Measurement of segmental lumbar spine flexion and extension using ultrasound imaging.

STUDY DESIGN: Clinical measurement, technical note. OBJECTIVES: To describe a technique to measure interspinous process distance using ultrasound (US) imaging, to assess the reliability of the technique, and to compare the US imaging measurements to magnetic resonance imaging (MRI) measurements in 3 different positions of the lumbar spine. BACKGROUND: Segmental spinal motion has been assessed using various imaging techniques, as well as surgically inserted pins. However, some imaging techniques are costly (MRI) and some require ionizing radiation (radiographs and fluoroscopy), and surgical procedures have limited use because of the invasive nature of the technique. Therefore, it is important to have an easily accessible and inexpensive technique for measuring lumbar segmental motion to more fully understand spine motion in vivo, to evaluate the changes that occur with various interventions, and to be able to accurately relate the changes in symptoms to changes in motion of individual vertebral segments. METHODS: Six asymptomatic subjects participated. The distance between spinous processes at each lumbar segment (L1-2, L2-3, L3-4, L4-5) was measured digitally using MRI and US imaging. The interspinous distance was measured with subjects supine and the lumbar spine in 3 different positions (resting, lumbar flexion, and lumbar extension) for both MRI and US imaging. The differences in distance from neutral to extension, neutral to flexion, and extension to flexion were calculated. RESULTS: The measurement methods had excellent reliability for US imaging (intraclass correlation coefficient [ICC3,3] = 0.94; 95% confidence interval: 0.85, 0.97) and MRI (ICC3,3 = 0.98; 95% confidence interval: 0.95, 0.99). The distance measured was similar between US imaging and MRI (P>.05), except at L3-4 flexion-extension (P = .003). On average, the MRI measurements were 1.3 mm greater than the US imaging measurements. CONCLUSION: This study describes a new method for the measurement of lumbar spine segmental flexion and extension motion using US imaging. The US method may offer an alternative to other imaging techniques to monitor clinical outcomes because of its ease of use and the consistency of measurements compared to MRI.

Delayed-onset muscle soreness induced by low-load blood flow-restricted exercise.

We performed two experiments to describe the magnitude of delayed-onset muscle soreness (DOMS) associated with blood flow restriction (BFR) exercise and to determine the contribution of the concentric (CON) versus eccentric (ECC) actions of BFR exercise on DOMS. In experiment 1, nine subjects performed three sets of unilateral knee extension BFR exercise at 35% of maximal voluntary contraction (MVC) to failure with a thigh cuff inflated 30% above brachial systolic pressure. Subjects repeated the protocol with the contralateral limb without flow restriction. Resting soreness (0-10 scale) and algometry (pain-pressure threshold; PPT) were assessed before and 24, 48 and 96 h post-exercise. Additionally, MVC and vastus lateralis cross-sectional area (CSA) were measured as indices of exercise-induced muscle damage. At 24-h post-exercise, BFR exercise resulted in more soreness than exercise without BFR (2.8 +/- 0.3 vs 1.7 +/- 0.5) and greater reductions in PPT (15.2 +/- 1.7 vs. 20 +/- 2.3 N) and MVC (14.1 +/- 2.5% decrease vs. 1.5 +/- 4.5% decrease) (p

Vastus lateralis fascicle length changes during stair ascent and descent.

STUDY DESIGN: Experimental descriptive laboratory study. OBJECTIVES: To describe the change in fascicle length of the human vastus lateralis (VL) muscle during the stance phase of stair ascent and descent. BACKGROUND: Muscle fascicle length changes during lower limb functional activities, such as walking and jumping, do not always coincide with joint angle changes. METHODS AND MEASURES: Thirty-three healthy, college-age women walked up and down 4 standard steps. VL fascicle length and pennation angle were measured using real-time ultrasonography. Knee angle was monitored using an electrical goniometer. Foot switches indicated foot contact and release. VL muscle activity was monitored using surface electrodes. The VL muscle-tendon complex and tendon length were calculated based on published models. RESULTS: During initial weight acceptance in stair ascent, the knee joint extended only 3 degrees , VL muscle activity increased to a maximum, VL fascicles shortened, and the tendon lengthened. As the knee extended to ascend the step, the fascicles and tendon shortened throughout the movement. During weight acceptance in stair descent, VL muscle activity increased, VL fascicle length did not change significantly, but the tendon lengthened as 10 degrees of knee flexion occurred. As the knee flexed to complete descent, VL muscle activity peaked, and VL fascicles and tendon lengthened. CONCLUSION: VL fascicles shorten and lengthen as expected during the respective knee extension and knee flexion phases of stair ascent and descent. However, during initial weight acceptance in both stair ascent and descent, the fascicle length change did not coincide with the knee joint kinematics.

Comparison of early phase adaptations for traditional strength and endurance, and low velocity resistance training programs in college-aged women.

The purpose of this study was to investigate the effects of a six-week (16-17 training sessions) low velocity resistance training program (LV) on various performance measures as compared to a traditional strength (TS) and a traditional muscular endurance (TE) resistance training program. Thirty-four healthy adult females (21.1 +/- 2.7 y) were randomly divided into 4 groups: control (C), TS, TE, and LV. Workouts consisted of 3 exercises: leg press (LP), back squat (SQ), and knee extension (KE). Each subject was pre- and posttested for 1 repetition maximum (1RM), muscular endurance, maximal oxygen consumption (VO2max), muscular power, and body composition. After the pretesting, TS, TE, and LV groups attended a minimum of 16 out of 17 training sessions in which the LP, SQ, and KE were performed to fatigue for each of 3 sets. For each training session, TS trained at 6-10 RM and TE trained at 20-30 RM both with 1-2 second concentric/1-2 second eccentric; and LV trained at 6-10 RM, with 10 second concentric/4 s eccentric. Statistical significance was determined at an alpha level of 0.05. LV increased relative LP and KE 1 RM, but the percent increase was smaller than TS, and not different from C in the SQ. For muscular endurance, LV improved similarly to TE for LP and less than TS and TE for KE. Body composition improved for all groups including C (significant main effect). In conclusion, muscular strength improved with LV training however, TS showed a larger improvement. Muscular endurance improved with LV training, but not above what TE or TS demonstrated. For all other variables, there were no significant improvements for LV beyond what C demonstrated.

Fascicle length change of the human tibialis anterior and vastus lateralis during walking.

STUDY DESIGN: A single-group descriptive experimental design. OBJECTIVES: To determine the fascicle length change in the tibialis anterior (TA) and the vastus lateralis (VL) muscles during walking. BACKGROUND: The length of the muscle fibers during isometric actions and during dynamic functional activities is affected by the compliance of the tendon and aponeurosis. The TA and VL muscles have important functions both in stance and swing phases of gait. Therefore, it is important to understand the dynamics of the muscle length change as it relates to the type of muscle actions in walking. METHODS AND MEASURES: Nine healthy subjects performed treadmill walking while fascicle length, muscle activity (electromyographic signal), and joint angle (knee and ankle) were recorded. Fascicle length was measured using real-time ultrasound imaging. Fascicle length and joint angle during the gait cycle were analyzed using a repeated-measures analysis of variance. RESULTS: During the initial portion of stance, when the TA and VL muscles were active, the ankle plantar flexed and the knee joint flexed, suggesting muscle-tendon complex lengthening, but the fascicle length of both muscles remained constant (TA, P = .93; VL, P = .22). The TA muscle was again active during the initial portion of swing phase, while the ankle dorsiflexed, and the fascicle length decreased (P < .05). The VL muscle became active again at the end of swing as the knee extended, and the fascicle length decreased (P < .05). CONCLUSIONS: The lack of change in fascicle length during the initial portions of stance phase suggests a nearly isometric muscle action of the TA and VL. There is a possible interaction occurring between the fascicle and tendon in the TA and VL such that the tendon lengthens to allow joint motion and potentially to store elastic energy.

The relationship between elbow flexor volume and angular stiffness at the elbow.

OBJECTIVE: The purpose of this experiment was to determine if a correlation exists between the volume of the elbow flexors and angular stiffness at the elbow, and to determine the contribution of the biceps brachii and the brachialis muscles to angular stiffness. DESIGN: This study is a descriptive, correlational study and presents a graphical model of the passive properties of muscle. BACKGROUND: The correlation between arm volume and angular stiffness has been shown, but the measurement of arm volume was not specific to the structures being strained. Pre-positioning a bi-articular muscle by stretching over one joint decreases the range of motion at the other joint and may affect the stiffness. METHODS: Angular stiffness at the elbow of 14 female and 15 male volunteers was measured, and the volume of the elbow flexors was calculated from compounded ultrasound imaging. Initial biceps length was set by pre-positioning the shoulder in two different positions. RESULTS: A significant linear relationship was observed between the slope of phase 1 of the stiffness curve and volume of the elbow flexors in both horizontal flexion (r = 0.92) and horizontal extension (r = 0.79) of the shoulder. Phase 2 of the stiffness curve showed no linear relationship to muscle volume in either shoulder position (flexion, r = 0.22; extension r = 0.33). The slopes of phases 1 and 2 were significantly greater with the shoulder in horizontal extension than in horizontal flexion. CONCLUSION: The volume of the elbow flexor muscles is a good predictor of angular stiffness in phase 1 of the curve. A model of the additive contribution of the biceps and brachialis muscles is presented to account for the increased stiffness in the shoulder extended position. RELEVANCE: Recognition of the correlation between muscle volume and stiffness, coupled with understanding that pre-positioning a bi-articular muscle may affect muscle stiffness may aid the clinician in accurately assessing muscle stiffness in patients with connective tissue disorders, neurological dysfunction and contractures.