Background: A number of studies have shown that proprioception training can reduce the risk of injuries in pivoting sports, but the mechanism is not clearly understood.
Aim: To determine the contributing effects of propioception on knee joint position sense among team handball players.
Study design: Prospective cohort study.
Methods: Two professional female handball teams were followed prospectively for the 2005–6 season. 20 players in the intervention team followed a prescribed proprioceptive training programme while 19 players in the control team did not have a specific propioceptive training programme. The coaches recorded all exposures of the individual players. The location and nature of injuries were recorded. Joint position sense (JPS) was measured by a goniometer on both knees in three angle intervals, testing each angle five times. Assessments were performed before and after the season by the same examiner for both teams. In the intervention team a third assessment was also performed during the season. Complete data were obtained for 15 subjects in the intervention team and 16 in the control team. Absolute error score, error of variation score and SEM were calculated and the results of the intervention and control teams were compared.
Results: The proprioception sensory function of the players in the intervention team was significantly improved between the assessments made at the start and the end of the season (mean (SD) absolute error 9.78–8.21° (7.19–6.08°) vs 3.61–4.04°(3.71–3.20°), p<0.05). No improvement was seen in the sensory function in the control team between the start and the end of the season (mean (SD) absolute error 6.31–6.22°(6.12–3.59°) vs 6.13–6.69°(7.46–6.49°), p>0.05).
Conclusion: This is the first study to show that proprioception training improves the joint position sense in elite female handball players. This may explain the effect of neuromuscular training in reducing the injury rate.
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The incidence of sports injuries is particularly great in women’s handball, with sprains and strains of the knee and ankle being the most frequent injuries. These injuries result in time lost from competition and, in addition to the economic costs of treatment, they also pose mental and social problems to athletes and can seriously affect their sports careers. Ligament injuries of the lower extremities are often related to non-contact situations such as pivoting, decelerating and cutting movements.1 Extrinsic and intrinsic factors play an important role in these injuries. Environmental, anatomical, hormonal and neuromuscular factors have all been explored as possible risk factors for serious non-contact injuries of the lower extremities.2–4
The neuromuscular risk factors may be grouped into those related to altered movement patterns,5–14 altered activation patterns15–17 and/or inadequate muscle stiffness/strength.18–22 Each of these neuromuscular risk factors may result in abnormal loading of the joint during the decelerating and cutting motion.18 23 24 This can be modified by training.1
Several studies have investigated the beneficial effect of a proprioception programme. Most have investigated the rate of knee ligament injury in a controlled trial. Although all studies have analysed their results with regard to the ability of the programme to decrease the injury rate, a few have investigated the effect of the programme on performance and alteration of risk factors25–29 but none have found a beneficial effect of the training on joint position sense (JPS) of the knee joint among elite athletes. The aim of this study was therefore to determine whether proprioceptive training improves the JPS of female handball players.
Box 1: Programme of proprioception training
(30 seconds and one repetition each)
Jogging end to end
Sideways running with crossovers
Forward running in a zigzag line
Backward running in a zigzag line
Static balance (10 repetitions each bare-footed)
Squats (one- or two-leg stance) with or without side steps
Squats (two-leg stance)
Passing the ball (two-leg stance, knee flexion 60°)
One-leg stance, other leg crossing over
Pushing each other off balance
One-leg stance giving the ball to the team mate with trunk rotation
Dynamic balance (10 repetitions each, bare-footed)
Two-leg jump from a small box to a soft mat into two-leg stance knee bent
Passing the ball during the previous exercise
Two-leg jump from a small box to a soft mat into two-leg stance while trunk rotated 90°
Passing the ball during the previous exercise
One-leg jump from a small box to a soft mat
Wobble boards and soft mats are placed next to each other: step along the wobble boards and jump along the soft mats
Exercises in shoes
Vertical jumps while the team mate pushes the player’s trunk in the air
All the members of two professional handball teams were invited to participate in this prospective cohort study. A total of 39 players (mean age 23.5 years) were recruited, 20 in the intervention team and 19 in the control team. There were no significant differences between the two groups with respect to baseline age, body height or weight. Because of club transfers and knee injuries, 39 players completed the first assessment and 31 (15 in the intervention team, 16 in the control team) completed the second evaluation. Players who were transferred to other clubs, had previous serious knee ligament injuries or suffered knee injuries during the season were excluded from the study. The follow-up period was 10 months.
At the beginning of the season, coaches of the intervention team were educated in the use of the prescribed proprioceptive training programme by a physiotherapist. The team was provided with wobble boards, soft mats and an instructional DVD. During the season the intervention team was visited three times by a sports physician and a physiotherapist to check compliance and ensure proper use of the training programme. The training programme was designed in collaboration with sports physicians of the Department of Sports Orthopedic Medicine and Rehabilitation. The main focus of the exercises was to improve awareness and control of the knees and ankles during standing, cutting, jumping and landing. The training programme, modified from Olsen and Myklebust et al,30 consisted of 24 basic exercises on and off the wobble board with variations on each exercise, and 5 additional stretching exercises (box 1). The programme was supervised by the assistant coach and conducted twice a week. It was performed before the training session during the whole handball season.
Players in the control team used a conventional warm-up before their training sessions.
Joint position sense (JPS)
The JPS4 technique was used. A twin axis goniometer (XM180, Biometrics, Cwmfelinfach, Gwent, UK,) was used; the telescopic end block was mounted laterally on the leg and the thigh so the axes of the leg and the thigh and end blocks coincided. JPS4 values were tested with the subjects in a seated position and the popliteal fossa did not touch the edge of the seat bottom when the leg was resting at 90° of flexion. The examiner passively extended the leg at a rate of 10°/s, starting from 90°, to an index angle between 10° and 80° of flexion; this angle was maintained for 3 s and the leg was then passively returned to the starting position at the same angular velocity (fig 1). The athletes then actively matched the index angle. In an attempt to prevent repeating the same index angle successively and to provide an equal distribution of index angles, we selected small (10–30°), medium (30–60°) or large (60–80°) index angle intervals. The number of replicates for each leg was 15 (5 in each index interval). Thus each testing session produced 30 estimates for each subject which were available for statistical analysis. To eliminate a learning effect, subjects were blindfolded to prevent visualisation of the legs, did not know the grade of misjudgment of the index angle and did not receive any feedback on the accuracy of their estimates.31
JPS was measured at the beginning and the end of the season in both teams and an additional measurement was made 4 months after the baseline assessment during the season in the intervention team. The JPS was measured by the same examiner throughout.
Three scores were calculated: the real error score (RES), the absolute error score (AES) and the error variation score (EVS). The RES was calculated as the true difference between the index and the matching angle and was expressed in terms of degrees of rotation, the AES was calculated as the absolute value of the RES, and the EVS was used to describe the variability and was calculated as the standard deviation. The mean absolute error, which enables comparisons within and between groups, also allows comparisons with the results of other researchers on position sense testing. Previous reports in the literature have found the JPS4 (AES) to be repeatable (intraclass correlation coefficient 0.8).32
Data were recorded on MS Excel sheets and analysed using Statistica Version 6.0. For comparison of data the ANOVA test with post hoc comparison (Scheffe process) was used. Statistical significance was assumed at p<0.05. The statistical power was 0.9.
Joint position sense
The mean AES, EVS and SEM were assessed with respect to side dominance before and after the intervention. In the intervention group there was a significant difference in the JPS at the second evaluation in the whole index interval (10–80°, table 1). The mean AES and EVS of both knees were larger before starting the intervention and decreased significantly after a 4-month period of training. There was no significant difference between the mean estimate error at the second and third evaluations in the whole index interval (10–80°) in the intervention team (table 2). There were no significant differences between the dominant and non-dominant legs before or after the intervention. A significant improvement was seen in the mean AES in JPS in both kees in the intervention group (fig 2). In the control group, no significant improvement was seen.
Most authors agree that proprioception training can reduce the incidence of serious ligament injuries of the lower limb.18 23 28 30 33–35 It appears that all successful programmes have one or several of the following components: traditional stretching and strengthening activities, aerobic conditioning, agilities, plyometrics and risk awareness training. Similar to rehabilitation programmes, prevention programmes should be designed to include a proprioceptive component that addresses the following three levels of motor control: spinal reflexes, cognitive programming and brainstem activity.36
What is already known on this topic
Knee injury has a high incidence among elite female handball players.
Proprioception training can reduce the injury rate in the lower extremities.
The exercises used in our programme were developed on the basis of previous successful intervention studies in team handball.23 30 The focus on alignment of the hip, knee and ankle, especially the knee over toe position, was supported by data from Ebstrup and Boysen-Moller37 38 and Olsen et al.39 Their video analyses of the mechanisms of injuries of the anterior cruciate ligament in team handball indicate that players could benefit from not allowing the knee to sag medially during plant and cut movements or when suddenly changing speed. Based on data from volleyball,28 our programme also focused on landing on both legs after jumps rather than just one leg and emphasised increased hip and knee flexion to attenuate the landing.
What this study adds
Proprioception training improves joint position sense in the knee joint in elite female handball players.
Improvement in the joint position sense may be one explanation for the reduction in injury rate.
Little is known to date about the effect of the prevention programme on coordination and JPS. The neuromuscular-sensorimotor system encompasses all of the sensory, motor and central integration and processing components involved in maintaining functional joint stability.40 Besides the muscle spindle, the sources of conscious proprioceptive information include mechanoreceptors such as Ruffini endings, Pacini corpuscles and Golgi tendon organs in and around the human knee that are responsible for sensating the joint position.41 The proprioceptive information travels to the higher brain centres through the dorsal lateral tracts (conscious appreciation) and the spinocerebellar pathways (stimulation and regulation of motor activities) The precise quantities being conveyed to both ascending tracts from each type of mechanoreceptor, as well as the temporal relationship between arrival at the cerebellum and the somatosensory cortex, are unknown.42 Most assessment techniques currently available evaluate the integrity and function of sensorimotor components by measuring variables along the afferent or efferent pathways, or the final outcome of skeletal muscle activation, or a combination of these.43 Evaluation of the proprioception of the knee joint is achieved by peripheral afferent acquisition and transmission measurements. Several different testing techniques have been developed to measure the conscious submodalities of proprioception. There are three submodalities (JPS, kinesthaesia and sense of tension) The JPS test measures the accuracy of position replication and can be conducted actively or passively in both open and closed kinetic chain positions.43 Both direct measurements of replicated joint angles (goniometers, potentiometers, video)44 45 and indirect measures (visual analogue scales)46 have been used.
Some authors have suggested that Tai Chi exercises may lead to improved balance, reduced fear of falling, increased strength, increased functional mobility and greater flexibility.28 47 They have investigated the improved balance by comparing the knee joint angle repositioning error of the intervention group with a control group of healthy subjects.48 We have used the JPS4 technique described by Beynnon et al.32 Several proprioceptive measurement techniques were evaluated, and JPS4 and AES were found to be the most accurate and repeatable. The applied angle index could not be seen by the subjects and a 1-litre intravenous bag was placed under the thigh to distribute the pressure at the interface between the seat and thigh. The advantage of this method is that the goniometer is portable in a simple small suitcase and each evaluation takes no more than about 5 min. The lack of normal communicative skills on the part of the subjects limits the applicability, and some authors found that proprioceptive ability cannot be inferred from independent tests of either kinesthesia or JPS.49 We excluded all participants from the JPS assessment who had previous serious knee ligament injuries or suffered knee injuries during the season because proprioceptive function is affected by knee injury.46 50 51 Our results showed a significant improvement in the mean AES in JPS in both knees in the intervention group (fig 2). In the control group, which followed a regular warm-up programme, no significant improvement was seen in the AES. To date, the minimum duration of an effective prevention training is not known. Some authors have suggested that athletes need a minimum of 6 weeks of training. This correlates with the time frame needed for increased motor recruitment but not with the time needed for muscle hypertrophy or improved endurance. However, the programmes are effective because they train neuromuscular factors and 6 weeks may be sufficient.52
Our results suggest that no further improvement in JPS would be achieved by continuing the neuromuscular training for more than 4 months. This contrasts with the results of Fong et al48 who found that Tai Chi training for >1 year might improve knee JPS. These changes may be associated with improved dynamic standing balance. Improved knee JPS was seen following 3 months of Tai Chi practice but this did not lead to a significant improvement in balance.
Team handball is a team sport that has a high incidence of knee ligament injuries which are typically sustained in non-contact situations, especially during side-cutting manoeuvres. Furthermore, it appears that the incidence is disproportionately high in female players.53 Treatment and rehabilitation costs are estimated at $17 000 per anterior cruciate ligament injury, which does not take into account the potential loss of long-term participation, loss of scholarship funding and future disability from arthritic changes in a reconstructed knee.54 Verhagen et al55 estimated that the cost of a proprioceptive balance board training programme to prevent one ankle sprain is approximately €450 using a similar protocol to ours. The clinical benefits therefore outweigh the cost of a proprioceptive balance board training programme.
The results of this study show that propioceptive training improves the JPS in the knee joint in elite female handball players. These findings may explain in part how these preventive measures can reduce the incidence of injury in the lower extremities.
Competing interests: None.
Ethics approval: The study was approved by the Medical Ethics Committee and all participants gave informed consent.
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