BACKGROUND:Individuals with chronic ankle instability are prone to inversion ankle sprains during landing.Moderately increasing the foot toe-out angle during landing may reduce the occurrence of inversion ankle sprains,but no studies have directly demonstrated this effect. OBJECTIVE:To explore the effect of increased toe-out angle during landing on the peak inversion angle,peak angular velocity,and the time to peak inversion among individuals with and without chronic ankle instability. METHODS:A total of 60 participants were recruited for this study,including 30 individuals with chronic ankle instability and 30 without chronic ankle instability.The study utilized a simulated sprain apparatus for drop-landing tests,featuring a platform that could tilt forward by 24° and inward by 15°,thus simulating the foot position during an ankle inversion sprain.Participants were required to perform drop-landing tests under two landing conditions:natural landing and toe-out landing,with the latter involving a greater foot toe-out angle,over 150%more than the former.Kinematic data of participants were recorded using a 12-camera three-dimensional motion capture system.Data analysis was conducted using two-way repeated measures analysis of variance and Spearman correlation analysis. RESULTS AND CONCLUSION:(1)Significant main effects of condition were found for peak inversion angle during drop-landing(P<0.001,η2 p=0.270),peak inversion velocity(P=0.015,η2 p=0.098),and peak inversion time(P<0.001,η2 p=0.260);a significant main effect of group was found for peak inversion velocity(P=0.029,η2 p=0.080).(2)There were significant negative correlations between the foot toe-out angle at landing and the peak ankle inversion angle(P=0.021,r=-0.310;P=0.042,r=-0.278)as well as the peak inversion time(P=0.018,r=-0.312;P=0.021,r=-0.309)in both chronic ankle instability and non-chronic ankle instability groups.Moreover,a significant negative correlation was also found between the foot toe-out angle and peak inversion velocity in the chronic ankle instability group(P=0.021,r=-0.312).(3)It is indicated that increasing the foot toe-out angle at landing can reduce the peak inversion angle,peak inversion velocity,and the peak inversion time during landing in patients with chronic ankle instability and non-chronic ankle instability,thereby decreasing the risk of ankle inversion sprains.

BACKGROUND:Unilateral chronic ankle instability has adverse effects on the affected limb,and evidence has shown that the nonaffected side may be similarly involved,but direct evidence is currently lacking.OBJECTIVE:To investigate the effects of unilateral chronic ankle instability on bilateral postural stability,proprioception,plantar tactile sensation,and muscle strength.METHODS:A total of 122 participants were recruited in this study,including 67 individuals with unilateral chronic ankle instability and 55 individuals without chronic ankle instability.Postural stability,proprioception,plantar tactile sensation and muscle strength were tested bilaterally in individuals with unilateral chronic ankle instability,as well as in those without chronic ankle instability.One-way analysis of variance or Kruskal-Wallis test was used for intergroup comparisons.RESULTS AND CONCLUSION:(1)Compared with individuals without chronic ankle instability,individuals with chronic ankle instability had longer time to stability in the anterior-posterior direction bilaterally(P=0.001-0.012),and longer time to stability in the medial-lateral direction on the affected side(P=0.012-0.025);had higher proprioception thresholds of plantarflexion,dorsiflexion,inversion,and eversion of the bilateral ankles(P=0.000-0.035);showed lower tactile sensation sensitivities of the bilateral great toe,first metatarsal head,fifth metatarsal head,arch,and heel(P=0.000-0.008);and had weaker muscle strength for inversion and eversion of the bilateral ankles(P=0.000-0.019).(2)Individuals with unilateral chronic ankle instability have bilateral deficits in postural stability,proprioception,plantar tactile sensation,and muscle strength.Therefore,the rehabilitation needs of both limbs should be fully considered when treating chronic ankle instability.

BACKGROUND:Ankle inversion injuries frequently occur during landing,injuring the anterior talofibular and calcaneofibular ligaments.Previous studies usually used indirect indicators,such as inversion angle,as an injury risk indicator,but epidemiological support is lacking.OBJECTIVE:To calculate anterior talofibular and calcaneofibular ligament strains using a three-dimensional multi-body foot model during a drop-landing and to investigate whether increasing the foot toe-out angle for landing would reduce the risk of inversion sprains.METHODS:Thirty-five participants with high sports demands[15 males and 20 females,age:(21.0±0.9)years,height:(176.2±8.8)cm,body mass:(71.6±12.8)kg]were recruited to perform a drop-landing test using a trapdoor device to simulate ankle inversion sprains.Two landing conditions were tested,i.e.,natural landing and toe-out landing.Kinematic data were collected using a 12-camera motion analysis system,the strains of the anterior talofibular and calcaneofibular ligaments were calculated using a three-dimensional rigid-body foot model.RESULTS AND CONCLUSION:From natural landing to toe-out landing conditions,the anterior talofibular ligament strain decreased[natural landing=(3.57±1.92)％,toe-out landing=(0.36±1.18)％,P＜0.001,Cohen's d=2.01),as was the calcaneofibular ligament strain[natural landing=(1.38±1.80)％,toe-out landing=(0.28±2.29)％,P=0.003,Cohen's d=0.81).It could be concluded that increasing foot toe-out angle reduces anterior talofibular and calcaneofibular ligament strains during drop-landing with ankle inversion,thereby reducing the potential of ankle inversion sprains.

BACKGROUND:Ankle inversion injuries frequently occur during landing,injuring the anterior talofibular and calcaneofibular ligaments.Previous studies usually used indirect indicators,such as inversion angle,as an injury risk indicator,but epidemiological support is lacking.OBJECTIVE:To calculate anterior talofibular and calcaneofibular ligament strains using a three-dimensional multi-body foot model during a drop-landing and to investigate whether increasing the foot toe-out angle for landing would reduce the risk of inversion sprains.METHODS:Thirty-five participants with high sports demands[15 males and 20 females,age:(21.0±0.9)years,height:(176.2±8.8)cm,body mass:(71.6±12.8)kg]were recruited to perform a drop-landing test using a trapdoor device to simulate ankle inversion sprains.Two landing conditions were tested,i.e.,natural landing and toe-out landing.Kinematic data were collected using a 12-camera motion analysis system,the strains of the anterior talofibular and calcaneofibular ligaments were calculated using a three-dimensional rigid-body foot model.RESULTS AND CONCLUSION:From natural landing to toe-out landing conditions,the anterior talofibular ligament strain decreased[natural landing=(3.57±1.92)％,toe-out landing=(0.36±1.18)％,P＜0.001,Cohen's d=2.01),as was the calcaneofibular ligament strain[natural landing=(1.38±1.80)％,toe-out landing=(0.28±2.29)％,P=0.003,Cohen's d=0.81).It could be concluded that increasing foot toe-out angle reduces anterior talofibular and calcaneofibular ligament strains during drop-landing with ankle inversion,thereby reducing the potential of ankle inversion sprains.

BACKGROUND:Unilateral chronic ankle instability has adverse effects on the affected limb,and evidence has shown that the nonaffected side may be similarly involved,but direct evidence is currently lacking.OBJECTIVE:To investigate the effects of unilateral chronic ankle instability on bilateral postural stability,proprioception,plantar tactile sensation,and muscle strength.METHODS:A total of 122 participants were recruited in this study,including 67 individuals with unilateral chronic ankle instability and 55 individuals without chronic ankle instability.Postural stability,proprioception,plantar tactile sensation and muscle strength were tested bilaterally in individuals with unilateral chronic ankle instability,as well as in those without chronic ankle instability.One-way analysis of variance or Kruskal-Wallis test was used for intergroup comparisons.RESULTS AND CONCLUSION:(1)Compared with individuals without chronic ankle instability,individuals with chronic ankle instability had longer time to stability in the anterior-posterior direction bilaterally(P=0.001-0.012),and longer time to stability in the medial-lateral direction on the affected side(P=0.012-0.025);had higher proprioception thresholds of plantarflexion,dorsiflexion,inversion,and eversion of the bilateral ankles(P=0.000-0.035);showed lower tactile sensation sensitivities of the bilateral great toe,first metatarsal head,fifth metatarsal head,arch,and heel(P=0.000-0.008);and had weaker muscle strength for inversion and eversion of the bilateral ankles(P=0.000-0.019).(2)Individuals with unilateral chronic ankle instability have bilateral deficits in postural stability,proprioception,plantar tactile sensation,and muscle strength.Therefore,the rehabilitation needs of both limbs should be fully considered when treating chronic ankle instability.

Objective To investigate the effects of 16-week Tai Chi exercise on muscle strength,plantar tactile sensation,kinesthesia,and postural control of older adults at different ages.Methods Thirty-nine older adults were divided into 60-75-year-old group(n=24)and the 76-90-year-old group(n=15),and both groups received Tai Chi practice for 16 weeks.The muscle strength,plantar tactile sensation,kinesthesia,and center of pressure root mean square(CoP-RMS)were measured before and after practice.Results After 16 weeks of Tai Chi exercise,the fifth metatarsal head tactile sensation and ankle dorsiflexion/plantarflexion kinesthesia thresholds decreased in the 76-90-year-old group.However,there was no significant change in the 60-75-year-old group.The CoP-RMS in the medial/lateral direction decreased in the 60-75-year-old and 76-90-year-old group.Conclusions After 16 weeks of Tai Chi exercise,muscle strength,plantar tactile sensation,kinesthesia,and postural control were improved.Especially for older adults aged over 75 years,Tai Chi exercise improved their plantar tactile sensation,kinesthesia,and postural control to a greater extent.Tai Chi practice provides a suitable and effective exercise form for older adults over 75 years.

Objective To investigate the effects of 16-week Tai Chi exercise on muscle strength,plantar tactile sensation,kinesthesia,and postural control of older adults at different ages.Methods Thirty-nine older adults were divided into 60-75-year-old group(n=24)and the 76-90-year-old group(n=15),and both groups received Tai Chi practice for 16 weeks.The muscle strength,plantar tactile sensation,kinesthesia,and center of pressure root mean square(CoP-RMS)were measured before and after practice.Results After 16 weeks of Tai Chi exercise,the fifth metatarsal head tactile sensation and ankle dorsiflexion/plantarflexion kinesthesia thresholds decreased in the 76-90-year-old group.However,there was no significant change in the 60-75-year-old group.The CoP-RMS in the medial/lateral direction decreased in the 60-75-year-old and 76-90-year-old group.Conclusions After 16 weeks of Tai Chi exercise,muscle strength,plantar tactile sensation,kinesthesia,and postural control were improved.Especially for older adults aged over 75 years,Tai Chi exercise improved their plantar tactile sensation,kinesthesia,and postural control to a greater extent.Tai Chi practice provides a suitable and effective exercise form for older adults over 75 years.

Objective To explore the effect of proprioceptive neuromuscular facilitation(PNF)on the knee abduction torque and vastus medialis-medial gastrocnemius(VM-MG)co-contraction index during walking among the old patients with medial compartment knee osteoarthritis. Methods From March to May,2022,32 old patients with medial compartment knee osteoarthritis in communities in Ji'nan were enrolled and randomly allocated to control group(n=16)and training group(n=16).The training group received PNF and the control group received home-based exercise,for six weeks.The knee abduction torque and VM-MG co-contraction index were measured using an infrared motion capture system synchronized with 3D force plate and electromyography system before and after treatment. Results Three cases in the control group and two cases in the training group dropped off.The first and the second peaks of knee abduction torque,and the VM-MG co-contraction index improved in the training group after treatment(|t|>2.460,P<0.05),and the first and the second peaks of knee abduction torque were better in the training group than in the control group(|t|>2.454,P<0.05). Conclusion PNF may optimize the load distribution between the medial and lateral compartments of the knee in patients with knee osteoarthritis.

Objective The reliability and validity of the SGGC-Net-based motion capture system(SGGC-Net system)and SIMI system for parsing walking gait were compared using a three-dimensional(3D)motion capture system(Vicon)with marker points as a reference standard.Methods Thirty healthy college students were recruited,and their gait characteristics while walking on a treadmill were analyzed.Kinematic data were collected using the Vicon system,and video data were collected synchronously using four cameras to obtain the right shoulder,elbow,hip,knee,and ankle joint angles.Reliability was assessed using intraclass correlation coefficients(ICCs)with 95％confidence intervals and standard error of measurement(SEM).Validity was assessed using multiple correlation coefficients(MCCs)and root mean square errors(RMSEs).Results The ICCs of the maximum and minimum 3D coordinate angles of the upper and lower limb joints of the SGGC-Net system ranged from 0.798-0.990 with an SEM of 0.04°-0.95°,and the ICCs of the SIMI system ranged from 0.650-0.967,with an SEM of 0.31°-1.24°.The ICCs of the SGGC-Net system were higher than those of the SIMI system for all joint angles except for the minimum hip and maximum knee angles.Compared to the joint angle curves derived from the SIMI system,the MCCs of the curves derived from the SGGC-Net system ranged from 0.945-0.996,with RMSEs of 1.44°-4.65°,and the multiple correlation coefficients of the SIMI system ranged from 0.815-0.986,with RMSEs of 2.56°-9.99°.The MCCs of the SGGC-Net system were greater than those of the SIMI system at all angles except for the ankle joint.The RMSEs of the SGGC-Net system were smaller than those of the SIMI system at all angles except for the ankle joints.Conclusions The SGGC-Net system has better reliability and validity than the SIMI system in most of the variables,and it has better repeatability and accuracy in analyzing walking gait.It can be applied to motion capture environments without marker points,such as technical analysis of athletes'movements and clinical gait analysis of special populations.

Objective:To explore the effects of whole-body fatigue on the balance and ankle proprioception during drop landing of individuals with functional ankle instability(FAI)by comparing the differences in balance and pro-prioception between the FAI group and the control group before and after fatigue. Method:A total of 31 participants with unilateral FAI and 31 healthy participants were included in this study.A static balance test,dynamic balance test,and ankle proprioception test were conducted before and after fa-tigue.Sway distance(D)of the center of pressure(COP),root mean square of the COP(RMS),95％confi-dence ellipse area of the COP movements(95％AREA),normalized reach distance,and the area under the curve(AUC)were calculated and analyzed. Result:Before whole-body fatigue,the static balance,dynamic balance,and ankle proprioception during drop landing in FAI group were significantly lower than those in control group.After whole-body fatigue,the static balance,dynamic balance,and ankle proprioception during drop landing in the FAI group and control group decreased significantly(P＜0.05),and the increase of D,RMS and 95％AREA in FAI group were significant-ly larger than those in control group(P＜0.05),and the decrease of normalized reach distance in the postero-medial and posterolateral directions and AUC were significantly larger than those in control group(P＜0.05). Conclusion:Whole-body fatigue reduced the static balance,dynamic balance,and ankle proprioception,and the reduction was larger in FAI individuals than in healthy individuals.Therefore,whole-body fatigue may in-crease the risk of recurrent ankle sprain by reducing posture control and proprioception in FAI individuals.