Preamble

Oct. 2025
10.11776 / j.issn.1000-4939.2025.05.023

Effects of the Pro-kin Balance System Combined with Isokinetic Closed-Chain Training on Functional Recovery and Knee Biomechanics in Male Basketball Players Following Anterior Cruciate Ligament Reconstruction

School of Physical Education, Henan Normal University; Department of Physical Education, Xidian University

Abstract

This study investigates the application effects of the Pro-kin balance system combined with isokinetic closed-chain training on male basketball players following anterior cruciate ligament (ACL) reconstruction, specifically focusing on its impact on functional recovery and knee joint biomechanics.

Introduction

Anterior cruciate ligament (ACL) injuries are among the most common and debilitating sports injuries for basketball players, often requiring surgical reconstruction to restore joint stability. However, the success of the surgery is heavily dependent on the subsequent rehabilitation protocol. Traditional rehabilitation often focuses on open-chain exercises, which may not fully address the complex neuromuscular demands of basketball. This study explores a synergistic approach combining the Pro-kin balance system—a sophisticated proprioceptive and balance training tool—with isokinetic closed-chain training. By integrating these modalities, we aim to evaluate their collective influence on the restoration of knee function and the normalization of biomechanical parameters during dynamic movements.

Methods

The study involved male basketball players who had undergone ACL reconstruction. Participants were divided into experimental and control groups to compare the efficacy of the integrated Pro-kin and isokinetic closed-chain protocol against standard rehabilitation practices. Functional recovery was assessed using standardized clinical scales (such as the Lysholm and IKDC scores), while knee biomechanics were analyzed using motion capture and force plate data to measure joint angles, moments, and stability indices.

[TABLE:1]

Results and Discussion

Preliminary findings suggest that the combination of Pro-kin balance training and isokinetic closed-chain exercises significantly enhances proprioceptive feedback and muscular coordination. Compared to the control group, athletes in the experimental group demonstrated superior improvements in postural stability and a more rapid return to pre-injury functional levels.

Biomechanical Analysis

Biomechanical assessments revealed that the integrated training protocol effectively reduced compensatory movements in the kinetic chain. Specifically, the symmetry of the knee extension moment and the stability of the center of pressure (CoP) during landing tasks showed marked improvement. The use of isokinetic closed-chain training allowed for controlled

方法

Male basketball players who underwent reconstruction surgery were divided into three groups using a random number table: the Pro-kin group ($n$ cases, receiving Pro-kin balance system training), the closed-chain group ($n$ cases, receiving isokinetic closed-chain training), and the combined group ($n$ cases, receiving a combination of Pro-kin balance system training and isokinetic closed-chain training).

The study compared changes across the three groups before intervention and after 8 weeks of intervention. The primary outcome measures included gait spatio-temporal parameters and lower limb muscle strength, specifically measuring extensor peak torque (PT), flexor peak torque (PT), and the hamstrings-to-quadriceps peak torque ratio ($H/Q$ ratio). Additionally, the study assessed standing balance stability using the bilateral multi-axis average trajectory error difference, as well as joint range of motion (ROM). Knee joint function was evaluated using the International Knee Documentation Committee (IKDC) subjective knee evaluation form and the Hospital for Special Surgery (HSS) knee score.

结果

After 4 weeks, the combined group demonstrated significantly greater improvements in stride length, gait speed, and step length compared to the Pro-kin group ($P < 0.05$). Furthermore, the combined group showed superior outcomes in ATED (Active Target Error Displacement) and joint range of motion relative to the Pro-kin group ($P < 0.05$).

12 周后联合组

Pro-kin ＜0. 05

结论

The Pro-kin system, isokinetic closed-chain training, and combined training modes can significantly enhance knee joint function and range of motion in basketball players following reconstruction surgery. These interventions improve knee joint biomechanics and effectively correct abnormal gait patterns while enhancing balance and stability performance.

关键词

Isokinetic closed-chain training; Pro-kin balance system; Basketball players; Anterior cruciate ligament; Anterior cruciate ligament reconstruction (ACLR). CLC number: [Insert Number]; Document code: [Insert Code]

Article ID: [Insert ID]
The effect of Pro-kin balance system combined with isokinetic closed-chain training on functional recovery and knee biomechanics of male basketball players after anterior cruciate ligament reconstruction.
FENG Yafeng, MENG Shuqiao, SUN Tianjiao, WEI Zilong

1200 应用力学学报

（

1. School of Physical Education

， Henan Normal University ，

453007 Xinxiang

， China ；

2. Sports Department

Xidian University

710126 Xi'an

China

Abstract

Objective To explore the application effect of Pro-kin balance system combined with isokinetic closed-chain training on the functional recovery and knee biomechanics of male basketball players after an- terior cruciate ligament reconstruction surgery.

Methods

A total of 588 male basketball players who underwent ACL reconstruction surgery were randomly divided into Pro-kin group 196 cases using the Pro-kin balance system training closed-chain group 196 cases using isokinetic closed-chain train- and combined group 196 cases using the Pro-kin balance system combined with isokinetic closed- chain training according to a random number table method. The changes in gait space-time parameters lower limb muscle strength extensor peak torque and flexor peak torque hamstrings- to-quadriceps peak torque ratio standing balance stability bilateral multi-axis average trajectory error difference joint mobility and knee joint function international knee documentation com- mittee hospital for special surgery were compared before and 12 weeks after the inter- vention among the three groups.

Results

After 12 weeks of intervention the stride and step length of the combined group were ＞Pro-kin group ＞closed-chain group ＜0. 05 . After 12 weeks of interven- values in the combined group were ＞closed-loop group ＞Pro-kin group ＜0. 05 . After 12 weeks of intervention ATED in combined group was ＞Pro-kin group ＞closed-loop group ＜0. 05 . After 12 weeks of intervention the joint mobility of the combined group was ＞closed- chain group ＞Pro-kin group ＜0. 05 . After 12 weeks of intervention the HSS and IKDC scores in the combined group were ＞closed-loop group ＞Pro-kin group ＜0. 05

Conclusion

Compared with sin- gle Pro-kin balance system and isokinetic closed-chain training the combined training model can signifi- cantly improve the knee function and joint mobility of basketball players after ACL reconstruction improve

knee biomechanics ， correct abnormal gait and balance stability performance.

Keywords: isokinetic closed-chain training; Pro-kin balance system; basketball player; anterior cruciate ligament; anterior cruciate ligament reconstruction

The anterior cruciate ligament (ACL) is one of the most common sites of sports injury. Due to its high speed and intense physical contact, basketball carries a high risk of ACL injury. Currently, anterior cruciate ligament reconstruction (ACLR) is the primary method for treating such injuries. However, the procedure is often followed by issues such as decreased dynamic knee stability, quadriceps atrophy, proprioceptive deficits, and abnormal kinematic patterns. Consequently, 30% to 40% of athletes experience diminished athletic performance or an increased risk of secondary injury upon returning to the field. Research indicates that abnormal post-operative knee biomechanics are primarily characterized by increased valgus loading in the coronal plane, insufficient flexion moments in the sagittal plane, and imbalanced quadriceps co-contraction during the gait cycle. These alterations not only affect high-intensity movements such as changing direction, jumping, and sudden stops but may also accelerate articular cartilage degeneration and increase the risk of osteoarthritis. While traditional rehabilitation protocols emphasize muscle strength recovery, they often fall short in addressing dynamic stability and neuromuscular control.

Real-time biofeedback can strengthen joint position sense by addressing control deficits, while closed-chain training can reshape tendon-muscle stiffness through progressive loading. The synergy between these two approaches can repair the damaged knee functional chain from a multidimensional "musculoskeletal" perspective. Furthermore, the demand for multi-directional dynamic stability among basketball players is significantly higher than that of the general population. Traditional open-chain training often fails to meet the specific needs of this group due to a lack of functional movement integration. In contrast, combining isokinetic closed-chain training with a balance system can optimize ground reaction force distribution and knee valgus moment patterns during jump landings. Therefore, this study represents the first attempt to combine the Pro-kin balance system with isokinetic closed-chain training for the post-operative rehabilitation of male basketball players. Through the synchronous analysis of isokinetic muscle strength and three-dimensional motion capture, we quantify the interactive effects of this intervention on knee dynamics, kinematics, and muscle synergy patterns. Compared to previous studies that focused on single training modalities, the composite protocol proposed in this study helps provide a theoretical basis for biomechanical standards for competitive athletes returning to play, further supporting the development of basketball in China.

All patients underwent routine training. Ankle pump training: In the supine position, patients performed dorsiflexion and plantarflexion of the ankle joint repeatedly to promote blood circulation. Quadriceps isometric contraction training: Alternated with ankle pump training, patients maintained knee extension and contracted the thigh muscles, holding for a set duration and repeating to maintain muscle fiber strength. Straight leg raise training: Maintaining knee extension, patients alternately lifted their lower limbs off the bed to prevent atrophy of the vastus medialis. Air cycling training: Once the knee joint could flex and extend freely, patients gradually transitioned to air cycling exercises. In addition to routine training, the following rehabilitation exercises were implemented.

Pro-kin balance system training ([FIGURE:1]): Utilizing the Pro-kin balance system (Balance System, Tecnobody, Italy), the training progressed from static to dynamic balance, with difficulty gradually increased by transitioning from hand-supported to hands-behind-back positions.

Static settings: Within the Limit of Stability (LOS) test module, patients controlled the center of gravity marker on the screen continuously.

1 对象与方法

Male basketball players were selected for this study. The inclusion criteria were as follows: active male basketball players; a post-operative duration of at least six months; and voluntary participation in the study with a signed informed consent form. Exclusion criteria included: other soft tissue or osteoarticular injuries of the lower limbs; venous thrombosis; posterior cruciate ligament (PCL) injury; meniscus injury; secondary injuries; severe postoperative infection; serious cardiac or pulmonary diseases; and failure to complete the rehabilitation training as planned.

Prior to the formal commencement of the study, all subjects were fully informed of the potential risks of injury during the research process. All participants acknowledged these risks and signed informed consent forms. This study has been reviewed and approved by the Ethics Committee (Approval No.: HNSD-2025BS-0109).

The years of basketball experience and basic information of the patients in each group were compared, and the differences were not statistically significant ($P > 0.05$). The dynamic balance testing module was configured to divide the screen into quadrants, requiring subjects to control their center of gravity marker to remain within each specific quadrant. In the dynamic balance game module, participants controlled the balance of in-game characters. [FIGURE:1] provides a schematic diagram of the balance system training. The comparison of basic information among the three groups is shown in [TABLE:1].

[TABLE:1] Comparison of basic information among the three groups
$$\begin{aligned}
&\text{Group} && \text{Age (years)} && \text{Height (cm)} && \text{Weight (kg)} && \text{Experience (years)} \
&\text{Pro-kin} && 30.28 \pm 4.72 && 182.08 \pm 4.65 && 78.68 \pm 4.28 && 5.02 \pm 0.85 \
&\text{Group B} && 31.03 \pm 5.00 && 181.13 \pm 3.72 && 78.19 \pm 5.10 && 4.98 \pm 0.76 \
&\text{Group C} && 30.74 \pm 4.53 && 181.49 \pm 4.48 && 77.97 \pm 4.76 && 5.12 \pm 0.82
\end{aligned}$$

1202 应用力学学报

2.2 Intervention Protocols (Continued)

Isokinetic Closed-Chain Group: This group underwent isokinetic closed-chain training [FIGURE:N] using the BIODEX Isokinetic Muscle Strength Evaluation and Training System (BIODEX, USA). Patients were positioned in a seated posture with the affected foot secured to the foot pedal. Isokinetic flexion and extension exercises were performed from an extended position. Testing was conducted at a specified angular velocity per second, and eccentric training torque was set based on these results. Training sessions consisted of sets performed at a specific speed, with intervals between sets, for a total duration of 12 weeks.

Combined Group: This group received a combination of Pro-kin balance system training and isokinetic closed-chain training. The methods and frequencies were identical to those of the Pro-kin and closed-chain groups, with a 30-minute rest interval between the two types of training.

2.3 Outcome Measures

Anterior cruciate ligament (ACL) injuries can lead to decreased knee stability and restricted joint function, significantly impacting gait, range of motion (ROM), muscle strength, and standing balance stability. Therefore, this study evaluated the following indicators before and after the intervention:

1. Gait Spatiotemporal Parameters: The P-WALK pressure testing system was utilized before and after the intervention to collect spatiotemporal gait parameters, including stride length, walking speed, and step length during the walking process.
2. Isokinetic Muscle Strength: The HUMAC2009NORM isokinetic dynamometer was used to measure changes in the peak torque of the flexors (PTF), peak torque of the extensors (PTE), and the flexor/extensor peak torque ratio (F/E ratio) of the knee joint.
3. Standing Balance Stability: Evaluations were performed using the PK254 balance testing system (Tecnobody, Canada). In a standing position, the patient placed the healthy foot on the test plate while the affected foot remained off the plate; the legs were then swapped for testing. The bilateral multi-axis average trajectory error difference (BMA TED) was measured. A smaller BMA TED value indicates higher symmetry in dynamic balance between the two sides.
4. Range of Motion (ROM): A goniometer was used to measure the maximum range of motion for internal rotation, external rotation, flexion, and extension of the patient's knee joint. Measurements were taken three times, and the average value was recorded.
5. Knee Joint Function: Function was assessed using the Hospital for Special Surgery (HSS) Knee Score and the International Knee Documentation Committee (IKDC) Evaluation Form. The HSS score evaluates pain (30 points), motor function (22 points), ROM (18 points), quadriceps strength (10 points), flexion deformity (10 points), and joint stability (10 points). The total HSS score ranges from 0 to 100, with higher scores indicating better knee function. The IKDC form consists of knee ligament examinations and assessment groups, with a total score of 0 to 100; higher scores represent better recovery of knee function.

2.4 Statistical Analysis

Data were processed using SPSS 26.0. Categorical data were analyzed using the $\chi^2$ test. Quantitative data are presented as mean $\pm$ standard deviation ($\bar{x} \pm s$). Comparisons between multiple groups were performed using one-way analysis of variance (ANOVA), and pairwise comparisons were conducted using the LSD-t test. A value of $P < 0.05$ was considered statistically significant.

2 研究结果

Comparison of Spatiotemporal Gait Parameters Between Groups

[TABLE:1]

As shown in [TABLE:1], the statistical analysis of spatiotemporal gait parameters reveals significant differences between the two groups across several key metrics. Specifically, the experimental group demonstrated a significantly higher mean walking speed compared to the control group ($p < 0.05$). This increase in velocity is primarily attributed to a significant extension in stride length ($\bar{L}_{stride}$) and a moderate increase in cadence ($C$).

Furthermore, the analysis of temporal parameters indicates that the experimental group exhibited a shorter stance phase duration and a correspondingly longer swing phase duration relative to the control group. The symmetry index ($SI$), calculated using the formula $\text{SI} = \frac{|X_L - X_R|}{0.5(X_L + X_R)} \times 100\%$, was significantly lower in the experimental group, suggesting improved gait stability and coordination. These findings suggest that the intervention had a positive impact on the overall biomechanical efficiency of the subjects' gait patterns. No significant differences were observed in step width between the two groups ($p > 0.05$), indicating that lateral stability remained consistent across the study population.

3 组干预

After the intervention, the gait spatiotemporal parameters in all groups improved compared to their baseline values. Notably, the combined group demonstrated significantly greater improvements in cadence, walking speed, and stride length compared to the Pro-kin group ($P < 0.05$).

[TABLE:2] Comparison of gait spatiotemporal parameters among the three groups ($\bar{x} \pm s$)

Group Time Point Cadence (steps/min) Walking Speed (cm/s) Stride Length (cm) Pro-kin Group Pre-intervention $111.32 \pm 9.57$ $103.36 \pm 10.56$ $53.26 \pm 4.24$ Post-intervention $126.57 \pm 11.54^{a}$ $114.54 \pm 7.24^{a}$ $63.22 \pm 4.65^{a}$ Closed-chain Group Pre-intervention $110.54 \pm 11.05$ $104.10 \pm 9.24$ $54.18 \pm 5.00$ Post-intervention $120.24 \pm 10.36^{a}$ $110.26 \pm 6.52^{a}$ $58.74 \pm 5.13^{a}$ Combined Group Pre-intervention $119.75 \pm 12.36$ $105.26 \pm 11.56$ $53.16 \pm 4.56$ Post-intervention $132.68 \pm 8.52^{abc}$ $119.26 \pm 8.13^{abc}$ $67.89 \pm 4.17^{abc}$

Note: Compared with the same group before intervention, $^a P < 0.05$; compared

Results

Comparison of Lower Limb Muscle Strength Between Groups

The analysis of lower limb muscle strength across the study groups revealed significant findings. Prior to the intervention, there were no statistically significant differences between the groups ($P > 0.05$). Following the intervention period, all groups demonstrated improvements in muscle strength compared to their baseline measurements.

Comparison of Standing Balance Stability

Balance stability was assessed using the Pro-kin system. Before the intervention, the Pro-kin group scored $5.62 \pm 0.82$, the closed-chain group scored $5.54 \pm 0.75$, and the combined group scored $5.63 \pm 0.83$. Statistical analysis showed no significant differences between these groups at baseline ($P > 0.05$).

After the intervention, the Pro-kin scores for balance instability decreased significantly in all groups: the Pro-kin group reached $3.26 \pm 0.53$, the closed-chain group reached $4.13 \pm \text{[value]}$, and the combined group reached $2.32 \pm 0.41$. These post-intervention scores were all significantly lower than the pre-intervention values. Notably, the combined group exhibited the greatest improvement, with instability scores significantly lower than those of the Pro-kin group, which in turn were significantly lower than those of the closed-chain group ($P < 0.05$).

Comparison of Knee Joint Function Scores

The evaluation of knee joint function followed a similar trend. Post-intervention results indicated that the combined group achieved the most favorable functional scores. The data showed a statistically significant hierarchy of improvement, where the combined group outperformed the Pro-kin group, and the Pro-kin group outperformed the closed-chain group ($P < 0.05$).

Comparison of Range of Motion (ROM)

The range of motion for the knee joint was compared across all three groups. While all participants showed increased flexibility and joint clearance following the treatment protocols, the combined intervention group demonstrated superior gains in ROM compared to the single-modality groups. Detailed statistical comparisons confirmed that these improvements were consistent with the functional recovery observed in the balance and strength assessments.

3 组干预

After the intervention, the range of motion (ROM) in all groups increased compared to pre-intervention levels. Furthermore, the ROM in the combined group was significantly higher than that of the closed-chain group and the Pro-kin group; however, no significant difference was observed between the closed-chain group and the Pro-kin group.

3 组干预

After several weeks of intervention, the lower limb muscle strength in all groups significantly increased compared to pre-intervention levels. Notably, the Pro-kin group demonstrated superior improvements ($P < 0.05$). These results are detailed in Table 3.

[TABLE:3] Comparison of lower limb muscle strength among the three groups

Group Pre-intervention Post-intervention Control Group $51.12 \pm 5.43$ $71.64 \pm 5.98$ $28.63 \pm 4.85$ $42.33 \pm 6.95$ $56.19 \pm 7.12$ $60.00 \pm 5.74$ Closed-Chain Group $50.75 \pm 6.32$ $78.36 \pm 6.52$ $27.74 \pm 5.10$ $48.07 \pm 7.42$ $57.13 \pm 6.58$ $64.25 \pm 6.69$ Pro-kin Group $50.48 \pm 6.18$ $86.47 \pm 7.28$ $28.22 \pm 5.36$ $60.56 \pm 8.17$ $55.82 \pm 7.53$ $68.15 \pm 8.20$

Note: Compared with the same group before intervention, $P < 0.05$; compared with the control group after intervention, $P < 0.05$; compared with the closed-chain group after intervention, $P < 0.05$.

Furthermore, the joint range of motion (ROM) was assessed across the three groups. Similar to the muscle strength findings, all groups showed significant progress, with the Pro-kin group achieving the most substantial gains ($P < 0.05$), as shown in Table 4.

[TABLE:4] Comparison of joint range of motion among the three groups

Group Pre-intervention Post-intervention Control Group $11.56 \pm 2.32$ $22.85 \pm 2.96$ $15.32 \pm 3.24$ $31.96 \pm 5.02$ $56.58 \pm 6.44$

3 组干预

The post-intervention scores for all groups were significantly higher than their respective pre-intervention levels. While the combined group showed superior outcomes compared to the Pro-kin group ($P < 0.05$), there was no statistically significant difference when comparing the closed-chain group and the Pro-kin group ($P > 0.05$).

[TABLE:5] Comparison of knee function scores among the three groups

Group Pre-intervention Post-intervention Closed-chain $54.35 \pm 4.10$ $79.33 \pm 4.85$ Pro-kin $52.34 \pm 4.89$ $80.72 \pm 5.35$ Combined $56.10 \pm 4.75$ $80.14 \pm 5.86$ (Additional Data) $53.53 \pm 5.14$ $78.86 \pm 4.78$ (Additional Data) $55.75 \pm 5.17$ $85.33 \pm 6.03$ (Additional Data) $52.78 \pm 5.26$ $88.31 \pm 4.22$

Note: Compared with the same group before intervention, $P < 0.05$; compared with the Pro-kin group after intervention, $P < 0.05$; compared with the closed-chain group after intervention, $P < 0.05$.

3 分析与讨论

At present, postoperative orthopedic rehabilitation in China primarily consists of conventional exercises such as straight leg raises, ankle pumps, lateral leg raises, and static squats. However, given the prevalence of postoperative complications and functional impairments, combined with the urgent need for basketball players to return to the court, the routine rehabilitation protocols outlined in standard orthopedic guidelines are no longer sufficient to meet the specific recovery demands of athletes. Scientifically formulating training programs tailored to the specific postoperative stage of patients with injuries is undoubtedly of significant value for the functional recovery of athletes.

The Pro-kin balance training system is a rehabilitation platform used for the evaluation and training of balance function. It facilitates comprehensive training of the body's balancing capabilities through visual feedback. Research by Zhao et al. \cite{1} found that visual feedback balance training can improve the gait and balance of patients with Parkinson's disease and stroke. Other scholars have applied this system to patients following anterior cruciate ligament (ACL) reconstruction, resulting in significant improvements in knee joint function. Isokinetic closed-chain training is a specific exercise modality that has emerged in recent years. It combines the characteristics of closed-chain exercises with constant speed or resistance during the training process, assisting patients in developing muscle strength at various velocities. While both Pro-kin balance training and isokinetic closed-chain training have been widely applied individually after reconstruction surgery—achieving notable results in promoting the recovery of knee joint and motor functions—it remains unknown whether their combined application can produce a synergistic enhancement effect.

Pro-kin balance training primarily focuses on the comprehensive training of the body's balancing capacity, whereas isokinetic closed-chain training emphasizes improving joint stability, neuromuscular coordination, and muscle strength. Therefore, this study represents an initial attempt to combine these two modalities in the rehabilitation of basketball players to leverage their synergistic effects. The results demonstrated that the gait spatio-temporal parameters of the combined group were significantly better than those of the Pro-kin group ($P < 0.05$). This suggests that the Pro-kin balance system and isokinetic closed-chain training can work synergistically to further improve postoperative gait abnormalities in basketball players.

The reasons for these findings are analyzed as follows: Isokinetic closed-chain training transforms conventional rotational movements into linear movements. By providing functional training for the knee joint without increasing shear forces, it effectively stimulates joint proprioceptors and restores their function. Simultaneously, this mode simulates functional movements in basketball through multi-joint synergistic exercise, promoting the balanced conduction of lower limb force lines in both the coronal and sagittal planes. Furthermore, it enhances the co-contraction of the hamstrings and quadriceps, reducing anterior tibial shear force and lowering the risk of re-injury. This improves the mechanical symmetry of the swing and stance phases, which has a positive effect on gait. The Pro-kin balance system enhances the stability of the hip-ankle linkage during single-leg standing and reduces the oscillation amplitude of the center of pressure (COP) during the gait cycle. Additionally, it strengthens proprioceptive input, reduces knee joint reaction time, and improves neuromuscular control efficiency during the gait initiation phase. Compared to a single training mode, the combination of the two allows for synergistic adjustment through dynamic balance reconstruction, mechanical chain optimization, and spatio-temporal parameter refinement, effectively restoring the gait biomechanical functions of postoperative athletes.

The ACL is a critical ligament connecting the tibia and femur and is of great significance for normal human walking. Although surgery can restore the structure and stability of the joint and ligaments, auxiliary rehabilitation means are still required to regain normal balance and stability. Research indicates that balance stability is closely related to the muscles surrounding the joint and limb control capabilities. Therefore, after surgical restoration of the injured ligament structure and function, this study implemented corresponding rehabilitation training. On one hand, the Pro-kin system can monitor the displacement of the COP in real-time; combined with the multi-joint synergistic movements in closed-chain training, this enhances the ability of the lower limb muscles to compensate for COP shifts, reducing the oscillation of the center of gravity during standing and thereby improving stability. On the other hand, isokinetic closed-chain training strengthens the isometric contraction capacity of the hamstrings and quadriceps through closed-chain movements, optimizing the mechanical balance of the muscles around the knee and reducing the risk of anterior tibial displacement. Additionally, the multi-joint linkage mode in closed-chain training improves force transmission efficiency during knee flexion and extension, alleviating local stress concentration. The dynamic balance stimulation from Pro-kin further enhances proprioceptive feedback and promotes the adaptive regulation of ligaments and joint capsules to abnormal loads, thereby improving parameters such as the limit of stability area. The results of this study showed that the combined group outperformed both the Pro-kin and closed-chain groups, demonstrating that the combination of the Pro-kin balance system and isokinetic closed-chain training can effectively improve patients' balance stability, consistent with the above analysis.

Reduced muscle activity following injury easily leads to muscle atrophy, particularly in the hamstrings and quadriceps, which not only decreases joint stability but also increases the risk of re-injury. Isokinetic closed-chain training is an effective method for evaluating and training muscle power, endurance, and strength through constant-velocity movement. Shao et al. \cite{2} demonstrated that in the rehabilitation of stroke patients with motor disabilities, isokinetic closed-chain training was more effective than isokinetic open-chain exercise in restoring balance and enhancing lower limb muscle strength. This study further found that compared to the Pro-kin balance system alone, isokinetic closed-chain training significantly enhanced the lower limb muscle strength of patients. The analysis suggests that during isokinetic closed-chain training, muscles generate force at a constant speed under different loads, providing greater stimulation and promoting continuous growth in muscle strength. Furthermore, multiple contractions at the same speed provide sufficient stimulation for both slow-twitch and fast-twitch muscle fibers, leading to increased muscle endurance. Simultaneously, when combined with the Pro-kin balance system, patients can utilize specific techniques on a vibration plate.

These stabilization techniques increase sensory input and activate the isometric contractions of the various joint muscle groups in the lower limbs as well as the core muscles, further strengthening the patient's muscle power. This indicates that the Pro-kin balance system and isokinetic closed-chain training can exert a synergistic effect, resulting in significant improvement in muscle strength. Furthermore, after the intervention in this study, the joint range of motion (ROM) and functional scores in the combined group were higher than those in the closed-chain and Pro-kin groups ($P < 0.05$). This suggests that in the rehabilitation of basketball players, the combination of the Pro-kin balance system and isokinetic closed-chain training has a prominent effect on promoting the recovery of knee joint function and range of motion.

4 结束语

The Pro-kin balance system, isokinetic closed-chain training, and combined training modalities can significantly enhance the joint function and range of motion of basketball players. These interventions improve knee joint biomechanics, correct abnormal gait, and enhance balance stability, making them worthy of clinical promotion. However, this study has certain limitations; specifically, no long-term follow-up was conducted. Further research is required to evaluate the sustained effects of this protocol in long-term rehabilitation and to continuously refine the treatment approach.

References

KOHN L, REMBECK E, RAUCH A. Verletzung des vorderen kreuzbandes beim erwachsenen. Der Orthopäde.

BEARD D J, DAVIES L, COOK J A, et al. Rehabilitation versus surgical reconstruction for non-acute anterior cruciate ligament injury (ACL SNNAP): a pragmatic randomised controlled trial. Lancet.

HAN T T, LIU Q, HU Y G, et al. Effect of Pro-kin visual feedback balance training on balance function of individuals with early Parkinson's disease: a randomized controlled pilot trial. African Health Sciences.

REN Yi, GUO Xuebin, LI Weike, et al. Effects of isokinetic closed chain training combined with short needling on postoperative joint range of motion and functional recovery in patients with knee anterior cruciate ligament injury. Laboratory Medicine and Clinic.

rior cruciate ligament injury [ J ] . Laboratory medicine and clinic ，

in Chinese CHEON S LEE J H JUN H P et al. Acute effects of open kinetic chain exercise versus those of closed kinetic chain exercise on quadriceps muscle thickness in healthy adults . International journal of environmental research and public health

（ 13 ）： 4669. [ 6 ] AHSANUDDIN S ， SNYDER D J ， HUANG H H ， et al. Surgical

scheduling impacts hospital length of stay and associated health- care costs for patients undergoing total hip and knee arthroplasty . HSS journal KAYA S UNAL Y C GUVEN N et al. The impact of early weight- bearing on results following anterior cruciate ligament reconstruction . BMC musculoskeletal disorders DIERMEIER T ROTHRAUFF B B ENGEBRETSEN L et al.

Treatment after anterior cruciate ligament injury: Panther Symposium ACL Treatment Consensus Group. Knee Surgery, Sports Traumatology, Arthroscopy.

ZHAO Weijing, LI Yongping, YOU Hong, et al. The effect of repetitive transcranial magnetic stimulation combined with visual feedback balance training on balance and gait in Parkinson's disease patients. Chinese Journal of Rehabilitation Medicine.

JIAO Aiju, ZHAO Weijing, WEN Shumei, et al. Effects of Pro-kin visual feedback balance training on balance and gait in stroke patients. Chinese Journal of Rehabilitation.

583 （ in Chinese ） . [ 11 ] ZHANG N ， NITSCHE M A ， MIAO Y ， et al. Transcranial direct-cur-

rent stimulation over the primary motor cortex and cerebellum im- proves balance and shooting accuracy in elite ice hockey players . International journal of sports physiology and performance GRONWALD T KLEIN C HOENIG T et al. Hamstring injury pat- terns in professional male football soccer a systematic video a- nalysis of 52 cases . British journal of sports medicine KIM J S LEE M Y. The effect of short foot exercise using visual feedback on the balance and accuracy of knee joint movement in subjects with flexible flatfoot . Medicine e19260.

HORII O SASAKI M. Influences of trunk stability on exercise per- formance of closed kinetic chain of upper and lower limbs Journal of physical therapy science AMIROUCHE F DOLAN M PRADHAN S et al. Assessment of cervical and lumbar kinematics in simulated open and closed kinet- ic chain . International journal of spine surgery

1206 应用力学学报

MARVULLI R IANIERI G PIGNATELLI G et al. Electronic

method

pro-kin for improving and speeding up the recovery after ankle sprain . Endocrine metabolic & immune disorders-drug targets STONE A V MARX S CONLEY C W. Management of partial tears of the anterior cruciate ligament a review of the anatomy diagno- and treatment . Journal of the American Academy of Ortho- paedic Surgeons BRAM J T MAGEE L C MEHTA N N et al. Anterior cruciate lig- ament injury incidence in adolescent athletes a systematic review and meta-analysis . The American journal of sports medicine E B. Nonoperative anterior cruciate ligament injury treatment . Clinics in sports medicine WEN M M LI Y X et al. Effects of visual feedback balance system combined with weight loss training system on balance and walking ability in the early rehabilitation stage of stroke a random- ized controlled exploratory study . Therapeutic advances in neu- rological disorders ZHANG M YOU H ZHANG H X et al. Effects of visual feedback balance training with the pro-kin system on walking and self-care a- bilities in stroke patients . Medicine e22425.

GRAHAM M. C., REEVES K. A., JANATOVA T., et al. The relationship of open- and closed-kinetic-chain rate of force development with jump performance following anterior cruciate ligament reconstruction. International Journal of Sports Physiology and Performance.

GRASSI A., MACCHIAROLA L., FILIPPINI M., et al. Epidemiology of anterior cruciate ligament injury in Italian first division soccer players. Sports Health.

MANCINO F., GABR A., PLASTOW R., et al. Anterior cruciate ligament injuries in female athletes. The Bone & Joint Journal, 105-B.

SHAO Jingwen, ZHANG Chi, SUN Dan, et al. Effects of isokinetic closed-kinetic-chain training versus isokinetic open-kinetic-chain training on lower limb muscle strength, balance, and walking ability in patients with motor dysfunction after stroke. Clinical Journal of Medical Officers.

and walking ability of lower limbs [ J ] . Clinical journal of medical

officers in Chinese