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Joint Loading in the Lower Extremities during Elliptical Exercise
Abstract
To determine the joint loading during elliptical exercise (EE) by a detailed three-dimensional dynamic analysis, and to compare the results with those during level walking.
Fifteen male adults performed level walking and EE while 3D kinematic data, right pedal reaction forces (PRF), and ground reaction forces (GRF) were measured. Pedal rate (cadence) and step length during EE without workload were set according to those measured during level walking for each subject. The motion of the body's center of mass, lower-limb-joint angles and moments were obtained.
Pedal rates and step lengths were 52.20 rpm (SD=2.34) and 50.56 cm (SD=2.14), respectively. During early stance the vertical PRF was smaller than the GRF, and the medial and posterior shear components were greater. PRF also occurred during swing. Loading rates around heelstrike during EE were all smaller than those during walking. During EE, the peak flexion angles of the hip, knee and ankle were greater. Peak hip flexor and knee extensor moments were also greater, whereas peak ankle plantarflexor moments and all abductor moments were smaller.
Different lower-limb kinematics and kinetics were found between EE and level walking. Smaller vertical PRF and loading rates during EE were achieved at the expense of greater hip flexor and knee extensor moments. Use of the elliptical trainer for athletic and rehabilitative training would have to consider users' joint function and muscle strength, especially at the knee, to avoid injuries.
... joint kinematics [4]. The benefits are even greater for elliptical trainers when comparing the amount of knee joint loading to other common activities such as walking and jogging [5][6][7]. In vivo measurements of peak tibial forces while using an elliptical trainer (2.24 ± 0.22 BW) were significantly lower than those found during jogging, but did not differ from treadmill walking (1.8-2.5 BW) [5]. ...
... In vivo measurements of peak tibial forces while using an elliptical trainer (2.24 ± 0.22 BW) were significantly lower than those found during jogging, but did not differ from treadmill walking (1.8-2.5 BW) [5]. Lower tibial forces accompanied by reduced loading rates [6] implies rehabailitation benefits of elliptical trainers for knee osteoarthritis (OA) or total knee arthroplasty (TKA) patients [6,8]. ...
... In vivo measurements of peak tibial forces while using an elliptical trainer (2.24 ± 0.22 BW) were significantly lower than those found during jogging, but did not differ from treadmill walking (1.8-2.5 BW) [5]. Lower tibial forces accompanied by reduced loading rates [6] implies rehabailitation benefits of elliptical trainers for knee osteoarthritis (OA) or total knee arthroplasty (TKA) patients [6,8]. ...
Background: Elliptical trainers are a popular cardiovascular exercise for individuals with
injuries or those post-operation. There is currently limited data on the impacts of direction
while on elliptical trainers for knee joint kinematic risk factors. This study compared lower
extremity kinematics between the forward and reverse direction at varying inclines on an
elliptical trainer modified with converging footpath and reduced inter-pedal distance.
Methods: Twenty-four college age participants exercised on the modified elliptical in both
directions at four ramp inclines: 6�, 12�, 25�, and 35�. Three-dimensional kinematics were
collected for each direction and ramp incline. A 2 � 4 (direction � incline) repeated measures analysis of variance was run with an alpha of 0.05. Simple effects analysis was run
with Bonferroni correction for significant interaction or main effect of ramp incline.
Results: The reverse direction had significantly greater peak knee valgus at 6� incline
(mean difference [MD] = 1.35�, p < 0.014, d = 0.31) and 12� (MD = 2.41�, p < 0.001,
d = 0.55), peak hip abduction at 6� (MD = 2.86�, p = 0.002, d = 0.49) and 12� (MD = 2.91�,
p < 0.001, d = 0.51), but decreased peak knee flexion angles (p = 0.032) at all inclines.
Conclusions: Individuals with knee pathologies such as knee osteoarthritis or anterior knee
pain should exercise in the reverse direction at lower inclines. However, switching to the
forward direction and/or increasing incline may increase quadriceps strength during a safe
activity such as elliptical trainers.
... Though not an objective of this study, limited independent quantitative analyses exist that examine directly the anatomical consequences of movement utilizing such equipment in comparison to the standard treadmill. Lu et al. (2007) examined joint loading in the lower extremities during elliptical exercise versus walking and found that the mobility of the pedal system may be a key indicator for potentially harmful loading at the knee (Lu et al. 2007). Increased loading on the quadriceps was also thought to in turn lead to premature fatigue of the engaged muscles thus negatively impacting the general effects of fitness training (Lu et al. 2007;Green et al. 2004). ...
... Though not an objective of this study, limited independent quantitative analyses exist that examine directly the anatomical consequences of movement utilizing such equipment in comparison to the standard treadmill. Lu et al. (2007) examined joint loading in the lower extremities during elliptical exercise versus walking and found that the mobility of the pedal system may be a key indicator for potentially harmful loading at the knee (Lu et al. 2007). Increased loading on the quadriceps was also thought to in turn lead to premature fatigue of the engaged muscles thus negatively impacting the general effects of fitness training (Lu et al. 2007;Green et al. 2004). ...
... Lu et al. (2007) examined joint loading in the lower extremities during elliptical exercise versus walking and found that the mobility of the pedal system may be a key indicator for potentially harmful loading at the knee (Lu et al. 2007). Increased loading on the quadriceps was also thought to in turn lead to premature fatigue of the engaged muscles thus negatively impacting the general effects of fitness training (Lu et al. 2007;Green et al. 2004). Recent research by the University of Wisconsin -La Crosse Department of Physical Therapy demonstrated that the use of the arc trainer in comparison to the elliptical cross trainer may decrease patellofemoral joint stress and the risk of patellofemoral pain syndrome (PFPS), or anterior knee pain, given the invariable path of motion compared to that of other non-impact cardio machines (University of Wisconsin 2012). ...
Older adults are at increased risk of injury when initiating exercise due to inactivity, functional limitation, illness, or fall risk. We studied a novel non-impact cardio unit in an effort to determine whether there were differences in physiologic, functional, and strength benefits compared to a treadmill (TM), while producing less stress on the knee and lessening the risk of fall and injury. Utilizing a prospective, randomized, non-blinded, cohort design, individuals aged 50–80 years were recruited and enrolled in a 16-week exercise program. Subjects were randomly allocated to either exercise on the Cybex arc trainer or on a TM. Participants exercised for 120 min per week. Resistance was adjusted to achieve a target RPE in each group. Functional, strength, and physiologic markers were analyzed through balance testing, ten – repetition max leg press, body composition analysis, and lipid panel results. Overall health-related quality of life was also measured. There was a significant improvement in triglyceride and very low density lipoprotein levels from baseline to exit within the arc trainer group. An equal and significant increase in strength capacity was observed in both the arc trainer and TM groups, as were feelings of increased energy, improved emotional well-being, and decreased fatigue. Leg strength increased, percentage of body fat decreased, and balance improved following use of either an arc trainer or a TM in a study population of 58 participants over a 16-week period. This study demonstrated that positive change occurs, physiologically and psychologically when an arc trainer or TM is utilized. Given the similar benefits seen in this study, use of a non-impact modality such as the arc trainer may be a better alternative in the older population.
... Although elliptical training has been recommended during rehabilitation for this population [39], there do not appear to be any biomechanical studies of knee joint loading during elliptical training for transtibial amputees. Previous studies with non-amputee populations have shown that elliptical training, compared to walking, produces similar kinematic and kinetic patterns [40,41] and reduces knee load impulses [42]. Elliptical training is recommended alongside cycling and swimming as non-weightbearing exercises when other exercises are challenging in persons with joint OA [43]. ...
... One cycling cycle was defined by one full crank rotation starting at top dead center (TDC; 0% = 1 st pass through TDC, 100% = 2 nd pass through TDC) [8]. One elliptical cycle was defined by one full crank rotation starting at the most anterior pedal position (APP; 0% = 1 st pass through APP, 100% = 2 nd pass through APP) [42]. ...
... Gait characteristics varied with leg type (midstance flexion angle timing, swing flexion angle) and participant type (midstance flexion angle, swing flexion angle) providing support for the second hypothesis. Knee joint compressive force, torques, and flexion angles were of similar magnitude to many other studies in both amputee and non-amputee populations in gait [16,17,21,54], cycling [55,56], and elliptical training [41,42,57] (see below for more details). ...
Transtibial amputees may experience decreased quality of life due to increased risk of knee joint osteoarthritis (OA). No prior studies have compared knee joint biomechanics for the same group of transtibial amputees in gait, cycling, and elliptical training. Thus, the goal of this study was to identify preferred exercises for transtibial amputees in the context of reducing risk of knee OA. The hypotheses were: 1) knee biomechanics would differ due to participant status (amputee, control), exercise, and leg type (intact, residual) and 2) gait kinematic parameters would differ due to participant status and leg type. Ten unilateral transtibial amputee and ten control participants performed exercises while kinematic and kinetic data were collected. Two-factor repeated measures analysis of variance with post-hoc Tukey tests and non-parametric equivalents were performed to determine significance. Maximum knee compressive force, extension torque, and abduction torque were lowest in cycling and highest in gait regardless of participant type. Amputee maximum knee extension torque was higher in the intact vs. residual knee in gait. Amputee maximum knee flexion angle was higher in the residual vs. intact knee in gait and elliptical. Gait midstance knee flexion angle timing was asymmetrical for amputees and knee angle was lower in the amputee residual vs. control non-dominant knees. The results suggest that cycling, and likely other non-weight bearing exercises, may be preferred exercises for amputees due to significant reductions in biomechanical asymmetries and joint loads.
... EKAM impulse was associated with pain like EKAM [26] and is more sensitive than peak EKAM [33], [34]. During stepping on an elliptical trainer, for patients with KOA, studies on knee kinetic variables and clinical relevance of those variables are, however, scarce, although kinematics [12], [14], [35]- [37] and knee moments [14] of other populations on an elliptical trainer have been reported. ...
... EKAM impulse was associated with pain like EKAM [26] and is more sensitive than peak EKAM [33], [34]. During stepping on an elliptical trainer, for patients with KOA, studies on knee kinetic variables and clinical relevance of those variables are, however, scarce, although kinematics [12], [14], [35]- [37] and knee moments [14] of other populations on an elliptical trainer have been reported. ...
... The patients' Kellgren-Lawrence grade was estimated based on the KOOS and Kellgren-Lawrence grade relationship given in Table 3 of [42]. An elliptical cycle (EC) was defined as follows: an elliptical cycle started at the time when the measured (right)-side foot reached the most anterior position and ended at the very next time the foot reached the same position [8], [9], [14]. A loading phase was determined as follows: it started at 0% elliptical cycle and ended at the time when the measured-side foot reached the most posterior position the very first time within the same elliptical cycle [14]. ...
We investigated differences in knee kinetic variables (external knee adduction, flexion, internal rotation moments, and impulses) between patients with knee osteoarthritis (KOA) and healthy controls during stepping on a custom elliptical trainer; and searched knee kinetic variable candidates for real-time biofeedback and for complementing diagnosis/evaluation on the elliptical trainer based on the knee kinetic variables associations with the knee injury and osteoarthritis outcome score (KOOS). Furthermore, we explored potential gait re-training strategies on the elliptical trainer by investigating the knee kinetic variables’ associations with 3-D ankle angles. The knee kinetic variables and ankle angles were determined in real-time in a patient group of 10 patients with KOA and an age-and sex-matched control group of 10 healthy subjects. The mean peak external knee adduction moment of the patient group was 47% higher than that of the control group. The KOOS-Sports and Recreational Activities and KOOS-Pain scores were found to be significantly associated with the knee kinetic variables. All the ankle angles were associated with the knee kinetic variables. The findings support the use of the knee kinetic variables on the elliptical trainer to complement KOA diagnosis quantitatively and provide potential real-time KOA gait re-training strategies/guides.
... 6,7 These forms of exercise could benefit runners who have lower extremity musculoskeletal injuries since elliptical training has been found to have reduced lower limb loading rates compared to walking. 8 Cross training such as a combination of cycling and running has been shown to be an effective way to maintain aerobic capacity for runners. 9 White et al 10 found that collegiate female distance runners who substituted 50% of their running time for cycling had similar aerobic fitness compared to females who ran 100% of their time during the cross country season. ...
... 14 Elliptical exercise has also been found to result in higher quadriceps and hamstring loading compared to walking as well as lower vertical reaction forces during elliptical cycling compared to walking. 8 It appears that cycling and elliptical training are effective exercise modes for muscle strengthening for individuals who prefer these devices instead of running or walking. ...
... 41 This may be advantageous for runners to maintain the hip flexor and knee extensor muscles using a simulated running gait pattern via the ElliptiGO®. Since elliptical cycling has been found to elicit smaller joint forces compared to walking, 8 we can only speculate that limb loading may also be reduced using the ElliptiGO® since it offers a similar pedal motion as the elliptical device. ...
Background:
Stationary equipment devices are often used to improve fitness. The ElliptiGO® was recently developed that blends the elements of an elliptical trainer and bicycle, allowing reciprocal lower limb pedaling in an upright position. However, it is unknown whether the muscle activity used for the ElliptiGO® is similar to walking or cycling. To date, there is no information comparing muscle activity for exercise on the treadmill, stationary upright and recumbent bikes, and the ElliptiGO®.
Purpose/hypothesis:
The purpose of this study was to assess trunk and lower extremity muscle activity among treadmill walking, cycling (recumbent and upright) and the ElliptiGO® cycling. It was hypothesized that the ElliptiGO® and treadmill would elicit similar electromyographic muscle activity responses compared to the stationary bike and recumbent bike during an exercise session.
Study design:
Cohort, repeated measures.
Methods:
Twelve recreationally active volunteers participated in the study and were assigned a random order of exercise for each of the four devices (ElliptiGO®, stationary upright cycle ergometer, recumbent ergometer, and a treadmill). Two-dimensional video was used to monitor the start and stop of exercise and surface electromyography (SEMG) were used to assess muscle activity during two minutes of cycling or treadmill walking at 40-50% heart rate reserve (HRR). Eight muscles on the dominant limb were used for analysis: gluteus maximus (Gmax), gluteus medius (Gmed), biceps femoris (BF), lateral head of the gastrocnemius (LG), tibialis anterior (TA), rectus femoris (RF). Two trunk muscles were assessed on the same side; lumbar erector spinae at L3-4 level (LES) and rectus abdominus (RA). Maximal voluntary isometric contractions (MVIC) were determined for each muscle and SEMG data were expressed as %MVIC in order to normalize outputs.
Results:
The %MVIC for RF during ElliptiGO® cycling was higher than recumbent cycling. The LG muscle activity was highest during upright cycling. The TA was higher during walking compared to recumbent cycling and ElliptiGO® cycling. No differences were found among the the LES and remaining lower limb musculature across devices.
Conclusion:
ElliptiGO® cycling was found to elicit sufficient muscle activity to provide a strengthening stimulus for the RF muscle. The LES, RA, Gmax, Gmed, and BF activity were similar across all devices and ranged from low to moderate strength levels of muscle activation. The information gained from this study may assist clinicians in developing low to moderate strengthening exercise protocols when using these four devices.
Level of evidence:
3.
... Most of the previous literature comparing different exercise machines have investigated electromyography patterns 5,24 ; biomechanics; kinematics 2,27 ; comparisons between elliptical training, stationary cycling, treadmill walking, and over-ground walking 7,24 ; ground reaction forces 21 ; and the effect of pedal rates on loading. 5 Use of the elliptical trainer for athletic and rehabilitative training would have to consider users' joint function and muscle strength, especially at the knee, to avoid injuries. ...
... 5 Use of the elliptical trainer for athletic and rehabilitative training would have to consider users' joint function and muscle strength, especially at the knee, to avoid injuries. 21 Elliptical training demonstrated greater rectus femoris activity and greater rectus femoris/semitendinosus coactivation when compared with stationary cycling, treadmill walking, and over-ground walking. These results may assist in selecting the most appropriate training device for specific patients. ...
... Repetitive loads can stimulate osteoblastic activity in fracture patterns and fixation constructs in load-bearing extremities. 21 This has particular significance to orthopaedic surgeons and rehabilitation personnel, who may utilize this information to recommend using the elliptical trainer, even at increasing resistance and incline, in conditions necessitating specific weightbearing limitations involving the lower limb and especially the foot and ankle. The general trend noted from all the changing parameters tested was that increasing resistance resulted in a corresponding increase in all APBW values. ...
Background:
Specific weightbearing instructions continue to be a part of routine orthopaedic clinical practice on an injured or postoperative extremity. Researchers and clinicians have struggled to define the best weightbearing strategies to maximize clinical outcomes.
Purpose:
To investigate the average percentage body weight (APBW) values, weightbearing distribution percentages (WBDP), and cadence values on the entire foot, hindfoot, and forefoot during changing resistance and incline on an elliptical trainer, as well as to suggest clinical implications.
Study Design:
Descriptive laboratory study.
Methods:
An original research study was performed consisting of 30 asymptomatic subjects (mean age, 29.54 ± 12.64 years; range, 21-69 years). The protocol included 3 consecutive tests of changing resistance and incline within a speed range of 70 to 95 steps/min. The SmartStep weightbearing gait analysis system was utilized to measure the values.
Results:
The APBW values for the entire foot ranged between 70% and 81%, the hindfoot values were between 27% and 57%, and the forefoot values between 42% and 70%. With regard to WBDP, the forefoot remained planted on the pedal (stance phase) 2 to 3 times more as compared with the hindfoot raise in the swing phase.
Conclusion:
The study findings highlight the fact that elliptical training significantly reduces weightbearing in the hindfoot, forefoot, and entire foot even at higher levels of resistance and incline.
Clinical Relevance:
Weightbearing on the hindfoot consistently displayed the lowest weightbearing values. Orthopaedic surgeons, now equipped with accurate weightbearing data, may recommend using the elliptical trainer as a weightbearing exercise early on following certain bony or soft tissue pathologies and lower limb surgical procedures.
... While the elliptical has been shown to reduce vertical forces as compared to walking and running, it increases shear forces in the joints. Also, whether or not elliptical training is a suitable replacement for running training is still up for debate [15]. The difference in kinematics and kinetics may result in a reduction in training value as the movements may not translate well to running. ...
... The difference in kinematics and kinetics may result in a reduction in training value as the movements may not translate well to running. Additionally, it is thought that these increases in shear forces and different ranges of motion could cause injury to those conditioned for running [15]. ...
Background: Millions of people are affected yearly by “runner’s knee” and osteoarthritis, which is thought to be related to impact force. Millions are also affected by chronic falling, who are usually both difficult to identify and train. While at first glance, these topics seem to be entirely disconnected, there appears to be a need for a device that would address both issues. This paper proposes and investigates the use of the Variable Stiffness Treadmill (VST) as a targeted training device for the different populations described above. Materials and Methods: The VST is the authors’ unique robotic split-belt treadmill that can reduce the vertical ground stiffness of the left belt, while the right belt remains rigid. In this work, heart rate and energy expenditure are measured for healthy subjects in the challenging asymmetric environment created by the VST and compared to a traditional treadmill setting. Results: This study shows that this asymmetric environment results in an increase in heart rate and energy expenditure, an increase in activity in the muscles about the hip and knee, and a decrease in impact force at heel strike. Conclusions: Compliant environments, like those created on the VST, may be a beneficial tool as they can reduce high-impact forces during running and walking, engage the muscles surrounding the hip and knee significantly more than normal walking allowing for targeted training and rehabilitation, and be a useful way to identify and train high fall-risk individuals.
... This machine promotes a different trajectory of movement when compared to the treadmill or bicycle (Sozen, 2010) and a different muscle recruitment activity (Cheng et al., 2007). That is why it is considered a good alternative to the treadmill and the classic bicycle, since it also allows muscular synchronization between the upper and lower limbs Lu et al., 2007;Sozen, 2010). Although it is important to note that the person must be aware during the execution when it comes to involving all the extremities, causing greater global muscle activation (Batté et al., 2003). ...
... If we focus on the biomechanical analysis, some studies have compared the influence on different joints between different machines Rogatzki et al., 2012), considering the elliptical or the bicycle as good equipment to take into account for the rehabilitation of athletes and the recreational field (Johnston, 2007;Lu et al., 2007). It has been seen how the activation is greater in the upper limbs in the elliptical with respect to other machines such as the treadmill or the bicycle (Sozen, 2010). ...
The objective of this article was to compare different cardiovascular training machines and their effects on the body, as well as to determine their suitability for people with low intensity or high intensity training needs. A total of 8 physically active and healthy male subjects (mean ± standard deviation; age: 28.45 ± 1.75 years; height: 1.84 ± 0.07 m; body weight 76.42 ± 8.62 kg; body mass index: 25.5 ± 2.6) were evaluated through of an incremental exercise test at different intensities on two different machines: Elliptical Domyos 680 (BED) and Deconstruct Elliptical 331-EF (DEC). To compare both machines against the two mentioned training needs, two different protocols were carried out: Low Intensity Protocol (LIP) and High Intensity Protocol (HIP). In addition, a thermographic analysis was carried out in order to determine the temperature differences reached in the musculature. No significant differences were found in HR and EE (p < .05) between the two machines. However, a greater and more progressive activation of the muscles of the upper extremities was observed in the DEC machine. In the HIP, HR and EE were measured, obtaining significant differences (p < .05) higher in the DEC machine. Therefore, in our comparison, the Deconstruct Elliptical machine produced more appropriate results for both low and high intensity training compared to the Elliptical machine. These results and the novel nature of the Deconstruct Elliptical raise the need for further studies to better understand this machine.
... Elliptical running can challenge the cardiopulmonary system to a similar extent to that of running on a treadmill and stair climbing while inducing a greater RPE of the lower extremities, despite similar overall RPEs. [98][99][100] However, while elliptical training reduces reaction force during the early stance phase and loading rates during heel strike compared to walking, medial and posterior shear forces placed on the knee as well as peak hip flexor and knee extensor moment were greater; additionally, hip, knee, and ankle flexion angles were greater. 100 Overground treadmill running is a commonly utilized cardiopulmonary training method post-ACLR, however, the vertical ground reaction forces applied to the lower extremity are typically much greater 101 when compared to walking, 102 but less than exercises such as unilateral or bilateral drop landing. ...
... [98][99][100] However, while elliptical training reduces reaction force during the early stance phase and loading rates during heel strike compared to walking, medial and posterior shear forces placed on the knee as well as peak hip flexor and knee extensor moment were greater; additionally, hip, knee, and ankle flexion angles were greater. 100 Overground treadmill running is a commonly utilized cardiopulmonary training method post-ACLR, however, the vertical ground reaction forces applied to the lower extremity are typically much greater 101 when compared to walking, 102 but less than exercises such as unilateral or bilateral drop landing. 103 However, recent technologies including the use of an unweighted treadmill, such as an AlterG® treadmill (AlterG, Inc., Fremont, CA), may provide a means to reduce loads to the lower extremities during running. ...
The cardiopulmonary system plays a pivotal role in athletic and rehabilitative activities following anterior cruciate ligament reconstruction, along with serving as an important support for the functioning of other physiologic systems including the integumentary, musculoskeletal, and nervous systems. Many competitive sports impose high demands upon the cardiorespiratory system, which requires careful attention and planning from rehabilitation specialists to ensure athletes are adequately prepared to return to sport. Cardiopulmonary function following anterior cruciate ligament reconstruction (ACLR) can be assessed using a variety of methods, depending on stage of healing, training of the clinician, and equipment availability. Reductions in cardiovascular function may influence the selection and dosage of interventions that are not only aimed to address cardiopulmonary impairments, but also deficits experienced in other systems that ultimately work together to achieve goal-directed movement. The purpose of this clinical commentary is to present cardiopulmonary system considerations within a multi-physiologic systems approach to human movement after ACLR, including a clinically relevant review of the cardiopulmonary system, assessment strategies, and modes of cardiopulmonary training to promote effective, efficient movement.
# Level of Evidence
5
... Additional novel findings in this study were determining C and E knee angles that were similar to those found in previous studies. In general, our FE angles agreed qualitatively with previous studies for C [58] and E [59][60][61][62]. AA angle ranges higher than G were predicted for C which corroborated with a previous study for C [58] but were higher than the AA angle range found in another study [63]. ...
... AA angle ranges higher than G were predicted for C which corroborated with a previous study for C [58] but were higher than the AA angle range found in another study [63]. Low AA angle ranges were predicted for E which matched the results from a study on kinematics during E [64] and was lower than measured in a previous study [61]. ...
When conducting motion analysis using 3-dimensional motion capture technology, errors in marker placement on the knee results in a widely observed phenomenon known as “crosstalk” [1-18] in calculated knee joint angles (i.e., flexion-extension (FE), adduction-abduction (AA), internal-external rotation (IE)). Principal Component Analysis (PCA) has recently been proposed as a post hoc method to reduce crosstalk errors and operates by minimizing the correlation between the knee angles [1, 2]. However, recent studies that have used PCA have neither considered exercises, such as cycling (C) and elliptical training (E), other than gait (G) nor estimated the corrected knee axes following PCA correction. The hypothesis of this study is that PCA can correct for crosstalk in G, C, and E exercises but that subject-specific PCA corrected axes differ for these exercises. Motion analysis of the selected exercises were conducted on 8 normal weight (body mass index (BMI) = 21.70 +/- 3.20) and 7 overweight participants (BMI = 27.45 +/- 2.45). An enhanced Helen Hayes marker set with 27 markers was used to track kinematics. Knee joint FE, AA, and IE angles were obtained with Cortex (Motion Analysis, Santa Rosa, CA) software and corrected using PCA to obtain corrected angles for each exercise. Exercise-specific corrected knee joint axes were determined by finding axes that reproduced the shank and ankle body vectors taken from Cortex when used with the PCA corrected angles. Then, PCA corrected gait axes were used as a common set of axes for all exercises to find corresponding knee angles. Paired t-tests assessed if FE-AA angle correlations changed with PCA. Multivariate Paired Hotelling’s T-Square tests assessed if the PCA corrected knee joint axes were similar between exercises. ANOVA was used to assess if Cortex angles, PCA corrected angles, and knee angles using PCA corrected gait axes were different. Reduced FE-AA angle correlations existed for G (p<0.001 for Cortex and p=0.85 for PCA corrected), C (p=0.01 for Cortex and p=0.77 for PCA corrected), and E (p<0.001 for Cortex and p=0.77 for PCA corrected). Differences in the PCA corrected knee axes were found between G and C (p<0.0014). Then, differences were found between Cortex, PCA corrected, and C and E knee angles using the PCA corrected G axes (p<0.0056). The results of this study suggest that if PCA is used to reduce crosstalk errors in motions other than G then it is recommended to adopt the use of a PCA corrected axes set determined from G to produce the PCA corrected angles.
... In addition, the rider loses balance when the center of mass of the body passes through the dead point of the crank as weight is transferred from one leg to the other, resulting in increased activation of leg muscles [4]. Similarly, an elliptical trainer, which is an exercise device operated in a standing posture, can induce an overuse knee injury because of the increased knee joint moment [7]. This shows that continuous operation of a bicycle in a standing posture without saddle support can significantly reduce the efficiency of driving movements and impose excessive stress on the lower limbs. ...
... Considering these measurements, the 3.04 cm COM displacement observed with the GP-crank was relatively small and comparable to that found at a slow walking speed of up to 1 m/s. Moreover, the COM displacement was considerably lower than the value of 5.1 cm that was measured during elliptical exercise [7]. Alternatively, a considerably larger measurement of 6.56 cm associated with the CON-crank was comparable to the COM displacement observed in a person running at a speed of 2-3 m/s [25]. ...
Gait stability is partly characterized by an extended stance phase that comprises 60% of the gait cycle. In this study, a gait pattern was employed for a crank drive system that allows for stable lower limb kinematics during stand-up cycling. A quick return mechanism was applied to the crank system to allow for a slow rotation of the crank during the stance phase and for a quick return during the swing phase. Design parameters for the quick return crank mechanism were defined, and kinematic simulations were performed to understand the behavior of the mechanism. To evaluate the design, an experimental instrument was fabricated, and the cycling motion was analyzed. The results indicated that this new drive system can stabilize the center of mass of the user. This study can contribute to the development of a stand-up bicycle that allows for more comfortable leg kinematics.
... In a gait laboratory, each subject wore 39 retroreflective markers to track the motions of the body segments (Lu, Chien, & Chen, 2007) and walked on an 8-meter walkway, first at his PWS and then randomly at speeds 30% lower than PWS and 20% higher. The lower and higher speeds were selected based on a pilot study in which the speed of 30% lower than PWS was reported by the subjects as distinguishably lower than their PWS, and 20% higher than PWS was the maximum speed before the subjects changed to running. ...
... Spatial-temporal parameters, namely walking speed, cadence, and gait cycle percentages of double-limb support (DLS), single-limb support (SLS) and stance phase, as well as the step length, step width, and medial/lateral (M/L) and/or proximal/distal (P/D) excursions of COM and COP, were calculated. With the measured marker data, a 13-body-segment model of the whole body was used to calculate the position of the body's COM as the weighted sum of the segmental COMs of all body segments (Lu et al., 2007), while the segmental inertial properties were determined using an optimization-based method, which has been shown to reduce errors in the calculated COM/COG when compared to commonly used prediction methods (Chen, Hsieh, Lu, & Tseng, 2011). Effects of soft tissue artifacts were reduced using a global optimization method (Lu & O'Connor, 1999). ...
Preferred walking speed (PWS) reflects the integrated performance of the relevant physiological sub-systems, including energy expenditure. It remains unclear whether the PWS during over-ground walking is chosen to optimize one’s balance control because studies on the effects of speed on the body’s balance control have been limited. The current study aimed to bridge the gap by quantifying the effects of the walking speed on the body’s center of mass (COM) motion relative to the center of pressure (COP) in terms of the changes and directness of the COM-COP inclination angle (IA) and its rate of change (RCIA). Data of the COM and COP were measured from fifteen young healthy males at three walking speeds including PWS using a motion capture system. The values of IAs and RCIAs at key gait events and their average values over gait phases were compared between speeds using one-way repeated measures ANOVA. With increasing walking speed, most of the IA and RCIA related variables were significantly increased (p < 0.05) but not for those of the frontal IA. Significant quadratic trends (p < 0.05) with highest directness at PWS were found in IA during single-limb support, and in RCIA during single-limb and double-limb support. The results suggest that walking at PWS corresponded to the COM-COP control maximizing the directness of the RCIAs over the gait cycle, a compromise between the effects of walking speed and the speed of weight transfer. The data of IA and RCIA at PWS may be used in future assessment of balance control ability in people with different levels of balance impairments.
... All subjects were free of neuromusculoskeletal dysfunction and had normal or corrected-tonormal vision as quantified by their visual acuity. Each subject wore 39 retroreflective markers to track the motions of the body segments [20]. ...
... With a 13-segment model of the body and the measured marker data, the position of the body's COM was calculated as the weighted sum of the segmental COMs of all body segments [20], while the subject-specific segmental inertial properties were determined using an optimization-based method [23]. The COP position was calculated using forces and moments measured by the forceplates and the instrumented treadmill. ...
Treadmills have been used in rehabilitation settings to provide convenient protocols and continuous monitoring of movement over multiple cycles at well-controlled speeds for gait and balance training. However, the potential differences in the movement control may affect the translation of the training outcomes to real life over-ground walking (OW). The similarities and differences in the balance control between treadmill walking (TW) and OW have largely been unexplored. The current study bridged the gap by comparing the motions of the body's center of mass (COM) relative to the center of pressure (COP) between TW and OW, in terms of the COM-COP inclination angle (IA) and its rate of change (RCIA). The movement of the COM and COP separately were quite different between OW and TW, but when describing the COM motion relative to the COP, the COM motions became similar qualitatively with similar butterfly patterns. However, significantly increased peak values in themediolateral RCIA and greater ranges of mediolateral IA were found during TW (p<0.004). In the sagittal plane, the posterior velocity of the belt led to an anterior RCIA (posterior RCIA in OW) with increasing anterior IA during early double-limb support phase, and reduced posterior RCIA (p<0.009) with an increased anterior IA (p<0.001) during the remainder of the phase. These differences between TW and OW may have to be taken into account in future designs of strategies to optimize the translation of treadmill gait training outcomes into real life over-ground walking.
... Each subject walked at a self-selected pace on an 8-meter walkway. Each subject wore 39 retroreflective markers for tracking the motions of the body segments [19] using a motion analysis system (Vicon 512, OMG, UK) while the ground reaction forces (GRF) were measured using two forceplates (AMTI, USA) [20]. Before the tests, subjects were allowed to walk on the walkway several times to familiarize themselves with the experimental environment. ...
... To reduce adverse effects from high frequency noise, F e (t), L e (t), (θ(t)) and M(t) were lowpass filtered using a fourth-order bi-directional Butterworth filter with a cut-off frequency of 10 Hz [19] before being used to calculate the leg and joint stiffness. The obtained leg and joint stiffness were smoothed using a moving average filter with a 50 ms time window [26]. ...
Individual joint deviations are often identified in the analysis of cerebral palsy (CP) gait. However, knowledge is limited as to how these deviations affect the control of the locomotor system as a whole when striving to meet the demands of walking. The current study aimed to bridge the gap by describing the control of the locomotor system in children with diplegic CP in terms of their leg stiffness, both skeletal and muscular components, and associated joint stiffness during gait. Twelve children with spastic diplegia CP and 12 healthy controls walked at a self-selected pace in a gait laboratory while their kinematic and forceplate data were measured and analyzed during loading response, mid-stance, terminal stance and pre-swing. For calculating the leg stiffness, each of the lower limbs was modeled as a non-linear spring, connecting the hip joint center and the corresponding center of pressure, with varying stiffness that was calculated as the slope (gradient) of the axial force vs. the deformation curve. The leg stiffness was further decomposed into skeletal and muscular components considering the alignment of the lower limb. The ankle, knee and hip of the limb were modeled as revolute joints with torsional springs whose stiffness was calculated as the slope of the moment vs. the angle curve of the joint. Independent t-tests were performed for between-group comparisons of all the variables. The CP group significantly decreased the leg stiffness but increased the joint stiffness during stance phase, except during terminal stance where the leg stiffness was increased. They appeared to rely more on muscular contributions to achieve the required leg stiffness, increasing the muscular demands in maintaining the body posture against collapse. Leg stiffness plays a critical role in modulating the kinematics and kinetics of the locomotor system during gait in the diplegic CP.
... Elliptical exercise has been shown to produce similar maximal physiological values compared to treadmill running in a non-runner population. 5 Further, while weight bearing, elliptical exercise produces primarily sagittal plane lower extremity joint motions similar to running and yield no impacts during exercise compared to walking 6 and presumably, running. ...
... As expected, relative VO2 (ml·kg -1 ·min -1 ) and caloric cost were similar between LE and TR, but were greater than SE. The lower load and lack of impact during elliptical exercise as suggested in previous literature 6,36,37 supports the lower VO2 during SE measured in this present study. The greater metabolic demands of LE may be attributed to the novelty of the movement, the increased frontal plane motion (i.e., greater frontal plane stabilizer involvement), and increased knee extensor activation. ...
The purpose of this study was to compare knee and hip joint kinematics previously associated with anterior knee pain and metabolic cost among treadmill running (TM), standard elliptical (SE), and lateral elliptical (LE) in healthy runners. Joint kinematics and metabolic parameters of sixteen runners were collected during all three modalities using motion capture and a metabolic system, respectively. Sagittal knee range of motion (ROM) was greater in LE (p < 0.001) and SE (p < 0.001) compared to TM. Frontal and transverse plane hip ROM were greater in LE compared to SE (p < 0.001) and TM (p < 0.001). Contralateral pelvic drop ROM was smaller in SE compared to TM (p = 0.002) and LE (p = 0.005). Similar oxygen consumption was found during LE and TM (p = 0.39) but LE (p < 0.001) and TM (p < 0.001) required greater oxygen consumption than SE. Although LE yields similar metabolic cost to TM and produces hip kinematics that may help strengthen hip abductors, greater knee flexion and abduction during LE may increase symptoms in runners with anterior knee pain. The findings suggest that research on the implications of elliptical exercise for injured runners is needed.
... Individuals with KOA are encouraged to participate in low-impact exercises suitable for lower limb muscle strengthening, such as elliptical training. Elliptical training induces smaller external KAM compared to overground walking and high-impact activities [16][17][18]. The smaller KAM during elliptical stepping may imply lower medial knee contact force during the stepping exercise. ...
Knee osteoarthritis (KOA) is an age-dependent disease dominantly affected by mechanical loading. Balancing the forces acting on the medial knee compartment has been the focus of KOA interventions. This pilot study investigated the effects of functional electrical stimulation (FES) of the biceps femoris and lateral gastrocnemius on reducing peak knee adduction moment (pKAM) in healthy adults and individuals with medial KOA while stepping on an instrumented elliptical system. Sixteen healthy individuals and five individuals with medial KOA stepped on the robotic stepping system, which measured footplate-reaction forces/torques and ankle kinematics and calculated 3-D knee moments in real time using inverse dynamics. Participants performed four different tasks: regular stepping without FES as the baseline condition, stepping with continuous FES of the lateral gastrocnemius (FESLG), biceps femoris (FESBF), and simultaneous FES of both lateral gastrocnemius and biceps femoris (FESLGBF), throughout the elliptical cycle. The 3-D knee moments, tibia kinematics, and footplate-reaction forces were compared between the baseline and the three FES stepping conditions. Healthy participants demonstrated lower pKAM during each of the three FES conditions compared to baseline (FESLG (p = 0.041), FESBF (p = 0.049), FESLGBF (p = 0.048)). Participants with KOA showed a trend of lower pKAM during FES, which was not statistically significant given the small sample available. Incorporating elliptical + FES as a training strategy is feasible and may help to enhance selective force generation of the targeted muscles and reduce the medial knee compartment loading.
... The fitness apparatus were getting more popular among the exercise population. A recent report by the Sporting Goods Manufacturers Association of the United States indicated that the population of elliptical trainer users had grown by 170% from 2000 to 2005 (Lu, Chien, & Chen, 2007). Moreover, elliptical trainer was among the top three "most essential" pieces of equipment reported by the respondents answering an open-ended question in the IDEA survey (Keller, 2006). ...
LANGUAGE NOTE | Document text in English; abstract also in Chinese. Elliptical cross trainer has become popular for cardio respiratory fitness training. Since new models of elliptical trainers are manufactured for better design and more effective in workout, the present study attempted to compare the physiological variables of the latest model of elliptical trainer, Precor AMT 100i, with the previous model, Precor EFX 576i. A total of 30 female university students participated in the 12-minute incremental elliptical test. Heart rate data and energy expenditure were recorded. Results showed that the latest elliptical model required higher heart rate and energy output, comparatively. However, it appeared that overestimation in energy expenditure was found from the machine-shown data, as compared to the actual metabolic measurement. All data between 60%, 80% heart rate reserve and the equivalent perceived exertion of subjects was found to be no correlation. 本文探討兩種橢圓運轉機對生理變數的影响。邀請了30位大學女生，在兩款橢圓運轉機(Precor EFX576i, Precor AMT 100i)上進行練習，收集心跳率、攝氧量、能量消耗及主觀感覺疲勞等數據。結果顯示: 新款型號的橢圓運轉機對身體的生理要求較大，而且兩種橢圓運轉機的預測數值，比實際量度的略大。
... Therefore, the elliptical trainer is developed to guide the users' feet to follow a track such that impact forces are minimized and the knees are well protected from being injured. Research on the lower extremity movements and forces generated during exercise on the elliptical trainer have demonstrated the elliptical motion which produces lower impact forces than treadmill running during elliptical exercise and walking [5][6][7]. ...
The existing elliptical trainer cannot provide the user with the real jogging exercising mode and does not meet the principles of ergonomics. The purpose of this paper is to propose and study an innovative elliptical trainer that imitates the right timing of the foot trajectory while jogging. First of all, this study proposes and illustrates the structure and function of the innovative elliptical trainer with quick-return effect. Then, by using vector-loop method and motion geometry of the mechanism, the proposed innovative mechanism is studied kinematically. A design example is presented for interpreting the design process. At last, the foot trajectory of the innovative elliptical trainer is analyzed and confirmed. The simulation results confirm that the timing of the foot trajectory of the foot support members satisfies the principles of ergonomics, and keeps the user’s legs from injury.
... and knee (r = 0.87-0.89) kinematics; although, elliptical trainers do elicit a greater amount of hip and knee flexion compared to overground walking (Lu et al., 2007;Burnfield et al., 2010Burnfield et al., , 2011. In addition, elliptical trainers have similar metabolic demands to treadmill jogging during submaximal exercise based on peak oxygen uptake (Brown et al., 2010). ...
Elliptical trainers that increase the inter-pedal distance may have potential benefits for knee osteoarthritis by decreasing the amount of knee varus. Modifying elliptical trainers with a converging footpath and reduced inter-pedal distance may be beneficial for reducing anterior knee pathology risk by decreasing knee valgus angles. Twenty-one college students participated in a single testing session. Participants exercised on two different elliptical trainers, one modified with a converging footpath and reduced inter-pedal width, and a standard elliptical trainer. Participants exercised for 2 min at three ramps incline at 120 strides per minute and constant work rate. Three-dimensional kinematics and electromyography of the dominant lower limb were recorded. Multiple 2 × 3 (Elliptical x Incline) ANOVAs with Bonferroni corrections were used to compare the two elliptical trainers at each incline for kinematics and muscle activity. The modified elliptical trainer displayed significantly decreased peak knee valgus (p = 0.031, η2p=0.234), peak knee flexion (p = 0.006, η2p=0.246), and interactions for peak knee flexion (p = 0.001, η2p=0.250) and vastus lateralis (p < 0.01, η2p=0.380) muscle activity compared to the standard elliptical trainer. The decreased peak knee valgus and flexion angles could be beneficial for reducing long-term injury risk for anterior knee pathologies.
... [1][2][3] Several skin marker-based and medical imaging-based techniques are available for measuring 3D knee kinematics, 4-7 but few allow noninvasive measurement with submillimeter accuracy. 8,9 Skin marker-based methods have been widely used in clinical gait analysis and sports biomechanics to reconstruct quantitatively the 3D kinematics of human body segments mainly via infrared stereophotogrammetry. 5,10,11 However, movements between the skin markers and the underlying bones (i.e., soft tissue artifacts) during activities are inevitable, 12 and have been shown to affect the measurement outcome of joint kinematics, [13][14][15] and thus the statistical comparisons between subject groups. Although mathematical compensation methods have the potential to reduce these errors, 16,17 the residual errors are still too large to reveal the detailed motions of the joint articular surfaces (i.e., arthrokinematics). ...
Purpose
The purpose of this study is to propose and evaluate a slice‐to‐volume registration (SVR) method integrating an advanced dual‐slice real‐time magnetic resonance image (MRI) and three‐dimensional (3D) MRI volume of the tibiofemoral joint for determining their 3D kinematics.
Methods
The real‐time and 3D MRI of the knee were collected from 12 healthy adults at 5 static flexion positions and during dynamic flexion/extension movement. The 3D positions and orientations of the femur and tibia were obtained by registering their volumetric models constructed from the 3D MRI to dual‐slice real‐time MRI using an optimization process. The proposed method was quantitatively evaluated for its performance in terms of the robustness and measurement accuracy, and compared to those of a single‐slice SVR method. Its repeatability in measuring knee kinematics during flexion/extension movement was also determined.
Results
In comparison to the single‐slice SVR method, the dual‐slice method was significantly superior, giving a successful registration rate > 95%, a bias less than 0.5 mm in translations and 0.6° in rotations and a precision <0.7 mm in translations and 0.9° in rotations for determining the 3D tibiofemoral poses. For repeatability of the dual‐slice SVR in measuring tibiofemoral kinematics during dynamic flexion/extension, the means of the time‐averaged standard deviations were <0.9° for joint angles and 0.5 mm for joint translations.
Conclusion
A dual‐slice SVR method in conjunction with real‐time MRI has been developed and evaluated for its performance in measuring 3D kinematics of the tibiofemoral joint in 12 young adults in terms of the accuracy, robustness, and repeatability. The proposed MRI‐based 3D measurement method provides a noninvasive and ionizing radiation‐free approach for 3D kinematic measurement of the tibiofemoral joint, which will be helpful for future academic and clinical applications.
... Few studies showed contact stresses exceeding 10 MPa causing earlier failure of the implant (Fryman, 2011). Studies by Regianni (2006) and Lu (2007) showed a total range of 8 o -10 o for internal-external rotation during stance phase of the gait cycle, and other studies applied a total range of 3 o -5 o for rotation under dynamic load ( Smyth et al., 2017), (Kincaid et al., 2013), ASTM F2665-09 (2014). In this study, a rotation angle of 15 o was used to apply the torsion load for determining the contact stresses and yearly wear rate which results in higher contact stresses and wear values than values obtained for dynamic loading. ...
Ankle arthritis constitutes about 10% of all joint arthritis cases, however, the revision rate of ankle replacement devices is three times higher than comparable hip and knee devices. With complicated bone morphology and surrounding ligament structures, the physiological and gait characteristics of the ankle joint presents a challenge to biomechanicians. As a result, there is a lack of fundamental understanding how the ligaments and articular surfaces interact. The objective of this doctoral research is to address the pattern of contact at the joint articulation, the fundamental role of ligaments in joint mobility, and biomechanics of total ankle replacement (TAR) devices. In this study, an attempt was made to describe the ankle joint kinematics under static and unloaded conditions by means of mechanical linkage. A rigid body linkage mechanism was subscribed to the 3D model of the ankle joint based on ligament markings to predict kinematic coupling. Motion analysis was conducted to derive articular curvature of the tibia and talus at the joint by simulating flexion motion. The joint biomechanics in the presence of TAR devices was simulated by finite element analysis (FEA). Gait loads were applied in TAR devices, and annual wear rate and contact pressure predicted and compared with published data.
... However, the magnitude of weight-bearing that occurs during traditional aerobic activity (ie, running, walking) can impact musculoskeletal pain during activity. Elliptical training provides similar physiological improvements to stair climbing and treadmill running [28], but has lower loading rates [29]. While aquatic exercise has not been commonly researched in obese populations, evidence suggests that it has moderate benefits on pain, physical function, and quality of life in adults with musculoskeletal conditions [30]. ...
Obesity and musculoskeletal health are inextricably linked across risk factors, prevalence rates, and societal burden. They are also linked across management strategies. It is necessary to consider the mutual impact of musculoskeletal health and obesity in order to inform effective and safe weight management and physical activity solutions.
... These also have smaller joint impact forces compared with treadmill walking. 36 Many individuals with CP experience earlier and greater joint deterioration because of their abnormal loading patterns and the high impact forces they may experience during walking, which may lead to a cessation of walking in adulthood. 37 Therefore, it is critically important that any long-term exercise or therapy does not significantly exacerbate joint stress and deterioration. ...
Background:
Locomotor training using treadmills or robotic devices is commonly utilized to improve gait in cerebral palsy (CP); however, effects are inconsistent and fail to exceed those of equally intense alternatives. Possible limitations of existing devices include fixed nonvariable rhythm and too much limb or body weight assistance.
Objective:
To quantify and compare effectiveness of a motor-assisted cycle and a novel alternative, an elliptical, in CP to improve interlimb reciprocal coordination through intensive speed-focused leg training.
Methods:
A total of 27 children with bilateral CP, 5 to 17 years old, were randomized to 12 weeks of 20 minutes, 5 days per week home-based training (elliptical = 14; cycle = 13) at a minimum of 40 revolutions per minute, with resistance added when speed target was achieved. Primary outcomes were self-selected and fastest voluntary cadence on the devices and gait speed. Secondary outcomes included knee muscle strength, and selective control and functional mobility measures.
Results:
Cadence on trained but not nontrained devices increased, demonstrating task specificity of training and increased exercise capability. Mean gait speed did not increase in either group, nor did parent-reported functional mobility. Knee extensor strength increased in both. An interaction between group and time was seen in selective control with scores slightly increasing for the elliptical and decreasing for the cycle, possibly related to tighter limb coupling with cycling.
Conclusions:
Task-specific effects were similarly positive across groups, but no transfer was seen to gait or function. Training dose was low (≤20 hours) compared with intensive upper-limb training recommendations and may be insufficient to produce appreciable clinical change.
... The vastus medialis obliquus (VMO) is one of the major knee extensors, and previous research showed greater activation of VMO and greater sagittal knee ROM during LE compared with SE. 23 Quadriceps strengthening can reduce symptoms in individu- als with AKP. 9,31 Therefore, the continuous weight-bearing with reduced impact in elliptical exercise, 6 greater VMO activation in LE compared with SE, 23 and greater concentric knee extension found in LE compared with both TR and SE may suggest that LE could help strengthen knee extensors. As a result, training on LE may help reduce symptoms in runners with AKP while maintaining aerobic fitness. ...
... In vivo knee loads (e.g. resultant joint contact and muscle forces) have been estimated using rigid body dynamics supplemented with pedal force measurements during bicycling [20,21,22], and elliptical training [23,24,25], and measured in vitro or in vivo using pressure sensitive film (during bicycling) [26] and instrumented prostheses (during bicycling and elliptical training) [27]. An extensive literature search produces only 1 previous FE modeling study, published as a conference paper [28], that predicted knee-joint OC tissue stress for stationary bicycling or elliptical exercises. ...
Osteoarthritis (OA) is a degenerative condition of cartilage and is the leading cost of disability in the United States. Motion analysis experiments in combination with knee-joint finite element (FE) analysis may be used to identify exercises that maintain knee-joint osteochondral (OC) loading at safe levels for patients at high-risk for knee OA, individuals with modest OC defects, or patients rehabilitating after surgical interventions. Therefore, a detailed total knee-joint FE model was developed by modifying open-source knee-joint geometries in order to predict OC tissue stress and strain during the stance phase of gait. The model was partially validated for predicting the timing and locations of maximum contact parameters (contact pressure, contact area, and principal Green-Lagrangian strain), but over-estimated contact parameters compared with both published in vivo studies and other FE analyses of the stance phase of gait. This suggests that the model geometry and kinematic boundary conditions utilized in this FE model are appropriate, but limitations in the material properties used, as well as potentially the loading boundary conditions represent primary areas for improvement.
... Prior studies have used instrumented prostheses to measure in vivo hip joint contact loads [45,46,47,48] or cartilage contact pressures [49,47,50,51], but results were limited to gait and everyday activities, neglecting exercise important for weight loss such as bicycling, elliptical training, or running. Extensive research has gone into estimating joint contact loads through computational means for activities such as bicycling [52,53,54] and elliptical training [55,56], but to the author's knowledge, no studies have been performed to measure loads or contact pressures during these activities, either in vitro or in vivo. Additionally, since these results are general, application to the wide range of patients seen by doctors evaluating injuries is difficult, especially considering the lack of data for overweight or obese persons or other high-risk groups. ...
Articular cartilage degeneration, called osteoarthritis, in the hip joint is a serious condition that affects millions of individuals yearly, with limited clinical solutions available to prevent or slow progression of damage. Additionally, the effects of high-risk factors (e.g. obesity, soft and hard tissue injuries, abnormal joint alignment, amputations) on the progression of osteoarthritis are not fully understood. Therefore, the objective of this thesis is to generate a finite element model for predicting osteochondral tissue stress and strain in the human hip joint during gait, with a future goal of using this model in clinically relevant studies aimed at prevention, treatment, and rehabilitation of OC injuries.
A subject specific finite element model (FEM) was developed from computerized tomography images, using rigid bones and linear elastic isotropic material properties for cartilage as a first step in model development. Peak contact pressures of 8.0 to 10.6 MPa and contact areas of 576 to 1010 mm2 were predicted by this FEM during the stance phase of gait. This model was validated with in vitro measurements and found to be in good agreement with experimentally measured contact pressures, and fair agreement with measured contact areas.
... Damiano reported that in a cross-exercise of lower limbs, the short moment arm of the bent knee joint is increased with the extension of the knee to support one's weight, which exerts significant stress on the knee extensor to stabilize the knee joint 16) . Lu showed that an increased moment arm requires greater force, and thus, the muscle activity of the knee extensor is greater than in other walking conditions 17) . The step climbing exercise extends the knee opposite to the stepping foot, and this could be more effective in strengthening the RF than stair gait exercise. ...
[Purpose] The objective of this study was to examine the effect of step climbing exercise on the walking ability of stroke patients. [Subjects and Methods] Among hospitalized stroke patients, 24 were selected based on the study criteria and randomly divided into two groups: an experimental group (12 patients) and a control group (12 patients). The patients in both groups participated in 15-minute exercise sessions three times a week for eight weeks. To analyze the effect of the exercise, muscle strength, the Timed Up and Go test, and step length were measured before and after the exercise. [Results] step climbing exercise improved the muscle strength in the lower limbs of the stroke patients, as well as their Timed Up and Go results and step lengths. [Conclusion] The effects were similar to a stair gait exercise, and thus, step climbing may be more broadly applied to the treatment of stroke patients.
... Because it is a relatively new exercise modality, there is limited research using the EE. Research has mainly focused on ground reaction forces and general responses of lower extremity biomechanics (Burnfield et al., 2007;D'Lima et al., 2008;Lu et al., 2007) as well as various physiological responses during EE exercise (Dalleck et al., 2004;Mercer et al., 2001;Mier & Feito, 2006). In addition, several investigations have developed GXT protocols (Dalleck et al., 2004), equations to predict VO 2max from submaximal exercise (Dalleck et al., 2006) and metabolic equations to estimate VO 2 (Dalleck & Kravitz, 2007) for the EE. ...
PURPOSE: The purpose of this project was to examine concurrent and construct validity of two newly developed Adult OMNI Elliptical Ergometry ratings of perceived exertion (RPE) Scales. METHODS: Fifty-nine sedentary to recreationally active, college-aged volunteers (males, n = 30; age = 21.3 + 3.3 yrs and females, n = 29; 22.3 + 3.5 yrs) participated in this study. A single observation, cross-sectional perceptual estimation trial was employed with subjects exercising to volitional fatigue on an elliptical ergometer. Oxygen consumption (VO2), heart rate (HR) and RPE-Overall Body (O), Legs (L) and Chest/Breathing (C) were recorded each stage from the Borg 15 Category Scale and two different OMNI RPE scale formats. One scale maintained the original format of the OMNI Picture System of Perceived Exertion. The second scale modified verbal, numerical and pictorial descriptors at the low end of the response range. Concurrent validity was established by correlating RPE-O, L and C from each scale with VO2 and HR obtained from each test stage during the estimation trial. Construct validity was established by correlating RPE-O, L and C from the Adult OMNI Elliptical Ergometry Scales with RPE-O, L and C from the Borg Scale. RESULTS: Correlation analyses indicated the relation between RPE-O, L and C from each OMNI RPE Scale distributed as a positive linear function of both VO2 (males, r = .941 - .951 and females, r = .930 - .946) and HR (males, r = .950 - .960 and females, r = .963 - .966). A strong, positive relation was also exhibited between differentiated and undifferentiated RPE from the Adult OMNI Elliptical Ergometry Scales and the Borg 15 Category Scale (males, r = .961 - .972 and females, r = .973 - .977). CONCLUSION: Concurrent and construct validity were established for both formats of the Adult OMNI Elliptical Ergometry Scale during partial weight bearing exercise. Either scale can be used to estimate RPE during elliptical ergometer exercise in health-fitness settings. However, because of the potential use of RPE in caloric expenditure indices and prediction models, the modified scale depicting the "rest" pictorial may be more practical.
... A 13-body-segment model of the whole body [24] was used to calculate the position of the body's COM as the weighted sum of the segmental COMs of all body segments. Body segmental inertial properties were obtained using an optimization-based method [25]. ...
... The working joint range of motion, type of muscle contraction, mechanism of loading and sequencing of exercises or activities can be varied while still keeping the same activity volume. Exercise choices can also vary within modes; for example, standing in the pedals during cycling has greater loading at the knee joint than sitting in the saddle, as the standing position more closely resembles an elliptical activity (Ericson & Nisell, 1986;Kutzner et al., 2012;Lu, Chien, & Chen, 2007). Lap swimming is different from shallow water walking, and the amount of weight bearing will vary with the speed of walking in the water (Masumoto, Takasugi, Hotta, Fujishima, & Iwamoto, 2004). ...
Articular cartilage is a unique biphasic material that supports a lifetime of compressive and shear forces across joints. When articular cartilage deteriorates, whether due to injury, wear and tear or normal aging, osteoarthritis and resultant pain can ensue. Understanding the basic science of the structure and biomechanics of articular cartilage can help clinicians guide their patients to appropriate activity and loading choices. The purpose of this article is to examine how articular cartilage structure and mechanics, may interact with risk factors to contribute to OA and how this interaction provides guidelines for intervention choices This paper will review the microstructure of articular cartilage, its mechanical properties and link this information to clinical decision making.
Copyright © 2014 Elsevier Ltd. All rights reserved.
... Few studies showed contact stresses exceeding 10 MPa causing earlier failure of the implant (Fryman, 2011). Studies by Reggiani et al. (2006) and Lu et al. (2007) showed a total range of 81-101 for internal-external rotation during stance phase of the gait cycle. In this study a rotation angle of 151 was used to apply the torsion load for determining the contact stresses and yearly wear rate which results in higher contact stresses and wear values. ...
Background:
There are several factors that contribute to the failure of total ankle replacement (TAR). Aseptic loosening is one of the primary mechanisms of failure in TAR. Since a cross-linked ultrahigh molecular weight polyethylene (UHMWPE) is used as liner material, there is a need to quantify and develop methods to estimate the wear rates of the liners. High contact stresses develop during the gait generates wear debris resulting in osteolysis and early loosening of the prostheses.
Methods:
In this paper wear characteristics of Wright State University (WSU) TARs were determined by applying shear and torsion loads. Viscoelastic properties were used to model the liner component. Finite element analysis was conducted to determine the wear rate by deriving Von Mises and contact stresses generated in the liner and wear rate equation was used to predict the wear rate.
Results:
Titanium alloy has shown less resistance towards shear forces when compared with other metal alloys. Under torsion, rotation angle plays a significant role in affecting the peak stress values. The maximum average contact stress was 14.46 MPa under torsion load which contributes to a wear rate of 0.67 (mm(3)/year) for one of the mobile bearing models. The maximum average contact stress and wear rate obtained from the analytical study were 10.55 MPa and 0.33 (mm(3)/year), respectively for mobile bearing models. When compared with mobile bearing model, fixed bearing model has shown higher stresses at different degrees of rotation.
Conclusion:
Both shear and torsion loads cause significantly lower contact stresses and wear when compared to the axial load. Further studies are necessary to accurately determine the wear behavior of fixed bearing TAR models.
... Few studies showed contact stresses exceeding 10 MPa causing earlier failure of the implant (Fryman, 2011). Studies by Reggiani et al. (2006) and Lu et al. (2007) showed a total range of 81-101 for internal-external rotation during stance phase of the gait cycle. In this study a rotation angle of 151 was used to apply the torsion load for determining the contact stresses and yearly wear rate which results in higher contact stresses and wear values. ...
Purpose
Modifying foot progression angle (FPA), the angle between the line from the heel to the second metatarsal head and the line of progression, can reduce peak knee adduction moment (pKAM). However, determining the optimal FPA that minimizes pKAM without inducing unnatural walking patterns can be challenging. This study investigated the FPA-pKAM relationship using a robotic stepping trainer to assess the feasibility of determining the optimal FPA based on this relationship. Additionally, it examined knee moments during stepping with three different FPAs, as stepping is a recommended exercise for knee osteoarthritis (KOA) rehabilitation.
Methods
Twenty-six asymptomatic individuals stepped on a robotic stepping trainer, which measured 6-axis footplate-reaction forces/torques and three-dimensional (3-D) ankle kinematics to determine external knee moments. The robot rotated the footplates slowly (~0.5 deg/sec) between 10°-toe-out and 10°-toe-in while participants stepped continuously, unaware of the footplate rotations. The slope of pKAM-FPA relationship during continuous stepping was determined. Peak 3-D knee moments were compared between the 10°-toe-in, 0°-FPA, and 10°-toe-out FPAs with repeated-measure ANOVA. Multiple linear regression determined the covariates that predicted pKAM during stepping.
Results
Eighteen participants had lower pKAM and KAM impulse with 10°-toe-in than 10°-toe-out (p < 0.001) and 0°-FPA (p < 0.001 and p = 0.008, respectively) (called toe-in responders). Conversely, eight participants reduced pKAM and KAM impulse with 10°-toe-out compared to 0°-FPA (p < 0.001, p = 0.017) and 10°-toe-in (p = 0.026, p = 0.004) (called toe-out responders). A linear pKAM-FPA relationship was determined for each individual, and its slope (the pKAM rate with FPA) was positive for toe-in responders (p < 0.01) and negative for toe-out responders (p = 0.02). Regression analysis revealed that smaller pKAM with toe-in in toe-in responders was explained by increased tibia medial tilt, tibia internal rotation, footplate-reaction lateral force, footplate-reaction anterior force, and decreased footplate-reaction internal rotation torque.
Conclusions
Individuals may exhibit different responses to FPA modification during stepping. The slope and intercept of the linear pKAM-FPA relationship can be determined for individual subjects. This allows for a targeted pKAM reduction through guided FPA positioning and potentially offers subject-specific precision KOA rehabilitation.
Background and Objectives: This study examined the influence of stationary bikes and elliptical machines on knee movement and joint load during exercise. Materials and Methods: Twelve healthy male participants engaged in pedaling exercises on stationary bikes and elliptical machines at speeds of 50 and 70 revolutions per minute (rpm). Knee movement and joint load were assessed using a motion analysis system. Results: The results indicated that elliptical machines induced higher knee joint torque compared to stationary bikes. Notably, peak torque occurred at different joint angles, with stationary bikes reaching an earlier peak at 70°–110° and elliptical machines showing a later peak at 135°–180°. Increased pedaling speed correlated with higher peak knee joint torque on both machines. With the elliptical machine, a higher pedaling frequency correlated with increased peak forces on the knee and ankle joints, as well as vertically. Interestingly, both types of equipment were associated with enhanced peak knee joint torques during high-speed pedaling. Conversely, constant pedaling on elliptical machines limited the ankle angle and could induce inward rotation. Conclusions: This study focused on knee joint torque variations during pedaling on indoor stationary bicycles and elliptical machines. Elliptical machines showed higher peak values of forces and torque, particularly during the propulsive and recovery phases, indicating potential challenges to the knee joint. Notably, peak pedal angles occurred earlier on indoor stationary bicycles, emphasizing the impact of equipment choice on joint kinetics.
Objective
One of the main objectives of practicing indoor cardiovascular exercise is to maximize caloric expenditure. This study aimed to compare energy expenditure (EE), oxygen consumption (VO2), and heart rate (HR) recorded in middle-aged adults while exercising on seven different indoor cardiovascular machines at self-selected maximal and submaximal intensity.
Method
Thirty recreational-active adult males (Age: 41.69 ± 4.64) performed 12-min bouts at RPE (Rate of perceived exertion) 17 and maximum intensity (MAX INT) on the following indoor cardio machines: Recumbent bike (r_BIKE), upright bike (u-BIKE), spin bike (s-BIKE), rowing machine (ROW), elliptical trainer (ELLIP), stair climber (STAIR), and treadmill (TMILL). Heart rate (HR) and oxygen consumption (VO2) were measured during exercise, whereas EE (energy expenditure) was calculated indirectly.
Results
Overall, TMILL induced the highest levels of EE, VO2, and HR, followed by STAIR, ELLIP, s_BIKE, u_BIKE, ROW, and r_BIKE. RPE was reliable across exercise modalities (r_BIKE, u-BIKE, s-BIKE, ROW, ELLIP, STAIR, and TMILL) and intensities (RPE 17 and MAX INT) for EE, HR, and VO2 measurements.
Conclusion
To maximize EE while performing indoor cardiovascular exercise for recreational active middle-aged male participants, the TMILL is the best option, followed by the STAIR and the ELLIP. The least recommended options are, respectively, s_BIKE, u_BIKE, ROW, and r_BIKE. Beyond caloric expenditure considerations, promoting exercises that participants genuinely enjoy can enhance adherence, fostering sustained health benefits. Furthermore, RPE is a reliable tool for assessing EE, VO2, and HR across different exercise modalities and intensities.
Introduction Spinal cord injury generates muscle weakness, impairing orthostatism and gait. The elliptical trainer (ET) and the ergometric bicycle (EB) are rehabilitation options for this subject. Understanding the pattern of muscle activation generated by these methods is important to answer questions arising from clinical practice. Objective To verify muscle activation with ET and EB with and without electromyographic biofeedback in subjects with incomplete spinal cord injury (ISCI). Methods Cross-sectional crossover study, enrolled in Clinical Trials (NCT05118971). Subjects with spinal cord injury (incomplete spinal cord injury group - ISCIG) and without spinal cord injury (reference group - RG) were randomized into four groups: elliptical group (EG), elliptical + biofeedback group (EBG), bicycle group (BG) and bicycle + biofeedback group (BBG). Subjects were assessed for functionality by the Functional Independence Measure, injury classification by the ASIA Scale, muscle tone by the modified Ashworth scale, and muscle activity by electromyography. Results There was greater activation of the tibialis anterior on cycling compared to other modalities in ISCIG. Biofeedback offered no difference in any of the groups. In RG the vastus medialis was the most activated muscle in all modalities, with more expressive activation in the ET. In this same group, the tibialis anterior was more activated on the EB. Conclusion This study showed that both ET and EB are safe and effective in recruiting the muscles investigated, encouraging its use by rehabilitation professionals when the objective is to strength muscles involved in gait.
This study investigated the effect of crank length on biomechanical parameters and muscle activity during standing cycling. Ten participants performed submaximal cycling trials on a stand-up bicycle using four crank lengths. Joint angles, moments, powers, and works of the lower limbs were calculated from motion data and pedal reaction forces. Electromyographic (EMG) data were recorded from gluteus maximus (GM), vastus medialis, rectus femoris, biceps femoris (BF), gastrocnemius medialis, soleus, and tibialis anterior, and used to obtain the integrated EMG. Statistical parametric mapping was employed to analyse the biomechanical parameters throughout the pedalling cycle. Knee and hip flexion angles and hip power increased at the initiation (0–20%) of pedalling with increasing crank length, while the BF and GM muscle activities increased during propulsion (20–40%). Additionally, increasing the crank length resulted in increased knee power absorption during upstroke phase (70–100%). Peak knee extension moment increased with decreasing crank length during propulsion, but the moment at a short crank length during propulsion was comparable to fast walking. Consequently, longer crank lengths require increased propulsion power by the lower limb muscles during standing cycling compared to shorter crank lengths. Therefore, shorter crank lengths are recommended for stand-up bicycles to avoid fatigue.
Knee injuries at risk of post-traumatic knee osteoarthritis (PTOA) and knee osteoarthritis (OA) are closely associated with knee transverse plane and/or frontal plane instability and excessive loading. However, most existing training and rehabilitation devices involve mainly movements in the sagittal plane. An offaxis elliptical training system was developed to train and evaluate neuromuscular control about the off-axes (knee varus/valgus and tibial rotation) as well as the main flexion/extension axis (sagittal movements). Effects of the offaxis elliptical training systemin improving either transverse or frontal neuromuscular control depending on subjects’ need (Pivoting group, Sliding group) were demonstrated through 6 week subject-specific neuromuscular training on subjects with knee injuries at risk of PTOA or medial knee osteoarthritis. The combined pivoting and sliding group, named as offxis group demonstrated significant reduction in pivoting instability, minimum pivoting angle, and sliding instability. The pivoting group showed more reduction in pivoting instability, maximum and minimum pivoting angle than the sliding group. On the other hand, the sliding group showed more reduction in sliding instability, maximum and minimum sliding distance than the pivoting group. Based on these findings, the offaxis elliptical trainer system can potentially be used as a therapeutic and research tool to train human subjects for plane-dependent improvements for their neuromuscular control during functional weight-bearing stepping movements.
Background:
A novel stair-climber called a pinnacle trainer (PT) provides both sagittal and frontal plane exercise, making it different from a step trainer (ST), which provides only sagittal plane exercise. Exercise with different trajectories may produce different biomechanical responses. There are currently no guidelines for choosing between a PT and a ST for different training or rehabilitation purposes.
Research questions:
Are there differences in the electromyographic patterns of lower extremity musculature and biomechanical responses of the knee joint during exercise between using a PT and a ST?
Methods:
This study utilizes a prospective observational study design. Eighteen healthy males participated in the study. A six-axis force and torque transducer embedded in the machine pedal synchronized with a three-dimensional motion capture system were utilized to measure kinematic and kinetic data of the right knee during the stepping movement. The activities of six lower extremity muscles of the same limb were captured with surface electromyography during exercise on the two trainer types.
Results:
The co-activation index of the vastus lateralis (VL) and the biceps femoris (BF) recorded during ST exercise was significantly greater than that for the PT exercise. Moreover, exercise using the ST produced a significantly greater knee downward force compared to that for the PT. Exercise with the PT produced a significantly greater internal knee varus moment compared to that for the ST.
Significance:
The ST provided greater co-activation of the BF and VL and a greater knee joint downward force, which may decrease the antero-posterior displacement of the tibia relative to the femur. Exercise with the PT produced a significant internal knee varus moment and a more balanced muscular activation on the vastus medialis and VL compared to that for the ST, which may decrease the maltracking of the patella.
Background:
A pinnacle trainer is a stair climber that has a biplane exercise trajectory and an adjustable pedal stance width (PSW). A pinnacle trainer integrated with a body weight support (BWS) system can help overweight individuals or individuals with poor balance exercise safely by reducing excessive or improper joint loads, preventing training-related injuries. However, few studies have investigated the biomechanical features of the lower extremities during pinnacle trainer exercise with and without partial BWS for various PSWs.
Research question:
We aimed to investigate the effects of partial BWS and PSW on the joint loading of the lower extremities during stepping on a pinnacle trainer.
Methods:
Seventeen healthy adults exercised on the pinnacle trainer with or without BWS using various PSWs. The joint resultant forces and joint moments of the lower extremities were calculated according to the kinematic and kinetic data measured via a motion capture system and force transducers on the pedals, respectively.
Results:
The joint resultant forces and joint moments of the lower extremities significantly decreased with increasing percentage of BWS. The internal knee adduction moment and internal hip abduction moment significantly increased with increasing PSW. For every kilogram of BWS, the joint loading of the lower extremities decreased by approximately 1% of the joint resultant forces of body weight during exercise with the pinnacle trainer.
Significance:
Exercise on the pinnacle trainer with partial BWS significantly reduced joint loading. Exercise with a wider pedal stance may be helpful for knee osteoarthritis rehabilitation as it produces greater internal hip abduction and internal knee adduction moments.
BACKGROUND: The aim of this study is to evaluate heart rate and muscle activity and exercise intensity in trained and untrained individuals during exercise in four different positions on Cardio-wave tM , a device that works simultaneously on three axes with a “sliding” movement of the lower limbs. METHODS: Twelve subjects were enrolled: 6 trained and 6 untrained, all performed a 12 minute fixed intensity protocol on the Cardio-wave tM . Heart rate and surface electromyography activity of the rectus femoris, vastus medialis and the biceps femorishad been recorded in four different positions. RESULTS: Hearth rate ranged between 79 to 100% HR max , with no difference between groups. A main effect (P<0.05) was found between positions. For surface electromyography activity data, a significant difference (P<0.05) emerged among Groups, Muscles and the interaction Groups x Muscles. Post hoc analysis showed that untrained subjects had significantly higher values and standard deviations only for rectus femoris(221±365%) and vastus medialis (196 ±309%) activation when compared to trained (rectusfemoris: 0±166%; vastus medialis: 64 ±159%). CONCLUSIONS: These finding suggest that some positions on Cardio-wave tM are more stressed as muscle soreness perceived during the work than other and HR monitoring of exercises on the CW device might not be sufficient to evaluate training status and work load.
This study proposes a crank drive system that considers gait characteristics and is without dead points (GP-crank) to decrease the knee joint load for stand-up bicycles. A comparative experiment was conducted from the perspective of cycling kinematics to investigate the differences between the proposed GP-crank and conventional crank drive systems. The pedaling motion was analyzed by measuring the three-dimensional movements and pedal reaction forces of 16 subjects driving cranks in a standing posture. Although no significant differences were found in the peak pedal reaction force, flexion angle of the lower limb joints, and joint flexion moments between the drive systems, the vertical displacement of the center of body mass was significantly smaller for the GP-crank. In addition, the knee joint was extended for the GP-crank at the time the knee moment reached its maximum. Consequently, decreased knee joint stress of the GP-crank was demonstrated by its comparatively reduced vertical displacement of the center of body mass and stress on the knee joint. This study shows that the disadvantages of existing stand-up bicycles can be addressed by using the proposed GP-crank.
Neuromuscular impairments in Parkinson’s disease (PD) alter the mechanics and control of the body, leading to an increased risk of falling during more challenging functional tasks such as obstacle-crossing. However, little is known about these changes. The current study aimed to bridge the gap by quantifying the motion of the body’s center of mass (COM) relative to the center of pressure (COP) in terms of COM-COP inclination angles (IA) and their rate of change (RCIA) in fifteen older adults with mild PD and fifteen healthy controls when crossing obstacles of heights of 10, 20 and 30% leg length. There were no between-group differences for either the leading or trailing toe clearances (p > 0.05). With the unaffected limb leading, the PD subjects significantly increased the crossing sagittal and frontal IA, crossing sagittal RCIA, the peak RCIA, and average sagittal and frontal RCIAs during double-limb support for all obstacle heights when compared to those with the affected limb leading and those of the Controls (p < 0.05). The poor balance control in the mediolateral direction during obstacle-crossing in PD indicated an increased risk of falling. The differences in the crossing patterns between leading with the affected or unaffected limb suggest that patients with PD should lead with the affected limb when crossing obstacles. The current findings suggest that early dynamic balance training is important in the management of patients with PD.
Treadmills are often used in clinical settings to improve walking balance control in patients with gait impairments. However, knowledge of the effects of belt speed on balance control remains incomplete. The current study determined such effects in terms of inclination angles (IA) and the rate of change (RCIA) of the center of mass (COM) motion relative to the center of pressure (COP) in twelve healthy adults at five belt speeds, including the subjects’ preferred walking speed (PWS), as measured using a motion capture system and an instrumented treadmill. The values of IAs and RCIAs at key gait events and their average values over single-limb support (DLS) and double-limb support (DLS) were compared between speeds using one-way repeated measures analysis of variances. While the COM-COP controls were different between SLS and DLS, they were inter-related to form an integrated whole. Among the belt speeds, the range of frontal IA during SLS was smallest at the PWS (p < 0.05). With increasing speed, most variables of the sagittal IAs and RCIAs, and of the frontal RCIAs during DLS showed a linearly increasing trend (p < 0.001). A linearly decreasing trend was found in the frontal IA at toe-off and in the average frontal RCIA during SLS (p < 0.05). The PWS appeared to be the best compromise between frontal stability during SLS and smooth weight-transfer during DLS. The current results provide useful baseline data for selecting speeds according to training needs, and may be helpful for developing protocols for gait retraining for patients with gait impairment.
This preliminary study examined the effects of off-axis elliptical training on reducing transverse-plane gait deviations and improving gait function in 8 individuals with cerebral palsy (CP) (15.5 +/- 4.1 years) who completed an training program using a custom-made elliptical trainer that allows transverse-plane pivoting of the footplates during exercise. Lower-extremity off-axis control during elliptical exercise was evaluated by quantifying the root-mean-square and maximal angular displacement of the footplate pivoting angle. Lower-extremity pivoting strength was assessed. Gait function and balance were evaluated using 10-m walk test, 6-minute-walk test, and Pediatric Balance Scale. Toe-in angles during gait were quantified. Participants with CP demonstrated a significant decrease in the pivoting angle (root mean square and maximal angular displacement; effect size, 1.00-2.00) and increase in the lower-extremity pivoting strength (effect size = 0.91-1.09) after training. Reduced 10-m walk test time (11.9 +/- 3.7 seconds vs. 10.8 +/- 3.0 seconds; P = 0.004; effect size = 1.46), increased Pediatric Balance Scale score (43.6 +/- 12.9 vs. 45.6 +/- 10.8; P = 0.042; effect size = 0.79), and decreased toe-in angle (3.7 +/- 10.5 degrees vs. 0.7 +/- 11.7 degrees; P = 0.011; effect size = 1.22) were observed after training. We present an intervention to challenge lower-extremity off-axis control during a weight-bearing and functional activity for individuals with CP. Our preliminary findings suggest that this intervention was effective in enhancing off-axis control, gait function, and balance and reducing in-toeing gait in persons with CP.
Copyright
High-heeled shoes increase the risk of falling during walking, especially in the presence of obstacles. The study aimed to compare the end-point (foot/shoe) trajectories and joint angles of the lower extremities in 12 healthy females crossing obstacles of different heights while barefoot and when wearing narrow-heeled shoes (heel heights: 3.9, 6.3 and 7.3 cm). During obstacle-crossing, young females in narrow-heeled shoes maintained the same leading toe-clearance as when barefoot, irrespective of the heel height, primarily through increased plantarflexion of the leading swing ankle. However, the shoe heel-clearance was significantly reduced when compared with barefoot, presumably related to the difficulty in precisely sensing the position of the shoe-heel tip. With an increasing obstacle height, the toe-clearance, heel-clearance and shoe heel-clearance were reduced linearly, indicating an increasing risk of tripping over the obstacle. The results will be helpful for the design and development of strategies to reduce the risk of falling when wearing narrow-heeled shoes.
Practitioner Summary: Knowledge of the influence of narrow-heeled shoes and obstacles on lower limb joint and end-point kinematics helps in shoe design to address fall risks. Compared to barefoot, narrow-heeled shoes reduced shoe heel-clearances, which were further reduced linearly with increasing obstacle height, indicating an increasing risk of tripping over the obstacle.
Maximal oxygen consumption ((V) over dotO(2)max) can be determined through multiple exercise modalities intended to elicit an individual's maximal aerobic exertion. Uphill treadmill running is considered the best modality for measuring (V) over dotO(2)max. Previous studies have examined correlations between treadmill and elliptical ergometer tests as well as the cycle ergometer, but none of the studies use an arm-leg elliptical ergometer (ALE). The purpose of this study was to develop an ALE (V) over dotO(2)max testing protocol and determine whether ALE produces valid (V) over dotO(2)max values as compared with the treadmill. Twelve undergraduate students (mean age: 20.8 years) completed 2 ((V) over dotO(2)max) tests, 1 on a treadmill and 1 on ALE. (V) over dotO(2)max correlation between ALE and treadmill was examined, and paired t-tests were run for (V) over dotO(2)max and maximum heart rate (HRmax). A strong positive correlation was found between ALE and treadmill (V) over dotO(2)max values (r = 0.84; p < 0.001). There were no differences between (V) over dotO(2)max values; however, HRmax values were higher on the treadmill than ALE (p = 0.003). Although future research is needed to examine the observed differences in HRmax between the 2 testing modalities and gender differences in muscle recruitment patterns, the results of this study suggest that ALE is a valid modality for ((V) over dotO(2)max) testing. This will be particularly valuable as a clinical tool to assess (V) over dotO(2)max in populations requiring low-impact exercise.
Physical inactivity is a current problem with harmful consequences to health. Physical activity is a valuable preventive tool. Cardiorespiratory fitness plays an important role, especially for the prophylaxis of cardiovascular diseases resulting from sedentary lifestyle. The easiest way to train cardiorespiratory fitness is the walk, but not alone. In the centers of physical activity and fitness centers has emerged the use of elliptical devices. Aim of this review has been to collect current information to justify the use of this element of training among general population. We performed a literature search in PubMed and SportDiscus database. The retrieved studies can conclude that elliptical devices are appropriated for the maintenance and improvement of cardiorespiratory fitness.
This study seeks to analyze plantar pressures as subjects perform activities on standard exercise equipment. F-Scan insoles (Tekscan, South Boston, MA) were used to measure peak pressure, pressure time integrals (PTIs), and contact area in 4 different regions of the foot: the frst metatarsal head, second through ffth metatarsal heads, midfoot, and hindfoot. Nine healthy adults participated in multiple trials during stationary bicycling, stair climbing, elliptical exercise, incline and fat treadmill walking, and ground walking. The stationary bike demonstrated the lowest plantar pressures in all regions of the foot, and the stair stepper demonstrated the lowest mean peak pressure of all of the weight-bearing exercises. The stationary bicycle should be considered when reductions in plantar pressure are necessary. The stair stepper should be considered if mechanical loading is desired to maintain bone strength and density and if increased PTI can be tolerated at the forefoot and midfoot.
Cycling is generally regarded as a low impact sport. It has a range of skills and disciplines, but the majority of cyclists are usually involved in the endurance aspect of the sport. The low impact nature, however, does not preclude cyclists from injury and musculoskeletal problems. Apart from the obvious trauma and sequelae involved in a fall from the bike, the prolonged postural adaptations combined with the repetitive limb movement from spending hours cycling seem to be one of the main reasons for lower limb and lower body problems. Those intending to become involved in the diagnosis and treatment of such problems should be aware of the plethora of mechanical and biomechanical issues when assessing an injured cyclist. This review of lower body problems in cycling highlights the typical patterns of injury and points out that to obtain a diagnosis for a cycling related problem a practitioner must evaluate faults in the bicycle as well as the cyclist. It also highlights that, despite some useful biomechanical input, there is a disturbing lack of evidence base for the treatment of some musculoskeletal complaints. This is unhelpful to those seeking more evidence-based practice, and may encourage an anecdotal approach to treatment for cyclists. All practitioners who are involved in the care of these sports people should continue to press for good quality studies so that cycling injuries of the lower limb may treated more efficaciously in the future.
The purpose of this study was to evaluate whether a combined resistance and aerobic training program would improve insulin sensitivity compared with aerobic training alone in postmenopausal women with type 2 diabetes. A second objective was to relate the improved insulin sensitivity to changes in abdominal adipose tissue (AT) and thigh muscle density.
A total of 28 obese postmenopausal women with type 2 diabetes were randomly assigned to one of three 16-week treatments: control, aerobic only training (Ae only), or aerobic plus resistance training (Ae+RT). Pre- and posttreatment outcome measures included glucose disposal by hyperinsulinemic-euglycemic clamp and computed tomography scans of abdominal AT and mid-thigh skeletal muscle.
Glucose infusion rates increased significantly (P < 0.05) in the Ae+RT group. Both exercise groups had reduced abdominal subcutaneous and visceral AT and increased muscle density. The Ae+RT training group exhibited a significantly greater increase in muscle density than the Ae only group. Improved glucose disposal was independently associated with changes in subcutaneous AT, visceral AT, and muscle density. Muscle density retained a relationship with glucose disposal after controlling for abdominal AT.
Adding resistance training to aerobic training enhanced glucose disposal in postmenopausal women with type 2 diabetes. The improved insulin sensitivity is related to loss of abdominal subcutaneous and visceral AT and to increased muscle density.
The authors assessed the effects of resistance training and walking exercise on measures of functional fitness. Sixty-four volunteers (average age 83.5 years) from an independent-living facility were randomly assigned to walking, resistance training, or control groups. Participants in the walking and resistance-training groups engaged in two exercise sessions per week for 16 weeks. Measures of functional fitness included upper and lower body strength, hip and shoulder flexibility, agility and balance, coordination, blood pressure, and resting heart rate. Repeated measures analysis of variance was used to examine pretest to posttest differences. Both exercise groups showed significant improvements relative to control group in upper and lower body strength, shoulder flexibility, and agility and balance exercise. Findings demonstrate that exercise can lead to improvements in multiple domains of functional fitness even among very old, previously sedentary individuals, possibly making activities of daily living easier to perform.
It is difficult to distinguish the independent effects of gravity from those of inertia on a running animal. Simply adding mass proportionally changes both the weight (gravitational force) and mass (inertial force) of the animal. We measured ground reaction forces for eight male humans running normally at 3 m s(-)(1) and under three experimental treatments: added gravitational and inertial forces, added inertial forces and reduced gravitational forces. Subjects ran at 110, 120 and 130 % of normal weight and mass, at 110, 120 and 130 % of normal mass while maintaining 100 % normal weight, and at 25, 50 and 75 % of normal weight while maintaining 100 % normal mass. The peak active vertical forces generated changed with weight, but did not change with mass. Surprisingly, horizontal impulses changed substantially more with weight than with mass. Gravity exerted a greater influence than inertia on both vertical and horizontal forces generated against the ground during running. Subjects changed vertical and horizontal forces proportionately at corresponding times in the step cycle to maintain the orientation of the resultant vector despite a nearly threefold change in magnitude across treatments. Maintaining the orientation of the resultant vector during periods of high force generation aligns the vector with the leg to minimize muscle forces.
Human locomotion on inclined surfaces has been little studied. This work investigated uphill and downhill walking of urban pedestrians on slopes of up to 9 degrees. During a 3-month period, the gait characteristics of 1200 female and 1200 male pedestrians were recorded as they traversed a ramp of naturally varying slope at Sydney's Circular Quay. Walking speed, cadence and step length were determined for each subject, and average population gait parameters, for each ramp angle, were also calculated. The most significant finding was that the pedestrians' step length was decreased during ramp descent. Since theoretical analysis concludes that a reduction in step length produces a reduction in the friction demand, a shortening of the stride length is probably a means of counteracting the higher friction demand that would otherwise be required at heel strike during downhill walking.
Perceived exertion during physical exercise is a major intrinsic factor for making decisions regarding intensity levels. The use of perceptual indices as a prescriptive guide of exercise intensity may be a valuable tool, should it be concomitant with physiological responses. The purpose of this study was to evaluate the physiologic response during exercise on an elliptical fitness cross-trainer at a prescribed level of perceived exertion.
Twenty, recreational exercisers (8 males, 12 females) were habituated to the elliptical cross-trainer and then assessed for their peak oxygen utilization (VO(2)) and peak heart rate (HR) using an incremental protocol. The point of volitional fatigue during the maximal test was used to anchor a modified Borg Category Ratio (CR-10) scale. Following a rest period of 48-72 hours, a second exercise session was performed at a prescribed perceived exertion level of 6. The subjects were instructed to manipulate the resistance and striding cadence to maintain the prescribed perceived exertion level for 15 min, during which VO(2) and HR were analyzed.
The results from this study demonstrated that at exercise steady state, which occurred 4 min after the start of the protocol, relative VO(2) averaged 75.2+/-12.9% and relative HR was 91+/-.01%. Oxygen utilization and HR values were found to be significantly higher than a corresponding relative RPE in 20 recreational exercises when exercising on an elliptical fitness cross-trainer.
This response has implications when using RPE as a prescriptive means of intensity regulation.
Elliptical exercise has recently increased in popularity. However, little is known regarding heart rate and perceptual responses during this exercise mode even though such information is important with respect to prescribing and regulating exercise intensity. In the current study, heart rate and perceived exertion were compared between treadmill and elliptical exercise. During treadmill exercise (TMEST) participants estimated RPE-Overall as well as RPE-Legs and RPE-Chest. Two elliptical sessions followed: (1) RPE estimation during elliptical exercise (ELEST): HR (b/min.) from TMEST was achieved during elliptical exercise, with participants estimating RPE-Overall, RPE-Legs, and RPE-Chest. (2) RPE production during elliptical exercise (ELPROD): RPE-Overall from TMEST was produced during elliptical exercise. There were no significant differences between modes for RPE-Overall (TMEST: 11.2 ± 2.2 vs ELEST: 11.9 ± 3.2) or RPE-Chest (TMEST: 11.0 ± 2.4 vs ELEST: 11.7 ± 3.2). Mean RPE-Legs was significantly different (TMEST: 11.2 ± 2.4 vs ELEST: 12.5 ± 3.1). Heart rate was not significantly different between TMEST (163 ± 16.6) and ELPROD (159 ± 20.0). Analysis indicated elliptical exercise is perceived as more intense with respect to leg (RPE-Legs) exertion. Further, RPE-Overall appears effective for regulating heart rate during elliptical exercise.
The purpose of this study was to determine the effects of limiting ankle motion on pedal forces. Sixteen adults pedaled an instrumented ergometer against constant cadence and frictional lead while wearing hinged braces. Ankle motion was limited under four randomly assigned conditions: both braces unlocked (UL), only the preferred leg (PL) brace locked, only the nonpreferred leg (NPL) brace leaked, and braces on both legs (BL) locked. Measurements of pedal force, crank, and pedal angles were sampled at 200/s for 20 s. With both braces locked, resultant force mean magnitude decreased during the downstroke, due to reduced radial crank force. Asymmetry between PL and NPL decreased during the power phase when only PL was braced but increased when only NPL was braced. It was concluded that constrained ankle motion, as may occur with ankle injury or hemiplegia, reduces the ability to transmit power during the downstroke while enhancing ability during the upstroke.
We must understand the natural history of immature walking in order to define and interpret pathological gait in young children. Step length, cadence and walking velocity show evidence of both central nervous system maturation and growth until approximately 4 years of age. Until 4 years-of-age the step factor (step length divided by leg length) increases, but thereafter the step factor remains constant and adult-like. After 4 years-of-age the changes in velocity, cadence, step length in normal children are appropriately attributed to changes in limb length. Dynamic joint angle measurements indicate stabilization of gait by 312 to 4 years-of-age. However, there is greater inter-subject and intra-subject variability of gait in children of all ages than of adults. Force plate measurements of subjects 2 to 7 years-of-age show an increasing definition of the mid-stance trough in the vertical force curve. The second peak of the vertical force curve is deficient, by adult standards, particularly in the younger age groups. Moment and power curves of hip, knee and ankle in subjects 4 years and older show patterns not unlike those of adult subjects. There are differences in magnitude, suggesting that the youngest children use their hip flexor and extensor muscles more than their ankle plantar flexors for power generation. A study from another center shows no age-related differences in hip, knee and ankle powers in children 5–16 years of age. All of the studies reported are very helpful in understanding gait maturation but researchers are needed to address remaining questions.
Management of hip injuries has evolved significantly in recent years with the advancement of arthroscopic techniques. These recent surgical advances require establishment of rehabilitation protocols that follow several basic principles including: (1) consideration of soft-tissue healing constraints, (2) control of swelling and pain to limit muscular inhibition and atrophy, (3) early range of motion (ROM), (4) limitations on weight bearing, (5) early initiation of muscle activity and neuromuscular control, (6) progressive lower extremity strengthening and proprioceptive retraining, (7) cardiovascular training, and (8) sport-specific training. The following protocols should not be considered a cookbook approach to rehabilitation, but rather guidelines that are used to achieve consistent outcomes. These guidelines will continue to evolve as we learn more about the hip joint and surrounding musculature.
During normal walking, repetitive impulsive forces are introduced into the musculo-skeletal system. At heelstrike, there is a sharp irregularity in the ground reaction force, known as the heelstrike transient. As a result of experimental evidence indicating possible correlations between impulse loading and joint degeneration, research interest in heelstrike transients has intensified. This paper outlines the nature of the heelstrike transient and the use of accelerometers and force platforms for skeletal transient investigation. Attention is given to two experiments that analysed the response of the human body to the impact forces experienced during walking. The possible causative links between excessive impulsive loading and the progression of two pathological conditions-osteoarthritis and low back pain, respectively-are discussed in detail.
Figure A.1 Walking Trial—Marker Locations and Mass and Frame Rate Information Table A.1 Raw Coordinate Data (cm) Table A.2(a) Filtered Marker Kinematics—Rib Cage and Greater Trochanter (Hip) Table A.2(b) Filtered Marker Kinematics—Femoral Lateral Epicondyle (Knee) and Head of Fibula Table A.2(c) Filtered Marker Kinematics—Lateral Malleolus (Ankle) and Heel Table A.2(d) Filtered Marker Kinematics—Fifth Metatarsal and Toe Table A.3(a) Linear and Angular Kinematics—Foot Table A.3(b) Linear and Angular Kinematics—Leg Table A.3(c) Linear and Angular Kinematics—Thigh Table A.3(d) Linear and Angular Kinematics—½ HAT Table A.4 Relative Joint Angular Kinematics—Ankle, Knee, and Hip Table A.5(a) Reaction Forces and Moments of Force—Ankle and Knee Table A.5(b) Reaction Forces and Moments of Force—Hip Table A.6 Segment Potential, Kinetic, and Total Energies—Foot, Leg, Thigh, and ½ HAT Table A.7 Power Generation/Absorption and Transfer—Ankle, Knee, and Hip
Revision anterior cruciate ligament (ACL) surgery is becoming increasingly common as the number of primary ACL reconstructions continues to rise. Revision ACL surgery is indicated for selected patients with recurrent instability after a failed primary procedure. Rehabilitation for primary ACL reconstructions has undergone an evolution, although very little has been published regarding rehabilitation following revision surgery. It is established that rehabilitation protocols following revision reconstruction should be more conservative than those used for patients with primary ACL reconstructions. The goal of revision surgery and rehabilitation is to recreate a functional knee that is stable for activities of daily living, and perhaps, stable enough to permit a return to sport. Rehabilitation following revision surgery must be individualized depending on a variety of factors including: staging, removal of hardware, graft selection, graft fixation, chondral defects, meniscal pathology, associated instability patterns, and alignment concerns. However, as with primary ACL rehabilitation, in general, the goal of early range of motion is crucial.
A simple planar static model of the knee joint was developed to calculate effective moment arms for the quadriceps muscle. A pathway for the instantaneous center of rotation was chosen that gives realistic orientations of the femur relative to the tibia. Using the model, nonlinear force and moment equilibrium equations were solved at one degree increments for knee flexion angles from 0 (full extension) to 90 degrees, yielding patellar orientation, patellofemoral contact force and patellar ligament force and direction with respect to both the tibial insertion point and the tibiofemoral contact point. The computer-derived results from this two-dimensional model agree with results from more complex models developed previously from experimentally obtained data. Due to our model's simplicity, however, the operation of the patellar mechanism as a lever as well as a spacer is clearly illustrated. Specifically, the thickness of the patella was found to increase the effective moment arm significantly only at flexions below 35 degrees even though the actual moment arm exhibited an increase throughout the flexion range. Lengthening either the patella or the patellar ligament altered the force transmitted from the quadriceps to the patellar ligament, significantly increasing the effective moment arm at flexions greater than 25 degrees. We conclude that the levering action of the patella is an essential mechanism of knee joint operation at moderate to high flexion angles.
In this first part of a two-part paper, the results of measurement of static pressure distribution on the tibial surface of the knee are presented. Results with intact menisci have been obtained from 18 specimens. Eight of these specimens were the subject of further measurements following medial meniscectomy. The study has been carried out at various flexion angles of the knee with the joint subjected to a compressive force, with or without an initial passive relative displacement between the joint members. The results indicate that a significant fraction of the joint compressive load is transmitted through the menisci and that total meniscectomy causes a drastic alteration in the pressure distribution on the tibial surface. Clinical implications of these results, in terms of post-meniscectomy degenerative changes and mechanism of meniscal lesions, have been discussed.
The hypothesis tested in this article was that the three-dimensional intersegmental knee loads would be reduced in cycling by foot/pedal platforms which permitted relative motion between the foot and pedal. To test this hypothesis, pedal load and lower limb kinematic data were collected from 11 subjects who pedaled with four foot/pedal platforms mounted on a six-load-component dynamometer. One of the four platforms did not allow any relative foot/pedal movement while the other three permitted either medial/lateral translation, adduction/abduction rotation or inversion/eversion rotation. Three-dimensional intersegmental knee loads were computed for each of the four platforms using a previously reported biomechanical model. A number of quantities describing each of the intersegmental knee load components was computed and compared using analysis of variance techniques. The key results were that the medial/lateral translation platform did not cause significant differences in intersegmental knee load quantities relative to those for the fixed platform. However, both of the platforms permitting rotations significantly reduced many but did not significantly increase any intersegmental knee load quantities. Of these two platforms, the abduction/abduction platform significantly reduced both the axial and varus/valgus knee moments while the inversion/eversion platform significantly reduced only varus/valgus moments. These results have application to bicycle pedal design where the goal is to reduce intersegmental knee loads, hence possibly alleviating overuse knee injuries.
The selection of an appropriate and/or standardized method for representing 3-D joint attitude and motion is a topic of popular debate in the field of biomechanics. The joint coordinate system (JCS) is one method that has seen considerable use in the literature. The JCS consists of an axis fixed in the proximal segment, an axis fixed in the distal segment, and a "floating" axis. There has not been general agreement in the literature on how to select the body fixed axes of the JCS. The purpose of this paper is to propose a single definition of the body fixed axes of the JCS. The two most commonly used sets of body fixed axes are compared and the differences between them quantified. These differences are shown to be relevant in terms of practical applications of the JCS. Argumentation is provided to support a proposal for a standardized selection of body fixed axes of the JCS consisting of the axis ê1 embedded in the proximal segment and chosen to represent flexion-extension, the "floating" axis ê2 chosen to represent ad-abduction, and the axis ê3 embedded in the distal segment and chosen to represent axial rotation of that segment. The algorithms for the JCS are then documented using generalized terminology.
To provide a scientific basis for the design of bicycle pedals which possibly alleviate over-use knee injuries, two hypotheses were tested in the present study. The two hypotheses were: (1) that the three-dimensional pedal constraint loads; and (2) that the three-dimensional intersegmental knee loads would be reduced more significantly by a foot/pedal platform allowing both adduction/abduction and inversion/eversion rotations simultaneously than by a platform which allowed either rotation individually. To test these hypotheses, pedal load and lower limb kinematic data were collected from 10 subjects who pedaled with four pedal platforms which allowed zero, one, and two degrees of freedom. A number of quantities describing both pedal loads and intersegmental knee loads was computed for each of the four pedal platforms using a previously reported biomechanical model. The quantities included the positive and negative extremes, averages, and areas, as well as the total absolute area and RMS. Quantities were compared using analysis of variance techniques. The key results were that there were significant reductions in the coupled nondriving moments at the pedal for the dual-rotation platform compared to each of the single-rotation cases. The significant reductions in the coupled moments at the pedal were not manifest at the knee. However, a general nonsignificant reduction in both coupled knee moments was evident. Also, the valgus knee moment was significantly reduced by the dual-rotation platform compared to the inversion/eversion only design. Although the axial knee moment was not significantly reduced by the dual-rotation platform over the adduction/abduction design, there was a general nonsignificant reduction. The lack of significance in knee load results occurred because of high intersubject variability. Accordingly, load reduction benefits made by introducing the second degree of freedom need to be considered individually.
A study was conducted to investigate the effects of walking speed on the magnitude of the heel strike initiated shock waves that propagate throughout the human musculoskeletal system.
Subjects walking on a treadmill at various speeds were used to acquire the experimental data regarding the heel strike-initiated shock waves. Fifteen young healthy men participated in this study. Each one walked on the treadmill at five various speeds, and their associated cadences, while the heel strike induced shock waves were recorded at the tibial tuberosity for each speed during a 16-s period at a sampling rate of 1 kHz.
The obtained data reveal a significant increase in the dynamic loading experienced by the human musculoskeletal system with an increase in the walking speed.
The analysis of the recorded acceleration suggests that an increase in walking speed contributes to an increase in dynamic loading on the human musculoskeletal system. Further, the evidence indicates that dynamic loading increases with the increase in speed at five times the rate of the ground reaction force increase.
A biarticulating two-dimensional model of the patellofemoral joint has been developed using geometric and force equilibrium constraints to calculate the orientation of the patella about its mediolateral axis. The equations developed from these constraints were solved using an iterative numerical procedure. The model predicts and explains the proximal rolling of the patella on the femur during flexion; it predicts transfer of contact from the trochlea to the femoral condyles at high knee flexion angles. Variation with flexion angle of the patellar mechanism angle and the patellofemoral joint reaction force magnitude agree well with published experimental results.
Objective:
The purpose of this study was to compare lower extremity generalized muscle moments across two workloads during recumbent bicycling in younger and older healthy adults.
Design:
The study design was a comparative investigation of cycling patterns.
Background:
Biomechanical data regarding muscle activation, kinematic, and kinetic patterns have been presented for upright cycling, but only a few studies have evaluated biomechanical patterns during the alternative configuration of recumbent cycling.
Methods:
Twenty-four healthy adults, classified by age into two different groups, under 35 and over 50 years of age, rode a recumbent bicycle at a constant cadence (60-65 rpm) and at two different resistances (0.5 and 1.0 kg m) while kinematic and kinetic data were recorded. General muscle moments were calculated using joint kinematic and kinetic data via inverse dynamic equations.
Results:
The ankle general muscle moment remained plantar flexor throughout the pedaling cycle; the knee general muscle moment remained flexor throughout the cycle, except during the power phase of the higher workload where an extensor general muscle moment was observed; and the hip general muscle moment was extensor with a transient flexor general muscle moment period during the recovery phase. Increased workload led to increases in ankle plantar flexor and knee extensor general muscle moment magnitudes, but no changes at the hip. Age had no effect on general muscle moment magnitudes or patterns.
Conclusions:
Configurational differences between the upright and recumbent bicycle do not affect patterns, but the total output requirements do affect the magnitudes of the general muscle moments.
Relevance:
Based on previous studies, the recumbent bicycle appears to be a safe rehabilitation tool for post-cerebrovascular accident and cardiorespiratory patients, but in order to more properly and efficiently use the recumbent bicycle as a rehabilitation tool, normative biomechanical data are necessary. The current study is the first such investigation to report normative data of lower extremity general muscle moment patterns during recumbent cycling. Effects of age and workload were also demonstrated.
Despite the growing popularity in recent years of the elliptical trainer aerobic exercise modality the physiological changes induced following a training program using elliptical trainers remains unknown. The present study investigated the metabolic and cardiorespiratory improvements following a 12-week aerobic training program using elliptical trainer, treadmill or stair-climbing modalities.
Twenty-two moderately active females (28.6 +/- 5.3 y, 1.65 +/- 0.05 m) were randomly assigned to treadmill running (n=7), elliptical trainer (n=8) or stair-climber (n=7) groups and trained 3 days x week(-1) initially at 70-80% of maximum heart rate (HRmax) for 30 min, progressing to 80-90% HRmax for 40 min. Subjects performed incremental exercise to volitional exhaustion using an electronically loaded cycle ergometer before and upon completion of the program. In addition, subjects performed sub-maximal fixed load tests at 0, 4, 8 and 12 weeks, using ergometers specific to their exercise group.
No significant inter-group differences were recorded for pre-training VO2max or VEmax. Significant (p<0.05) post-training increases in cycling VO2max and VEmax were observed for treadmill (mean +/- SEM, 40.7 +/- 2.2 vs 43.4 +/- 2.6 ml x kg(-1) x min(-1) and 82.9 +/- 5.1 vs 90.2 +/- 6.4 l x min(-1)), elliptical trainer (36.9 +/- 2.5 vs 39.6 +/- 2.4 ml x kg(-1) x min(-1) and 86.8 +/- 2.3 vs 92.5 +/- 4.1 l x min(-1)) and stair-climber (37.4 +/- 2.9 vs 39.2 +/- 3.1 ml x kg(-1) x min(-1) and 95.9 +/- 5.8 vs 97.4 +/- 5.8 l x min(-1)) modalities, however, the increases were not significantly different between groups. For all groups, sub-maximal HR significantly decreased from week 0 to 4, and from week 4 to 8.
In moderately active females similar physiological improvements were observed using stair-climber, elliptical trainer and treadmill running when training volume and intensity were equivalent.
Previous findings from studies of demanding tasks in humans and slope walking in quadrupeds suggest that human slope walking may require specialized neural control strategies. The goal of this investigation was to gain insight into these strategies by quantifying lower limb kinematics and kinetics during up- and downslope walking. Nine healthy volunteers walked at a self-selected speed on an instrumented ramp at each of five grades (-39%, -15%, 0%, +15%, +39%; or -21 degrees, -8.5 degrees, 0 degrees, +8.5 degrees, +21 degrees, respectively). For each subject, the selected speed was maintained at all grades to minimize the effect of speed on gait dynamics. Points of interest were identified in the kinematic and kinetic outcome measures and compared across grades; a significant grade effect was found for all points except the magnitude of the peak hip extensor moment during late stance. Kinematic postural changes were consistent with the need to raise the limb for toe clearance and heel strike and to lift the body during upslope walking, and to control the descent of the body during downslope walking. The support moment increased significantly during both upslope and downslope walking compared to level: the increases were predominantly due to the increasing hip extensor moment during upslope walking, and to the increasing knee extensor moment during downslope walking. In addition, the hip and knee joint moment patterns showed significant differences from the patterns observed during level walking. This non-uniform distribution of joint moment increases during up- and downslope walking compared to level walking suggests that these three tasks are not governed by the same control strategy.
This paper is an analysis of the motion of the leg and foot in the swing phase of a step. The analysis is based on the hypothesis that the behavior will be such as to minimize the amount of mechanical work done. Results of the analysis are the geometric position of the leg and the equivalent forces in the hip and knee joints as functions of time. Also included is the amount of work done as a function of cadence. Comparison is made with experimental results that are available in the literature.
Recalcitrant patellar tendinosis is difficult to treat, and results are varied.
Surgical removal of necrotic tissue, surgical stimulation of remaining tendon, and aggressive and specific rehabilitation after patellar tendonectomy will allow athletes to return to sports.
Case series; Level of evidence, 4.
From December 1996 to July 2002, 16 high-level athletes (4 professional, 2 Olympic, 9 collegiate, 1 preparatory), aged 16 to 25 years (mean, 19.7 years), with 22 symptomatic patellar tendons had failed nonoperative care of their patellar tendinosis symptoms and were unable to compete effectively in their sports. Magnetic resonance imaging showed confirmation of disease, with typical findings being necrosis in the posterior half of an abnormally thick patellar tendon, often in conjunction with partial tearing of the posterior half with a compensatory enlargement of the anterior half. Each patient then underwent tendonectomy of the necrotic portion in conjunction with stimulation of the remaining tendon by making multiple longitudinal cuts in the tendon. Patients participated in a postoperative rehabilitation protocol that included immediate range of motion, full flexion, and immediate high-repetition, low-resistance quadriceps muscle exercise.
Subjective improvement was noted in all athletes. Return to the same sport at prior level of intensity was accomplished by 14 of 16 patients (87.5%) at a mean of 8.1 months (range, 3-12 months).
Overall, tendonectomy, surgical tendon stimulation, and aggressive postoperative rehabilitation were found to be a safe, effective way to return high-level athletes to their sports.
The effecs of sloped surfacesonlocomotion:akinematicandkineticanalysis
- A N Lay
- C J Hass
LAY, A. N., C. J. HASS, and R. J. GREGOR. The effecs of sloped surfacesonlocomotion:akinematicandkineticanalysis. J Biomech. 39:1621–1628, 2006
Sports Participation Topline Report: Sporting Goods Manufacturers Association
- Sporting Goods
- Association
SPORTING GOODS MANUFACTURERS ASSOCIATION. Sports Participation Topline Report. Washington, DC: Sporting Goods Manufacturers Association, 2006.