SYNOPSIS: The sport of volleyball creates considerable dynamic trunk stability demands. Back injury occurs all too frequently in volleyball, particularly among female athletes. The purpose of this clinical commentary is to review functional anatomy, muscle coactivation strategies, assessment of trunk muscle performance, and the characteristics of effective exercises for the trunk or core. From this information, a conceptual progressive 3-phase volleyball-specific training program is presented to improve dynamic trunk stability and to potentially reduce the incidence of back injury among volleyball athletes. Phase 1 addresses low-velocity motor control, kinesthetic awareness, and endurance, with the clinician providing cues to teach achievement of biomechanically neutral spine alignment. Phase 2 focuses on progressively higher velocity dynamic multiplanar endurance, coordination, and strength-power challenges integrating upper and lower extremity movements, while maintaining neutral spine alignment. Phase 3 integrates volleyball-specific skill simulations by breaking down composite movement patterns into their component parts, with differing dynamic trunk stability requirements, while maintaining neutral spine alignment. Prospective research is needed to validate the efficacy of this program. LEVEL OF EVIDENCE: Level 5.

J Orthop Sports Phys Ther. 2008; 38(11):703-720, Epub 24 October 2008. doi:10.2519/jospt.2008.2814

KEY WORDS: abdominal muscles, electromyography, erector spinae, kinetics, lumbar spine

We present a clinical commentary of existing evidence regarding popliteus musculotendinous complex anatomy, biomechanics, muscle activation, and kinesthesia as they relate to functional knee joint rehabilitation. The popliteus appears to act as a dynamic guidance system for monitoring and controlling subtle transverse- and frontal-plane knee joint movements, controlling anterior-posterior lateral meniscus movement, unlocking and internally rotating the knee joint (tibia) during flexion initiation, assisting with 3-dimensional dynamic lower extremity postural stability during single-leg stance, preventing forward femoral dislocation on the tibia during flexed-knee stance, and providing for postural equilibrium adjustments during standing. These functions may be most important during mid-range knee flexion when capsuloligamentous structures are unable to function optimally. Because the popliteus musculotendinous complex has attachments that approximate the borders of both collateral ligaments, it has the potential for providing instantaneous 3-dimensional kinesthetic feedback of both medial and lateral tibiofemoral joint compartment function. Enhanced popliteus function as a kinesthetic knee joint monitor acting in synergy with dynamic hip muscular control of femoral internal rotation and adduction, and ankle subtalar muscular control of tibial abduction-external rotation or adduction-internal rotation, may help to prevent athletic knee joint injuries and facilitate recovery during rehabilitation by assisting the primary sagittal plane dynamic knee joint stabilization provided by the quadriceps femoris, hamstrings, and gastrocnemius.

J Orthop Sports Phys Ther. 2005;35(3):165-179. doi: 10.2519/jospt.2005.1414

Key Words: knee, lateral meniscus, lower extremity

Study Design: One group; pretest, posttest design. Objective: To assess the effect of a 2-hour cheerleading practice on the anterior knee laxity, hamstring extensibility, and dynamic postural stability (preferred stance leg during vision-denied unilateral stance) of 17 nonimpaired members of a college cheerleading team (8 females, 9 males; 18-25 years old). Background: Anterior knee laxity and hamstring extensibility increase following exercise. The relationship between exercise induced anterior knee laxity, hamstring extensibility, and dynamic postural stability, however, has not been examined. Methods and Measures: Pre- and postpractice measurements were compared using paired t tests and Bonferroni's correction for multiple comparisons. A 3 x 2 analysis of variance (force level applied to the arthrometer by condition) and Tukey honest significant difference post hoc test were used to evaluate specific arthrometer force level by condition effects (P < .05). Results: Mean laxity at 133 N and hamstring extensibility increased (mean ± SD) 1.5 ± 1 mm and 3 ± 4°, respectively, following practice. Mean medial-lateral stabiliometer platform angulation (frontal plane position) moved medially following practice (2.9 ± 3°) and produced a weak correlation with increased knee laxity (r = 0.58). Hamstring extensibility did not significantly relate to stabiliometry or knee laxity variables. Conclusions: The relationship between the medially directed platform angulation and the increase in anterior knee laxity following cheerleading practice suggests a relationship between subtalar joint position and anterior cruciate ligament strain.

J Orthop Sports Phys Ther. 1999;29(8):455-462.

Key Words: anterior cruciate ligament, dynamic postural stability, fatigue

Study Design: Single group, post-test design using the uninvolved lower extremity as the experimental control. Objectives: To determine relationships between ankle swelling and flexor digitorum longus and peroneus longus H-reflex amplitude and latency. Background: Primary capsuloligamentous injury, neural injury, and joint effusion and swelling may contribute to H-reflex changes following inversion ankle sprain. The relationship between ankle swelling and invertor or evertor H-reflexes has not been reported. Methods and Measures: Fifteen subjects with acute grade I or II inversion ankle sprains (mean ± SD) 6.5 ± 3 days after onset participated in this study. Swelling was estimated using a tape measure and the figure-of-eight girth assessment method. H-reflexes were determined using standard techniques. Paired t-tests were used to compare mean differences in ankle girth (swelling) and ankle invertor or evertor H-reflex amplitude and latency between the involved and uninvolved limbs. Pearson product moment correlations were used to assess relationships between swelling and H-reflex variables. Results: Involved limb ankle girth was increased with respect to the uninvolved limb (1.5 ± 0.9 cm) and the involved ankle flexor digitorum longus latency was delayed (0.72 ± 0.7 ms). There was a moderate positive association (r = 0.73) between the latency delay in the involved ankle flexor digitorum longus and swelling. There were no significant differences in H-reflex amplitude and peroneus longus latency between ankles. Conclusions: Grade I or II inversion sprains and the related swelling appear to delay involved ankle flexor digitorum longus latency to a greater extent than peroneus longus latency. Clinicians need to direct greater attention to the ankle invertors when designing and implementing ankle rehabilitation programs, particularly during the swelling management phase of treatment.

J Orthop Sports Phys Ther. 1999;29(6):339-344.

Key Words: neuromuscular inhibition, electromyography, latency

This study attempted to determine the effect of eccentric quadriceps femoris, hamstring, and placebo fatigue on stance limb dynamics during the plant-and-cut phase of a crossover cut. Twenty female college students (task trained) were tested. Hamstring fatigue resulted in decreased peak impact knee flexion moments (p = .01), increased internal tibial rotation at peak knee flexion (p = .05), and decreased peak ankle dorsiflexion (p = .05). Quadriceps fatigue resulted in increased peak ankle dorsiflexion moments (p < .01), decreased peak posterior braking forces (p = .01), decreased peak knee extension moments (p = .01), delayed peak knee flexion (p = .01), delayed peak propulsive forces (p < .01), and delayed subtalar peak inversion moments (p = .05). Fatigue of either muscle group produced earlier peak ankle plantar flexion moments (p = .05) and decreased peak propulsive knee flexion moments (p = .05). Variables requiring further study (p = .1) provide discussion data. Soleus, gastrocnemius, tibialis anterior, and deep posterior compartment calf muscles serve as dynamic impact force attenuators, compensating for fatigued proximal muscles.

J Orthop Sports Phys Ther. 1997;25(3):171-184.

Key Words: women, muscle, fatigue, compensatory dynamics

Injury to the distal tibiofibular syndesmosis (DTFS) may be more common than previously reported. This injury is typically caused by external forces, which produce sudden ankle dorsiflexion or plantar flexion in combination with external rotation of the foot. Common mechanisms include direct contact with another player or uneven physical terrain. Improper diagnosis of this injury may greatly delay the return to normal functional status and promote the development of chronic instability, degenerative joint changes, and pain. The purpose of this clinical commentary is to review the ligamentous anatomy of the ankle and the incidence of injury to the lateral ligaments of the ankle, with emphasis on DTFS injury. Special tests that enhance the recognition of DTFS injury, such as the external rotation stress test and the distal tibiofibular compression test, and a rehabilitation progression are presented.

J Orthop Sports Phys Ther. 1995;21(4):197-205.

Key Words: ankle, anatomy, rehabilitation

Recently, there has been attention to the clinical application of closed kinetic chain and joint isolation exercise. Our purpose was to compare the effect of joint isolation and closed kinetic chain exercise on quadriceps muscle performance and perceived function in patients with patellofemoral pain. Twenty-three patients participated in an 8-week training period and were assigned to either a closed kinetic chain or a joint isolation exercise training group. An 8-inch (20.3 cm) retro step-up test was performed at baseline, 8 weeks, and 1 year. Seated knee extension testing was measured at baseline and at 8 weeks using peak concentric torque on an isokinetic dynamometer at 90°/sec, 180°/sec, and 360°/sec. Perceived functional status was rated as excellent, good, fair, or poor based on questionnaire response. Statistical analysis showed that both groups had significant improvement in peak torque at all speeds, but only the closed kinetic chain group showed significant improvement in closed kinetic chain testing and perceived functional status. We concluded that closed kinetic chain training may be more effective than joint isolation exercise in restoring function in patients with patellofemoral dysfunction.

J Orthop Sports Phys Ther. 1996;24(3):136-141.

Key Words: muscle strength, patellofemoral pain, kinetic chain

Understanding the afferent neural system of the knee is considered to be vital to rehabilitation planning. An intricate relationship exists involving the afferent neural receptors in the inert and contractile tissues of the knee. Traditional rehabilitation strategies may not exploit this extensive afferent neural system. Closed kinetic chain functional training (CKCFT) may provide a method for more effectively rehabilitating an injured or reconstructed knee. The rationale for CKCFT has traditionally focused on mechanical aspects. Sensorimotor integration through motor learning is believed to be an important component of CKCFT. The purposes of this review are to discuss: 1) the afferent neural system of the knee with emphasis on the mechanoreceptors, 2) the influence of the afferent neural system of the knee on motor learning, and 3) how CKCFT uses the afferent neural system of the knee and motor learning during knee rehabilitation. This review reinforces the use of CKCFT in knee rehabilitation plans.

J Orthop Sports Phys Ther. 1994;19(1):2-11.

Key Words: articular neurology, motor learning, knee rehabilitation

Fatigue may be related to lower extremity injury. The effect of lower extremity fatigue on ground reaction force production, lower extremity kinematics, and muscle activation during the landing phase of a run and rapid stop was investigated. Subjects were 19 female, Division 1 collegiate basketball and volleyball players (x¯ age = 20.8 ± 1.8 years, x¯ weight = 71.7 ± 6.9 kg, x¯ height = 174 ± 5 cm). Dominant leg ground reaction and muscle activation data were sampled at 2,000 Hz. Lower extremity kinematic data were sampled at 200 Hz, and 3-dimensional analysis was performed. Knee extensor/flexor muscle activation tended to be delayed during fatigue (p=.08). Maximum knee flexion tended to occur earlier during fatigue (p=.09). Step-wise multiple regression suggested that the knee may be the primary site of force attenuation following fatigue. During fatigue, biodynamical compensations in the mechanical properties of the knee extensor musculature, as evidenced by differences in knee kinematics and muscle activation times, may occur to enhance knee stability.

J Orthop Sports Phys Ther. 1994;20(3):132-137.

Key Words: run and rapid stop, muscle action, biodynamics