Acute effects of lateral shoe wedges on joint biomechanics of patients with medial compartment knee osteoarthritis during stationary cycling

Validity, reliability, and bias between instrumented pedals and loadsol insoles during stationary cycling

The purpose of this study was to evaluate the validity and reliability of the loadsol in measuring pedal reaction force (PRF) during stationary cycling as well as lower limb symmetry. Ten healthy participants performed bouts of cycling at 1kg, 2kg, and 3kg workloads (conditions) on a cycle ergometer. The ergometer was fitted with instrumented pedals and participants wore loadsol plantar pressure insoles. A 3 x 2 (Condition x Sensor Type) ANOVA was used to examine the differences in measured peak PRF, impulse, and symmetry indices. Root mean square error, intraclass correlation coefficients, and Passing-Bablok regressions were used to further assess reliability and validity. The loadsol demonstrated poor (< 0.5) to excellent (> 0.9) agreement as measured by intraclass correlation coefficients for impulse and peak PRF. Passing-Bablok regression revealed a systematic bias only when assessing all workloads together for impulse with no bias present when looking at individual workloads. The loadsol provides a consistent ability to measure PRF and symmetry when compared to a gold standard of instrumented pedals but exhibits an absolute underestimation of peak PRF. This study provides support that the loadsol can identify and track symmetry differences in stationary cycling which means there is possible usage for clinical scenarios and interventions in populations with bilateral asymmetries such as individuals with knee replacements, limb length discrepancies, diabetes, or neurological conditions. Further investigation of bias should be conducted in longer cycling sessions to ensure that the loadsol system is able to maintain accuracy during extended use.

Muscle-driven simulations and experimental data of cycling

Muscle-driven simulations have provided valuable insights in studies of walking and running, but a set of freely available simulations and corresponding experimental data for cycling do not exist. The aim of this work was to develop a set of muscle-driven simulations of cycling and to validate them by comparison with experimental data. We used direct collocation to generate simulations of 16 participants cycling over a range of powers (40-216 W) and cadences (75-99 RPM) using two optimization objectives: a baseline objective that minimized muscle effort and a second objective that additionally minimized tibiofemoral joint forces. We tested the accuracy of the simulations by comparing the timing of active muscle forces in our baseline simulation to timing in experimental electromyography data. Adding a term in the objective function to minimize tibiofemoral forces preserved cycling power and kinematics, improved similarity between active muscle force timing and experimental electromyography, and decreased tibiofemoral joint reaction forces, which better matched previously reported in vivo measurements. The musculoskeletal models, muscle-driven simulations, simulation software, and experimental data are freely shared at https://simtk.org/projects/cycling_sim for others to reproduce these results and build upon this research.

Can changes of workrate and seat position affect frontal and sagittal plane knee biomechanics in recumbent cycling?

Changes in the workrate and seat position have been linked to changes in internal knee extension moment. However, there is limited research on effects of those changes on knee kinetics in recumbent bike. The purpose of this study was to examine the effects of different seat positions and workrates on KAbM, knee extension moment and perceived effort during stationary recumbent cycling. Fifteen cyclists cycled on a recumbent ergometer in 6 test conditions of pedalling in far, medium and close seat positions in each of the two workrates of 60 and 100 W at the cadence of 80 RPM. A three-dimensional motion analysis system and a pair of instrumented pedals collected kinematic and kinetic data. A 3 ×2 repeated measures ANOVA was used to examine the effect of seat positions and workrates on selected variables of interest. Different seat positions did not change either peak KAbM (p = 0.592) or knee extension moment (p = 0.132). Increased workrates significantly increased peak KAbM (p <0.001 and ηp2 =0.794) and knee extension moment (p <0.001 and ηp2=0.722). This study showed that the far or close seat position did not increase frontal-plane or overall knee joint loading and provided evidence for prescribing recumbent bike for healthy population.

Medial and Lateral Tibiofemoral Compressive Forces in Patients Following Unilateral Total Knee Arthroplasty During Stationary Cycling

Patients following unilateral total knee arthroplasty (TKA) display interlimb differences in knee joint kinetics during gait and more recently, stationary cycling. The purpose of this study was to use musculoskeletal modeling to estimate total, medial, and lateral tibiofemoral compressive forces for patients following TKA during stationary cycling. Fifteen patients of unilateral TKA, from the same surgeon, participated in cycling at 2 workrates (80 and 100 W). A knee model (OpenSim 3.2) was used to estimate total, medial, and lateral tibiofemoral compressive forces for replaced and nonreplaced limbs. A 2 × 2 (limb × workrate) and a 2 × 2 × 2 (compartment × limb × workrate) analysis of variance were run on the selected variables. Peak medial tibiofemoral compressive force was 23.5% lower for replaced compared to nonreplaced limbs (P = .004, G = 0.80). Peak medial tibiofemoral compressive force was 48.0% greater than peak lateral tibiofemoral compressive force in nonreplaced limbs (MD = 344.5 N, P < .001, G = 1.6) with no difference in replaced limbs (P = .274). Following TKA, patients have greater medial compartment loading on their nonreplaced compared to their replaced limbs and ipsilateral lateral compartment loading. This disproportionate loading may be cause for concern regarding exacerbating contralateral knee osteoarthritis.

Cycling kinematics in healthy adults for musculoskeletal rehabilitation guidance

Background

Stationary cycling is commonly used for postoperative rehabilitation of physical disabilities; however, few studies have focused on the three-dimensional (3D) kinematics of rehabilitation. This study aimed to elucidate the three-dimensional lower limb kinematics of people with healthy musculoskeletal function and the effect of sex and age on kinematics using a controlled bicycle configuration.

Methods

Thirty-one healthy adults participated in the study. The position of the stationary cycle was standardized using the LeMond method by setting the saddle height to 85.5% of the participant’s inseam. The participants maintained a pedaling rate of 10–12 km/h, and the average value of three successive cycles of the right leg was used for analysis. The pelvis, hip, knee, and ankle joint motions during cycling were evaluated in the sagittal, coronal, and transverse planes. Kinematic data were normalized to 0–100% of the cycling cycle. The Kolmogorov-Smirnov test, Mann-Whitney U test, Kruskal-Wallis test, and k-fold cross-validation were used to analyze the data.

Results

In the sagittal plane, the cycling ranges of motion (ROMs) were 1.6° (pelvis), 43.9° (hip), 75.2° (knee), and 26.9° (ankle). The coronal plane movement was observed in all joints, and the specific ROMs were 6.6° (knee) and 5.8° (ankle). There was significant internal and external rotation of the hip (ROM: 11.6°), knee (ROM: 6.6°), and ankle (ROM: 10.3°) during cycling. There was no difference in kinematic data of the pelvis, hip, knee, and ankle between the sexes (p = 0.12 to 0.95) and between different age groups (p = 0.11 to 0.96) in all anatomical planes.

Conclusions

The kinematic results support the view that cycling is highly beneficial for comprehensive musculoskeletal rehabilitation. These results might help clinicians set a target of recovery ROM based on healthy and non-elite individuals and issue suitable guidelines to patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04905-2.

Does saddle height influence knee frontal-plane biomechanics during stationary cycling?

INTRODUCTION

Cycling is a common modality for rehabilitation and exercise. However, there is a lack of information in the literature on the effects of saddle height adjustments on internal peak knee abduction moment, which is an important loading variable for the medial compartment of tibiofemoral joint for patients with knee osteoarthritis. The purpose of this study was to examine effects of saddle height on frontal-plane biomechanics of the knee during cycling.

METHODS

Fourteen recreational cyclists (age: 57.1 ± 6.37 years) performed 2-min bouts of cycling at three saddle heights of 40°, 30° and 20° knee extension angle at bottom crank position, at two workrates of 80 and 120 W. Three-dimensional kinematic, kinetic, and electromyography data were collected and analyzed using a 3 × 2 (height × workrate) analysis of variance (ANOVA).

RESULTS

There were no changes in internal knee abduction moment across saddle heights. Increases in saddle height from 40° to both 30° and 20° reduced the knee extension moment (d = 0.3 and 0.4, respectively, P = 0.012). Increases in workrate increased both knee abduction and extension moments (η²_p = 0.75 and 0.88, respectively, P < 0.001 for both).

CONCLUSIONS

Increased knee extension moment with decreased saddle height is likely to indicate increased knee joint load.

Increased Q-factor increases medial compartment knee joint contact force during cycling

As Q-Factor (QF: inter-pedal distance) is increased, the internal knee abduction moment (KAbM) also increases, however it is unknown if this increased KAbM is associated with increased medial compartment knee joint contact force in cycling. In the absence of in vivo measurement, musculoskeletal modeling simulations may provide a viable option for estimating knee joint contact forces in cycling. The primary purpose of this study was to investigate the effect of increasing QF on knee joint total (TCF), and medial (MCF) compartment contact force during ergometer cycling. The secondary purpose was to evaluate whether KAbM and knee extension moment are accurate predictors of MCF in cycling. Musculoskeletal simulations were performed to estimate TCF and MCF for sixteen participants cycling at an original QF (150 mm), and wide QF (276 mm), at 80 W and 80 rotations per minute. Paired samples t-tests were used to detect differences between QF conditions. MCF increased significantly, however, TCF did not change at wide QF. Peak knee extensor muscle force did not change at wide QF. Peak knee flexor muscle force was significantly reduced with wide QF. Regression analyses showed KAbM and knee extension moments explained 87.4% of the variance in MCF when considered alongside QF. The increase of MCF may be attributed to increased frontal-plane pedal reaction force moment arm. Future research may seek to implement QF modulation as a part of rehabilitation or training procedures utilizing cycling in cases where medial compartment joint loading is of importance.

Stationary cycling exercise for knee osteoarthritis: A systematic review and meta-analysis

OBJECTIVE

To evaluate effects of stationary cycling exercise on pain, function and stiffness in individuals with knee osteoarthritis.

DATA SOURCES

Systematic search conducted in seven databases (PubMed, Embase, Cochrane Library, Web of Science, EBSCO, PEDro, and CNKI) from inception to September 2020.

REVIEW METHODS

Included studies were randomized-controlled trials involving stationary cycling exercise conducted on individuals with knee osteoarthritis. End-trial weighted mean difference (WMD) and 95% confidence interval (CI) were analyzed, and random-effects models were used. Methodological quality and risk bias were assessed by using the Physiotherapy Evidence Database scale and Cochrane Collaboration tool, respectively.

RESULTS

Eleven studies with 724 participants were found, of which the final meta-analysis was performed with eight. Compared to a control (no exercise), stationary cycling exercise resulted in reduced pain (WMD 12.86, 95% CI 6.90-18.81) and improved sport performance (WMD 8.06, 95% CI 0.92-15.20); although most of the meta-analysis results were statistically significant, improvements in stiffness (WMD 11.47, 95% CI 4.69-18.25), function (WMD 8.28, 95% CI 2.44-14.11), symptoms (WMD 4.15, 95% CI -1.87 to 10.18), daily living (WMD 6.43, 95% CI 3.19 to 9.66) and quality of life (WMD 0.99, 95% CI -4.27 to 6.25) for individuals with knee osteoarthritis were not greater than the minimal clinically important difference values for each of these outcome measures.

CONCLUSIONS

Stationary cycling exercise relieves pain and improves sport function in individuals with knee osteoarthritis, but may not be as clinically effective for improving stiffness, daily activity, and quality of life.

Knee joint biomechanics of patients with unilateral total knee arthroplasty during stationary cycling

Stationary cycling is typically recommended following total knee arthroplasty (TKA) operations. However, knee joint biomechanics during cycling remains mostly unknown for TKA patients. Biomechanical differences between the replaced and non-replaced limb may inform applications of cycling in TKA rehabilitation. The purpose of this study was to examine the knee joint biomechanics of TKA patients during stationary cycling. Fifteen TKA participants cycled at 80 revolutions per minute and workrates of 80 W and 100 W while kinematics (240 Hz) and pedal reaction forces using a pair of instrumented pedals (1200 Hz) were collected. A 2x2 (limb × workrate) repeated measures ANOVA was run with an alpha of 0.05. Peak knee extension moment (KEM, p = 0.034) and vertical pedal reaction force (p = 0.038) were significantly reduced in the replaced limbs compared to non-replaced limbs by 21.3% and 5.3%, respectively. Peak KEM did not change for TKA patients with the increased workrate (p = 0.750). However, both peak hip extension moment (p = 0.009) and ankle plantarflexion moment (p = 0.017) increased due to increased workrate. Patients following TKA showed similar decreases in peak KEM and vertical pedal reaction force in their replaced compared to non-replaced limbs, as previously seen in gait. Patients of TKA may rely on their hip and ankle extensors to increases in workrate. Increasing intensity by 20 W did not exacerbate any inter-limb differences for peak KEM and vertical PRF.

Increased Q-Factor increases frontal-plane knee joint loading in stationary cycling

BACKGROUND

Q-Factor (QF), or the inter-pedal width, in cycling is similar to step-width in gait. Although increased step-width has been shown to reduce peak knee abduction moment (KAbM), no studies have examined the biomechanical effects of increased QF in cycling at different workrates in healthy participants.

METHODS

A total of 16 healthy participants (8 males, 8 females, age: 22.4 ± 2.6 years, body mass index: 22.78 ± 1.43 kg/m², mean ± SD) participated. A motion capture system and customized instrumented pedals were used to collect 3-dimensional kinematic (240 Hz) and pedal reaction force (PRF) (1200 Hz) data in 12 testing conditions: 4 QF conditions-Q1 (15.0 cm), Q2 (19.2 cm), Q3 (23.4 cm), and Q4 (27.6 cm)-under 3 workrate conditions-80 watts (W), 120 W, and 160 W. A 3 × 4 (QF × workrate) repeated measures of analysis of variance were performed to analyze differences among conditions (p < 0.05).

RESULTS

Increased QF increased peak KAbM by 47%, 56%, and 56% from Q1 to Q4 at each respective workrate. Mediolateral PRF increased from Q1 to Q4 at each respective workrate. Frontal-plane knee angle and range of motion decreased with increased QF. No changes were observed for peak vertical PRF, knee extension moment, sagittal plane peak knee joint angles, or range of motion.

CONCLUSION

Increased QF increased peak KAbM, suggesting increased medial compartment loading of the knee. QF modulation may influence frontal-plane joint loading when using stationary cycling for exercise or rehabilitation purposes.

Lower-limb joint reaction forces and moments during modified cycling in healthy controls and individuals with knee osteoarthritis

BACKGROUND

Osteoarthritis (OA) is a clinical problem affecting an estimated 27 million adults in the United States, with the only clear treatment options being pain management. Cycling is an integral component of exercise for individuals with knee osteoarthritis, while the joint reaction forces during cycling remain unknown.

METHODS

Thirteen subjects with medial compartment knee osteoarthritis and eleven healthy subjects performed a cycling protocol with a neutral pedal and four pedal modifications. Six hundred muscle-actuated inverse-dynamic simulations (24 subjects, 5 trials in each of 5 conditions) were performed to estimate joint reaction force differences between conditions.

FINDINGS

Subjects with knee osteoarthritis had many significant changes among them was a reduction in knee adduction-abduction moment by 45% (5° lateral wedge), 77% (10° lateral wedge), 54% (5° toe-in) and 58% (10° toe-in). Conversely the healthy subjects had no significant changes in the knee adduction-abduction moment for the lateral wedge conditions and the 5° toe-in but did decrease by 18% for the 10° toe-in condition. When comparing the cohorts across the different pedal conditions, the data showed many significant differences among the groups.

INTERPRETATION

This study showed that while cycling in different pedal modifications, the knee osteoarthritis subjects had more beneficial changes in their knee adduction-abduction moment compared to the healthy subjects with the lateral-wedge modification resulting in the greatest impact on the subjects with knee osteoarthritis. Both groups had greater contact forces at the hip and ankle across pedal modifications compared to neutral. For the knee, subjects with osteoarthritis mostly decreased their knee contact forces but the healthy subjects mostly increased these forces with all pedal modifications.

Individuals With Knee Osteoarthritis Demonstrate Interlimb Asymmetry in Pedaling Power During Stationary Cycling

Cycling is commonly prescribed for physical rehabilitation of individuals with knee osteoarthritis (OA). Despite the known therapeutic benefits, no research has examined interlimb symmetry of power output during cycling in these individuals. We investigated the effects of external workload and cadence on interlimb symmetry of crank power output in individuals with knee OA versus healthy controls. A total of 12 older participants with knee OA and 12 healthy sex- and age-matched controls were recruited. Participants performed 2-minute bouts of stationary cycling at 4 workload-cadence conditions (75 W at 60 rpm, 75 W at 90 rpm, 100 W at 60 rpm, and 100 W at 90 rpm). Power output contribution of each limb toward total crank power output was computed over 60 crank cycles from the effective component of pedal force, which was perpendicular to the crank arm. Across the workload-cadence conditions, the knee OA group generated significantly higher power output with the severely affected leg compared with the less affected leg (10% difference; P = .02). Healthy controls did not show interlimb asymmetry in power output (0.1% difference; P > .99). For both groups, interlimb asymmetry was unaffected by external workload and cadence. Our results indicate that individuals with knee OA demonstrate interlimb asymmetry in crank power output during stationary cycling.