Kinematics of cycling in relation to anterior knee pain and patellar tendinitis

The coronal and sagittal plane leg movements of 24 experienced male cyclists were assessed using video analysis while cycling on a Kingcycle windload simulator. The cyclists were grouped into those with a history of injury and an asymptomatic group on the basis of self-reported injury status. The ages, cycling experience, competition distances and competition speeds of the two groups were compared using Student's t-test. No significant differences (P?<0.05) were found for any of these variables. The maximum and minimum shank adduction, shank adduction velocities, knee flexion and ankle dorsiflexion values were also compared using Student's t-test. Significant differences were found at the point of maximum adduction (1.9°; P?=?0.019) and minimum dorsiflexion (4.9°; P?=?0.014). These differences indicated more dorsiflexion and greater abduction on the part of the symptomatic cyclists, supporting previous research that found that cyclists with a history of injury differ from those without a history of injury in the coronal plane leg movement patterns they adopt. Also, the most extreme medial position of the knee relative to the ankle occurred during knee extension. This supports the potential injury mechanism proposed by Francis (1986), which had previously only been examined using coronal plane kinematics.     

Effect of a preventive intervention programme on the prevalence of anterior knee pain in volleyball players

Abstract

Chronic knee disorders, such as patellofemoral pain syndrome and patellar tendinosis, are common injuries in volleyball players. Using a randomized clinical trial, the aim of the present study was to determine the effect of a 4-month in-season intervention programme on the prevalence of anterior knee pain in volleyball players. No significant differences were observed between the intervention and control group for the prevalence of anterior knee pain after the intervention programme (odds ratio =1.58 [95% confidence interval: 0.60–4.20]). Also, no significant differences were observed for individuals with previously sustained anterior knee pain (OR =0.81 [95% CI: 0.33–2.20]). It was revealed that the risk for recurrent anterior knee pain is significantly higher than the risk for newly sustained anterior knee pain (OR =5.79 [95% CI: 1.59–21.00]). In conclusion, we were unable to confirm any preventive effect of the intervention programme on the prevalence of anterior knee pain. However, a previous study using the same intervention and measuring the effect on the intrinsic risk factors of anterior knee pain showed a positive effect.     

Influence of saddle setback on knee joint forces in cycling

Abstract

Knee functional disorders are one of the most common lower extremity non-traumatic injuries reported by cyclists. Incorrect bicycle configuration may predispose cyclist to injury but the evidence of an effect of saddle setback on knee pain remains inconclusive. The aim of this study was to determine the effect of saddle setback on knee joint forces during pedalling using a musculoskeletal modelling approach. Ten cyclists were assessed under three saddle setback conditions (range of changes in saddle position ~6 cm) while pedalling at a steady power output of 200 W and cadence of 90 rpm. A cycling musculoskeletal model was developed and knee joint forces were estimated using an inverse dynamics method associated with a static optimisation procedure. Our results indicate that moving the saddle forwards was not associated with an increase of patellofemoral joint forces. On the contrary, the tibiofemoral mean and peak compression force were 14 and 15% higher in the Backward than in the Forward condition, respectively. The peak compression force was related to neither pedal force nor quadriceps muscle force but coincided with the eccentric contraction of knee flexor muscles. These findings should benefit bike fitting practitioners and coaches in the design of specific training/rehabilitation protocols.     

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/m^2, 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.     

推拿对膝关节骨性关节炎髌韧带、关节 软骨作用效应的动物实验研究

采用点揉、点穴、膝关节摇法、膝关节屈伸等推拿手法,对实验兔骨关节炎实施手法,通过对膝关节活动度、髌韧带拉伸长度及强度的对照比较,证明推拿治疗能改善关节活动度,恢复韧带弹性。通过检测和对比软骨厚度以及IL-1、IL-6在软骨中的平均光密度表达,证实推拿可使炎性反应明显减轻,关节软骨缺失得到延缓。     

The effect of torsional shoe sole stiffness on knee moment and gross efficiency in cycling

Altering torsional stiffness of cycling shoe soles may be a novel approach to reducing knee joint moments and overuse injuries during cycling. We set out to determine if the magnitude of three-dimensional knee moments were different between cycling shoe soles with different torsional stiffnesses. Eight trained male cyclists cycled at 90% lactate threshold power output in one of two cycling shoe conditions in a randomized crossover design. The shoe sole was considered torsionally flexible (FLEX) compared to a relatively stiffer (STIFF) sole. Gross efficiency (GE) and knee joint moments were quantified. No significant effect of shoe condition was seen in GE (21.4 ± 1.1% and 20.9 ± 1.6% for FLEX and STIFF, respectively, P = 0.12), nor in three-dimensional knee moments. 4 of the 8 subjects had reduced knee moments in at least 2 of the 3 moment directions. These “responders” were significantly shorter (1.73 ± 0.02 m vs 1.81 ± 0.04 m, P = 0.017) and had a higher relative maximal aerobic power (MAP) (4.6 ± 0.3 W?kg-1 vs 3.9 ± 0.3 W?kg-1, P = 0.024) compared to non-responders. These results suggest that certain shoe characteristics may influence certain individuals differently because these participants belong to different “functional groups”; certain individuals may respond positively to FLEX, while others may not. Further studies should test this proposed hypothesis.     

Hydration status affects mood state and pain sensation during ultra-endurance cycling

Laboratory-based studies indicate mild dehydration adversely affects mood. Although ultra-endurance events often result in mild to moderate dehydration, little research has evaluated whether the relationship between hydration status and mood state also exists in these arduous events. Therefore, the purpose of this study was to evaluate how hydration status affected mood state and perceptual measures during a 161 km ultra-endurance cycling event. One hundred and nineteen cyclists (103 males, 16 females; age = 46 ± 9 years; height = 175.4 ± 17.9 cm; mass = 82.8 ± 16.3 kg) from the 2011 and 2013 Hotter’N Hell events participated. Perceived exertion, Thermal, Thirst, and Pain sensations, Brunel Profile of Mood States, and urine specific gravity (USG) were measured pre- (~1 h before), mid- (~97 km), and post-ride. Participants were classified at each time point as dehydrated (USG ≥ 1.022) or euhydrated (USG ≤ 1.018). Independent of time point, dehydrated participants (USG = 1.027 ± 0.004) had decreased Vigour and increased Fatigue, Pain, Thirst, and Thermal sensations compared to euhydrated participants (USG = 1.012 ± 0.004; all P < 0.01). USG significantly correlated with Fatigue (r = 0.36), Vigour (r = ?0.27), Thirst (r = 0.15), and Pain (r = 0.22; all P < 0.05). In conclusion, dehydrated participants had greater Fatigue and Pain than euhydrated participants. These findings indicate dehydration may adversely affect mood state and perceptual ratings during ultra-endurance cycling.     

Recurrent pain and discomfort in relation to fitness and physical activity among young school children

Abstract

As an increase in pain symptoms among children has been shown in the last decades, the aim of this study was to describe perceptions of recurrent pain, measured physical fitness and levels of reported physical activity (PA) in children, and to investigate if any associations between PA, fitness and recurrent pain could be identified. A school-based study comprised 206 Swedish children 8–12 years old, 114 boys, 92 girls. A questionnaire with questions about perceived pain, self-reported PA and lifestyle factors was used. Health-related fitness was assessed by 11 physical tests. A physical index was calculated from these tests as a z score. High physical index indicated high fitness and low physical index indicated low fitness. ANOVA test, chi-square test and logistic regression analysis were used to compare active and inactive children. The prevalence of one pain location (head, abdomen or back) was 26%, two 11% and three 4% (n=206). Female gender, living in single-parent families, low PA and low subjective health were associated with reported recurrent pain. Children reporting high levels of PA had high physical index and reported low prevalence of pain symptoms. The physical index and level of self-reported PA decreased gradually the more pain locations. Physically active children had higher fitness levels and reported less pain symptoms than inactive peers. Coping with pain is an integral part of PA, and active children learn to cope with unpleasant body sensations which together with high fitness may reduce the perception of pain.     

Biomechanical analysis of knee and trunk in badminton players with and without knee pain during backhand diagonal lunges

The contribution of core neuromuscular control to the dynamic stability of badminton players with and without knee pain during backhand lunges has not been investigated. Accordingly, this study compared the kinematics of the lower extremity, the trunk movement, the muscle activation and the balance performance of knee-injured and knee-uninjured badminton players when performing backhand stroke diagonal lunges. Seventeen participants with chronic knee pain (injured group) and 17 healthy participants (control group) randomly performed two diagonal backhand lunges in the forward and backward directions, respectively. This study showed that the injured group had lower frontal and horizontal motions of the knee joint, a smaller hip–shoulder separation angle and a reduced trunk tilt angle. In addition, the injured group exhibited a greater left paraspinal muscle activity, while the control group demonstrated a greater activation of the vastus lateralis, vastus medialis and medial gastrocnemius muscle groups. Finally, the injured group showed a smaller distance between centre of mass (COM) and centre of pressure, and a lower peak COM velocity when performing the backhand backward lunge tasks. In conclusion, the injured group used reduced knee and trunk motions to complete the backhand lunge tasks. Furthermore, the paraspinal muscles contributed to the lunge performance of the individuals with knee pain, whereas the knee extensors and ankle plantar flexor played a greater role for those without knee pain.     

Metabolic demand and muscle damage induced by eccentric cycling of knee extensor and flexor muscles

The aim of this study was to examine the metabolic demand and extent of muscle damage of eccentric cycling targeting knee flexor (FLEX) and knee extensor (EXT) muscles. Methods: Eight sedentary men (23.3?±?0.7?y) underwent two eccentric cycling sessions (EXT and FLEX) of 30?min each, at 60% of the maximum power output. Oxygen consumption (VO₂), heart rate (HR) and rated perceived exertion (RPE) were measured during cycling. Countermovement and squat jumps (CMJ and SJ), muscle flexibility, muscle soreness and pain pressure threshold (PPT) of knee extensor and flexor muscles were measured before, immediately after and 1–4 days after cycling. Results: FLEX showed greater VO₂ (+23%), HR (+14%) and RPE (+18%) than EXT. CMJ and SJ performance decreased similarly after cycling. Muscle soreness increased more after EXT than FLEX and PPT decreased in knee extensor muscles after EXT and decreased in knee flexor muscles after FLEX. Greater loss of muscle flexibility in knee flexor muscles after FLEX was observed. Conclusion: Eccentric cycling of knee flexor muscles is metabolically more demanding than that of knee extensors, however muscle damage induced is similar. Knee flexors experienced greater loss of muscle flexibility possibly due to increased muscle stiffness following eccentric contractions.     

The effect of patellar taping on EMG activity of vasti muscles during squatting in individuals with patellofemoral pain syndrome

Although patellar taping has been shown to reduce pain in participants with patellofemoral pain syndrome, the mechanisms of pain reduction have not completely been established following its application. The purpose of this study was to evaluate EMG activity of vastus medialis and vastus lateralis following the application of patellar taping during a functional single leg squat. Both vastus medialis obliquus-vastus lateralis onset and vastus medialis obliquus/vastus lateralis amplitude of 18 participants with patellofemoral pain syndrome and 18 healthy participants as controls were measured using an EMG unit. This procedure was performed on the affected knee of participants with patellofemoral pain syndrome, before, during, and after patellar taping during unilateral squatting. The same procedure was also performed on the unaffected knees of both groups. The mean values of vastus medialis obliquus-vastus lateralis onset prior to taping (2.54 ms, s = 4.35) were decreased significantly following an immediate application of tape (-3.22 ms, s = 3.45) and after a prolonged period of taping (-6.00 ms, s = 3.40 s) (P < 0.05). There was also a significant difference between the mean values of vastus medialis obliquus-vastus lateralis onset among controls (-2.03 ms, s = 6.04) and participants with patellofemoral pain syndrome prior to taping (P < 0.05). However, there were no significant difference between the ranked values of vastus medialis obliquus/vastus lateralis amplitude of the affected and unaffected knees of participants with patellofemoral pain syndrome and controls during different conditions of taping (P > 0.05). Decreased values of vastus medialis obliquus-vastus lateralis onset may contribute to patellar realignment and explain the mechanism of pain reduction following patellar taping in participants with patellofemoral pain syndrome.     

Muscle activation characteristics in cross-country skiers with a history of anterior compartment pain

A large proportion of elite cross-country skiers suffer from chronic anterior compartment syndrome (CACS). This study used surface electromyograms (EMGs) to investigate whether differences existed in the activation characteristics of the tibialis anterior muscle between elite cross-country skiers with a history of anterior compartment pain (symptomatic group) and a pain-free control group. Based on self-reported pain symptoms, twelve young, national-level cross-country ski athletes were assigned to a symptomatic group (N = 5), a control group (N = 4), or analyzed individually if their diagnosis was not certain (N = 3). During skating, EMGs were recorded on five lower leg muscles. The relative increase in EMG power per step when increasing the effort level of skating was larger in the symptomatic group than in the control group for tibialis anterior (143 ± 12% vs. 125 ± 23%; Cohen's d = 1.17), peroneus longus (123 ± 24% vs. 107 ± 6%; d = 0.91), and gastrocnemius lateralis (167 ± 51% vs. 117 ± 12%; d = 1.64). The symptomatic group showed more power in the lower frequency bands of the tibialis anterior's EMG spectra (p < 0.001), whereas no group differences were found in other muscles (all p>0.2). Within the step cycle, these differences appeared in the swing phase and in the gliding phase during single leg support. The observed differences in the EMG spectra may serve as an early identification of athletes who are at risk of developing CACS.     

优秀散打运动员后鞭腿动作的运动学分析

运用高速摄影对8名优秀散打运动员后鞭腿动作进行解析分析。研究表明:各关节曲线中,髋关节速度较小且变化不大;膝关节、踝关节和脚尖的速度曲线变化明显;膝关节较早达到速度峰值,然后减速,接着在踢中目标瞬间踝和脚尖几乎同时达到速度最大值。     

Prevalence of shoulder pain in Swedish flatwater kayakers and its relation to range of motion and scapula stability of the shoulder joint

Few studies have investigated the incidence of injuries in kayakers. The aim was to study the prevalence of shoulder pain in competitive flatwater kayakers and to evaluate any differences in range of motion or scapula stability of the shoulder joint among kayakers with or without the history of shoulder pain. Thirty-one kayakers were participated in the study, and a questionnaire including background data was used. Shoulder range of motion was measured with a goniometer, and the participants were observed for scapula dyskinesis in flexion and abduction. Of the participating kayakers, 54.8% (n = 17) had experienced shoulder pain. Kayakers who had experienced shoulder pain showed a significantly lower degree of internal rotational range of motion versus kayakers with no reported shoulder pain, with a mean degree of internal rotation in the right shoulder 49.3 vs 60.0 (P = 0.017) and the left shoulder 51.9 vs 66.0 (P = 0.000). Kayakers who had experienced shoulder pain were also observed with a scapular dyskinesis (n = 15 of 17 kayakers) to a significantly higher degree (P = 0.001) than kayakers with no reported shoulder pain. Findings suggest that screening for scapular dyskinesis and testing for rotational range of motion in the shoulder joint is essential in order to treat and maybe prevent shoulder pain in kayakers.     

Kinetics and kinematics analysis of incremental cycling to exhaustion

Technique changes in cyclists are not well described during exhaustive exercise. Therefore the aim of the present study was to analyze pedaling technique during an incremental cycling test to exhaustion. Eleven cyclists performed an incremental cycling test to exhaustion. Pedal force and joint kinematics were acquired during the last three stages of the test (75%, 90% and 100% of the maximal power output). Inverse dynamics was conducted to calculate the net joint moments at the hip, knee and ankle joints. Knee joint had an increased contribution to the total net joint moments with the increase of workload (5–8% increase, p < 0.01). Total average absolute joint moment and knee joint moment increased during the test (25% and 39%, for p < 0.01, respectively). Increases in plantar flexor moment (32%, p < 0.01), knee (54%, p < 0.01) and hip flexor moments (42%, p = 0.02) were found. Higher dorsiflexion (2%, for p = 0.03) and increased range of motion (19%, for p = 0.02) were observed for the ankle joint. The hip joint had an increased flexion angle (2%, for p < 0.01) and a reduced range of motion (3%, for p = 0.04) with the increase of workload. Differences in joint kinetics and kinematics indicate that pedaling technique was affected by the combined fatigue and workload effects.     

Kinetics and kinematics analysis of incremental cycling to exhaustion

Technique changes in cyclists are not well described during exhaustive exercise. Therefore the aim of the present study was to analyze pedaling technique during an incremental cycling test to exhaustion. Eleven cyclists performed an incremental cycling test to exhaustion. Pedal force and joint kinematics were acquired during the last three stages of the test (75%, 90% and 100% of the maximal power output). Inverse dynamics was conducted to calculate the net joint moments at the hip, knee and ankle joints. Knee joint had an increased contribution to the total net joint moments with the increase of workload (5-8% increase, p < 0.01). Total average absolute joint moment and knee joint moment increased during the test (25% and 39%, for p < 0.01, respectively). Increases in plantar flexor moment (32%, p < 0.01), knee (54%, p < 0.01) and hip flexor moments (42%, p = 0.02) were found. Higher dorsiflexion (2%, for p = 0.03) and increased range of motion (19%, for p = 0.02) were observed for the ankle joint. The hip joint had an increased flexion angle (2%, for p < 0.01) and a reduced range of motion (3%, for p = 0.04) with the increase of workload. Differences in joint kinetics and kinematics indicate that pedaling technique was affected by the combined fatigue and workload effects.     

Development and reliability of the KIM cycling scale – a measurement tool for the development process to cycling independently

ABSTRACT

Background: Cycling has gained more attention as an important lifelong physical activity. Learning to cycle independently without assistance is a milestone for most children that requires time and practice to master. Cycling was recently added to the motor development model and so a valid and reliable measure of cycling ability is required to allow accurate assessment of the skill. Cycling has many health benefits along with being a commonly reported physical activity globally and therefore is an important skill to promote in early childhood and throughout life. To date, there are no measurement tools examining the developmental process to independent cycling in the early childhood years. The current study aimed to develop and assess the inter-rater and test-retest reliability of the ‘KIM Cycling Scale’.

Methods: Development of the scale occurred in four phases: (1) development of criteria and stages, which used observation of children when learning to cycle and expert panels to develop the initial developmental stages, (2) review of instructions and criteria and pilot inter-rater and test-retest reliability, to ensure that the scale could be used as a standalone scale without requiring further instructions (3) cycling intervention, which allowed assessment of the developmental nature of children along the scale as they learn to cycle independently and to assess typical and alternate routes to independent cycling and (4) inter-rater and test-retest reliability.

Results: Ninety children took part in phase 1, thirty-six children took part in phase 2, seventy-four children took part in phase 3 and one hundred and forty-nine children took part in phase 4. All three hundred and forty-nine children were between 2 and 6 years. The developed scale included eight stages in total. The scale was found to have excellent inter-rater reliability (ICC?=?0.97, 95% CI?=?0.96–0.98) and good to excellent test-retest reliability [(ICC?=?0.91, 95% CI?=?0.87–0.94) & (ICC?=?0.90, 95% CI?=?0.85–0.93)]. Typical routes to independent cycling along the scale were examined and reported as being step-wise on all occasions except one where a two stage jump was as common as the step-wise route. Alternate routes were also reported.

Conclusion: The current study developed a reliable measurement tool for assessing children between 2 and 6 years of age on the developmental process to independent cycling. Having a cycling scale will allow teachers and practitioners to assess competence in cycling and moreover, track changes in skill development. Furthermore, parents could also use the scale to better understand and better asses their child’s progression when learning to cycle.     

The association of bike fitting with injury,comfort, and pain during cycling: An international retrospective survey

Although bike fitting is recommended to help reduce injury risk, little empirical evidence exists to indicate an association between bike fitting and injury incidence. The aim of the study was to determine the effect of bike fitting on self-reported injury, comfort, and pain while cycling from a worldwide survey of cyclists. A total of 849 cyclists completed an online questionnaire between February and October 2016. Questionnaire collected data on respondent demographics, cycling profile, bike fitting, comfort and pain while cycling, and injury history. The main predictor variable was bike fitting (yes, by the respondent, i.e. user bike fitting; yes, by a professional service; or no). Covariates included demographic and cycling profile characteristics. Logistic regression models estimated the odds of injury within the last 12 months, reporting a comfortable body posture while cycling, and not reporting pain while cycling. Odds ratios (OR) with 95% confidence intervals (CI) were reported. User bike fitting was associated with increased odds of reporting a comfortable posture (OR?=?2.28, 95%CI: 1.06, 4.68). User (OR?=?2.35; 95%CI: 1.48, 3.84) and professional bike fitting (OR?=?2.35; 95%CI: 1.42, 3.98) were both associated with increased odds of not reporting pain while cycling. No associations were found between bike fitting and injury within the last 12 months. In conclusion, we found an association between bike fitting and reported comfort and pain while cycling. We recommend integrating bike fitting into cycling maintenance. However, further studies with longer follow-up are necessary to determine the presence of an association between bike fitting and injury.     

Electromechanical delay of the knee flexor muscles after anterior cruciate ligament reconstruction using semitendinosus tendon

The purpose of the study was to evaluate whether using only the semitendinosus as a tripled short graft would affect the electromechanical delay (EMD) of the knee flexors. EMD was evaluated in volunteers (N = 15) after they had undergone surgery for anterior cruciate ligament (ACL) reconstruction where the semitendinosus tendon alone was used as a graft. The results were compared with the intact leg and healthy controls (N = 15). After warming up, each subject performed four maximally explosive isometric contractions on an isokinetic dynamometer. Torques were measured by the dynamometer, while the electrical activity of the semitendinosus and biceps femoris muscles was detected using surface electromyography. EMD was found to be significantly increased (p = 0.001) in patients who had undergone ACL reconstruction compared to the controls. On the contrary, no significant differences (p = 0.235) were found for the biceps femoris muscle between the two groups. Similar results were found when the study group was compared with the intact leg group (p = 0.027 for semitendinosus and p = 0.859 for biceps femoris). Harvesting the semitendinosus tendon increases the EMD for the semitendinosus muscle but does not influence the EMD outcomes for the biceps femoris muscle.     

对优秀散打运动员后手直拳的运动学分析

文章探讨了右直拳动作的力学原理,并对如何提高右直拳速度进行了分析研究。结论认为:各关节速度曲线中肩关节速度最早变化且肩角变化在80-90°之间;肘关节、腕关节、拳峰速度曲线变化明显比肩关节较早达到速度峰值,在击中目标瞬间腕、拳峰几乎同时达到速度最大值。