics, and Force Production During the Reverse Hyperextension Exercise

Michael A. Lawrence, Matthew J. Somma, and Brian T. Swanson

The reverse hyperextension exercise is used to strengthen posterior chain musculature without axially loading the spine; however, there are no suggestions for loading. Twenty recreationally active individuals (13 males and 7 females; aged 25.4 [2.5] y; height 1.76 [0.09] m; mass 79.3 [15.8] kg) performed 2 sets of 10 repetitions with 50%, 100%, and 150% of bodyweight. Surface electromyography measured erector spinae, gluteus maximus, and biceps femoris activity. Motions of the trunk, lower extremities, and reverse hyperextension exercise pendulum were tracked. A 1-way repeated-measures analysis of variance was used to analyze differences. Few differences were found between 100% and 150% loads; however, heavier loads resulted in increased hip (5.0°) and trunk (4.0°) flexion compared with the 50% load. Similar patterns emerged for peak and integrated muscle activity, with erector spinae and gluteus maximus activity greater in the 100% and 150% loads than in the 50% load, and biceps femoris activation increasing as load increased. Peak force significantly (P < .001) increased with 100% (28% [31%]) and 150% (34% [40%]) loads compared with the 50% load. Findings suggest the reverse hyperextension exercise targets posterior chain musculature, but increasing loads does not linearly increase force and muscle activation.

Restricted access

Metatarsophalangeal Joint Dynamic Stiffness During Toe Rocker Changes With Walking Speed

Luke Nigro and Elisa S. Arch

Dynamic joint stiffness (or simply “stiffness”) is a customization criteria used to tune mechanical properties of orthotic and prosthetic devices. This study examines metatarsophalangeal (MTP) joint stiffness during the toe-rocker phase of barefoot walking and establishes baseline characteristics of MTP joint stiffness. Ten healthy individuals walked at 4 speeds (0.4, 0.6, 0.8, and 1.0 statures·s−1) over level ground. MTP sagittal plane joint angles and moments were calculated during the toe-rocker phase of stance. Least-squares linear regressions were conducted on the MTP moment versus angle curve to determine joint stiffness during early toe rocker and late toe rocker. Multilevel linear models were used to test for statistically significant differences between conditions. Early toe rocker stiffness was positive, while late toe rocker was negative. Both early toe rocker and late toe rocker stiffness increased in magnitude significantly with speed. This study establishes baseline characteristics of MTP joint stiffness in healthy walking, which previously had not been examined through a range of controlled walking speeds. This information can be used in the future as design criteria for orthotic and prosthetic ankle and ankle–foot devices that can imitate, support, and facilitate natural human foot motion during walking better than existing devices.

Restricted access

Methods of Estimating Foot Power and Work in Standing Vertical Jump

Kundan Joshi and Blake M. Ashby

Experimental motion capture studies have commonly considered the foot as a single rigid body even though the foot contains 26 bones and 30 joints. Various methods have been applied to study rigid body deviations of the foot. This study compared 3 methods: distal foot power (DFP), foot power imbalance (FPI), and a 2-segment foot model to study foot power and work in the takeoff phase of standing vertical jumps. Six physically active participants each performed 6 standing vertical jumps from a starting position spanning 2 adjacent force platforms to allow ground reaction forces acting on the foot to be divided at the metatarsophalangeal (MTP) joints. Shortly after movement initiation, DFP showed a power absorption phase followed by a power generation phase. FPI followed a similar pattern with smaller power absorption and a larger power generation compared to DFP. MTP joints primarily generated power in the 2-segment model. The net foot work was –4.0 (1.0) J using DFP, 1.8 (1.1) J using FPI, and 5.1 (0.5) J with MTP. The results suggest that MTP joints are only 1 source of foot power and that differences between DFP and FPI should be further explored in jumping and other movements.

Restricted access

Quadriceps Muscle Action and Association With Knee Joint Biomechanics in Individuals with Anterior Cruciate Ligament Reconstruction

Amanda E. Munsch, Alyssa Evans-Pickett, Hope Davis-Wilson, Brian Pietrosimone, and Jason R. Franz

Insufficient quadriceps force production and altered knee joint biomechanics after anterior cruciate ligament reconstruction (ACLR) may contribute to a heightened risk of osteoarthritis. Quadriceps muscle lengthening dynamics affect force production and knee joint loading; however, no study to our knowledge has quantified in vivo quadriceps dynamics during walking in individuals with ACLR or examined correlations with joint biomechanics. Our purpose was to quantify bilateral vastus lateralis (VL) fascicle length change and the association thereof with gait biomechanics during weight acceptance in individuals with ACLR. The authors hypothesized that ACLR limbs would exhibit more fascicle lengthening than contralateral limbs. The authors also hypothesized that ACLR limbs would exhibit positive correlations between VL fascicle lengthening and knee joint biomechanics during weight acceptance in walking. The authors quantified VL contractile dynamics via cine B-mode ultrasound imaging in 18 individuals with ACLR walking on an instrumented treadmill. In partial support of our hypothesis, ACLR limb VL fascicles activated without length change on average during weight acceptance while fascicle length on the contralateral limb decreased on average. The authors found a positive association between fascicle lengthening and increase in knee extensor moments in both limbs. Our results suggest that examining quadriceps muscle dynamics may elucidate underlying mechanisms relevant to osteoarthritis.

Restricted access

Weighted Baseball Training Affects Arm Speed Without Increasing Elbow and Shoulder Joint Kinetics

Michael E. O’Connell, Kyle E. Lindley, John O. Scheffey, Alex Caravan, Joseph A. Marsh, and Anthony C. Brady

Long-term training effects of weighted ball throwing programs have been well documented. However, the mechanisms that facilitate these effects are poorly understood. The purpose of this study is to investigate within-session effects of throwing overload and underload baseballs to provide mechanistic evidence for weighted baseball training methods. Twenty-six collegiate- and professional-level baseball pitchers aged 20–30 years (mean age 23.5 [2.7] y) participated in a biomechanical evaluation while pitching a series of leather weighted baseballs. A 1-way repeated-measures analysis of variance was used to evaluate the intrasubject effect of ball weight on a total of 15 kinematic, kinetic, and performance parameters. Ball weight significantly affected pitch velocity, maximum elbow flexion, maximum pelvis rotation velocity, maximum shoulder internal rotation velocity, maximum elbow extension velocity, and anterior trunk tilt at ball release. None of the measured arm joint kinetics were significantly affected by ball weight. Training with 3- to 7-ounce (85- to 198-g) baseballs can be used to work on increasing pitching velocity without increasing throwing arm joint kinetics.