Military exercises, knee and ankle joint position sense, and injury in male conscripts: a pilot study

Ankle sprains in male Israeli infantry soldiers during training: prevalence and risk factors

BACKGROUND

Given the high incidence and heavy burden of ankle sprains in recruits, large-scale, multifactorial investigations into potential risk factors are warranted. This study aimed to identify the incidence of ankle sprains and associated risk factors among new military recruits during their infantry training.

METHODS

The study included 365 infantry recruits (aged 18-21 years), who were inducted into service in March 2022. These recruits were monitored for ankle sprains throughout their basicy and advanced infantry training by a physiotherapist. Preinduction smoking habits, physical fitness preparation and recurrent ankle sprains were recorded. Anthropometric measures, lower-extremity functional movement, Achilles tendon structure, perceived ankle instability, and mechanical ankle instability were assessed at the onset of both training periods.

RESULTS

Ankle sprains were diagnosed in 109 trainees (29.9%) during both the basic and the advanced training periods. Preinduction recurrent ankle sprains were reported by 28.2% of the participants. The relative risk of a recruit with preinduction ankle sprains suffering a subsequent sprain during training was 1.66 (p=0.001). Logistic regression analysis indicated that reduced proprioception ability (OR=0.002), higher body mass index (OR=1.08), preinduction recurrent sprains (OR=1.95) and lack of physical fitness preparation (OR=3.12) were related to ankle sprains throughout the complete basic-and-advanced training period. Preinduction recurrent ankle sprains (OR=3.37) and reduced Achilles tendon quality (OR=1.30) were associated with ankle sprains during the advanced training period.

CONCLUSIONS

Lower-extremity functional movement, body mass index, preinduction recurrent sprains, physical preparation and reduced Achilles tendon quality were associated with the risk of ankle sprains during training. These findings could contribute to developing prevention and intervention programmes for reducing ankle sprains in military trainees.

Acute effects of Nordic hamstring exercise on hip and knee joints proprioception

BACKGROUND AND OBJECTIVES

Nordic Hamstring Exercise (NHE) is one of the best exercises proposed for injury prevention of hamstring muscles. However, its effects on lower extremity proprioception are unclear. The aim of this study was to investigate the immediate effects of a single bout of NHE on hip and knee joints' proprioception.

METHODS

Forty collegiate male soccer players participated in this study with a mean age of 22.85 ± 1.82 years and were randomized into either control (n = 20) or experimental (n = 20) groups. Each subject participated in pre-test measurements in which hip and knee active joints position sense (JPS) were assessed in standing and lying tasks using the image-capturing method. The experimental group then performed three sets of NHE with 10 repetitions in each set, while the control group rested for 10 min. Paired and independent t-tests were used for calculating the differences within and between groups on SPSS software, respectively. The level of significance was P ≤ 0.05.

RESULTS

Hip JPS in the lying task and knee JPS in both of the standing and lying tasks were impaired significantly after performing a single bout of NHE (P ≤ 0.05). However, the effects of this exercise on hip JPS in the standing task were not significant (P ≥ 0.05).

CONCLUSIONS

NHE performing with three sets of 10 repetitions can significantly impair hip and knee JPS immediately after exercise and reduce the proprioception acuity of the lower limbs. It is recommended to perform this exercise at a time rather than before training or match sessions.

The Effect of Muscle Fatigue on the Knee Proprioception: A Systematic Review

This study aimed to systematically review and summarise the evidence about the effect of muscle fatigue on the knee proprioception of trained and non-trained individuals. A search in PubMed, Scopus, Web of Science and EBSCO databases and Google Scholar was conducted using the expression: "fatigue" AND ("proprioception" OR "position sense" OR "repositioning" OR "kinesthesia" OR "detection of passive motion" OR "force sense" OR "sense of resistance") AND "knee". Forty-two studies were included. Regarding joint-position sense, higher repositioning errors were reported after local and general protocols. Kinesthesia seems to be more affected when fatigue is induced locally, and force sense when assessed at higher target forces and after eccentric protocols. Muscle fatigue, both induced locally or generally, has a negative impact on the knee proprioception.

Advances in Understanding and Managing Floating Knee Injuries: A Comprehensive Review

Fractures of the ipsilateral tibia and femur, frequently combined with soft tissue damage and dislocations, describe floating knee injuries, a complicated orthopedic condition. Epidemiological data suggest that floating knee injuries account for a small but significant proportion of traumatic orthopedic injuries, with a higher incidence observed in younger males engaged in high-risk activities. Anatomically, floating knee injuries involve fractures of the femur and tibia, ligamentous disruptions, and soft tissue damage, contributing to the complexity and severity of these injuries. An extensive analysis of floating knee injuries is given in this paper, including information about epidemiology, anatomy, pathophysiology, categorization, management approaches, complications, prognosis, and current and upcoming developments.

Chronic Ankle Instability and Neuromuscular Performance in Prerecruitment Infantry Soldiers

CONTEXT

Ankle instability can describe various impairments, including perceived instability (PI), mechanical instability (MI), and recurrent sprains (RSs), alone or combined.

OBJECTIVE

To examine the prevalence of 8 ankle impairment subgroups and their effect on neuromuscular performance in prerecruitment combat soldiers.

DESIGN

Cross-sectional study.

SETTING

Military infantry basic training base.

PATIENTS OR OTHER PARTICIPANTS

A total of 364 infantry male combat soldiers entering basic training (aged 18-21 years).

MAIN OUTCOME MEASURE(S)

Participants were assessed for PI (via the Cumberland Ankle Instability Tool), MI (using the Anterior Drawer Test and Medial Talar Tilt Test), and RSs (based on history) of their dominant and nondominant legs. Injuries were categorized in 8 subgroups: PI, RSs, PI + RSs, MI, PI + MI, MI + RSs, PI + MI + RSs, and none. Participants were screened for neuromuscular performance (dynamic postural balance, proprioceptive ability, hopping agility, and triceps surae muscle strength) during the first week of military basic training.

RESULTS

For the dominant and nondominant legs, RSs were reported by 18.4% (n = 67) and 20.3% (n = 74) of the participants, respectively; PI was reported by 27.1% (n = 99) and 28.5% (n = 104) of the participants, respectively; and MI was seen in 9.9% (n = 36) and 8.5% (n = 31) of the participants, respectively. A 1-way analysis of variance showed differences in the mean proprioceptive ability scores (assessed using the Active Movement Extent Discrimination Apparatus) of all subgroups with impairments in both the dominant and nondominant legs (F = 6.943, η2 = 0.081, P < .001 and F = 7.871, η2 = 0.091, P < .001, respectively). Finally, differences were found in the mean muscle strength of subgroups with impairment in the nondominant leg (F = 4.884, η2 = 0.056, P = .001).

CONCLUSIONS

A high prevalence of ankle impairments was identified among participants who exhibited reduced abilities in most neuromuscular assessments compared with those who did not have impairments. Moreover, participants with 1 impairment (PI, MI, or RSs) exhibited different neuromuscular performance deficits than those with >1 impairment.

Epidemiology of musculoskeletal injury in military recruits: a systematic review and meta-analysis

BACKGROUND

Injuries are a common occurrence in military recruit training, however due to differences in the capture of training exposure, injury incidence rates are rarely reported. Our aim was to determine the musculoskeletal injury epidemiology of military recruits, including a standardised injury incidence rate.

METHODS

Epidemiological systematic review following the PRISMA 2020 guidelines. Five online databases were searched from database inception to 5th May 2021. Prospective and retrospective studies that reported data on musculoskeletal injuries sustained by military recruits after the year 2000 were included. We reported on the frequency, prevalence and injury incidence rate. Incidence rate per 1000 training days (Exact 95% CI) was calculated using meta-analysis to allow comparisons between studies. Observed heterogeneity (e.g., training duration) precluded pooling of results across countries. The Joanna Briggs Institute Quality Assessment Checklist for Prevalence Studies assessed study quality.

RESULTS

This review identified 41 studies comprising 451,782 recruits. Most studies (n = 26; 63%) reported the number of injured recruits, and the majority of studies (n = 27; 66%) reported the number of injuries to recruits. The prevalence of recruits with medical attention injuries or time-loss injuries was 22.8% and 31.4%, respectively. Meta-analysis revealed the injury incidence rate for recruits with a medical attention injury may be as high as 19.52 injuries per 1000 training days; and time-loss injury may be as high as 3.97 injuries per 1000 training days. Longer recruit training programs were associated with a reduced injury incidence rate (p = 0.003). The overall certainty of the evidence was low per a modified GRADE approach.

CONCLUSION

This systematic review with meta-analysis highlights a high musculoskeletal injury prevalence and injury incidence rate within military recruits undergoing basic training with minimal improvement observed over the past 20 years. Longer training program, which may decrease the degree of overload experienced by recruit, may reduce injury incidence rates. Unfortunately, reporting standards and reporting consistency remain a barrier to generalisability.

TRIAL REGISTRATION

PROSPERO (Registration number: CRD42021251080).

Risk factors for injuries along an infantry commanders course

To determine the influence of prevention programme on somatosensory ability in combat soldiers during 14-weeks of an infantry commanders course, two cohorts were recruited (INT-group, n = 196; CONT-group, n = 169). Soldiers were tested pre-and post-course for anthropometric measurements, proprioceptive ability, dynamic postural balance, and filled CAIT questionnaire. The INT-group performed injury prevention exercises and the CONT-group continued with their routine physical fitness lessons. All musculoskeletal injuries were recorded along the course. In the CONT-group 24.2% and in the INT-group 19.9% suffered injury during the course. The rates of injuries were not significantly different between groups (χ2(1) = .677 p = .411). Previous injury (OR = 3.349, 95% CI = 1.283-8.740), pre-course BMI (OR = 1.216, 95% CI = 1.064-1.389), and pre-course proprioception ability (OR = .870, 95% CI = .810-.935) were factors associated with injury in the CONT-group. Pre-course proprioception ability (OR = .769, 95% CI = .699-.846) and pre-course CAIT score (OR = .087, 95% CI = .027-.276) were factors in the INT-group. Soldiers who received injury prevention exercises had a similar prevalence of total musculoskeletal injuries as those who did not receive these exercises. Risk factors for injuries were different in the two groups.

Injury Prevention Exercises for Reduced Incidence of Injuries in Combat Soldiers

ABSTRACT

Steinberg, N, Bar-Sela, S, Moran, U, Pantanowitz, M, Waddington, G, Adams, R, Band, SS, and Funk, S. Injury prevention exercises for reduced incidence of injuries in combat soldiers. J Strength Cond Res XX(X): 000-000, 2021-The aim of this study was to determine the influence of an "all-cause injury" prevention program, focused on static-to-dynamic transitions, on injury prevalence in a military commanders course. Two cohorts of male infantry commanders were recruited (intervention [INT group], n = 196 and controls [CO group], n = 169) and tracked by a physiotherapist, who recorded any injuries that occurred during the 14-week course. Soldiers were tested precourse, midcourse, and postcourse for anthropometrics, proprioception ability, and dynamic postural balance (DPB). The INT group performed injury prevention exercises for 5 minutes, 3 times a week, and the CO group continued with their routine physical fitness sessions. The prevalence of injuries reported to the physiotherapist during the course was significantly lower for the INT group compared with the CO group (14.8 and 34.3%, respectively, p < 0.001). Similarly, rates of injury in the INT group were significantly lower than in the CO group (p < 0.001; hazard = 2.53, 95% confidence interval = 1.62-3.95). Precourse proprioception ability was significantly lower in those that became injured during the commanders course, irrespective of the group. Likewise, for DPB parameters, the injured subjects in both groups had significantly lower precourse scores than the noninjured subjects. From pretesting to midtesting, the injured soldiers in the INT group improved their ability up to the level of the noninjured subjects. A reduced prevalence of injuries was found for soldiers who completed the injury prevention program. Because the subjects soldiers injured on the course had reduced somatosensory abilities at the outset, and as these abilities can be improved by static-to-dynamic exercises, identifying at-risk soldiers and providing them with appropriate strategies for improvement beforehand is indicated.

Effect of verbal encouragement on quadriceps and knee joint function during three sets of knee extension exercise

BACKGROUND: Although the common practice of verbal encouragement is scientifically supported, its effect on the maintenance of force output in fatiguing exertions is unknown. OBJECTIVE: To examine the effects of verbal encouragement on exercise-induced quadriceps and knee joint function during three sets of knee extension exercise. METHODS: Sixty-five healthy males (23.3 years, 175.8 cm, 75.3 kg) underwent testing using the administration of verbal encouragement (n= 32) or not (n= 33) during assessment of quadriceps and knee joint function. Assessments were performed at baseline and times 1, 2, and 3. The knee concentric isokinetic extension at 60∘/s, was performed between the time points. For quadriceps function, maximal isometric strength and activation (central activation ratio) were recorded. Absolute error values on knee flexion replications at 15∘ or 45∘ were recorded for knee joint function. RESULTS: There was no verbal encouragement effect over three sets of exercise in quadriceps strength (condition × time: F3,189= 1.71, p= 0.17) and knee flexion replication (condition × time for 15∘: F3,189= 0.11, p= 0.96; 45∘: F3,189= 0.63, p= 0.6). However, subjects who had received verbal encouragement maintained quadriceps activation (condition × time: F3,189= 5.49, p= 0.001). Specifically, quadriceps activation in the verbal condition was 3.0% higher at time 2 (p= 0.01) and 4.7% higher at time 3 (p= 0.0003) versus in the non-verbal condition. CONCLUSIONS: Verbal encouragement appears to be effective in maintaining central activation, but is insufficient for promoting strength. This supports the idea that peripheral contributing factors play a larger role in force production when performing multiple sets of exercises.

Overuse-Related Injuries of the Musculoskeletal System: Systematic Review and Quantitative Synthesis of Injuries, Locations, Risk Factors and Assessment Techniques

Overuse-related musculoskeletal injuries mostly affect athletes, especially if involved in preseason conditioning, and military populations; they may also occur, however, when pathological or biological conditions render the musculoskeletal system inadequate to cope with a mechanical load, even if moderate. Within the MOVIDA (Motor function and Vitamin D: toolkit for risk Assessment and prediction) Project, funded by the Italian Ministry of Defence, a systematic review of the literature was conducted to support the development of a transportable toolkit (instrumentation, protocols and reference/risk thresholds) to help characterize the risk of overuse-related musculoskeletal injury. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach was used to analyze Review papers indexed in PubMed and published in the period 2010 to 2020. The search focused on stress (overuse) fracture or injuries, and muscle fatigue in the lower limbs in association with functional (biomechanical) or biological biomarkers. A total of 225 Review papers were retrieved: 115 were found eligible for full text analysis and led to another 141 research papers derived from a second-level search. A total of 183 papers were finally chosen for analysis: 74 were classified as introductory to the topics, 109 were analyzed in depth. Qualitative and, wherever possible, quantitative syntheses were carried out with respect to the literature review process and quality, injury epidemiology (type and location of injuries, and investigated populations), risk factors, assessment techniques and assessment protocols.

Factors associated with musculoskeletal injuries in an infantry commanders course

OBJECTIVES

To evaluate the prevalence of injuries among young combat soldiers as assessed and reported by the military physicians, and to investigate whether parameters such as anthropometric measures, postural balance, proprioceptive ability, and chronic ankle instability are related to injuries during and following an infantry commanders course.

METHODS

In this cross-sectional study, 165 soldiers were tested for anthropometric measurements, proprioceptive ability, and dynamic postural balance (DPB), as well as for their responses to an ankle stability questionnaire (CAIT), on three occasions: pre-course, middle-course, and end-course testing. All musculoskeletal injuries were assessed and recorded in the digital medical file of each participant by specialist military physicians before and during/following the course.

RESULTS

Ninety-eight soldiers (59.4%) were injured before the course. Forty soldiers (24.2%) incurred an injury during/following the course (with 33 out of the 40 [82.5%] soldiers that were injured during/following the course having also been injured before the course). Sixty soldiers had no injury before/during/following the course. A survival curve showed that half of the soldiers who were injured during/following the course (20 soldiers) were recorded as injured in the first half of the course (during the first 46 days of the 92-day course). Logistic regression showed that the pre-course parameters that were significant among injured soldiers compared with the non-injured soldiers were: low CAIT results (OR = 2.736, 95% CI = 1.178-6.354), high BMI (OR = 1.234, 95% CI = 1.082-1.406) and reduced proprioceptive ability (OR =.858, 95% CI =.797-.924).

CONCLUSION

With a high prevalence of soldiers injured during and following a commanders course, a somatosensory intervention program should be generalized into the practical daily preparation and training routines of the soldiers for improving somatosensory abilities, optimizing military physical readiness, and for preventing future musculoskeletal injuries.

Altered Dynamic Postural Stability and Joint Position Sense Following British Army Foot-Drill

Impaired proprioceptive acuity negatively affects both joint position sense and postural control and is a risk factor for lower-extremity musculoskeletal injury in athletes and military personnel. British Army foot-drill is an occupational military activity involving cyclical high impact loading forces greater than those observed in athletes during high level plyometrics. Foot-drill may contribute to the high rates of lower-extremity overuse injuries observed in recruits during basic training. There is limited research investigating foot-drill specific injury risk factors in women, despite greater incidences of musculoskeletal injury reported in women (522 vs. 417 per 1,000 personnel, OR: 1.53) when compared to men during basic training. This study aimed to quantify changes in ankle joint proprioception and dynamic postural stability following a period of British Army foot-drill. Fourteen women of similar age to British Army female recruits underwent pre-post foot-drill measures of frontal plane ankle joint position sense (JPS) and dynamic postural stability using the dynamic postural stability index (DPSI). Passive ankle JPS was assessed from relative test angles of inversion 30% (IN30%) and eversion 30% (EV30%) and IN60% of participants range of motion using an isokinetic dynamometer. The DPSI and the individual stability indices (medio-lateral [MLSI], anterior-posterior [APSI], and vertical [VSI]) were calculated from lateral and forward jump-landing conditions using force plates. Foot-drill was conducted by a serving British Army drill instructor. Significantly greater absolute mean JPS error for IN30% and EV30% was observed post foot-drill (p ≤ 0.016, d ≥ 0.70). For both the lateral and forward jump-landing conditions, significantly greater stability index scores were observed for MLSI, APSI, and DPSI (p ≤ 0.017, d ≥ 0.52). Significantly greater JPS error and stability index scores are associated with the demands of British Army foot-drill. These results provide evidence that foot-drill negatively affects lower-extremity proprioceptive acuity in recruit age-matched women, which has implications for increased injury risk during subsequent military physical activity, occurring in a normal training cycle.

Joint position sense error and muscle torque ratios of agonist and antagonist muscles in the ankle and knee joints of young adults

BACKGROUND

Many studies have investigated the correlation between muscle torque and joint position sense (JPS), but few studies have been performed on the correlation between torque ratio and JPS.

OBJECTIVE

The aim of this study was to investigate JPS and muscle torque ratios of agonist and antagonist muscles in the ankle and knee joints of young adults.

METHODS

A total of 38 right handed healthy participants, 12 males and 26 females, were recruited. All participants measured their peak torque of knee flexor/extensor and ankle dorsiflexor/plantar flexor by using a Biodex system. They also used the Biodex to assess the proprioception through active joint reposition sense test in knee and ankle joint. Peak torque of each muscle, agonist/antagonist torque ratio and JPS error were collected, and Pearson's correlation analysis was used to examine correlations between peak torque, torque ratio and JPS error.

RESULTS

For knee joints, correlations were found between flexion and extension torque, extension torque and torque ratio, and torque ratio and JPS error (r= 0.825/p= 0.000, r=-0.482/p= 0.002, and r=-0.685/p= 0.000, respectively). For ankle joints, correlations were found between dorsiflexion and plantar flexion torques, plantar flexion torque and torque ratio, plantar flexion torque and JPS, and torque ratio and JPS (r= 0.654/p= 0.000, r=-0.621/p= 0.000, r=-0.563/p= 0.000, and r=-0.761/p= 0.000, respectively).

CONCLUSIONS

JPS error of lower extremity joint may be more related with agonist/antagonist torque ratio rather than peak torque. Therefore, people who will have training for reducing JPS error need to consider torque ratio, too.

Self-Reported Knee Pain Does Not Impact Physical Training Negatively in Conscripts

INTRODUCTION

Despite the great number of investigations on the effects of injuries during military service, there is limited information available on the use of self-reported instruments. This study evaluated self-reported knee pain (KP) and its effect on physical performance during military service in the Estonian Defense Forces.

MATERIAL AND METHODS

Ninety-five male conscripts aged 19-25 years were divided into two study groups based on the occurrence of KP or not. Self-reported KP and function according to the Knee Injury and Osteoarthritis Outcome Score (KOOS) were measured. Physical fitness level was scored using the Army Physical Fitness Test (APFT). KOOS and APFT were measured in the beginning and at the end of the 6-month period of military service.

RESULTS

Significant differences in favor of the group without KP (P < 0.001) were found for all subgroups of the KOOS. In spite of KP, the physical condition improved significantly (P < 0.001) in both study groups as measured with both the APFT test (22.2% increase) and running time (10.3% decrease).

CONCLUSION

In conclusion, self-reported KP and limited function according to KOOS did not hinder the improvement of physical condition and running speed as assessed by APFT in Estonian conscripts.

Effects of two exercise programmes on joint position sense, dynamic balance and countermovement jump in male amateur football players. A randomised controlled trial

Introduction: The injury prevention and warm-up exercises programmes improve physical performance and injury ratio, but it is poorly investigated in amateur football. Objectives: To assess the effects of two warm-up multi-station programmes (IAI-Programme and FIFA11+) through JPS, LSDT and CMJ. Study design: Randomised controlled trial. Methods: 36 football players were randomised into 2 groups: IAI-Programme (n = 18) and FIFA11+ (n = 18) and performed the intervention protocol for 6 weeks. JPS, LSDT and CMJ were measured at baseline, after 6, 10 and 18 weeks (from baseline). The inter-group and intra-group differences were assessed by repeated-measures analysis of variance test (ANOVA). Results: Significant differences between groups were found after 18 weeks in the absolute angular error (-2.18[-4.33,-0.047], d = 0.69, p < 0.05) of the JPS and in the CMJ (p = 0.001, ŋ²p=,0.298) in favour of IAI-Programme when compared to FIFA11 +. No significant differences between groups were found in the LSDT. There were also intra-group differences observed in the LSDT in both groups. Conclusions: IAI-Programme can provide sensitive benefits with respect to the proprioceptive ability of knee flexion and CMJ than FIFA11 +. Both IAI-Programme and FIFA11+ present improvements in the dynamic postural control measured by the LSDT.

Incidence of injuries and factors related to injuries in combat soldiers

Introduction

Musculoskeletal injuries to the lower extremities are major factors contributing to drop out from military tasks. The aim of the present study was to determine the incidence of musculoskeletal injuries and the parameters that differentiate between the soldiers who incurred these injuries and those who did not along 14 weeks of an infantry commanders course.

Methods

One-hundred and sixty-eight participants were recruited from an infantry commanders course. The soldiers were tested before (pre), in the middle (middle) and at the end (last) of the course for anthropometric measurements, proprioceptive ability and dynamic postural balance (DPB), and filled out an ankle stability questionnaire (Cumberland Ankle Instability Tool (CAIT). A physiotherapist followed and recorded all musculoskeletal injuries incurred by the participants during the course.

Results

Fifty-eight participants out of the 168 (34.5%) reported some pain/injury. Time effects were found for body mass index, DPB asymmetry, DPB in posterior-medial (P-M) direction and proprioception ability. Injury effects were found for DPB asymmetry, DPB in P-M direction, CAIT and proprioception ability. An interaction was found for proprioception ability. The Cox regression showed that the variables that are mostly effecting injuries were pretesting proprioception ability, DPB asymmetry and CAIT.

Conclusions

More than one out of three participants incurred musculoskeletal injuries, with deficits in proprioception ability, DPB and ankle stability in pretesting as major factors contributing to injuries. Further studies should look at the effect of specific exercises such as proprioception, DPB and ankle stability exercises for prevention and treatment of musculoskeletal injuries among combat soldiers.

Paradoxical relationship in sensorimotor system: Knee joint position sense absolute error and joint stiffness measures

BACKGROUND

Relationships between joint position sense and the sensorimotor characteristics such as joint stiffness, time to detect motion, and time to peak torque during a perturbation test have rarely been investigated due to methodological challenges. The purpose of this study was to compare joint position sense and the sensorimotor characteristics in healthy individuals.

METHODS

A total of 26 subjects were recruited and completed joint position sense and a perturbation test on isokinetic dynamometer. Joint position sense was assessed by comparison of the absolute angle difference between a reference and replicated position. During the perturbation test, the dynamometer moved the knee flexion angle from 70° to 30° (0° represents a full knee extension) at the velocity of 500° per second at random. Subjects were asked to react and pull back the leg as soon as they perceived the movement. Pearson or Spearman's correlation coefficients were used to assess these relationships (P < 0.05).

FINDINGS

Larger joint position sense absolute error values were significantly correlated with higher short-range at 50 milliseconds (r = 0.572, P = 0.002), at 100 milliseconds (ρ = 0.416, P = 0.035), and reactive joint stiffness (r = 0.395, P = 0.046).

INTERPRETATION

There was a paradoxical relationship between higher joint stiffness and worsened joint position sense. Potential reasons include sensory weighting within the sensorimotor system and thixotropic properties (after-effects of muscle eccentric contractions to increase stiffness and alter joint position sense).

Can a short neuromuscular warmup before tackling improve shoulder joint position sense in rugby players?

BACKGROUND

In rugby the tackle is a complex task requiring joint position sense (JPS). Injuries commonly occur during the tackle and these account for significant time lost from training and play. Simulated tackling tasks have previously shown a reduction in shoulder joint position sense and it is possible that this may contribute to injury. There is growing evidence in support of injury prevention programs, but none so far are dedicated specifically to tackling. We postulate that a brief neuromuscular warmup could alter the negative effects of fatigue on shoulder JPS.

METHODS

In this field based, repeated measures design study, 25 semi-professional Rugby players participated. JPS was measured at criterion angles of 45° and 80° of right arm shoulder external rotation. Reproduction accuracy prior to and following a neuromuscular warmup and simulated tackling task was then assessed.

RESULTS

In pre-warmup JPS measures, the spread of angle errors were larger at the 80° positions. Adding the warmup, the spread of the angle errors at the 80° positions decreased compared to pre-intervention measures. Two one-sided tests (TOST) analysis comparing pre- and post-testing angle errors, with the addition of the warmup, indicated no difference in JPS.

CONCLUSIONS

The neuromuscular warmup resulted in a decrease in JPS error variance meaning fewer individuals made extreme errors. The TOST analysis results also suggest the neuromuscular warmup used in this study could mitigate the negative effects of tackling on JPS that has been seen in prior research. This neuromuscular warmup could play a role in preventing shoulder injuries. It can easily be added to existing successful injury prevention programs.

Effects of fatigue on ankle biomechanics during jumps: A systematic review

Fatigue is common during physical activity and can have an effect on ankle biomechanics during different actions, such as a jump. Yet current research on the topic is very heterogeneous and hinders clarity on what changes are actually due to fatigue. Therefore, the aim of this review was to summarise and analyse the current literature that investigates the effects of fatigue on ankle biomechanics during a jump. Searches were conducted in five databases and studies with activities eliciting fatigue and comparing outcomes under a fatigue and non-fatigue conditions were selected. Twelve studies were included, six analysed double legged jumps and six single legged jump. When comparing ankle biomechanics between a fatigued condition and a non-fatigued condition, findings suggested that at initial contact at landing, dorsiflexion increased in single legged jump and plantarflexion increased in double legged jump; at maximum knee flexion after landing, dorsiflexion decreased in double legged jumps and plantarflexion increased at full foot contact in single legged jumps. Also, ankle power (for double legged jump) and ground reaction force (for double and single legged jump) reduced at initial contact to maximum knee flexion at landing after fatigue and ankle power also reduced at takeoff in single legged jumps. The current review shows that fatigue affect ankle biomechanics by reducing dorsiflexion, from initial contact to maximum knee flexion at landing, and power during the jump takeoff. Such information could have implications for injury prevention.

Introduction to Equine Physical Therapy and Rehabilitation

Physical therapy (physiotherapy, or PT) can be broadly defined as the restoration of movement and function and includes assessment, treatment, and rehabilitation. This review outlines the history, definition, and regulation of PT, followed by the core scientific principles of PT. Because musculoskeletal physiotherapy is the predominant subdiscipline in equine PT, encompassing poor performance, back pain syndromes, other musculoskeletal disorders, and some neuromuscular disorders, the sciences of functional biomechanics, neuromotor control, and the sensorimotor system in the spine, pelvis, and peripheral joints are reviewed. Equine PT also may involve PT assessment and treatment of riders.